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FONDAZIONE «ALESSANDRO VOLTA» ANNESSA ALL'ACCADEMIA NAZIONALE DEI LINCEI
XIV INTERNATIONAL CONFERENCE
ENERGY CRISIS, WATER SHORTAGE AND CLIMATE CHANGES IN THE MEDITERRANEAN AREA: THE INVOLVEMENT OF CHEMISTRY
CASTIGLIONE DELLA PESCAIA (GROSSETO) 2 – 6 MAY 2008
PROGRAMME
THE CONFERENCE
Problems connected to the energy crisis, climate changes and water shortage were dramatically increasing in the last decade and represent today a major obstacle to the socio-economical development of a large number of countries. These problems are particularly important in the Mediterranean area, owing to its high natural climatic variability, to its peculiar geographical situation and to its millenary history of fragmentation.
For these reasons the Accademia Nazionale dei Lincei has decided to organise a meeting in which highly qualified experts from all countries of the Mediterranean region are invited to present their opinions and suggestions and to analyse the future actions to ensure a sustainable future to the Mediterranean area.
INTERNATIONAL ORGANIZING COMMITTEE
Salvatore CALIFANO (Italy), Sergio CARRÀ (Italy), Luisa CIFARELLI (Italy), Christos FLYTZANIS (France), Venice K. GOUDA (Egypt), Joshua JORTNER (Israel), Emilio PICASSO (Italy), Ugo ROMANO (Italy), Luis VÁZQUEZ (Spain).
INTERNATIONAL ADVISORY COMMITTEE
Sultan T. ABU-ORABI (Jordan), Vincenzo BALZANI (Italy), Aaron CIECHANOVER (Israel), Mostafa A. EL-SAYED (USA/Egypt), Giovanni GIACOMETTI (Italy), Dweik HASAN SALAH (Palestinian Authority), Bassam HAYEK (Jordan), Jean Marie LEHN (France), Lamberto MAFFEI (Italy), Costas PAPANICOLAS (Cyprus), Gregoris STEPHANOPOULOS (Greece), Francisco VALERO (Spain), Ahmed ZEWAIL (Egypt). Conference Secretariat: Dr. Nathalie Santini
Accademia Nazionale dei Lincei Via della Lungara 10 00165 Rome, Italy E-mail: [email protected]
Sponsored by
ENTE CASSA DI RISPARMIO
DI FIRENZE
FONDAZIONE «GUIDO DONEGANI»
F R I D A Y M A Y 2nd Afternoon session: Climate changes I 16.00 Welcome addresses 16.20 Costas PAPANICOLAS: Climate Change, Energy and Water Crisis:
Manifestations of the physical basis of globalization 17.10 Sylvie JOUSSAUME: Past and future climate changes with a focus on the
Mediterranean Region Chair: Venice K. Gouda 18.00 Coffee Break 18.20 José Luis SANCHEZ GOMEZ: Storm activity and precipitation from different
points of view: microphysics, radar meteorology, mesoscale modeling, hail climatology and trends
19.10 Franco PRODI: Climate changes: natural and anthropic causes Chair: Manuel R. Llamas 20.00 - 22.00 Dinner
S A T U R D A Y M A Y 3rd
Morning session: Climate changes II
09.00 Hervé LE TREUT: The mechanism of climate science in response to greenhouse
increase and the associated uncertainties 09.50 HRH Princess Sumaya BINT EL HASSAN: El Hassan Science City; making a
change to adapt for climate change 10.30 Euripides STEPHANOU: Eastern Mediterranean: a crossroad of toxic pollutants Chair: Sylvie Joussaume 11.20 Coffee Break 11.40 Giorgio FIOCCO: Brief survey of modern instruments for the study of the
atmosphere 12.20 Tatiana DI IORIO: Transport of desert dust in the Mediterranean basin 12.40 Alcide G. DI SARRA: Radiative effects of desert dust Chair: Hervé Le Treut 13.00 Lunch Afternoon Session: Climate changes III - Water shortage I 15.00 Jos LELIEVELD: Air quality and climate change in the Mediterranean basin 15.50 Gideon DAGAN: Modelling of Water flow and pollutant transport by groundwater Chair: Costas Papanicolas 16.40 - 17.00 Coffee Break 17.00 Andrea RINALDO: River networks and ecological corridors 17.50 Guido VISCONTI: Hydrological and meteorological changes related to the land uses
variations in the Mediterranean Region Chair: Franco Prodi 18.30 ROUND TABLE - CLIMATE: Joshua Jortner, Sylvie Joussaume, Franco Prodi,
Costas Papanicolas, Jos Lelieveld, Dweik Hasan Salah 20.00 Banquet
S U N D A Y M A Y 4th Morning session Water shortage II 09.00 Venice K. GOUDA: The role of chemistry in mitigating water shortage threats
09.50 Manuel R. LLAMAS: The role of the advances of Science and Technology to solve the water problems
10.40 Dweik HASAN SALAH: The water crises in Palestine. Health and environmental impact
Chair: Christos Flytzanis 11.10 Coffee Break 11.30 Marcello BENEDINI: Availability of the water resources in the Mediterranean
countries 12.20 Mohamed SABRY ABDEL-MOTTALEB: Field solar photocatalytic
decontamination and disinfection of drinking water using low cost compound parabolic collector and paper supported nanostructured TiO2.
Chair: Gideon Dagan 13.00 Lunch Afternoon session: Water shortage III - Energy I 15.00 Manuel R. LLAMAS: The groundwater development silent revolution in the EU
Southern Member States 15.50 Gregoris STEPHANOPOULOS: Combining the chemistry of life with the
chemistry of man to generate new sources of liquid transportation fuels Chair: Marcello Benedini 16.40 Coffee Break 17.00 Costas VAYENAS: Climate changes, fuel cells and our energy future 17.40 Omar FASSI-FEHRI: The question of the energy in Morocco 18.20 Felix TELLEZ: Status and perspectives of concentrating Solar Power (CSP)
technology and market development Chair: Ugo Romano 20.00 Dinner 21.30 ROUND TABLE - WATER: Christos Flytzanis, Marcello Benedini, Venice K.
Gouda, Manuel R. Llamas, Gideon Dagan.
M O N D A Y M A Y 5th Morning session: Energy II 09.00 Jean-Luc DUPLAN: Fuels from biomass: Prospects and R&D Challenges 09.50 Sergio CARRA’: The role of chemistry in the incoming energy scenario 10.40 Maria FLYTZANI-STEPHANOPOULOS: Nanocatalysis for Clean Energy and
Sustainability Chair: Joshua Jortner
11.30 Coffee Break 11.50 Francesca FERRAZZA: Photovoltaic technology: current status and future
perspectives 12.20 Vincenzo BALZANI: The Future of Energy Supply: Challenges and Opportunities Chair: Sergio Carrà 13.00 Lunch Afternoon Session: Energy III 15.00 Ugo ROMANO: Future Trends in the Oil & Gas Industry: New Production and
Upgrading Technologies 15.50 Iakovos VASALOS: The role of catalysis for a sustainable environment 16.40 Presented papers Chair: Maria Flytzani-Stephanopoulos 17.30 Coffee Break 17.50 Sultan T. ABU-ORABI: The necessity for Nuclear power to Jordan 18.30 Giorgio Mario GIACOMETTI: Bio-production of hydrogen by photosynthetic water
splitting Chairman: Jean-Luc Duplan 19.30 Dinner 21.30 ROUND TABLE – ENERGY & ECOLGY: U. Romano, S. Carrà, G.
Stephanopoulos, J.L. Duplan, O. Fassi-Fehri, Hervé le Treut, Euripides Stephanou
TUESDAY MAY 6th Morning session: Conclusions 09.00 ROUND TABLE – INTERNATIONAL SCIENCE TECHNOLOGY
COLLABORATIONS IN THE MEDITERRANEAN AREA: Joshua Jortner, Venice K. Gouda, HRH Princess Sumaya Bint El-Hassan, Christos Flyzanis, Manuel R. Llamas, Salvatore Califano
11.00 Conclusions and Farewell greetings 13.00 - 15.00 Lunch
TiO2 – Based Nanomaterials for Applications in Environmental Photochemistry and Dye-Sensitized Solar Cells Fabrication
M. S. A. Abdel-Mottaleb
Nano-Photochemistry and Solarchemistry Lab, Department of Chemistry, Faculty of Science, Ain
Shams University, 11566 Abbassia, Cairo, Egypt
[email protected] www.photoenergy.org
Abstract
The review reports shortly on our recent applied research results in the field of environmental photochemistry and solarchemistry as well as chemical solar cells. The paper will focus on the production of nanostructured TiO2 and lanthanide doped TiO2 – based nanomaterials for different applications in the fields of clean energy (sunlight conversion by DSSC) and water treatment (photocatalytic degradation of water contaminants). Collaborative international projects of the Nano-Photochemistry and Solarchemistry Group at Ain Shams University result in interesting outcomes that could be profitably exploited. Keywords: Photocatalysis, Solar Cells, Water Treatment, Supported TiO2 and doped-TiO2 nanomaterials, Textile dyes, Clean energy. Bibliographical Notes: Professor M.S.A. Abdel-Mottaleb is the founder and PI of Nano-Photochemistry and Solarchemistry Labs at the Department of Chemistry, Faculty of Science, Ain Shams University, Cairo. His research interest is production of nanomaterials for application in the fields of clean energy and water treatment. 1 Introduction
Global largest challenges in the current century are a secure long-term energy supply and clean water. Water and energy are the key factors to global human development. In addition to the slowly diminishing availability and scarcity, and concerted price rise of fossil fuels other factors such as efficiency of use, environmental and climate concerns, as well as the risk for social and political unrest play increasingly important roles and appeal for committed and forceful efforts to replace the present energy system by a sustainable one. Securing fresh water is also a very urgent and important issue for sustainable development. However, we are still away from reaching truly sustainable energy/water systems. Intensive international efforts to a truly sustainable energy/water system have been progressively carried out.
This article deals with an overview of our research efforts that may point out the role played by some critical nanomaterials, which may contribute to the development of a more efficient and sustainable energy/water systems. The prime objective is to give examples from our own research results reflecting the potential of nanomaterials for the current and future energy and environmental systems.
Heterogeneous photocatalysis is considered one of the new ‘‘Advanced Oxidation
Technologies’’ (AOT) for air and water purification treatment. Titanium dioxide (TiO2) photocatalysis
is a possible alternative or complementary technology to current drinking water treatment/disinfection
processes. TiO2 photocatalysis does not require the addition of consumable chemicals and does not
produce hazardous waste products. When TiO2 particles are illuminated with near UV irradiation
(<400nm), electron hole pairs are generated within the metal oxide semiconductor. The valence band
hole has a very positive reduction potential and is capable of oxidizing water, or hydroxide anions, to
form hydroxyl radicals (.OH) in water. The (.OH) radical is highly toxic towards microorganisms and
very reactive in the oxidation of organic substances. Photocatalytic inactivation of bacteria such as
Escherichia coli, Bacillus pumilus and several others, as well as several Phages is also well known. The
use of TiO2 in suspension is efficient due to the large surface area of catalyst available for the reaction.
Nevertheless, the catalyst must be removed following the treatment. Post-treatment removal requires a
solid liquid separation stage, which adds to the overall capital and running costs of the plant.
Alternatively, the catalyst may be immobilized onto a suitable solid support which would eliminate the
need of post-treatment removal, but which would also create a decrease in the surface area available for
photocatalytic reaction. Titania (TiO2) is a well-known photocatalyst for decomposing a wide range of
substances and mong three crystalline phases of TiO2; nanosized anatase TiO2 possesses enhanced
photocatalytic activity and solar energy conversion capability [1-6].
Moreover, singlet oxygen has been appeared recently, to have good potential for inactivation
of bacteria. Among singlet oxygen photosensitizers (Sens), ruthenium(II) complexes with
polyazaheterocyclic ligands are bound to occupy a prominent place. These coordination compounds
display a number of advantages compared to other reference 1O2 sensitizers such as rose Bengal,
phenalenone or methylene blue. Ru(II) coordination compounds show strong absorption in the visible,
quantitative intersystem crossing quantum yield from the singlet excited state (S1) to the triplet excited
state (T1), a long excited state lifetime (s) allowing efficient quenching (close to the diffusion control
limit) by molecular oxygen, good thermal and (photo)chemical stabilities, high 1O2 production
quantum yields (UD = 1 in methanol for some of them) and they can be immobilized on different
polymer supports by a judicious selection of the substituents in the coordinated ligands [7-9]
We will report here on testing photoactivities of two different catalysts: TiO2 (Millennium
PC500) supported on a non-woven paper of synthetic fiber prepared by Ahlstrom firm (France) and
Ru(II) photosensitizer immobilized on polymer strips, in both decontamination and disinfection
experiments. Gallic acid, one of the most frequent phenolic compounds in wastewater, was chosen as
the model pollutant for detoxification experiments. E. coli, a classical bacterial indicator of fecal
pollution, was chosen as the model microorganism for disinfection experiments. The set of the results
and its potential application for water disinfection are studied within the framework of the AQUACAT
(EU-DGXII, contract: ICA3-CT2002-10016) INCO project [3].
The study has been extended to the application of novel copolymer-TiO2 membranes for some
Textile dyes adsorptive removal from aqueous solution and photocatalytic decolrization. The studies
were concerned with testing the photoactivities of easily removable TiO2 photocatalyst supported over
low-density polyethylene-grafted-Poly (4-vinylpyridine-co-acrylamide) (LDPE-g-(4-VP/AAm))
copolymers of several composites, in the decontamination of Remazol Red RB-133 (RR RB 133) and
reactive blue 2 (RB2) textile azo dyes.
It is well known that, one disadvantage of TiO2 is the high band gap energy (3.2 eV), which
limits its wide application in visible range of the sunlight. Therefore, UV illumination is necessary to
photoactivate this semiconductor. Another disadvantage of TiO2 is that charge carrier recombination (e-
/h+) occurs within nanoseconds, as a consequence, its photocatalytic activity is limited. Recent studies
demonstrated that doping TiO2 with metal ions of d or f electronic configuration could slow down or
reduce the (e-/h+) recombination significantly. Furthermore, doping extends the wavelength response of
TiO2 into the visible region and inhibits anatase-rutile phase transformation. Moreover, such doping
would provide complexation centers on the TiO2 surface, thus enhancing its photoactivity.
Doped TiO2 nanoparticles prepared by the Sol-Gel technique posses many desirable properties
such as high homogeneity, high surface area. In addition this technique has the advantage of low
temperature treatment and low cost. Here we will also report on the properties of this new class of
nanomaterials produced in our labs in view of their possible application in light-emitting devices and
photocatalysis [1].
Dye-sensitized solar cell or the so-called Graetzel type solar cell (DSSC) receives strong
interest due to their low fabrication cost, lightweight, and flexible structure. Recently, it has been
exploited profitably in electronic devices and photoelectrochromic windows.
We will give an overview on the sensitization of semiconductor nanoparticles TiO2 by organic
dyes such as xanthenes (rhodamine 101, fluorescein and 5(6)-carboxyfluorescein) and azo dyes
(alizarin yellow R, alizarin yellow 2G and carboxyarsenazo), towards visible light. Photostability of
these dyes has been determined for possible use as sensitizers for the nanocrystalline solar cell. The
role played by redox couple (e.g. I3-/I-) electrolyte in regenerating the neutral sensitizer dye molecules,
and thus, stabilizes the dye molecule has been emphasized. The chosen dyes possessing carboxylate or
hydroxyl function groups that enable direct interaction with the surface of TiO2 nanoparticles, thereby
providing the path for electron transfer from the excited dye adsorbate to the semiconductor [5]. A note
will be mentioned on the current research project related to Chemical Solar Cell (CSC) using recently
produced TiO2 nanotubes in collaboration with VCU in the framework of US-Egypt funds [6].
2 Experimental
All experimental details, methods and materials have been reported elsewhere [1 – 6]. 3 Results & Discussion 3.1. Wastewater Treatment using Autonomous Solar Reactor [3,4]
The photocatalytic processes under sunlight using nanosized TiO2 supported on Ahlstorm
non-woven fibrous paper have been efficiently applied for the degradation of phenolic compounds such
as Gallic acid. Moreover, the photodegradation rate of GA slightly increases when using TiO2
supported photocatalyst in combination with Ru-complexes, as a singlet oxygen photosensitizer, in a
CPC photoreactor.
Fig. 1. Pilot autonomous Photoreactor module at Ain shams University Campus, Egypt. Compound parabolic concentrator (CPC) Photoreactor manufactured by partners of AQUACAT project and supplied by AoSol company (CPC geometry with coaxial-type photocatalyst configuration). It has been mounted on a platform tilted 37o N (local latitude). It is consists of four borosilicate glass tubes 1500 × 50 mm (46 mm i.d.) that connected in series (two U-shapeed), so water would flow from the highest and the lowest and then to a tank. The immobilized catalysts are hold on polypropylene piece (1500 mm x 41 mm x 6 mm) placed in the axis of each glass tube perpendicularly to the collector inclination. A 12W DC Centrifugal pump (NH-10PX-H, Pan World, Japan) is used to circulate water. The overall surface collector area of the solar CPC is 1 m2. The Photoreactor was placed in an open area near Faculty of Science in Ain Shams University Campus. For further details, see the URL of the ‘‘Aquacat’’ project http:// aquacat.univ-lyon1.fr/index.htm.
0 20 40 60 80 100 120 140
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
kRu
= 0.018 min-1± 3.99E-4
kRu/TiO
2
= 0.02 min-1± 0.001
kTiO
2
= 0.017 min-1± 1.90E-4
ln (
A/Ao
)
Time (min)
Supported TiO2 photocatalyst
Immoblized Ru(II) photosensitizer Combination between TiO
2& Ru(II)
Fig.2 Photodegradation rate kinetics of 30mg/l GA using; (■) the supported TiO2 (PC 500); (∗) immobilized RDP2+ photosensitizer, (▲) combination between the supported TiO2 photocatalyst and RDP2+ photosensitizer in series.
On the other hand, the effectiveness of the supported TiO2 (PC500) on non-woven paper is
higher than that of Ru(II)-complex, Figure 2.
(a) 0 Time of exposure to sunlight 60 minutes
(b)
0 10 20 30 40 50 60
0
1
2
3
4
5 exp.1 control exp2
Time (min)
C (
CF
U/m
l) x
10
6
Data: Data3_exp2Model: Exp2PMod1 Equation: y = a*exp(b*x) Weighting:y No weighting Chi 2/DoF = 0.20401R^2 = 0.94864 a 4.75694 ±0.42767b -0.04995 ±0.00976
Fig.3 (a) Bacteria disinfection rates with the supported TiO2 and (b) The results two independent disinfection experiments performed under the same experimental conditions. Two control measurements have been performed at time zero and after 60 minutes of light exposure.
No advantages regarding bacteria inactivation are noticed in case of combining titania
photocatalyst with Ru(II)-complex Figures 3 and 4. The results show that the use of UV sunlight to
disinfect contaminated water in a full-scale continuous flow solar reactor is promising and could be
exploited as an appropriate technology for water treatment in arid and semi-arid remote areas.
0 10 20 30 40 50 60
0
20
40
60
80
100
Time (min)
%S
urv
iva
l
k= 0.01 min -1
k= 0.05 min-1
k= 0.025 min -1
TiO2
Ru(II) TiO
2/Ru(II)
Fig.4 Bacterial disinfection rates with the use of (■) TiO2 (PC500) on non-woven paper, (●) immobilized Ru(II)-complex and (▲)combination between the TiO2 photocatalyst and Ru(II) photosensitizer.
3.2 Adsorptive removal of Textile dyes [2]
Immersion of the of LDPE-g-(4-VP/AAm) copolymer membranes (of different composites
and of ≈ 16 cm2 surface area) in 100 ml of 5 X 10-5M RR RB 133 or RB 2 at pH < 11.5 resulted in
complete adsorption of RR RB 133 and RB 2 dyes over the different composites of LDPE-g-(4-
VP/AAm) copolymers (Figure 5).
+
+
+
+
Fig. 5 Adsorptive removal of RR RB133 red dye and RB2 blue dye by thin film of copolymer supported TiO2 catalyst
The photocatalytic activity of TiO2 immobilized on the different composites of the studied
copolymers has been tested by following up the decolorization rate of thin transparent copolymer films
of 5×10-4 M of impregnated RR RB 133 and RB 2. The degradation reactions follow a first order
kinetics.
The results clearly demonstrate the practical advantages of direct and ease of removal of the
pollutant dyes from the environment by adsorption on the catalyst, makes it a viable technique for the
safe disposal of textile wastewater into the water streams.
3.3 Photocatalytic Activity of Doped-TiO2 [1] Mesoporous Ln(III)–TiO2 (Ln = Tb, Eu, Sm) nanomaterials composites have been
successfully synthesized in our laboratory by using sol-gel technique.
XRD pattern, FT-IR, Raman spectra, and SEM were used to characterize the Ln(III)-TiO2
nanomaterials. The prepared lanthanide doped TiO2 nanomaterials have anatase phase and exhibit Ti-
O-Ln bond. The absorption spectra of all prepared samples reflect the increasing photoresponse of
doped samples to visible light over pure TiO2 (Figure 6). Surface area is remarkably increased from
about 18 m2.g-1 to around 89 m2.g-1 due to lanthanide ion doping.
300 400 500 6000.0
0.2
0.4
0.6
Red Shift
4
3
2
1
Sample !max
(nm)
1. Pure TiO2 332
2. Tb(III) - TiO2 341
3. Eu(III) - TiO2 333
4. Sm(III) - TiO2 341
A
Wavelength (nm)
Fig. 6: The absorption spectra of pure TiO2 and 0.7% Ln(III)–TiO2 nanocrystals calcined at
500oC for 3 h in air.
Two newly prepared Ln(III)–TiO2 (Ln = Eu , Sm) luminescent nanomaterials exhibit
enhanced pure red or orange light emission due to energy transfer from host TiO2 to guest Eu(III) or
Sm(III), respectively (Figure 7.).
(a)570 600 630 660 690 720
0
100
200
300
400
360 nm
370 nm
375 nm380 nm
390 nm
Wavelength (nm)
Em
issio
n inte
nsity (
a.u
.)
400 nm
Exc
itatio
n wav
elen
gth (nm
)
(b)375380390400
Excitation wavelength (nm)
Em
issio
n w
avele
ngth
(nm
)
700
650
616
593
580
10.00
50.00
100.0
150.0
200.0
300.0
400.0
450.0
500.0
Fig. 7: a) The emission spectra of Eu(III)– TiO2 phosphor, b) Contour view of the emission spectra at different excitation wavelengths
In addition, the commercially available textile dye Remazol Red RB-133 degradation
was used as a probe reaction to determine the efficiency of the Ln(III)-TiO2 photocatalysts. The
Ln(III) doping brought about remarkable improvement in the photoactivity over pure TiO2 (Table 1.)
3.4 Dye Sensitized Solar Cells (DSSC) [5, 6]
Stable surface complexes were observed due to the interaction of sensitizing dyes [xanthenes
(rhodamine 101, fluorescein and 5(6)-carboxyfluorescein) and selected azo dyes (alizarin yellow R,
alizarin yellow 2G and carboxyarsenazo) with TiO2. We have carried out a series of experiments to
evaluate the performance of these dyes as electron injectors by light absorption.
Interestingly, the presence of KI/I2 electrolyte results in a dramatic increase in the
photostability of dye-TiO2 complex molecules as has been seen from the examination of the absorption
spectrum of the complexes for over hours of light illumination. This could be attributed to the fast
regeneration of the oxidized dye in the presence of the electrolyte according to the following
mechanism:
(Dye-TiO2 )+ hν→ (Dye*-TiO2 )
(Dye*-TiO2) → (Dye+ -TiO2)+ ejected e-
(Dye+ -TiO2)+ 3/2 I- → (Dye-TiO2 )+ 1/2 I3-
The photocurrent action spectrum of the surface-modified TiO2 film with carboxyfluorescein
(CFL) closely matches the absorption spectrum of the sensitizer as shown in Figure 8. Photocurrent
action spectrum showed the origin of photoelectric output to be optical absorption of the CFL dye.
Similar results were obtained for other dyes.
Table 1: The photocatalytic decolorization/mineralization percentage of Remazol Red RB-133 with different Ln(III) doped-TiO2 catalyst after one hour exposure to UV-Vis irradiation
Catalyst Decolorization% Mineralization %
Pure TiO2 13.9 00.0 0.7% Tb-TiO2 74.0 35.0 0.7% Eu-TiO2 92.0 62.5 0.7%Sm-TiO2 72.0 13.4
350 400 450 500 550
0
1
2
3
absorption photocurrent
norm
aliz
ed A
bsorb
ance
norm
aliz
ed p
hoto
curr
ent
Wavelength (nm)
Fig. 8. Photocurrent action spectrum of CFL photoelectrochemical cells (broken line), and absorption spectrum of CFL-TiO2 surface complex aqueous solution
It is thus obvious that, when the TiO2 electrode is illuminated with visible light, the sensitizer
antenna molecules absorb light and inject electrons into the TiO2 nanoparticles. These electrons are
then collected at the conducting glass surface to generate anodic photocurrent. The redox couple (e.g.
I3-/I-) present as electrolyte in the DSC quickly regenerates the neutral sensitizer dye molecules and
photocurrent flows continuously as long as the cell is illuminated.
Current-Voltage characteristics [the I-V curves] for the cells have been plotted (see Figure 10
for CFL as an example). The electrical output values are remarkable, considering the simple
preparation procedure for this cell. CFL dye sensitized cell is the only promising system between other
DSC’s tested in that study. The overall energy conversion efficiency of CFL dye sensitized cell is
found to be 4.8% at 45 mW/cm2. Lower photoconversion efficiencies were obtained in case of other
dyes. It is noteworthy to mention that no relationship was found between the photoconversion
efficiency and association constant of dyes studied [5].
Recently, we fabricated bilayer polymer-based solar cell devices using Gd-doped TiO2
nanotubes grown in our labs to enhance charge transport. These devices achieved low efficiency.
However, additional efforts are underway to increase the efficiency using aligned nanotubes [6].
4 Conclusions
The photocatalytic processes under sunlight using nanosized TiO2 supported on Ahlstorm
non-woven fibrous paper have been efficiently applied for the degradation of phenolic compounds such
as Gallic acid. Moreover, the photodegradation rate of GA slightly increases when using TiO2
supported photocatalyst in combination with Ru-complexes, as a singlet oxygen photosensitizer, in a
CPC photoreactor. No advantages regarding bacteria inactivation are noticed in case of combining
titania photocatalyst with Ru(II)-complex. The use of UV sunlight to disinfect contaminated water in a
full-scale continuous flow solar reactor is promising and could be exploited as an appropriate
technology for water treatment in arid and semi-arid remote areas.
The textile dyes tested RR RB 133 and RB 2 showed enhanced affinity to the surface of TiO2
supported LDPE-g-(4-VP/AAm) copolymer. Upon irradiation of transparent solid thin film samples of
RR RB 133 and RB 2 impregnated on the surface of TiO2 supported LDPE-g-(4-VP/AAm) copolymer
of different composites, a photo-assisted degradation reaction occurs. The LDPE-g-(4-VP/AAm)
copolymers supported TiO2 photocatalyst has the practical advantages of easy separation and removal
from the polluted environment. It could be a viable technique for the safe disposal of textile wastewater
into the water streams.
The newly produced Ln(III)-TiO2 nanocrystals (Ln = Tb, Eu, Sm) are of improved properties
over pure TiO2 nanoparticles: are of higher surface area, with extended photoresponse to the visible
light and have been proven to be used as more efficient photocatalysts than pure TiO2 nanoparticles.
Moreover, Eu(III) – TiO2 and Sm(III) – TiO2 solid matrices exhibit high pure red and orange
lanthanide characteristic light emission upon excitation of TiO2 molecules due to energy transfer from
the TiO2 to the corresponding excited state energy levels of the lanthanide ion, respectively.
The interaction of sensitizing dyes [xanthenes (rhodamine 101, fluorescein and 5(6)-
carboxyfluorescein) and selected azo dyes (alizarin yellow R, alizarin yellow 2G and carboxyarsenazo)
with TiO2 results in complex formation at the surface of TiO2 nanoparticles. A series of experiments
have been carried out to evaluate the performance of these dyes as photosensitizers in fabricating
efficient DSSC. It has been found that the overall energy conversion efficiency of CFL dye sensitized
cell is 4.8% at 45 mW/cm2 pointing to the feasibility of being used as a promising photosensitizer in
DSSC.
5 Acknowledgements I would like to thank members of my research group who have been involved in the
work reported here: Dr. Mona Saif, Dr. Hoda Hafez, Dr. Doaa Mekkawi, Dr. Samah El-Bashir, Dr.
Amr Essawy, Dr. Amr El-Hag Ali, Dr. Hosam Shawky and Dr. Magdy H. El-Sayed for their creative
research and efforts. A portion of the work presented is supported by AQUACAT project financed by
EU. Moreover, I acknowledge the US-Egypt Joint Science and Technology Board for their support of a
portion of the work related to polymer solar cells.
6 References
1. Saif, M. and Abdel-Mottaleb M.S.A. (2007) ‘Titanium dioxide nanomaterials doped with
trivalent lanthanide ions of Tb, Eu and Sm: Preparation, characterization and potential applications’
Inorganica Chimica Acta, vol. 360, no. 9, pp. 2863–2874
2. Essawy, Amr A., El-Hag Ali A. , Abdel-Mottaleb M.S.A. , (2008) “Application of Novel
Copolymer-TiO2 Membranes for Some Textile Dyes Adsorptive Removal from Aqueous Solution and
Photocatalytic Decolorization” Journal of Hazardous Materials, Volume 157, Issues 2-3, 15 September
2008, Pages 547-552
3. Hafez, . H.S, Ali El-Hag A., and Abdel-Mottaleb M. S. A. (2005) ‘Photocatalytic efficiency
of titanium dioxide immobilized on PVP/AAc hydrogel membranes: A comparative study for safe
disposal of wastewater of Remazol Red RB-133 textile dye’ International Journal of Photoenergy, vol.
7, no. 4, pp. 181–185
4. Shawky H.A., A. El-Hag Ali A. , El-Sayed M. H. and Abdel-Mottaleb M. S. A. (2006)
‘Treatment of polluted water resources using reactive polymeric hydrogel’ Journal of Applied Polymer
Science, vol. 100, no. 5, pp. 3966–3973
5. EL Mekkawi D. and Abdel-Mottaleb M. S. A. (2005) ‘The interaction and photostability
of some xanthenes and selected azo sensitizing dyes with TiO2 nanoparticles’ International Journal of
Photoenergy, vol. 7, no. 2, pp. 95–101
6. McLeskey, Jr. James T. , Saif Mona M., Hafez, Hoda S., and Abdel-Mottaleb, M.S.A.
(2008) ‘Solar cells from a water-soluble polymer’, International Conference on Nano-/Molecular
Photochemistry, Photocatalysis and Solar Energy Conversion, Cairo, Egypt, 24 – 28 Feb
7- Orellana G. and D. Garcı´a-Fresnadillo, (2004) Environmental and industrial optosensing
with tailored luminescent Ru(II) polypyridyl complexes. In: Narayanaswamy, R., Wolfbeis, O.S.
(Eds.), Optical Sensors: Industrial, Environmental and Diagnostic Applications, Springer Series in
Optical Sensors and Biosensors, vol. 1. Springer, Berlin-Heidelberg 309–357.
8- E. M. Jimenez-Hernandez, F. Manjon, D. Garcia-Fresnadillo and G. Orellana, (2006)
‘Solar water disinfection by singlet oxygen photogenerated with polymer-supported Ru(II) sensitizers’
Solar Energy, 80,1382-1387.
9- M. I. Gutierrez, C. G. Martınez, D. G. Fresnadillo, A. M. Castro, G. Orellana, A. M. Braun,
and E. Oliveros, (2003) ‘Singlet Oxygen (1∑g) Production by Ruthenium(II) Complexes in Micro
heterogeneous Systems’, J. Phys. Chem. A, 107, 3397-3403
The Future of Energy Supply – Challenges and Opportunities
Vincenzo Balzani
Dipartimento di Chimica “G. Ciamician”
Università di Bologna, Via Selmi 2, 40126 Bologna (Italy).
E-mail: [email protected]
I am going to present a general overview on the future of energy supply, based on a
recently published essay [1]. I will try to show that solving the energy issue is indeed a
challenge, but it may also be an unprecedented opportunity to change what is wrong in
our life stile and, hopefully, to shape a more peaceful world.
A prophecy
The Chemistry Department in my university is named in honor of Giacomo Ciamician,
the father of modern photochemistry and the prophet of solar energy conversion. In a
paper published on Science in 1912 [2], Ciamician discussed the problem of energy
supply and concluded that the best, if not the only, solution would have been the
conversion of sunlight into fuels by artificial photosynthesis:
“Up until now the development of civilization has been based on coal, which is fossil
solar energy. It would be much more convenient to use present solar energy, the solar
energy that arrives every day on the earth. … On the arid lands there will spring up
industrial colonies without smoke and without smokestacks; forests of glass tubes will
extend over the plants and glass buildings will rise everywhere; inside of these will take
place the photochemical processes that hitherto have been the guarded secret of the
plants, but that will have been mastered by human industry which will know how to
make them bear even more abundant fruit than nature, for nature is not in a hurry and
mankind is. … and if in a distant future the supply of coal becomes completely
exhausted, civilization will not be checked by that, for life and civilization will continue
1
as long as the sun shines! … If our black and nervous civilization, based on coal, shall
be followed by a quieter civilization based on the utilization of solar energy, that will
not be harmful to the progress and to human happiness”.
The spaceship Earth
An Italian writer, Italo Calvino, said that if you wish to understand something well, you
should look at it from far away. Indeed, any discussion about the energy problem should
start from looking at a picture of our planet taken from the space, so as to realize that
our planet Earth is nothing else than a spaceship [1]. A huge spaceship which travels in
the infinity of the universe. It does not need energy to travel, but needs a lot of energy to
keep alive its 6.7 billions of passengers. The Earth population increases by 80 millions
per year; every minute we have 32 new-born Indians and 24 new-born Chinese.
Everybody needs energy to eat, drink, work, travel, ….
Fossil fuels
Most of the energy used by mankind comes from fossil fuels. Currently the world’s
consumes about 1000 barrels of oil a second [3], which means, as an average, about 2
liters a day per person. In the affluent countries we are living in a fossil fuel bonanza. In
spite of the recent increase in price, oil is still cheaper than some mineral waters.
Energy is important not only because we use it to make things working (e.g. a car, a
washing machine, a TV set), but also because there is energy embedded in any object
around us. Everything is made by using energy. For example, making a computer
requires an amount of energy equivalent to that produced by 240 kg of oil, which means
that a computer has already consumed about 75% of its life cycle energy before being
switched on for the first time.
Large quantities of energy are also embedded in food. For example, to grow a cow an
amount of energy equivalent to six barrels of oil is needed, and about 7 liters of oil
energy is embedded in a kg of veal. Growing greenhouse tomatoes requires about 50
times their energy content. Modern agriculture is in fact an industry that uses land to
convert oil into food.
Using fossil fuels is very easy and convenient but, as everybody knows, several related
problems begin to arise. The first one is that they are a gift of nature that is going to be
2
exhausted. This is well known even in the oil country, Saudi Arabia, where a proverb
says: My grandfather used to ride a camel, I am driving a car, my son drives a jet, his
son will ride a camel. The scientific version of this proverb is the so called-oil peak [4]:
the increasing consumption of oil will lead to a day in which production will not be able
to satisfy the request. From that day on, the price of oil will continue to increase, there
will be economic slumps and even wars to control the remaining reserves. It is difficult
to say when the oil peak will be reached. The two Gulf wars and the exponential growth
of the oil price seem to indicate that the peak has already been reached, and even the
most optimist scientific evaluations predict that it will be reached in a few decades [5].
A great political difficulty in dealing with fossil fuels is that the most important reserves
of oil and gas are concentrated in a few countries of the world.
Pollution and greenhouse effects
An inescapable law of nature is that any time we use a resource to produce something
useful, waste is also produced. Waste is never “innocent”: it is always dangerous,
sometimes in more than one way. This is the case of fossil fuels: their use causes severe
troubles to human health and irreversible changes to the environment [6,7,8]. Use of
fossil fuels produces a variety of pollutants which cause illnesses and reduce life
expectancy. Furthermore, combustion of gas, oil and carbon causes the formation of
carbon dioxide which is responsible for the greenhouse effect. Perhaps we are not fully
aware of that because, while we see that the gasoline contained in the tank of our car is
consumed, we do not see that three times more carbon dioxide are produced.
Disparities in energy consumption
A third problem that we have to face deals with the strong disparities in energy
consumption. As an average, an American consumes 7.8 toe (tons of oil equivalent) per
year. This quantity is approximately the same as that consumed by two Europeans, three
Chinese, fifteen Indians, and thirty Africans [7]. With less than 5% population, USA
consumes 25% of the overall world energy consumption. Such disparities are extremely
serious if we consider the number of people living in the various countries. In USA
(about 300 million people) there are 780 cars for 1000 inhabitants. In China (1300
million people) and India (1100 million people) there are less than 20 cars for 1000
3
inhabitants. Clearly, it will be impossible to find enough oil to bring Chinese and
Indians to the car-per-person level of USA. In fact, we would be terrified to think at the
amount of pollution and carbon dioxide produced if such a large amount of oil would be
available.
These few remarks lead to the conclusion that an urgent global action is needed to solve
the energy problem. Otherwise, we are going into big troubles because of the
occurrence of irreversible physical events (e.g, fossil fuel exhausting, strong climate
changes) and serious social problems (massive migrations, revolutions, wars).
Other resources
What has been said above for fossil fuels is true for any other non renewable resource.
Take, for example, copper. In the United States it has been estimated that approximately
1/3 of the copper contained initially in the mines is now in the waste, 1/3 is in use, and
only the remaining 1/3 remains to be extracted [9]. As another example, let us consider
the catalytic converters: they are based on platinum and rhodium, two precious metals
that are in shortage [10]. In principle, non renewable resources could be, at least in part,
recycled, but this will only be possible if a renewable source of energy is available.
Making use of solar energy, the Earth can regenerate some fundamental resources like
water, trees, fish, air. But here too there are limitation. According to authoritative
studies [11], mankind is currently consuming renewable resources at a rate higher than
that of regenerative biocapacity, which means that we live above our possibilities. A
clear example is given by fishing: when there were only a small number of boats with
small fishing nets there was plenty of fish in the sea. Now, however, there are many
large boats with huge fishing nets and fish ha not enough time to fully reproduce.
The same concept can be expressed by the parameter called ecological footprint, which
indicates the surface of earth needed for supplying the resources consumed and taking
care of the waste generated by a person [11,12]. Based on biocapacity, the average
footprint is 1.8 hectare pro capita, but today the world average is 2.2, showing again that
we are living above our possibilities. Going into more detail, one can see that the
footprint is 9.6 for Americans, 4.5 for Germans, 4.2 for Italians, 1.5 for Chinese, 0.8 for
Indians, and much less for people of several African countries. If all the 6.7 billion
people of the Earth were to live at current American standard, we should look around
4
for other three planets to accommodate them.
An unequal World
The differences in the ecological footprint can be used to introduce another serious
problem of our spaceship: the 6.7 billion of passengers are located in very different
classes. Once a year the newspapers tell us that the three richest men of the planet have
more money than the GDP of the 48 poorest African countries. Even more disturbing is
the fact that while three billion people live with less that 2 $ a day, in the European
Community a farmer receives a subsidy of 2 € day for growing a cow. It looks like it is
better to be a cow in Europe than a person in Africa! Disparities in wealth, of course,
translate into disparities not only in food, but also in education, medical care, etc. For
example, in Italy there is a medical doctor every 200 people, to be compared with a
doctor every 50.000 people in Eritrea. With such disparities it should not be surprising
to see that every day hundreds of people try to come from the coast of North Africa to
Italy by any means, often losing their lives during the trip. As a matter of fact, if the
disparity does not decrease, many more people will come and we will not be able to
cope with this invasion. Even if we leave aside ethical problems, it is indeed our interest
that people living far from us can reach a satisfactory level of wellbeing. A sustainable
world will not be possible if we do not take care of the ecological and social constraints
[13].
Solutions for the energy crisis
Going back to energy, we need to find a way to solve, or at least to control, the
upcoming crisis.
The first step is saving energy in any circumstance of our life. There is no need to
explain how, because everybody is aware of the huge amount of wasted energy. To
learn saving energy is one of the most important messages we should pass on the young
generations. Most people believe that the quality of life is increasing with increasing
availability of energy. This is true for developing countries, in which energy
consumption is very low, but not in the affluent countries where, above a definite
threshold, increase in energy consumption is accompanied by inefficiency: traffic jams,
waste of time, medical expenses.
5
Another important step to face the energy crisis is to increase energy efficiency. This is
again a huge field which includes thermal isolation of houses, novel industrial
processes, preferential use of public transportation, energy saving appliances, new
lighting devices, etc.
Of course, energy conservation and better efficiency will not be sufficient to face the
energy crisis. If we have to leave fossil fuels, we need other energy sources. There are
only two abundant energy resources in our future: nuclear energy and renewable
energies (mostly, solar energy).
Nuclear energy
Nuclear energy can be obtained by fission or fusion. While fission is largely used,
fusion is still at the level of experiments (except for bombs). Nuclear fission has several
problems [14] related to: safety and security of the reactors, safe disposal of radioactive
waste, proliferation of nuclear weapons, limited amount of nuclear fuel (uranium), high
cost and long time for plant construction e decommissioning. Furthermore, its
development would lead to colonization of poor countries by the technologically
advanced ones. One of the most serious problems of nuclear energy is that of finding
safe repositories for the nuclear waste which contains material that will be radioactive
for tens of thousands of years. Suffice it to say that even in the United States, the richest
and most technologically advanced country of the world, the problem of finding a
suitable repository has not yet been solved, in spite of 30 years of work and more than
60 billion dollars invested [15].
Renewable energies (solar energy)
Resorting to renewable energies, and particularly to solar energy, is not a hobby, but a
necessity and we should make a virtue of this necessity. We should develop the use of
any kind of renewable energy (solar, wind, geothermal, hydroelectric, tide, biomass) as
much as possible, wherever it is available [16].
In particular, we should operate to make the Sun our service station:
- it will be open every day for the next 4 billion years;
6
- it sends us an unbelievably large amount of energy (more energy from sunlight
strikes Earth in one hour than all the energy consumed by mankind in an entire
year) [17];
- it arrives everywhere on the earth surface, with relatively small differences (for
example, between Rome and London there is only a factor 1.6 in solar
irradiation)
Solar energy conversion
In order to be profitably used, the diluted (ca. 170 Wm2) solar energy must be converted
into other energy forms: heat, electricity and fuels. Admittedly, the energy conversion
efficiency in most cases is still low and we need much scientific research to improve the
available conversion processes and perhaps to find new ones [18]. In the meantime, we
should begin to use what is now available [16,19].
Thermal collectors are already competitive with other energy sources to obtain hot
water. They are very easy to install and to use. Wide diffusion of thermal collectors
would substantially alleviate the energy and environmental bill of the residential sector.
At the end of 2007, thermal collectors producing a power of 125 GW had been installed,
with a 20% increase compared to the end of 2006. In Austria there are 343.4 square
meters of thermal collectors per 1000 persons; in Italy, only 14.8!
Solar energy can be produced by photovoltaic (PV) cells. They can be profitably used
both in developed and developing countries. They can be connected to the electricity
grid where a grid is available. In developing countries, where millions households do
not have access to power from a grid, PV cells can be connected to batteries and can
supply a fair amount of power for essential needs. By the end of 2007, the installed PV
power amounts to 11 GW. Solar cells are still expensive and have low efficiency (below
15%), but scientific research is very active and new concepts, design, materials and
technologies are being developed.
Fuel is the most useful energy form for mankind since it can be stored and transported.
Production of fuel by solar energy takes place in nature: fossil fuels are indeed fossil
solar energy. Such a natural conversion process, however, is 500.000 times slower than
the present consumption rate of fossil fuels. Fuels can also be obtained by suitable
treatment of biomass, but production of biofuels poses two difficult problems. The first
7
one is related to efficiency, since a large amount of energy has to be used to grow and
process crops. It may happen that the energy balance (energy input compared with
energy generated from biofuels) is negative or only slightly positive. The other problem
is of ethical nature since the use of fertile land for fuel production reduces the land
available for growing food, with all the related consequences (food shortage, increase in
the price of food).
Finally, much hope is based in the so called artificial photosynthesis, a process which is
now the object of intense investigations in many research centers. The aim of this
process is that of using sunlight to produce directly a fuel without using fertile land.
This was indeed the dream of Giacomo Ciamician [2]: … “in the desert regions,
unsuitable to any kind of cultivation, photochemistry will artificially put their solar
energy into practical uses”. Currently, research on artificial photosynthesis is focused
on the splitting of water into hydrogen and oxygen by using photosensitizers in
homogeneous or heterogeneous conditions. If successful, such a process would solve
both the energy and environmental problems since it would produce a fuel (namely, H2)
which, burning with oxygen or combining with it in fuel cells, will produce energy in a
closed, pollution free cycle.
Conclusion
There is a need to launch a massive and concerted plan for research and development of
solar energy conversion [1] because solar energy is abundant, inexhaustible, well
distributed all over the planet. Furthermore, solar energy conversion does not need
sophisticated technologies and cannot be used for war purposes.
If we succeed to convert solar energy with low cost and high efficiency, we will have
enough energy to recycle all the non renewable resources of our planet, thereby
reaching the goal of a materially sustainable world. An if the diluted nature of solar
energy will force us to modify our way of living, this will not necessarily mean that our
lives will be less enjoyable because we will live in more peaceful world.
[1] N. Armaroli, V. Balzani, Angew. Chem. Int Ed., 2007, 46, 52
[2] G. Ciamician, Science 1912, 36, 385.
8
[3 P. Tertzakian, A Thousand Barrels a Second, McGraw-Hill, New York, 2006.
[4 ]K. S. Deffeyes, Beyond Oil, Hill and Wang, New York, 2005.
[5] P. W. Huber, M. P. Mills, The Bottomless Well, Basic Books, New York, 2005
[6] (a) D. M. Kammen, S. Pacca, Annu. Rev. Environ. Resour. 2004, 29, 301. (b) R. A.
Kerr, Science 2006, 311, 1698.
[7] V. Smil, Energy, Oneworld, Oxford, 2006.
[8] http://www.ipcc.ch/
[9] J. Hill, E. Nelson, D. Tilman, S. Polasky, D. Tiffany, Proc. Natl. Acad. Sci. U.S.A.
2006, 103, 11206.
[10] J. Tollefson, Nature, November 15, 2007, 334.
[11] M. Wackernagel, N. B. Schulz, D. Deumling, A. C. Linares, M. Jenkins, V. Kapos,
C. Monfreda, J. Loh, N. Myers, R. Norgaard, J. Randers, Proc. Natl. Acad. Sci.
U.S.A. 2002, 99, 9266.
[12] http://www.footprintnetwork.org/
[13] T. Princen, The logic of sufficiency, MIT press 2005
[14] H. Caldicott, Nuclear power is not the answer, The New Press 2006
[15] http://www.ocrwm.doe.gov/ym_repository/index.shtml
[16] http://www.ren21.net/
[17] R. F. Service, Science 2005, 309, 548.
[18] http://www.nrel.gov/
[19] T. Bradford, Solar revolution, MIT Press 2006
9
Availability of water resources in the Mediterranean countries: reality, problems and trends
Marcello Benedini, Rome, Italy
Summary Life in the countries facing the Mediterranean depends to a large extent on water. The Mediterranean shores are characterised by the variability of climate, population density and economical growth, and future perspectives seem to enhance the existing oddness, imposing serious problems for policy making. The peculiarities of the existing water resources are described in the framework of the actual climatic pattern, focussing on the main problems connected to the actual situation and in view of realistic trends of future development. Some possible solutions for the correct use of the available water are also examined and discussed. Key words: Water resources management; drought; Mediterranean
1. Information sources Several initiatives, at national and international level, are now devoted to the problems of the Mediterranean basin, among which those concerning climate and water resources are of primary importance, calling the attention of the scientific community and the responsible authorities. A long list of references is therefore available, with the description of specific cases of interest and proposing solutions for the most impellent situations. One of the most reliable source of information are the outcomes of the Blue Plan, an initiative promoted by a French institution supported by the United Nations and working in close contact with the Food and Agriculture Organisation and the national bodies of all the countries facing the Mediterranean. The Blue Plan has so far published several reports with adjourned data, which have been used for the considerations developed in the following chapters. Other sources of information are the reports and the proceedings of ad hoc meetings, frequently convened by the governmental institutions of the Mediterranean countries, in which the scientific community is deeply involved.
2. Layout of the Mediterranean basin The Mediterranean basin is conventionally made up by the Mediterranean Sea and the countries facing it from the European, African and Asian continent. The Black Sea and the relevant riparian countries are not included in this aggregation, and expected effects of their connection can be considered like exogenous constraints. Several independent states are washed by the Mediterranean Sea, as shown in Fig. 1 and described in Table 1, with their main characteristics and the length of their relevant coastal line. There is a great variability in geographical characteristics, size and population density, as countries of limited extension are accompanied by others with hundred thousands of square kilometres; some countries have a short coastal line, while others are entirely surrounded by the sea. Altogether the aggregation numbers more than 400 million inhabitants, with different economic, social and cultural characteristics. The Mediterranean basin is still one of the most important areas of the world, taking also into consideration its history, and its particular problems are seen with much attention as significant examples. For these countries, belonging to the basin entails particular attention to its problems, with administrative and political commitments. The countries participate in an active way to the international initiatives, aiming especially at assessing valid agreements for peaceful living conditions, in the frame of a harmonised social and economical development. The European Union, sharing the problems of its member states, pays a lot of attention to the Mediterranean aspects, also
1
in view of launching efficient and persistent ties with the non-member and non-European countries belonging to the basin.
Fig 1.The Mediterranean basin (countries are identified with the acronym of the international automobile licence plate) Water plays a capital role in all the Mediterranean countries, as a principal component of the economical and social development, and in the environmental protection. The Mediterranean water is strictly connected to the particular climatic pattern, extremely variable from one site to the other, and more and more characterised by a trend toward drier conditions, with less annual precipitation
Tab. 1. Characteristics of the countries facing the Mediterranean. Country Total
population Total
country areaLength of coastline
Country Total population
Total country area
Length of coastline
(Mill. inh.) (km²) (km) (Mill. inh.) (km²) (km) Albania 3.3 28,748 418 Libya 4.7 1,759,540 1,770 Algeria 23.0 2,381,740 1,200 Macedonia 2.1 25,700 0 Bosnia-Herz. 4.5 51,129 20 Malta 0.4 316 180 Croatia 4.9 56,538 5,790 Monaco 0.0 2 4 Cyprus 0.5 9,251 782 Morocco 26.1 446,500 512 Egypt 59.0 1,001,450 950 Serbia 10.6 102,173 274 France 56.6 547,026 1,703 Slovenia 2.0 20,251 32Gaza Strip 0.8 365 0 Spain 39.4 504,783 2,580 Greece 10.3 131,944 15,000 Syria 13.8 185,180 183 Israel 5.5 20,770 160 Tunisia 8.8 163,610 1,300 Italy 57.1 301,277 7,953 Turkey 61.6 779,452 5,191 Lebanon 3.0 10,230 225 West Bank 1.4 4,893 0
and hotter seasons, not counterbalanced by the serious extremes events of heavy rainfall that cause flood and inundation. In spite of including some of the most economically advanced places in the world, especially on the European shore, the Mediterranean still groups together a lot of the world population that is considered «poor», having less than 1000 m³/inhabitant/year of water. These occurrences are common in the southern and eastern areas, but can be found also in some limited corners of the European countries. Twenty-seven million Mediterraneans are still deprived of access to improved sanitation systems, mainly in the South and in the Middle East. In all the Mediterranean area the water demand is very high and destined to increase, due to the rise in the demographic rate in the South and the East, and to the development of tourism, industry and
2
irrigated land. This demand should match the existing water resources, threatened by a foreseeable shortage due to the climate change, and already exploited at a very high level. In too many cases, the exploitation of water resources is already the cause of environment deterioration, with effects expected to become very worrisome in the future. A rational water demand is therefore essential for the development of a suitable policy of economical development, in order to guaranty the best living conditions to the incoming generation. Assessing the water demand in the Mediterranean countries is the task of the frequent meeting convened by the governmental institutions of the interested countries. In the past years, the increase of demand had traditionally met the offer with the available resources, but has reached now, or is going to reach, its natural limits, confronted with growing social, economic and ecologic obstacles in nearly all the Mediterranean countries, as stated in a workshop held in 1997 (Frejus Report, 1977). A correct management of water demand has been defined the way that will permit the most progress for the Mediterranean water policies. Taking into account the possible gains in efficiency, the “Convention of Contracting Parties” (Barcelona, 1997) has drawn up some propositions, chosen in the form of recommendations. In a first progress report (Fiuggi, 2002) a series of concrete case studies of water demand has been presented, focussing on tools suitable to implement the most appropriate policies for water management. A «Mediterranean Strategy for Sustainable Development» has been adopted (Barcelona Convention, 2005) in order to set up the strategy for improving the integrated management of water resources. Among the fundamental principles outlined, the water demand should be stabilised through the reduction of water losses and the elimination of wasteful uses. This action could greatly contribute to the increase of available resources, with an increase of the added value per cubic metre of water used. The integrated management at the watershed scale should be also promoted, including surface and groundwater, in the general framework of eco-systems protection, with the pollution abatement. The access to safe drinking water and sanitation is recognised as the primary goal, to be achieved through an active co-operation at local and national level.
3. The Mediterranean catchment Under the administrative and political view, the water problems are normally considered within the national boundary, as an objective involving the entire country with its governmental structures. Nevertheless, an approach aiming at the hydrological aspects is more correct taking into consideration the catchment area, in which the water resources have a real significance. The catchment area is at the base of any consideration on water management problems and is also the subject of official approach in national legislation. The European Union, in its “Water Framework Directive 2000/60”, strongly recommends the adoption of the catchment area as the appropriate territorial entity on which the member states should develop their national legislation on water. In the Mediterranean countries the catchment area does not always coincide with the national territory. Normally it covers only a portion of the political and administrative area, regardless the national boundaries. For a few countries the catchment area covers the entire territory. This is not only the case of the small islands like Malta and Cyprus, but also that of other countries in which the national boundary coincides with the natural divide. Italy, although its national territory covers also a few square kilometres of the Danube catchment discharging into the Black Sea, is normally considered entirely in the Mediterranean catchment.
3
Fig. 2. The Mediterranean catchment (darker areas). The Mediterranean basin conceived under its hydrological identification is mapped in Fig. 2. Table 2 shows the extent on which the Mediterranean catchment covers the national territories. The considerations developed in the following chapters will be based essentially on the catchment entity.
Tab. 2. Sharing of the Mediterranean catchment in the various riparian countries
Total country Mediterranean catchment Country Area
(A) Population
(B) Population
Density Area (A1)
Ratio
Population (B1)
Ratio
Population Density
(A/B) (A1/A) (B1/B) (A1/B1) (km²) (million inhab,) (Inhab. /km²) (km²) % (million inhab,) % (inhab./km²)
Albania 28,748 3.26 113 28,748 100 3.26 100 113 Algeria 2,381,740 23.04 10 133,000 6 10.79 47 81 Bosnia-Herzegovina 51,129 4.47 87 16,301 32 0.55 12 33 Croatia 56,538 4.90 87 37,205 66 1.40 29 38 Cyprus 9,251 0.50 54 9,251 100 0.50 100 54 Egypt 1,001,450 58.98 59 200,000 20 46.55 79 233 France 547,026 56.56 103 130,100 24 11.94 21 92 Gaza Strip 365 0.84 2310 365 100 0.84 100 2310 Greece 131,944 10.26 78 131,944 100 10.26 100 78 Israel 20,770 5.47 263 10,500 51 5.47 100 521 Italy 301,277 57.10 190 301,266 100 57.10 100 190 Lebanon 10,230 3.00 293 9,800 96 3.00 100 306 Libya 1,759,540 4.70 3 158,864 9 3.25 69 20 Macedonia 25,700 2.10 82 25,700 100 2.10 100 82 Malta 316 0.36 1146 316 100 0.36 100 1146 Monaco 2 0.03 15000 2 100 0.03 100 15000 Morocco 446,500 26.07 58 80,000 18 4.43 17 55 Serbia 102,173 10.58 104 6,322 6 1.25 12 197 Slovenia 20,251 2.02 100 4,835 24 0.23 11 47 Spain 504,783 39.43 78 185,600 37 16.36 41 88 Syria 185,180 13.81 75 22,000 12 4.53 33 206 Tunisia 163,610 8.79 54 90,000 55 8.03 91 89 Turkey 779,452 61.64 79 195,000 25 17.18 28 88 West Bank 4,893 1.41 288 2,420 49 1.41 100 581
4
The lowest zones of the River Nile, one of the largest rivers in the world, are included in the Mediterranean catchment. These zones are conventionally identified with the catchment belonging to the national territory of Egypt, but the presence of the river, concerning its flow and the main hydrological aspects, is entirely considered in the receiving sea. The Mediterranean catchment covers an area of about 1,800,000 km² and includes a total population of more than 210 million inhabitants, with a density variable from 20 inh./km² for Libya to 15,000 inh./km² for the tiny Monaco Principality. The attention for the water resources problems is called towards the areas belonging to the largest countries, in which the management of water resources has very strong ties with the political, social and economical aspects.
4. The Mediterranean climate The climatic pattern of the Mediterranean basin is the subject of detailed investigations, some outcomes of which are presented in this meeting. The following paragraphs of this note will try just to focus how the climate characterises the availability of water resources. Regarding the northern shore of the Mediterranean basin, two different sub-areas arise from the most recent and accurate investigations, namely:
- the Western basin, including Spain, France and Italy, in which the occurrence of long periods of severe precipitation scarcity is interposed with short periods of high intensity rainfall events;
- the Eastern basin, including Greece, in which the persistence of dry periods is still predominant, perhaps with the characteristics of an incoming desertification.
- the northern African countries, where the characteristics of the nearby deserts are predominant, with very low annual precipitation.
Fig. 3. Aridity index in the Mediterranean basin.
Several procedures are available to interpret the impact of climate on water resources, focussing on the various phenomena that transform the meteorological event into runoff, taking into account the effect of soil characteristics, vegetation and man intervention [Andreu et al., 2006].These procedures have allowed the definition of particular “indexes”, very useful to identify the zone in which the scarcity of water rises to worrisome values. The European Environment Agency [2003] proposes the “aridity index” defined as the ratio between the yearly mean rainfall and the yearly
5
mean potential evapotranspiration. As structured, the smaller is this index, the greater is the aridity and the same Agency has plotted its spatial representation on the Mediterranean basin, shown in Fig. 3. The extreme variability of the natural conditions is clearly evident. The way the climatic pattern can affect the water resources management requests some more accurate investigation, especially as concerns the possibility of long term and real time forecast of extreme hydrological events. An adequate monitoring network is therefore necessary for the benefit of the responsible authorities, especially in view of preventive action for a correct use of a resource becoming more and more scarce and for the adoption of emergency measures. During the last 50 years the average precipitation in the Western basin has decreased of about 20%. Such a reduction is greater the lower is the latitude. Something seems to have changed in the more recent time. Looking at the past climatological and hydrological records, the high precipitation events seem now to be less frequent, with long periods of interposed droughts having often worrisome characteristics. On the other hand, the magnitude of the rare extreme high precipitation events has tremendously increased. Such a situation is peculiar of the Mediterranean area, where high intensity rainfall events, occurring after dry periods lasting several decades, cause the inundation of fertile land, urban and industrial settlements, sometimes with casualties. The complexity of water problems is therefore enlarged by the need of facing, beside the water scarcity, also an increased occurrence of floods.
5. Natural water availability An inventory of the available water in the Mediterranean catchment requires an accurate information source based on refined and long term measures. In spite of remarkable efforts in all the interested countries, such information still lacks of precision, and only a little number of singular places can provide significant data. The extrapolation to larger areas suffers of imprecision and
Tab.3. Hydrological balance in the Mediterranean catchment
Country Precipitation
(P) Evapotranspiration
(E) Runoff
(R) Ratio R/P
(km³/year) (km³/year) (km³/year) Albania 42.70 15.80 26.90 0.63 Algeria 68.50 56.85 11.65 0.17 Bosnia-Herzegovina 22.00 8.00 14.00 0.64 Croatia 26.50 8.50 18.00 0.68 Cyprus 4.65 3.75 0.90 0.19 Egypt 12.00 11.20 0.80 0.07 France 125.00 63.00 62.00 0.50 Gaza 0.12 0.07 0.05 0.42 Greece 113.40 58.40 55.00 0.49 Israel 3.00 2.40 0.60 0.20 Italy 296.00 135.00 161.00 0.54 Lebanon 8.60 3.80 4.80 0.56 Libya 10.00 9.40 0.60 0.06 Malta 0.18 0.13 0.05 0.28 Morocco 21.00 17.00 4.00 0.19 Serbia 22.00 6.00 16.00 0.73 Slovenia 8.00 2.55 5.42 0.68 Spain 112.00 84.00 28.00 0.25 Syria 13.42 9.12 4.30 0.32 Tunisia 33.00 29.53 3.47 0.11 Turkey 137.60 81.70 55.90 0.41 West Bank 1.40 1.00 0.40 0.29
6
must be accepted with approximation. Nevertheless, the available data seem to be valid for a general picture of the situation in the various zones of the basin, allowing also to identify the most significant cases and formulate reliable trends and forecast. The hydrological balance of Table 3 shows the consistence of water in the catchment. The runoff/precipitation ratio confirms the high variability dictated principally by the latitude and by the presence of other geographical singularity, like the orography and the vicinity of outside zones having stronger characteristics. The amount of runoff is indicative of the quantity of surface water that can be annually found in the catchment, and can provide an indication of the total amount of water on which some general consideration can be drawn. The quantity effectively available, known as “technically and economically usable water”, is normally a portion varying from 50 to 80 %, according to the real possibility of exploitation. A rise in polluted wastewater contributes to reduce the useable quantity and, among the various constraints to take into consideration, the necessity of maintaining the “minimum acceptable flow” is becoming more and more cogent. And everywhere, many rivers are subjected to chronic pollution due principally to non-treated domestic and industrial discharges, or by receiving contaminated agricultural water irrigation surplus. Any consideration on surface water, directly controlled by the meteorological events, must be accompanied by one on groundwater. Surface water percolating through the upper layers of the soil is responsible of aquifer replenishment, but the real consistency of groundwater complies with different times. Moreover, an evaluation of the existing and usable groundwater is very difficult and so far has been done only in a restricted number of countries. At the extension of the Mediterranean catchment, only some estimation is possible, the result of which is shown in Fig. 4, in comparison with the available surface water.
Albania
Algeria
Egypt
France
Greece
Israe
lIta
ly
Leban
onLibya
Marocc
oSpain
Syria
Tunisia
Turkey
0
10
20
30
40
50
60
km²/y
ear
groundwatersurface water
Fig. 4. The source of natural water in the Mediterranean catchment Also this figure emphasises the discrepancy existing in the catchment and stresses the general scarcity of available groundwater. It must be remembered that some countries of the African shore, primarily Libya, can rely on fossil groundwater, not related to the hydrological cycle. Anyhow, such a resource, although conspicuous, is not renewable and can be emptied in a short time interval, contributing only in a partial way to the solution of water problems. Finally, a consideration of the available water in relation to the catchment’s population is very useful for a general picture of the Mediterranean water problems, and the most significant results are shown in Fig. 5. The variability is further increased by the effect of the population density.
7
Looking ahead, the water availability is destined to decrease as an effect of the expected growth of the inhabitant number. With the exception of few European countries, the forecast of the
Albany
Algeria
Cypru
sEgyp
t
France
Greece
Israe
lIta
ly
Leban
onLibya
Morocc
oSpain Syri
a
Tunisia
Turkey
Yugoslavia
(f.)
0
5
10
15
20
1000
m³/i
nhab
.
19972025 maximum population2025 average population2025 minimum population
Fig. 5. Annual per-capita water resources availability, today and in the future for different scenarios of
population growth. Mediterranean population, even though considering different scenarios of growth rate, will increase in the next future, relying always on a resource that will probably decrease, both due to the climatic change and to the rise of the unusable portion of the water currently available.
6. Water demand in the Mediterranean catchment An evaluation of the demand for the principal uses requires detailed investigations, taking into account many factors characterising the way water is drawn and utilised, including traditional practices, level of technology, costs and customers’ requests. It is a conspicuous information hardly available even for the most developed countries. For the Mediterranean catchment only an approximate estimate is feasible, with the scattered and inhomogeneous data released by the national organisations responsible of water. These data are sufficiently significant to allow some general consideration to be done. Fig. 6 summarises a situation close to the late 1990s, in terms of global amount of used water, with further specification for the main forms of utilisation. The resource used for these purposes is assumed to be freshwater coming from natural surface and underground bodies. The community use is normally the most important, being directly associated with the human life. The agricultural use is essentially relevant to irrigation, necessary to enhance the cultivation of food crops. Among the various conditioning factors, the climatic pattern is of primary importance and, due to the scarcity of precipitation in many parts of the catchment, is expected to be very high. The industrial use is strictly tight to the level of the national economical development. Countries belonging to the European shore have traditionally an advanced productivity and are expected to further increase their industrial power. Also some “developing country” of the Asian and African shore is now enhancing its industrial facilities, with an expected demand of water. The demand for energy reflects entirely the cooling of thermal powerplants by using freshwater.
8
Conventionally the hydroelectricity is not considered, because it is “non-consuming” and does not affect the consistency of the natural bodies.
Algeria
Cypru
sEgyp
t
France
Gaza
Greece
Israe
lIta
ly
Leban
onLibya
Malta
Morocc
oSpain
Syria
Tunisia
Turkey
0
10
20
30
40
50
60
km³/y
ear
Total demandCommunitiesAgricultureIndustryEnergy
Fig. 6. Estimate of the water demand in the Mediterranean catchment in late 1990s.
The amount of water indicated in the figure is comparable with the amount of natural water resources indicated in the previous pages. This underlines once more the importance of the water problems for the life of the catchment and for the participating countries as well.
7. Water uses and the formulation of water demand An insight to the mechanism governing the water withdrawal and utilization for the various uses is essential to better understand the necessary quantity of water and to consider how the available resources can meet the demand, presently and in the future. Concerning the community use, Fig. 7 sketches the way water is utilized and includes the potable water and the secondary uses, both inside the household, like washing and gardening, and inside the urban context, mostly related to shops, handicrafts, hospital and services. The partition indicated in the figure has an important implication on the usable water, in terms of quantity and quality. The potable use benefits from particular criteria to assess how much water should be delivered and its chemical and biological requirements, which must by of the highest standard for the preservation of the human life. Vice versa, the secondary uses can be performed with lower quality and there is no reason to use pure drinkable water to wash the floor or flush a toilet. Community use is normally performed under the commitment of a public authority, by means of complex delivering networks, in which there can be also the occurrence of losses. The management of community water implies administrative and technical commitments that can be determinant also on the quantity of delivered water. A very important point for the correct running of a community water supply scheme is to assess how much water is necessary, as an average, for a single person, namely the “per-capita demand”. The actual value varies in the range from 60 l/inh.day, for the scattered country houses, to 600 l/inh.day and more for the largest urban settlements.
9
Fig. 7. Water utilization in a community.
Another fundamental action is the reduction of losses in the conveyance mains and delivery networks. In some existing network the actual losses are much higher than the so-called “physiological losses”, conventionally of 5 – 10 percent of the total conveyed volume. Reduction of losses is connected with a continuous and accurate maintenance of the entire water supply scheme. Promising results are found when the water is delivered in condition of free market, in which the customers pay a reasonable price, with a tariff suddenly rising if the amount of water purchased exceeds a rational per-capita value. Essential is also the sensitivity of users, and appropriate information and training can have remarkable effect on the reduction of the quantity of water to be subtracted from the natural body. Various are the sources of community water; the utilisation of surface water is very frequent in all the Mediterranean catchment, requesting very often compensation storage in large reservoirs. The utilisation of groundwater is sometimes preferred, because, if adequate environmental protections are activated, the water withdrawn from subsoil is of high quality and can be delivered without complex and costly treatment. The way water is used for irrigation is sketched in Fig. 8. The quantity of water delivered to the crop can be rationally determined according to the species irrigated, the level of the plant growth and to the climatic pattern. Nevertheless, also in some economically advanced country a conspicuous withdrawal from surface and groundwater bodies is greater than the necessary requirement and a remarkable quantity remains unused, or is lost in the surrounding environment. In the majority of cases the demand of water for irrigation is formulated following traditional procedures, without any attention to the specific needs of the crop. Running an irrigation scheme requires high professional knowledge on the vegetation characteristics of the crop. In turn, the selection of plants to be cultivated requires accurate analysis on how and when the agriculture
10
products can profitably put in the market. In a quite general view of the agriculture economy, the “dry crops” requesting little quantity of water can give higher profit than the irrigated crops.
.
Fig. 8. Water utilisation in agriculture.
Concerning the quality, there is no need of special requirements and the irrigation can be efficiently performed using urban and industrial wastewater. Obviously, water must be safe from the viewpoint of hygiene. The water used for industrial purposes can be grouped into two categories, namely
a- the process water, which enters the final product of the plant and is consumed, normally characterised by small quantity but high quality;
b- the “washing water”, used for the needs of the plant and for the productive activities; its quality can be poor but generally the quantity high and is eventually discharged in the environment with quality alteration.
Also for this use there are some attempts to evaluate the necessary quantity in accordance with the specific process, the size of the plant and the characteristics of the final product of the plant. There are some attempts to identify rational criteria for assessing the industrial demand, based on the amount requested by a unit product, or by a unit person employed in the factory. Unfortunately these criteria are found to be too dependent on local conditions and to identify a reliable value more accurate and detailed analyses are necessary, taking in due account several determinant factors relevant to the site and the size of the production plant and to the real value of the final product. Fig. 9 shows the possible way this water follows in the productive factory. The recycle can have a remarkable effect on saving the amount withdrawn from the natural bodies. Finally, the constraints imposed by the environment protection relevant to the discharge of wastewater can also contribute to assess the quantity and quality of water demand. Close to the industrial use is that for cooling in the thermal powerplants. Its quantity can be very high, with no particular requirement concerning quality, in a way that allows this use to be
11
performed by means of seawater. The used amount of water is totally returned to the environment with an increased temperature. The possibility of cooling processes and devices able to use a small quantity is currently considered for the design of the new plants and the improvement of the existing ones. Very satisfactory are the cooling towers, which request very low quantity of water, in comparison with the heat exchangers supplied directly and discharging into the natural bodies.
Fig. 9. The use of water in an industrial plant. Showing the way the water is utilized, the preceding figures can help to intervene in a planning procedure, in order to meet a demand dictated by economical, social and political considerations, which must be accompanied in any case by an accurate evaluation of the available resource suitable to be used.
8. The future water demand In principle, the overall water demand in the Mediterranean catchment is expected to grow in the next future, like in the other parts of the world. There are several reasons supporting this, but the principal one is that the foreseeable economic development, together with an increase of population, will require more and more water. This statement has been confirmed during the last decades, when the demand in the Mediterranean catchment has doubled in the second half of the 20th century when the population has increased of 60 %. A more detailed analysis of the available data, at the various national realities, seems to disagree, at least for some Mediterranean countries. First of all, as anticipated in Sect. 6, also in the basin there are countries in which the population denotes a very low rate of growth, sometimes negative, that could change completely the demographic horizon developed so far. A second reason can be that the people have acquired the consciousness that water cannot grow, but, on the contrary, is perhaps destined to decrease. This has convinced the people that something must be done in order to balance the needs of water with the resource that can be effectively used. It is a very challenging goal that entails a strong commitment of the responsible persons and institutions, with an adequate scientific support. The matter is still to be confirmed, because the factors affecting such an analysis are mostly uncertain, depending on many aspects for which a future extrapolation is very difficult.
12
Nevertheless, some result has been proposed, which is worthy to be seriously taken into consideration. Fig. 10a shows, as an example, the forecast of community demand for some countries, at national level. The attempts to foresee future situations have followed different hypothesis, according to the data available and the experience achieved so far. The case of Italy, which clearly denotes a decrease, has taken into consideration improved and more rational criteria to assess the per-capita amount of water that can be delivered to a person, together wit a possible reduction of the country’s population. The case of Egypt, for which the demand will in any case increase, stresses the trend to accompany the population growth with higher standard of living conditions. Similarly, some examples for the agricultural use are in Fig. 10b. The demand seems to stabilise in the countries in which the use has already reached predominant values in respect to the others, but could still increase under the pressure of an increasing population that demands more food in zones characterised by water scarcity.
Egypt high
Egypt low
Italy high
Italy low
1990 2000 2010 2020 20302
3
4
5
6
7
8
9
10
km³/y
ear
Algeria high
Algeria low
Egypt high
Egypt low
Italy high
Italy low
1990 2000 2010 2020 20300
10
20
30
40
50
60
km³/y
ear
Fig. 10a. Fig. 10b.
Fig. 10. Forecast of water demand for some significant Mediterranean countries, for communities (a) and agriculture (b), at national level.
The cases of industrial and energy demand are illustrated in Fig. 11. For both some foreseeable growth can be expected, with different rates, but also some decrease.
Egypt high
Egypt low
France high
France low
Spain highSpain low
1990 2000 2010 2020 20300
5
10
15
km³/y
ear
France high
France low
Spain high
Spain low
1990 2000 2010 2020 20300
5
10
15
20
25
30
km³/y
ear
Fig. 11a. Fig. 11b.
Fig. 11. Forecast of water demand for industry (a) and electricity generation (b), in some significant Mediterranean countries, at national level.
13
The situation described in the preceding figures can be transferred to the portion of the national territory belonging to the Mediterranean catchment, allowing some general thoughts in respect to the total area taken into consideration. As the first thought, the discrepancies already emphasised in the various zones of the catchment will persist in the future, conditioning the water uses, which will develop in different way from site to site. The goal of reaching everywhere high standard of life will force the developing countries to raise their demand. Some expedient can contribute to keep the demand close to the actual values or, in some particular case, to reduce it, in a way that the used quantity could match the usable resource. The expedient will depend on the specific conditions of the considered zone.
9. Increasing the usable water Water resources are a gift of nature and nothing, or very little, the man can do in order to increase their quantity, which unfortunately will decrease as an effect of climate and increasing pollution. Nevertheless, a foreseeable unbalance between the usable water and the demand in the Mediterranean catchment suggests searching for the availability of different types of water that can be used in order to meet all the requirements. In the preceding chapters the efficiency of the supply network has been already outlined, showing how the reduction of losses can provide very often a sufficient quantity. The importance of the water quality has been also recalled, identifying requirements that can be satisfactorily met even by means of wastewater. The first attempt in the evaluation of the “non-conventional resources” should therefore consist of an accurate check on the amount of low quality water that can be utilised, directly or after a low cost treatment. There are several opportunities in nature. Brackish water, with low salinity, is available in many coastal zones of the Mediterranean and can be utilised for the secondary uses in the community. In these zones the fire prevention service can be performed by means of seawater. The utilisation of saline water implies the construction of ad hoc delivery networks to be laid in parallel to the principal ones; special non corrosive materials are necessary and proper running regulations should be adopted, but the relevant problems can be easily solved. An accurate inventory of the wastewater discharged by an urban agglomeration can provide large amount of water to irrigation. Recent investigations confirmed that this practice encounters favourable answer. Utilising urban and domestic wastewater for irrigation requests special engineering works, including the seasonal storage capacity, taking into account that the watering period does not necessarily coincide with the availability of water. Reusing the wastewater can also help to reduce the pollution caused by the discharge of wastewater in the natural bodies. Urban wastewater can be also utilised in the industrial plants; vice versa, lesser is the probability of utilising industrial wastewater for irrigation, because its very low quality will imply high treatment cost not easily bearable by the farmers. As already mentioned, the success in saving industrial water lies principally in the recycle inside the production plant. Concerning the energy use, the future thermal powerplants can find satisfactory location on the coast, where they can benefit from the availability of seawater. There are already some examples of reusing wastewater in the Mediterranean catchment. Recent surveys show that considerable amounts of urban wastewater is already used for irrigation, also in the countries of the African shore. Fig. 12 can be useful to estimate the possibility of utilising wastewater in the catchment. Large amount of it is discharged into the sea, but could be almost entirely used. The remaining “consumed” part includes also some portion that could be effectively taken into consideration.
14
Albania
Algeria
Egypt
France
Greece
Israe
lIta
ly
Leban
onLibya
Marocc
oSpain Syri
a
Tunisia
Turkey
0
10
20
30
40
50
km³/y
ear
Discharged into the seaConsumption in the various uses
Fig. 12. Unusable water a in some countries of the Mediterranean basin.
Searching for “non conventional” resources entails also the sea and brackish water desalination. Many researches have been done in the past to point out efficient and inexpensive procedures, but the process is still greatly dependent on the cost of energy. Some plants are already efficiently working in the Mediterranean countries, as summarised in Fig. 13. Desalinated water is normally used to integrate the supply for potable use.
123
110 51 2632
141
10
17
30
23 12 39 8
Algeria
Cypru
sEgyp
t
France
Greece
Israe
lIta
ly
Leban
onLibya
Malta
Morocc
oSpain Syri
a
Tunisia
Turkey
0
100
200
300
400
500
600
700
1000
m³/d
ay
Fig. 13. Availability of desalinated water and number of working plants in some Mediterranean countries. Other initiatives to search for “non conventional water” can be the attempt for the artificial rainfall stimulation, which has so far encountered satisfactory results in some restricted zones of the catchment. The “water harvesting”, in the attempt to capture the water content in the atmosphere, has had so far a very limited success.
15
10. Conclusive remarks A high variety of natural conditions characterises the Mediterranean catchment, accompanied by a variety of economical a social conditions, which make very peculiar and urgent the relevant water problems. Against limited natural resources, a very high demand for the main uses results in a massive abstraction of water from the natural bodies, some of which are already close to the limit threshold of renewable resource. The demand is destined to increase in the future, further worsening the imbalance between withdrawal and availability. This situation stresses the importance of water for the catchment’s life. Facing the water problems in the area entails primarily a detailed knowledge of the natural aspects, starting from a thorough investigation on climate, geology and other geographic conditions, in order to clearly ascertain the peculiarity and the consistence of the natural resources, in time and space. An efficient hydrological survey system should be recommended, working with instruments and procedures able to provide homogeneous data, comparable all over the catchment. The acquired information should call the attention of the scientific community, in order to improve the knowledge of the natural phenomena governing the surface and underground water resources. In a parallel way, an accurate survey of the economical, social and environmental aspects is essential, in a close contact with the political and administrative institutions responsible of water. The knowledge of these aspects is necessary to assess the water demand, presently and in the future. Focusing on them should enable to devise criteria for the best management of the Mediterranean water resources. Initiatives relevant to the catchment level should be preferable, stimulating the countries to accept transboundary actions, in order to enhance the natural aspect of the usable water. A solution of the Mediterranean water problems lies on the correct identification of how to meet the future demand with the existing resources, if necessary, introducing “non conventional” water. The balance between availability and used quantity should be able to generate harmonised living conditions in an area that must preserve its historical and cultural heritage. Rome, April 2008 References
Andreu J., Rossi g., Vagliasindi f. and Vela A. (edit.), 2006. “Drought Management and Planning for Water Resources”, Taylor and Francis, Boca Raton, U.S.A., pp252.
European Environment Agency, 2003. “Climate Qualità Index”, Copenhagen, Denmark.
Blue Plan Ducuments:
Margat J., Vallee D., “Water resources and uses in the Mediterranean Countries: figures and facts” - UNEP MAP -
Plan Bleu, 1999 Plan Bleu – Regional Activity Centre, “Plan Bleu – Activity Report 2006” – Sophia Antipolis, May 2007 Plan Bleu – Regional Activity Centre, “A sustainable future for the Mediterranean: the Blue Plan’s, Environment &
development Outlook” – Sophia Antipolis, 2005 Plan Bleu – Regional Activity Centre, “Methodological sheets of the 34 priority indicators for the <Mediterranean
Strategy for Sustainable Development> Follow-up” – Sophia Antipolis, May 2006 Other official documents:
MAP Mediterranean Action Plan. “Water demand management, progress and policies”. Proceedings of the 3rd Regional Workshop on Water and Sustainable Development in the Mediterranean, Zaragoza, Spain, 19 - 21 March 2007
16
Joint Mediterranean EUWI/WFD Process, “Mediterranean Groundwater Report”, Mediterranean Groundwater Working Group (MED-EUWI wg on groundwater, (15 February 2007)
Commission of the European Communities, “Communication from the Commission to the Council and the
European Parliament – Establishing an Environment Strategy for the Mediterranean” – COM (2006) 475 final – Brussels, 2006
Joint Mediterranean EUWI/WFD Process, “DRAFT Mediterranean Water Scarcity and Drought Report”, Water
Scarcity and Drought Working Group, November 2007
17
Role of chemistry in the incoming Energy scenario Sergio Carrà , Politecnico Milano Nowadays, the total energy consumption in the world amounts approximately at 13.8
TW. Its behaviour, starting from the beginning of the expired century, follows a
curve that, after a slow increase, undergoes a sharp rise in correspondence of the first
half of the century. This behaviour follows the increase of human population that
represent the driving factor of energy consumption. Concerning the different sources’
distribution, it must be observed that fossil fuels, which still are the less expensive,
represent the lion’s share since contributing with 85% to the total amount of energy.
Nuclear energy, deriving from 439 reactors not evenly distributed among the
different countries worldwide, supplies roughly a 6% of the whole, while the
remaining percentage is provided by renewable sources as it will be discussed further
on.
The relevant role of fossil sources justifies the wide interest that, up to now, has been
devoted to researches on combustion chemistry. The combustion reaction of
hydrocarbons can be lumped as follows:
CnHm + (n+0.25 m) O2 → nCO2 + (m/n)H2O
Actually, it occurs through a very complex network of reactions involving several
highly reactive species. Their rates are required for improving the design of power
plants and reducing the formation of harmful compounds. In fact, their presence
transforms the tropospherical environment into a chemical soup characterized by
various interconnected reactions that occur in different phases and involve liquid
drops and solid particles. The most dangerous pollutant is soot; its formation is
investigated by exploring the reaction paths potentially relevant in the formation of
aromatic hydrocarbons that are the carbonaceous particles’ precursors.
1
The relevance of fossil fuels in energy production raises the question of the
possibility to supply the energy needed in the near future utilizing them. According to
the information at disposal, it seems that there are sufficient reserves to produce oil,
at the current flow rates, for at least the first half of the present century and natural
gas for longer time. Due to the use of new technologies, the world oil reserves have
been increasing in the past years, going from 1000 billion barrels in 1994 to 1200
billion barrels in 2006. Then the peak oil production seems still lay some years away.
Following to the concept of resources triangle, fossil resources are distributed in
nature as illustrated in the figure below. Of course, the much larger low quality
deposits require improved technology and product prices adjustment.
The search of new sources is raising the problem of the origin of oil. According to the
official hypothesis its origin is due to organic matter present in the ground, subject to
an anaerobic fermentation. Following a heretic idea that was introduced by
Mendeleev and further supported by Thomas Gold, oil and natural gas have nothing
to do with biology and their inorganic formation is still filling the reservoirs. Such a
possibility has been confirmed in laboratory by obtaining methane by heating FeO
and CaCO3 in the presence of water at 1500°C and at a pressure of 5.7 Gpa.
2
The oil minister of South Arabia Yamani has stated that: “The stone age came to an
end not for a lack of stones, and the oil age will end but not for a lack of oil”. Apart
from this it seems that renewable resources will not play a large role in primary
power generation until, or unless:
- Cost breakthroughs in carbon-free technologies are achieved.
- Externalities are introduced, such as environmentally driven carbon taxes due
to the increase of carbon dioxide in the atmosphere.
Actually, despite the apparent reassuring resources of fossil fuels, geopolitical and
regional factors can affect significantly the price of energy. As mentioned the
population growth is the key driver for energy demand. A reasonable projection
estimate that in 2050 the population will be almost 9 billion people, and than it is
supposed that the energy demand will increase till about 30TW. If its production will
mostly relay on fossil fuel as now, the increase of carbon dioxide in the atmosphere
could seriously affect the future of the planet.
But why should I do anything for posterity? What posterity ever done for us? This
sentence due to Groucho Marx is of course indefensible. On the other hand we can
assume that Governments must value the welfare of all present and future citizens
equally and give no special preference to current voters. This position that belongs to
Sir Nicholas Stern is operationally impossible since the problem of weighting the
present and the future equally is that there is too much future.
Actually the development of energetic technologies is rising new and stimulating
challenges for science, and particularly for chemistry. They concern:
- The complex system behaviour including many degree of freedom.
- The chemistry of small molecules involved in atmospheric evolution,
combustion, new fuel synthesis, excitation and transfer of electrons.
- The chemistry of carbon dioxide concerning the knowledge on movements and
reactions in the earth and its role in determining the behaviour of the
atmosphere and oceans. Besides to explore possible new uses in large scale
3
chemistry and its catalytic reduction using hydrogen. Nature’s photosynthesis
apparatus may provide inspiration for efficient conversion of sunlight.
- The design of new catalytic systems apt to the direct activation of methane to
methanol or the photo reduction of carbon dioxide to methanol.
In conclusion a secure energy future depends heavily on whether chemists will be
able to obtain more efficient stable and economic catalysts for the production of
alternative fuels. In fact their research can open important perspectives towards the
synthesis of new fuels, as the one involving methanol as intermediate.
Role of chemistry in renewable energy
Because of the ethic conflicts behind the use of biomasses in terms of land
requirements, the renewable sources today able to match the future needs of energy
are wind , geothermal and solar (thermal and photovoltaic) . The following table
offers a picture of present employment of renewable energy sources with a potential
perspective (pv) towards the future:
-hydroelectric 0.3 pv=0.9
-geothermal 0.01 pv=40
-wind 0.003 pv=2
-solar 0.001 pv= 600
The figures in the first column express as the total rate of renewable energy
production, in TW, is shared between different resources, while the second column
gives an estimation of their potential values evaluated by accounting their technical
availability. Actually the sunlight falling on the Earth exceeds world’s needs by
almost four orders of magnitude. The reported value refers only to the planet areas in
which solar radiations can be profitably captured. It comes out that solar energy is
the only source able to supply the carbon free power needed at 2050, and therefore is
tempting to imagine that one day solar technologies could displace much of today’s
fossil fuel power generation.
4
In nature solar energy is harvested through photosynthesis in which two massive
protein complexes split water and carbon dioxide and forge new energy-storing bonds
in sugar molecules. The man built solar cells, based on photovoltaic effect, capture
photons by exciting electrons across the band gap of a semiconductor. Electron-holes
pairs are charge separated at n-p junctions. In both photosynthesis and solar cells the
capture of solar radiations occurs through an electron transfer and the similarity has
a parallel in thermodynamics since the maximum energy generated per electron under
black body radiation at temperature Ts can be expressed as:
)1(s
m TT
−Δ=Φ ε
that is the energy gap times the Carnot efficiency.
On the basis of the present efficiency of solar cells it can be shown that the full
energy consumed in the world can be produced in a tropical land with a squared area
with a side of 700 Km. In other worlds it is sufficient to cover about 0.17% of the
territory.
Photovoltaic is a dynamic and rapidly growing industry that is enjoying around a
forty per cent of annual growth. Market is shared by different materials, but silicon
dominates with a presence of about 93% of crystalline products, that are single-,
multi- and poly-nano-silicon. The main method to obtain the material for solar
applications is the Chemical Vapor Deposition (CVD), and many different
technologies are rushing for high efficiency and low cost. The emerging strategy is to
employ the cheapest materials by taking advance of scale economy by overcoming
the difficulties to move from lab scale efficiency to module efficiency, whose
difference is shown in the figure.
5
Module efficiency Lab scale Max efficiency
HIT heterojunctionintrinsic thin film
Module efficiency Lab scale Max efficiency
HIT heterojunctionintrinsic thin film
Probably, there will be no main impact of technological breakthroughs on the
industry for the next few years. Instead, the existing technologies will evolve in the
direction of cost reduction in most distributed applications in less than 10 years, as it
is shown in the following figure. After that, competition with fossil fuel generation is
expected to be achieved in the following years with the likely introduction of
significantly different technologies compared to todays.
0.1
1
10
100
1 10 100 1,000 10,000 100,000 1,000,000Cumulated production (MW)
Mod
ule
pric
e ($
/W) (
$200
2)
1978$30.14/W
1980$21.83/W
1986$10.48
2000$3.89/W
2023$0.65
2013$1.44/W32%/pa
Present energy generation capacity (USA)
Distributed energy price (USA)
Energy generation price (USA)
hystorical predicted
0.1
1
10
100
1 10 100 1,000 10,000 100,000 1,000,000Cumulated production (MW)
Mod
ule
pric
e ($
/W) (
$200
2)
1978$30.14/W
1980$21.83/W
1986$10.48
2000$3.89/W
2023$0.65
2013$1.44/W32%/pa
Present energy generation capacity (USA)
Distributed energy price (USA)
Energy generation price (USA)
hystorical predicted
It is worthwhile to remember that Shockley and Queasier developed an analysis on
the performance of solar cells based on the following assumption:
1- presence of a single p-n junction
2- only one electron-hole pair are excited for incoming photon
3- the electron-hole pair energy in excess of the band gap is dissipated through
thermal relaxations
4- the illumination occurs with non concentrated sunlight
6
A maximum yield not higher of 31% is obtained. Such a limit can be exceeded only
by violating one or more of the previous premises, by using cells with intermediate-
band, with quantum-well or with multiple junctions. In fact the addiction of nano
particles, obtained by chemical synthesis, allows the tuning of the optical properties
of the materials through the control of their size . Variable sizes dots have absorption
spectra extending from IR to UV, and then they allow the harvesting of a larger
portion of the available solar spectrum.
A further development is the employment of polymer materials, customary referred
as excitonic solar cells, in which sunlight frees an electron and an electron vacancy
which migrates to the border between different materials and then to the oppositely
charged electrodes. Adding metal nano particles increases the light absorption and the
number of generated charges.
In conclusion the new developments in nanotechnology and material sciences may
enable step-change approaches to cost-effective systems for solar energy use. In such
a frame, a deeper insight in the mechanism of excitation and transfer processes of
electrons involved in solar energy harvesting is of primary importance. For instance
photosynthesis has immense appeal for the capture of the energy coming from the sun
and the understanding of its basic processes can suggest how to create systems that
mimic biological molecules and produce energy more efficiently. Human ingenuity is
entering in the game since work is in progress to gather a hierarchical assembly of
molecular machines to simulate photosynthesis. In the meanwhile, an
interdisciplinary approach is emerging aimed to design high efficiency catalytic
systems, inspired by natural metabolic pathways that have evolved for the survival
and reproduction the organisms. The relevant steps might be isolated and connected
directly to produce fuels such as hydrogen, methane and alcohols, by opening
interesting perspectives towards a post petroleum economy.
Conclusions
7
Researching, developing, and commercializing carbon-free primary power
technologies, capable of supplying the energy needed in the present century, is
requiring significant efforts, at international level. Unfortunately, following
Shakespeare, it must be stated that: “Though it be honest, it is never good to bring
bad news. (Anthony and Cleopatra)”. In fact:
-Fossil fuels: are penalized by carbon dioxide sequestration
-Nuclear fission: requires high investments and nevertheless it does not yet represent
an alternative to fossil fuels, unless new technological breakthrough will emerge
-Wind, geothermic and biomass energies : can only give an integrating support to
the wide incoming energy requirements
-Solar energy: there are many ideas about creating new high efficiency low-cost
cells, but whether and when they can revolutionize the solar business remains the
field ‘s biggest unknown .
In the immediate the external limitations on carbon dioxide emissions imply the
adoption of precautions that will be introduced through a mix of different carbon
free technologies in a mutual integrated system (energy saving, increase in the
employment of natural gas instead of carbon, increase of renewable sources and
nuclear) . The following stabilization triangle is divided in sectors each one
corresponding to an advisable reduction of the emitted carbon. Relevant importance
must be attributed to the improvement of efficiency.
But actually it must be to taken into account that technological advancement is
hierarchical guided by the intelligence of technological innovations and the main
factors are the information content and the material content of the manufactured
8
goods. Then the complexity in the manufacturing sector depends on the value of their
ratio for the obtained products. The time evolution of such a ratio moves towards
high values, particularly in accord to the increase of the information. The fallout of
the previous approach to energy production suggests of avoiding large scale and high
temperatures technologies in which not renewable wastes that impoverishes the
planet resources are produced. But probably this is utopia.
References
-Lewis N., Powering the planet, Mrs Bulletin, 32, pag.808 (2007).
-Smalley R.E., Future global energy prosperity: The terawatt challenge , Mrs
Bulletin, 30, pag.445 (2005).
-IEA, Key World Energy Statistic, www.wind-energie.
-Maugeri L., L’era del petrolio, Milano, Feltrinelli (2006).
-Socolow R.H., Pacala S.W., A plan to keep carbon in check , Scientific American,
295, pag.28 (2006).
-Service R.F., Solar energy : It is time to shoot for the sun?, Science, 309, pag.548
(2005).
-Carrà S., Le fonti di energia, Mulino, Bologna (2008).
9
ANCIENT AND MODERN HYDROLOGY: THE COMMON GROUND AND RECENT TRENDS
Gedeon Dagan Faculty of Engineering
Tel Aviv University Israel
TZIPPORI (SEPHORIS) ARCHEOLOGICAL SITE
Tzippori (near Nazareth, Israel) was a flourishing Jewish town in the Hellenistic
period (332-142 BC), during the Roman and Byzantine periods and fell from grace
after the Crusaders retreat (12th century).
In the last decades rich mosaics were unveiled by archeologists. The "Nile festival"
building dating from 5th century (Byzantine), is of unknown origin. The mosaic
depicts an allegoric festival, celebrating the raise of the Nile. The detail of interest: a
symbolic representation of a Nilometer
1
2
HYDROLOGY: ONE OF THE OLDEST PROFESSIONS IN THE
WORLD
"Egypt," Herodotus remarked more than 2000 years ago, referring to the vast
irrigation project that sustains that country's agriculture, "is the gift of the river." The
Nile River has always been the backbone of Egypt. The mighty river flows for some
4,000 miles from the mountains of Equatorial Africa (Blue Nile) and Lake Victoria
(White Nile) before it empties into the Mediterranean Sea. Without the Nile River and
its annual inundation Ancient Egypt would never have come into being.
3
Ancient Hymn to the Nile, around 2100 BCE
Hail to thee, O Nile! Who manifests thyself over this land, and comes to give life to
Egypt! Mysterious is thy issuing forth from the darkness, on this day whereon it is
celebrated! Watering the orchards created by Re, to cause all the cattle to live, you
give the earth to drink, inexhaustible one! Path that descends from the sky, loving the
bread of Seb and the first-fruits of Nepera, You cause the workshops of Ptah to
prosper!
Inundation of the Nile, offerings are made unto you, men are immolated to you, great
festivals are instituted for you. Birds are sacrificed to you, gazelles are taken for you
in the mountain, pure flames are prepared for you. Sacrifice is metle to every god as it
is made to the Nile
Nilometers
According to Lancelot Hogben book Mathematics for the Million: "The Egyptian
temples were equipped with nilometers with which the priests made painstaking
records of the rising and falling of the sacred river. With these they could predict the
flooding of the Nile with great accuracy“
Nilometers could be traced back to 3000 BC (first dynasty). The readings were
accurate (1 cubit~26 cm, 1 finger~1 cm). Records were used for prediction that served
the Pharaoh administration for policy making (taxation, storage). The priests that
analyzed and interpreted the records are the ancient hydrologists, rendering
Hydrology as one of the oldest professions in the world.
The related Biblical story of Joseph Genesis 41
Joseph Interprets Pharaoh's Dream:
1 And it came to pass at the end of two full years, that Pharaoh dreamed: and, behold,
he stood by the river.
2 And, behold, there came up out of the river seven well-favored kine and fat-
fleshed; and they fed in a meadow.
3 And, behold, seven other kine came up after them out of the river, ill-favored and
lean-fleshed; and stood by the other kine upon the brink of the river.
4
4 And the ill-favored and lean-fleshed kine did eat up the seven well-favored and fat
kine. So Pharaoh awoke...
25 And Joseph said unto Pharaoh, The dream of Pharaoh is one: God hath showed
Pharaoh what he is about to do.
26 The seven good kine are seven years; and the seven good ears are seven years: the
dream is one.
27 And the seven thin and ill-favored kine that came up after them are seven years;
and the seven empty ears blasted with the east wind shall be seven years of famine.
Assumption: Joseph consulted hydrologists…
Recent analysis of Nile records (from 622 AD with gaps)
Kondrashov, Feliks & M. Ghil, Oscillatory modes of extended Nile River records
(A.D. 622–1922), Geophys. Res. Lett., 32, 2005.
Summary of the article:
• SSA(M-SSA) can be used for filling gas in geophysical data sets, by
using dominant spatio-temporal modes of the data
5
• The 7-8 yr period in Nile River records equals that of a North Atlantic
spectral peak [Ghil & Vautard, 1991; Moron et al., 1998, Wunsch,
1999]
• This peak may be due to intrinsic ocean variability [Speich et al., 1995;
Dijkstra & Ghil, 2005; Simonnet et al., 2005]
• Our results suggest that the climate of East Africa has been subject to
influences from the North Atlantic, besides those already documented
from the Tropical Pacific.
ANCIENT AND MODERN HYDROLOGY: THE COMMON
GROUND
There are four constituents of the ancient hydrology that are shared by the modern
one:
• Hydrology is a quantitative discipline: it deals with data and with
mathematical analysis.
• Hydrology is an applied science: the motivation and aims were related
to the needs of society.
• Hydrology dealt with prediction under uncertainty: the ancient
hydrologist had to use sophisticated time series analysis in order to
predict occurrence of extreme events.
• Hydrology is intertwined with economy, political and social issues:
predictions had a serious impact on the sustainability and wellbeing of
society.
6
Subsurface Hydrology And Contaminant Transport
The Hydrological Cycle
Groundwater and the Hydrological Cycle
Groundwater is a major source of fresh water (Israel 2/3)
7
Pollution of groundwater has become a major problem. Sketch of contaminant
sources and transport by groundwater.
8
Mathematical Modeling of Flow and Transport in Porous Formations
The medium is highly heterogeneous and flow and transport are complex at pore scale
(0.01-1 mm). In applications we are interested in averages of flow and transport
variables over much larger scales (laboratory scale 10-100 cm). Macroscopic
variables: pressure, water flux, solute concentration. Mathematical modeling requires
deriving macroscopic balance equations by averaging the microscopic ones.
Balance equations:
• conservation of water mass
• momentum (inertial term are negligible) leads to Darcy’s Law (balance
of pressure gradient, friction, gravity)
• transport i.e. mass balance of solute (change of concentration,
advection by water, diffusions, reaction)
• state equations (concentration-density, physical-chemical reactions(
These are partial differential equations which include macroscopic properties of the
medium: permeability, effective diffusion (dispersion) coefficient, effective reaction
9
coefficients. In the traditional approach, the solution of the equations of flow and
transport, with appropriate boundary and initial conditions, are used in order to
analyze and predict flow and transport problems, e.g. discharge and contaminant
concentrations in wells.
Subsurface Stochastic Modeling (SSM)
Unlike laboratory samples, natural formations (aquifers), of scales 10-10,000 meters,
display heterogeneity at a much larger scale than the pore scale.
Illustration: permeability distribution in a cross section of the Borden Site aquifer in
Canada (lines of constant –lnK, cm/sec)
Heterogeneity:
• erratic spatial variability
• subjected to uncertainty due to lack of data
• Stochastic modeling regards formation properties, flow and transport
variables as random.
Spatial variability of formation properties has a large impact on transport of
contaminants. Spreading is enhanced by orders of magnitude relative to pore-scale
dispersion. Solute concentration varies irregularly and prediction is subjected to
uncertainty.
Illustration: Snapshots of vertically averaged concentrations in the Borden Site field
experiment.
10
11
Realization Of Medium Of Random Hydraulic Conductivity Distribution
Heterogeneous Medium: Stochastic Approach
Homogeneous Medium: Deterministic Approach
Water
Flow
Initial Solute Plume t = 0
Solute Plume at time t = T
Solute Plume at time t = TInitial Solute Plume t = 0
Challenges Faced By Stochastic Subsurface Modeling
Quantitative discipline SSM is highly mathematical.
Challenges:
- communication with the more descriptive disciplines (geochemistry, geohydrology)
- conveying results in a simple form to practitioners
SSM is motivated by applications, primarily contaminant transport. It belongs to engineering sciences.
Challenges:
-to avoid highly theoretical and esoteric developments, divorced from hydrological
applications-to provide tools to be used in practice
Involvement in social, economical and political issues
Contaminant transport and groundwater pollution are topics of great social impact.
This is underscored by the subject being at the core of two popular movies: A Civil
Action and Erin Brokovich
Challenge: -to account for these issues in the developments of SSM.
12
Fuels from biomass prospects and R&D challenges
Jean-Luc DUPAN (a Pure.Applied.Chemistry paper - www.ifp.fr )
The world demand for transportation fuels is predicted to increase. These fuels are mainly derived from oil, generating growing and uncontrolled CO2 emissions. Production of fuels derived from biomass appears as an alternative to oil. The two main types of current biofuels are ethanol, directly used in gasoline engines in most cases or as ETBE in some countries, and vegetable oil methyl esters with applications in diesel engines. However, costs production and restricted land volume, because of competition with food crops, lead R&D work to find solutions to produce new biofuels based on lignocellulosic materials. This biomass resource is more abundant and cheaper to use than food crops. A "thermochemical" and an enzymatic pathways are currently under development to produce fuels from lignocellulosic biomass : wood, straw and wastes. Willingness to reduce their oil dependence and necessity to promote low-carbon energies are the two main drivers for states to support biofuels development. Current biofuels
Today, there are two main types of biofuel (Figure 1): ethanol for use in “gasoline” type engines and vegetable oil methyl esters (VOMEs) for “diesel” type engines. Ethanol is the most commonly used biofuel in the world: 40 Mt in 2006, of which 80% was used for motor fuel, versus slightly less than 6 Mt for biodiesel. The United States, Brazil and Europe account for most of this growth, although many other countries are also showing interest in motor fuels of vegetable origin. Ethanol is currently made from two types of crop (Figure 1): sugar-producing plants (sugar cane, sugar beets) and plants yielding amylaceous material (wheat, corn). These different pathways all include a fermentation step to convert the sugars to ethanol and a distillation step, more or less advanced, to separate alcohol from water. This generates coproducts whose value often is key to project profitability. For instance, the ex- corn or ex-wheat pathway yields large quantities of grain residue (a little more than a ton of residue per ton of ethanol) that can be sold on the animal feed market.
Ethanol can be used pure, blended with motor fuels or in its ether form, ETBE, produced in reaction with refinery or petrochemical isobutene. It cannot be used pure or at very high concentrations (e.g. at 85% in E85) unless the vehicle has been modified for that purpose (injection systems, engine settings, compatibility of plastics and gaskets, special mea- sures for cold starts when ethanol is used pure).
Ethanol is generally used at lower contents, between 5 and 10%. At these levels, the engine does not have to be adapted. On the other hand, certain technical difficulties can arise making it necessary to modify the logistics system. For ins- tance, the gasoline and alcohol phases can separate in the pre- sence of water at low ethanol concentrations, a phenomenon known as demixtion. Furthermore, adding ethanol to gasoline increases the vapor pressure, hence its propensity to evapo- rate. ETBE is used, mostly in Europe, to overcome these disadvantages.
Fig. 1 First-generation biofuel technologies
Sugar beet Sugar cane
Fermentation
Wheat, corn, potato
Starch
Sugars
Ethanol
ETBE
Gazoline blend
Transesterification
Rapeseed oil Sunflower oil
Vegetable oil methyl esters or biodiesel
VOME
Diesel blend
VOMEs are produced from vegetable oils including rapeseed, sunflower, soybean or palm oils. When an oil is obtained by grinding oilseeds such as rapeseed, soybeans or sunflower seeds, a solid residue or “cake” is produced (1-1.5 ton per ton of oil) that is generally used for animal feed. Not suitable for direct use in existing passenger vehicle diesel engines, vegetable oils must be transformed by a reaction of transesterification with an alcohol. Currently, methanol is used to produce vegetable oil methyl esters and glycerin (0.1 ton per ton of VOME). A co-product with numerous applications, glycerin, contributes substantially to the ultimate profitability of this technology.
Like ethanol, VOMEs can be used pure or in blends. When used pure, the vehicle must be converted. Today, they are generally blended, with contents ranging from a few percen- tage points to 30% in captive fleets. A new vegetable oil ester production process has been developed by IFP and known as Esterfip-H™. This new process uses a solid catalyst developed at IFP Esterfip-H™ is used to obtain a biodiesel (VOME) and a glycerin (co-product of biodiesel production) of higher quality and with improved efficiency. It also has other advantages over industrial units already producing biodiesel, in that soya or palm can replace rapeseed as the raw material. The process is therefore likely to be of interest to the Mediterrannean, Asian and American markets. Moreover, the quality of the glycerin produced should enable it to find new outlets, even though the current market for ordinary glycerin is already saturated.
The new biofuel production pathways
In the wake of first-generation biofuels, other pathways are emerging based on other resources or other processing methods. The objective is to diversify available resources while improving product quality.
The pathways of intermediate generation
These new biofuel generations start with intermediate generation: – Animal oil methyl esters. The use of waste animal
fats broadens the range of suitable raw materials. While the potential of this type of conversion is limited, it could nevertheless prove useful in certain local situations.
– Vegetable oil ethyl esters (VOEEs). This variant of VOME fuel uses ethanol to synthesize the ester instead of methanol from natural gas. The final product possesses properties equivalent to those of VOMEs. However, the quantities of ethanol used are relatively low (15% by weight) and the final product is likely to be more expensive in Europe than VOMEs, due to technical constraints at the production stage and a large price difference between ethanol and methanol (a ratio of about 2 in 2006)..
- Syndiesel obtained by treating vegetable oils with
hydrogenation. Two approaches are possible: coprocessing or the dedicated unit.
Coprocessing involves mixing a vegetable oil into an oil stream on its way to the hydrotreatment unit, then processing the mixture with hydrogen. The advan tage of this option is that biodiesel production can benefit from the effects of scale inherent to the oil industry. This avenue is being explored by the Brazilian state-owned company Petrobras via its H-bio product.
The “dedicated unit” option has been developed by the Finnish company Neste Oil. The product obtained, NexBtL®, is of 100% vegetable origin: no other oil besides vegetable oil enters the industrial unit. The properties of NexBtL® (e.g. a very high cetane number) make it very attractive as an addition to the pool of component streams used to make diesel fuel. It must be stressed that these units need substantial invest- ment: this type of installation costs at least four times more than a VOME production unit of equivalent capacity1. More research is needed to minimize costs
– Butanol. Here, the BP-Dupont project is an interesting example. The physical properties of butanol, a replacement fuel for gasoline, help overcome difficulties connected with the use of ethanol, e.g. problems of volatility or the fact that ethanol attacks some of the plastics used in the motor industry. Biobutanol can be blended with gasoline at contents as high as 10% volume without having to modify the engine. In future, it may be possible to boost this percentage to 16%2. Biobutanol can also be used in blends with ethanol and gasoline or even diesel fuel.
.
(1) A NexBtL®-type unit costs €100 M versus €25 M for a VOME unit of equivalent capacity (i.e. about 160,000 t/yr).
(2) For all pathways that incorporate alcohol into motor fuels in Europe: existing regulations will have to be modified before any blend containing more than 5% can be developed.
Second-generation biofuels
The so-called second-generation biofuels can be defined as those using lignocellulosic biomass as the raw material. The principal advantage is that they can be used to extract value from the most abundant carbon source on our planet (cf. Panorama www.ifp.fr “Resources”).
Lignocellulosic biomass is composed mainly of three poly- mers from the cell wall of plants: cellulose, hemicellulose and lignin, present in varying proportions, depending on the plant (cf. Table 1).
Table 1 Composition of lignocellulosic biomass
Biomass
Lignin (%)
Cellulose (%)
Hemicellulose (%)
Softwood Hardwood Wheat straw
27-30 20-25 15-20
35-42 40-50 30-43
20-30 20-25 20-27
It also contains other elements (inorganic, silica, etc.) in proportions ranging from 5 to 15%.
These three polymers are closely interconnected in the layers of the cell wall, forming a rigid matrix that is hard to destructure.
Two pathways are under study today (Figure 2): one to produce diesel motor fuel and kerosene (BTL) and the other to produce ethanol (Since ethanol is used to replace gasoline, it may be considered to be a biogasoline). Biomass to Liquid technology
BTL technology is a “thermochemical” pathway whereby a liquid synfuel is obtained from biomass. It involves three important steps: biomass conditioning; gasification then pro- cessing of the syngas; synthesis of the motor fuel.
Some of these steps have been tested in industrial projects using natural gas (GTL) or coal (CTL) as the raw material. In the past, CTL technology has provided a solution to oil sup- ply problems, for instance, in Germany during World War II and during the embargo on the apartheid regime in South Africa.
• Biomass conditioning
The first step is to transform the vegetable resource into a homogeneous material that can be injected into a gasifier. This usually involves thermal and mechanical transformations. Two methods can be used: pyrolysis and torrefaction.
Pyrolysis uses heat to break biomass down into three phases: solid (coal), liquid (bio-oil) and gas (mostly carbon dioxide, carbon monoxide, hydrogen and methane).
How these three phases are distributed depends on operating conditions (temperature, heating rate and residence time).
Slow pyrolysis, which is the better-known process, yields a solid (charcoal). Fast pyrolysis is the method envisaged for the BTL pathway. It involves maintaining a temperature of 500°C for a few seconds and produces mostly liquid (a bio-oil) with some coal in varying amounts.
Although these bio-oils look very much like petroleum, they are actually quite different. They contain several hundred che- mical compounds (e.g. phenols, sugars, alcohols, organic acids and aromatic compounds) in proportions that vary greatly, and present the particularity of not being miscible with any petro- leum product. These oils are then introduced directly into the gasifier.
Current research is seeking to convert these oils directly to motor fuels via hydrogen treatments. Although attractive, this direct pathway seems hard to implement, given the quantities of hydrogen needed and the fact that the chemical nature of the bio-oils produced is very different from that of conventional automotive fuels.
The second method being considered for biomass pretreatment is torrefaction (roasting). Since the 1980s, a great deal of research has been done on the torrefaction of wood, which imparts very good resistance to attack by fungi and some types of insect. But it also lowers the mechanical strength of the wood, a cha- racteristic exploited by BTL methods: torrefaction makes it easier to grind wood and thus obtain a finely divided solid sui- table for certain gasification technologies.
Torrefaction is like a final drying operation (temperature: 240 to 300°C, residence time: up to one hour). Carried out at temperatures much lower than in pyrolysis, this process is much less energy intensive.
• Gasification and syngas processing
Unlike pyrolysis, which takes place in the absence of a reactive gas, gasification is a thermal operation that takes place in the presence of a gaseous reactive (water vapor, oxy- gen) and produces what is called a syngas that mostly contains hydrogen and carbon monoxide. It also contains impurities (carbon or inorganic) and other gases. In industrial use today, this mix is combusted in coal-fired or IGCC power plants (Integrated Gasification Combined Cycle). Blends like this were formerly used to power automobiles, e.g. the “Gazogène” wood gasifier used during World War II fuel shortages or water gas.
In a BTL process, which aims to produce a liquid motor fuel, the constraints imposed on syngas composition are more severe than for direct combustion. The idea is to maximize production of carbon monoxide (CO) and hydrogen (H2) while achieving a H2/CO ratio (about 2) compatible with motor fuel synthesis. It is also vital to eliminate impurities that would otherwise “poison” the catalyst used in Fischer-Tropsch syn- thesis. That's why biomass gasification generally takes place at a very high temperature (1,200°-1,300°C) and is followed by syngas purification steps.
These operations generate large quantities of CO2, mostly as a result of combustion to supply process heat, and these emis- sions represent lost carbon that is not converted to motor fuel. This is the main explanation for the low fuel mass efficiency (< 20%). This efficiency could be increased by supplying additional external energy, electrical for instance, and/or addi- tional hydrogen. In France, this solution has been proposed jointly by the French atomic energy agency (CEA) and IFP. For the two latter options, the overall energy efficiency of this technology is adversely affected (divided by two) in favor of the mass efficiency.
No specific biomass gasification technology has reached the industrial stage. Most of the solutions that have been put for- ward are derived from technologies for natural gas, coal or petroleum already in industrial use.
• The synthesis of motor fuel
Fischer-Tropsch synthesis, named for the two German chemists who invented it in the 1920s, is a reaction used to produce gasoline, diesel fuel and kerosene from syngas obtained by gasification.
This chemical reaction requires catalysts, of which two types are used: iron-based or nickel-based. In the presence of an iron-based catalyst, the Fischer-Tropsch reaction produces gasoline. In the presence of a cobalt-based catalyst, it yields bases for diesel fuel and kerosene. The products obtained are free of sulfur, nitrogen and aromatics.
The syndiesel has a cetane number of about 70, much higher than required under current standards (~50). Carmakers appre- ciate the fact that this motor fuel is of very high quality for vehicles. It emits fewer polluting emissions, especially parti- culates, than conventional diesel fuel.
Several Fischer-Tropsch technologies exist and some have reached the industrial or demonstration stage (Sasol, Shell, Statoil, Exxon, BP, Conoco, Rentech, IFP/ENI and Syntroleum). Producing ethanol from lignocellulosic materials
The steps in the production of ethanol from lignocellulosic materials are much the same as those used in the ex-corn or ex-wheat process: – the raw material is prepared; – the cellulose is converted to glucose (sugar); – the sugars are fermented to yield ethanol; – the ethanol undergoes distillation and final purification.
We will only describe the first two steps. Unlike the other two, they are specific to the second-generation pathway. • Pretreatment of the raw material
Two methods are currently used to pretreat the raw material once the straw has been shredded or the wood has been cut into chips. The structure of the lignocellulose is opened using the steam explosion or heating in the presence of dilute acid methods, offering access to the “sugars” (i.e. hemicellulose and cellulose); only cellulose can be converted to ethanol.
The dilute-acid pretreatment involves putting the plant mate- rial in the presence of an acid, preferably sulfuric acid, at a moderate temperature (about 150°C) for about 15 to 20 minutes. Processes that include a second step, carried out at a higher temperature (240°C for a few minutes), are also being investigated.
Steam explosion pretreatment. To destructure the lignocellulosic matrix, the raw material is briefly exposed to high pressure and temperature conditions (15 to 23 bar; 180 to 240°C) in the pre- sence of steam then, suddenly, to low pressure. The development
of this technology has been taken as far as the industrial stage (the Stake and Iogen processes).
Both of these pretreatments increase the cost of the process. In particular, they require investment in equipment that can withstand the pressure and corrosive acid conditions.
• Converting cellulose to glucose
The second stage consists of breaking down the cellulose molecules into glucose with the help of enzymes (enzymatic hydrolysis). From the economic standpoint, this operation is heavily penalized by the fact that enzyme consumption is bet- ween 10 and 100 times that of conventional methods (ex-corn or wheat). Many R&D projects aim to improve this method of conversion by optimizing the process directly and to work on increasing enzyme activity (molecular biology).
The glucose obtained is then converted in a very conventional manner, i.e. fermented, to produce ethanol. Some research studies are striving to combine the operations just descri- bed enzymatic hydrolysis and fermentation into a single step.
Using hemicellulose to produce ethanol is another avenue under investigation, the idea being to boost the competitive- ness of this pathway. Today, glucose can only be obtained from cellulose, which represents about 50% at most of lignocellulo- sic materials. Hemicellulose contains pentoses, which are sugars that cannot be converted to ethanol by the organisms usually used in fermentation. Obviously, this considerably inhibits profitability.
References: www.ifp.fr (panorama 2007) D.Casanave, J-L.Duplan, E.Freund, Pure Appl.Chem, Vol 79, n°11, pp.2071-2081, 2007
First-generation biofuels are driving the development of new pathways, especially with a view to increasing “mobilizable” resources, including those that can be used as natural plant feedstock for refineries. This reflects the growing importance of biofuels in the oil-dependent transport sector. Finally, oil companies have a competitive edge on this market owing to their knowledge of the transport sector (product quality) and to their technologies. Some majors are making a substantial move into the development of second-generation pathways.
A number of research projects now underway, especially in the United States and Europe, are focusing on second-genera- tion technologies. IFP is a major player on the research scene both in France, where it is involved in the national bioenergy research plan, and in Europe, where it is leading the NILE3
Project bearing on the production of ethanol from lignocellu- losic materials. A prime objective of these projects is to reduce production costs: today, it costs about €1/liter oil equi- valent for both second-generation (ethanol and BTL) path- ways. Ambitious targets have been set: €0.4/l for ethanol and €0.7/l for the BTL pathway by 2010-2015. Looking even far- ther in the future, some foresee a cost of €0.5/l oil equivalent for BTL. We might compare these figures with the current prices of gasoline and diesel fuel, which stand at €0.32/l and €0.37/l respectively, with the barrel of crude at USD 60.Today, the development of biofuel pathways is also closely associated with targets for the reduction of greenhouse gas (GHG) emissions in the transport sector. Well-to-wheel assessments indicate that, in most cases, the use of these automotive fuels of vegetable origin reduces GHG emissions and fossil energy consumption compared to petroleum-based automotive fuels.
Dr. Jean-Luc Duplan [email protected]
(3) New Improvement for Ligno-cellulosic Ethanol.
(3) New Improvement for Ligno-cellulosic Et
Fig. 2 Second-generation biofuel technologies IFP 1 et 4, avenue de Bois-Préau - 92852 Rueil-Malmaison Cedex - France Tel.: +33 1 47 52 60 00 - Fax: +33 1 47 52 70 00 IFP-Lyon BP 3 - 69390 Vernaison - France Tel.: +33 4 78 02 20 20 - Fax: +33 4 78 02 20 13 www.ifp.fr
WATER CRISES IN PALESTINE - HEALTH AND ENVIRONMENTAL PROBLEMS
BY
HASAN S. DWEIK
AL-QUDS UNIVERSITY
Presented at the Conference
Energy crisis, water shortage and climate changes in the Mediterranean area: the involvement of chemistry
Castiglione della Pescaia, Italy
2 - 6 May 2008
INTRODUCTION
Demand for water by Palestinians in the West Bank and the Gaza Strip has been increasing since the 1920s. This could be explained to the natural population growth, the increased number of homes connected to a central water network. The demand for water increased at a greater rate after the Israeli occupation to west bank and Gaza ,in 1967.
However, Israel's tight control of the water sector in the Occupied Territories prevented development that would enable the water sector to meet Palestinians' increasing demand for water. These restrictions and prohibitions are a principal reason for the water shortage and the resultant water crisis.
Israel's water policy in the Occupied Territories benefited Israel in two primary ways:
1. Preservation of the unequal division of the shared groundwater in the West Bank's Western Aquifer and Northern Aquifer.
This division was created prior to the occupation, a result of the gap between economic and technological development in Israel as opposed to the West Bank.
2. Utilization of new water sources, to which Israel had no access prior to 1967, such as the Eastern Aquifer (in the West Bank) and the Gaza Aquifer, primarily to benefit Israeli settlements established in those areas.
For residents of the Occupied Territories, the primary result of the change in the law and transfer of powers over the water sector to Israeli bodies was the drastic restriction on drilling new wells to meet their water needs. According to military
1
orders, drilling a well required obtaining a permit,. The vast majority of applications submitted during the occupation were denied. The few that were granted were solely for domestic use, and were less than the number of wells that, after 1967, had ceased to be used due to improper maintenance or because they had dried up.
The water crisis in the Occupied Territories resulted not only from the restrictions Israel placed on Palestinian residents, but also from Israel's relatively minimal investment in water infrastructure. The neglect in infrastructure was conspicuous in two areas:
1- in construction of infrastructure to connect rural communities to a running-water network,
2- and in maintenance (to prevent loss of water) of the existing networks. .
The water-pipe leaks resulting from improper maintenance led in some instances to a loss of up to 60 percent of the quantity of water supplied. This was true, for example, in Jenin and Gaza.
The conditions for the Palestinians water needs did not improve ,as a result of signing the Peace agreements of Oslo .
From the perspective of the water needs of the Palestinians, the sole "achievement" of the interim agreement of 1995 is the joint understanding to increase the supply of water to the Occupied Territories annually by 28.6 million cubic meters (mcm/year). This addition currently constitutes 10 percent of the overall water supply of the Occupied Territories, and 30 percent of domestic and urban use. This quantity is classified as intended for "immediate needs... during the interim period," i.e., from September 1995 to May 1999. As of June 2000, more than a year after expiration of the interim period, only 16 mcm of the addition were actually produced and provided to the Palestinian population.
The agreement also provides that the Palestinians are allowed to develop an additional 41-51 mcm, which presently represents an addition of 17-20 percent of their overall supply, and 40-50 percent of their domestic and urban use. These quantities are intended to meet "future needs." The agreement does not set a timetable for producing this water, and the source of this additional water is unclear.
2
Joint water Committee
Pursuant to the Interim Agreement, the parties established the Joint Water Committee (JWC), the body charged with approving every new water and sewage project in the West Bank. The JWC is comprised of an equal number of representatives of Israel and the Palestinian Authority. All its decisions are made by consensus, and no mechanism is established to settle disputes where a consensus cannot be attained. This method of decision-making means that Israel is able to veto any request by the Palestinian representatives to drill a new well to obtain the additions stipulated in the agreement.
POPULATION , Demography ,
Population (2005): 4,012,200-WB-GS
– West Bank: 2,531,150 – Gaza Strip : 1,481,050
Area : 6,020km2 -WBGS – West Bank: 5,655 km2 – Gaza Strip : 365 km2
Population density(person/km2): – West Bank : 463.5 – Gaza Strip : 3,945.5
Public water net work : 89.2% - WB-GS – West Bank: 84.1 % – Gaza Strip : 99.3 %
Water consumption 70 L/C/D -WB-GS Public sewerage system : 50.8 %-WB-GS
The Gaza Strip has approximately 1.5 million people in a 365 square kilometer area and this makes Gaza one of the highly densely populated areas on earth. Seventy percent of the people there live below the poverty line. , the amount of water they draw from the aquifer is over 150 mcm ,however the the amount that they can drawn without damaging the aquifer is 55 mcm . close to 30 million cubic meters of waste and sewage is now seeping back into the ground and into the aquifer, highly polluting it. Creating a vast health problems.
a comparison between the people in Gaza and their Israeli neighbors show the discrepancy between water use is one of the Palestinians have about 70 cubic meters per person per year use, where their neighbors right across the way, the Israelis, have an average of 330 cubic meters per person per year.
3
Water RESOURCES :
Palestinian water originates from two sources:
1-Surface water and
2- Ground water.
Surface water is that water which flows permanently in the form of rivers and wadis, or is held in seasonal reservoirs. The Jordan River is an international river basin whose riparians include Lebanon, Syria, the Palestinian territories, and Jordan. In 1953, the Jordan River had an average flow of 1,250 mcm per year at the Allenby Bridge (the main crossing point between the West Bank and Jordan), but now records annual flows of 200 mcm of poor quality water. The reason for this is that, following the June 1967 war, Israel secured control over Jordan River headwaters, destroyed 140 Palestinian water pumps in the Jordan Valley, and diverted Jordan River water through its National Water Carrier, thereby denying Palestinians their historic rights to this river. Israel uses approximately 500 mcm per year of water from this source, amounting to some one-fourth of water consumed in Israel.
Ground water is the primary source of the Palestinians freshwater supply. In the West bank
The three principle underground aquifers of Palestine,are found largely in the West Bank. These mountain aquifer areas have a water saturated substratum 200-600 meters deep. Light blue areas (see map )indicate land with less water, in which the thickness of the saturated subterranean stratum is no greater than 200 meters, with low potential water yield. Violet areas have little or no water.
The mountain aquifers are:
Western Aquifer (1) This supplies Israel with about 340 million cubic meters of water annually, which are used by the Jerusalem-Tel-Aviv area. Palestinians use about 20 million cubic meters a year.
North –Eastern Aquifer (2) This supplies Israel with about 115 million cubic meters a year, largely for agricultural irrigation in the (cooperative settlements) in Galilee.
The Eastern Aquifer (3) . This supplies about 40 million cubic meters annually to the Israeli settlements in the Jordan Valley, and about 60 million cubic meters to the Palestinians.
4
.
Water Consumption among Palestinians and Israelis
The discrimination in utilization of the resources shared by Israel and the Palestinian Authority is clearly seen in the figures on water consumption by the two populations.
Israel takes more than 80 percent of Palestinian water from the West Bank aquifers, accounting for 25 percent of Israel’s water needs. As a result of Israeli policies, Palestinians currently are utilizing 246 mcm annually to supply three and a half million Palestinians in the West Bank (including East Jerusalem) and Gaza for their domestic, industrial, and agricultural needs.
By comparison, Israel’s population, comprised of fewer than six million persons, is consuming 1,959 mcm annually. Thus, on an annual, per capita basis, Israelis consume 340 cubic meters of water, compared to 82 cubic meters consumed by Palestinians—more than four times as much. In addition, the approximately 380,000 Israeli settlers in the West Bank and East Jerusalem and some 5,000-7,000 settlers in Gaza annually consume 65 and 10 mcm, respectively.
Per capita water consumption in the West Bank for domestic, urban, and industrial use is only 26 cubic meters a year, which translates into 70 liters per person per day.
There is a huge gap between Israeli and Palestinian consumption. The average Israeli consumes for domestic and urban use approximately 103 cubic meters a year, or 282 liters per person per day. In other words, per capita use in Israel is four times higher than in the Occupied Territories. To make a more precise comparison, by also taking into account industrial water consumption in Israel, per capita use per year reaches 128 cubic meters - 350 liters per person a day - or five times Palestinian per capita consumption.
The World Health Organization recommends 100 liters of water per person per day as the minimum quantity for basic consumption. This amount includes, in addition to domestic use, consumption in hospitals, schools, businesses, and other public institutions.
5
Features of the Water Crisis in the Occupied Territories
1-Lack of a Water Network
Among those particularly suffering from the water shortage are residents of villages and refugee camps in the Occupied Territories not connected to a running-water network. In the West Bank alone, as of June 2000, the number of such residents amounted to at least 215,000 persons living in more than 150 villages. The principal water source for these people is rainfall, which is collected on rooftops and stored in cisterns near each house. This source meets their water-consumption needs for only a few months, generally from November to May. In the summer, these residents must collect water from nearby springs (if such exist) in plastic bottles and jerricans, and purchase water from private dealers at high prices.
2-Discriminatory and Insufficient Supply of Water
Several municipalities in the West Bank are compelled to implement rotation plans, particularly during the summer, to distribute the little water available. Under these plans, residents in a particular area of the city receive water for a day.
6
The flow is then shut off for several days, while water is supplied to other areas until the sector's turn comes again. Hebron, Bethlehem, and Jenin implement such plans.
This system is made necessary due to the increased demand for water during the hot season. However, while there is increased demand both among Palestinians and among Israeli settlers, Mekorot [Israel's water company] discriminates and increases the amount of water supplied to the settlers, and does not increase, or even decreases, supply to Palestinian towns. Reduction at times when water consumption increases is accomplished by closing the valve of the main water pipelines through which water flows to Palestinian towns.
3-Poor Water Quality
Unlike the West Bank, the worst problem in the Gaza Strip's water sector is not the shortage or irregular supply during the summer, but the poor quality of water flowing through the pipes. The poor condition of the water seriously affects the quality of life of the local residents and exposes them to severe health risks. The sole local water source is the Gaza Aquifer, which provides 96 percent of overall water consumption in the Gaza Strip. Since the 1950s, this aquifer has become polluted and salinated, a process that has worsened with the increased consumption and extraction of water. The main reasons for the pollution and salinization of the aquifer are:
a- "over-pumping,"
b-penetration of untreated sewage, and
c-penetration of pesticides and fertilizers.
Gaza's drinking water crisis was aggravated over the past few years . In addition to the shortage of water supplies to households, the municipal authorities in the Gaza Strip ran out of materials (Chemicals) essential for the treatment of water. the Palestinian Water Authority instructed Gaza's people to boil the water at their homes before using it for cooking or drinking. This includes filtered water, which is widely used in households all over the Strip. Israel's restrictions on movement, which were tightened since 14 June 2007, caused a shortage in hypochlorite, a substance that is commonly used to disinfect and clean drinking water. As a result, the 52 out of 140 water wells had to stop pumping. Water from these wells is too polluted and cannot be safe for human consumption, even after boiling it.
7
as the Israeli government continue to reduce fuel and electrical supplies to Gaza, which disrupts the operation of many water wells, thus affecting the authorities' ability to pump water to the population. People living in high rise buildings particularly lack water supplies since they depend heavily on energy to pump it to their homes. Certain areas in Gaza have not had any water for days.
International Law on Water
How to Achieve sustainability
We identify three main components in order to reach such a solution.
First, the need to reallocate the existing shared resources according to international law.
International law standards should be applied between the parties on the bilateral level. This means an increase of water to the Palestinians over time. Israel is desalination plant to compensate the water used by the Palestinians.
Second, we’re not harming the Israeli current use because the day after the agreement the Israelis will have in their tap in their housesthe same amount of water they used before the agreement. Whenever Palestinians are able to build and take their part or share of water, we will take it.
The third component related to the solution, which we envision, is the importance of desalination. This is why we’re saying that it will not harm Israel because whatever they give Palestinians today, a certain amount, an “x” amount, they will be able to develop an equivalent amount, if not a “y” amount which is greater than the amount they give the Palestinians. Here is why we emphasize the importance of the third party, to come and help the parties achieve such a solution.
Water Issues under the Oslo Accords
The interim agreement that Israel and the Palestinian Authority signed in September 1995 (Oslo 2) includes the most updated understanding on water that has been reached in the peace process framework. It is also more detailed than previous documents. The subject appears in article 40 of the Protocol on Civil Affairs (Annex 3). Israeli officials relate to it as a turning point at which responsibility for the water sector is transferred to the Palestinian Authority. However, this agreement did not significantly change the scope of Israeli control.
8
The point of departure for the understanding on division of water from the shared sources is that the quantity of water that Israel consumes, both within the Green Line and in the settlements, will not be reduced. According to this principle, any additional water for the Palestinians would be produced from previously unutilized sources, and not by re-distribution of existing sources. This means that almost every addition of water to the Palestinians under this agreement must come from the Eastern Aquifer of the West Bank, which, according to the agreement itself, is the only source that had not been fully utilized prior to signing of the agreement.
From the perspective of the water needs of the Palestinians, the sole "achievement" of this agreement is the joint understanding to increase the supply of water to the Occupied Territories annually by 28.6 million cubic meters (mcm/year). This addition currently constitutes 10 percent of the overall water supply of the Occupied Territories, and 30 percent of domestic and urban use. This quantity is classified as intended for "immediate needs... during the interim period," i.e., from September 1995 to May 1999. As of June 2000, more than a year after expiration of the interim period, only 16 mcm of the addition were actually produced and provided to the Palestinian population.
The agreement also provides that the Palestinians are allowed to develop an additional 41-51 mcm, which presently represents an addition of 17-20 percent of their overall supply, and 40-50 percent of their domestic and urban use. These quantities are intended to meet "future needs." The agreement does not set a timetable for producing this water, and the source of this additional water is unclear.
Israel recognized that the Gaza Strip and the West Bank comprise one territorial unit. However, the Interim Agreement stipulates that, regarding water resources, the Gaza Strip will constitute a separate water sector. Other than the small quantity that Israel undertook to sell, residents of the Gaza Strip will have to meet their needs solely from resources located within its borders, i.e., they are not allowed to obtain water from the West Bank. The failure of the Interim Agreement to re-distribute the water resources shared by the West Bank and Israel prevented any "surplus" of water in the West Bank that could increase the supply of water to the Gaza Strip. As a result, the severance of the Gaza Strip and the West Bank continued, further damaging the Gaza Aquifer because of the necessity to continue the over-extraction.
Pursuant to the Interim Agreement, the parties established the Joint Water Committee (JWC), the body charged with approving every new water and sewage project in the West Bank. The JWC is comprised of an equal number of representatives of Israel and the Palestinian Authority. All its decisions are made by consensus, and no mechanism is established to settle disputes where a consensus cannot be attained. This method of decision-making means that Israel
9
is able to veto any request by the Palestinian representatives to drill a new well to obtain the additions stipulated in the agreement.
Israel's control of extraction of water from the shared aquifers is not limited to its veto power in the JWC over new drillings. If a well approved by the JWC is situated in Area C, which is under Israel's complete control, the High Planning Committee of the Civil Administration must also approve the project.
Israeli Views on solving the water crises in Palestine The only viable long-term solution for the West Bank” involves major desalination on the Mediterranean coast (proposed at Hadera), funded by the donor community or by the Palestinians. This assessment and conclusion, which has not been accepted by the Palestinian Authority, is flawed in a number of respects: 1- It fails to address the high costs of pumping desalinated water from the Mediterranean Sea to the West Bank; 2- It fails to acknowledge the fact that desalinated water produced within Israel at the Mediterranean coast would far better be utilized by the near-coastal Israeli population; 3- It ignores the need for a reallocation of the existing regional water resources, to attain an equitable and reasonable allocation between two independent Sovereign States existing peacefully side-by-side; and 4- It fails to recognize Israel’s responsibilities in relation to customary international water law (see below), or to other elements of international law. I
10
ANNEX
Discrimination between Palestinians and Israeli Settlers
Article 27 of the Fourth Geneva Convention of 1949 prohibits the occupying state from discriminating between residents of the occupied territory.* The quantity of water supplied to the settlements is vastly larger than is supplied to the Palestinians. Similarly, the regularity of supply is much greater in the settlements. This discrimination is especially blatant during the summer, when the supply to Palestinians in some areas of the West Bank is reduced to meet the increased demand for water in the settlements Annex
Prohibition on altering legislation
Article 43 of the 1907 Hague Regulations prohibits the occupying state from changing the legislation in effect prior to occupation. The military orders that Israel issued regarding the water resources and the supply of water in the Occupied Territories significantly changed the legal and institutional structure of the water sector. The water resources in the Occupied Territories were integrated Three instruments, all of which constitute evidence of customary international law, are of particular note in the latter respect: First : The Helsinki Rules on the Uses of the Waters of International Rivers, adopted by the International Law Association in 1966; Second: The Seoul Rules on International Groundwaters, adopted by the International Law Association in 1986; and Third: The Convention on the Law of the Non-Navigational Uses of International Watercourses, adopted by the United Nations General Assembly and opened for signature in 1997.
11
12
13
14
Major Aquifers .1- western Aquifer 2-North East Aquifer 3-Eastern Aquifer
15
16
Photovoltaics – current status and future perspectives
Francesca Ferrazza - Eni S.p.A.
1. - Introduction
The direct conversion of sunlight into electricity is a very elegant process
to generate renewable (and sustainable) energy from the most abundant
and promising source of energy- the Sun. This process, usually referred
to as photovoltaic solar energy (PV), is inherently modular and quiet, and
has a huge potential. Therefore it has a broad range of applications and
can contribute substantially to our future energy needs. Although the
basic principles of PV have been discovered in the 19th century, it took
until the 1950s and 1960s before solar cells found practical use as
electricity generators. This was mainly triggered by the early
development of silicon semiconductor technology for electronic
applications. Today, a range of PV conversion technologies is available
on the market and under development in the labs.
Complete PV systems consist of modules (also referred to as panels),
which contain solar cells, and the so-called Balance-of-System (BoS).
The BoS mainly comprises electronic components, cabling, support
structures and, if applicable, electricity storage or optics & sun trackers
(the latter for concentrator systems). The BoS costs also include labour
costs for turn-key installation.
Although reliable PV systems are commercially available and widely
applied, ambitious further development of PV technology is crucial to
enable PV to become a major source of sustainable energy and to
strengthen the position of the European PV industry sector. In fact,
despite a decade of unprecedented growth at approximately 40% per
year, photovoltaics only represents a marginal share of the world’s
energy mix. The current price level of PV systems, which has dropped
substantially compared to its levels of only ten years ago, allows solar
electricity to compete with peak power in grid-connected application and
with alternatives like diesel generators in stand-alone applications, but it
does not yet allow direct competition with consumer or wholesale
electricity prices. A drastic further reduction of turn-key system prices is
therefore needed - and fortunately possible.
2. – Market aspects
The market for PV modules has increased by an order of magnitude in
the last decade, and at least by 40% per year in the last 5 years, with a
record 60% or more in 2007. It has now reached a yearly production of
3-3,5 GW, depending on the source, and an installed capacity of about 8
GW World-wide [1] driven mainly by two large well established
subsidised markets - Germany and Japan. Newer opportunities are now
arising in Spain (the fastest growing market in 2007), Italy and the United
States (particularly California), and are expected to give larger and
growing contributions in the next years. At the same time, manufacturing
costs and selling prices have decreased at about 5% per year, and solar
cell efficiency has greatly improved, with best performers now producing
full size cells - not lab samples! – well into the 20% range. Other
important steps ahead include the drastic reduction of the energy pay-
back time. Once considered (wrongly) as almost infinite, it has been
clearly shown in different studies, such as the one published by IEA-
PVPS [2], that complete systems installed in Southern Europe have paid
their energy duty back after less than two years All this did not happen
by chance: it is the result of the combination of market assisting
measures, research, development and demonstration activities, with
both private and public support.
0
500
1000
1500
2000
2500
3000
3500
4000
00 01 02 03 04 05 06 07
MW
Japan
Europe
United States
Rest of theWorld
Fig.1. - Photovoltaic production World-wide by region (source: Photon
International)
Wafer-based crystalline silicon has been the dominant technology since
the birth of photovoltaics. It is abundant, reliable and scientifically well
understood as it has enjoyed the knowledge and technology originally
developed for the microelectronics industry. Progress in silicon wafer-
based technology with time has determined the price-learning curve of
PV modules - a decrease of about 20% for each doubling of capacity –
driven by market size and technology improvement. Silicon wafer based
technology has represented 85-95% of the global PV market production
in the last decade, with a growing trend. In the last five years, the share
was over 90% broken into more than 50% multicrystalline silicon,
around 35% single crystalline, and less than 5% ribbon technology. In
2007 however the share has slightly decreased, allowing thin films to
gain over 10% of the production share.
It is important to mention that the incumbence of wafered silicon
technology has well established roots in technology, manufacturing
ability and capability in cost reddictions: for instance, amongst the
largest areas of improvement, the thickness of silicon wafers has
decreased from 400 μm in 1990 to 240 μm in 2005 and around 200 μm
nowadays, cell area has increased in surface from 100 cm2 to 240 cm2,
and modules have improved in efficiency from about 10% in 1990 to an
average of about 13 -15 % today, with best performers up to above
17%. Further, manufacturing facilities have increased from the typical 1-
5 MW/year size of 1990 to several hundreds of megawatts per year
today, with the expectation of GW-sized factories to be seen soon.
In the meanwhile, other technologies are gaining larger volumes of the
market – specifically, as mentioned, thin films and ribbon technologies,
taking advantage of the growing demand for PV products and of a raw
silicon shortage which has been creating some tension on the availability
of silicon feedstock for wafer manufacturing for the last few years. Many
initiatives are under way in thin films – and other technologies too such
as concentrators, or organic solar cells – as witnessed by the interest in
equipment vendors to supply turn-key plants.
In a nutshell, market assistance measures such as the feed-in tariffs
have allowed demand to grow, and the resulting silicon supply
bottleneck has induced faster technology improvements and cost
reduction measures, while allowing different technologies to begin
industrial scale up.
The challenge for the whole PV sector is to reduce manufacturing costs
and increase volumes in order to provide electricity at prices comparable
to conventional sources ( and therefore being capable of getting rid of
incentives) and to represent a much larger share in the energy mix
compared to the negligible numbers of today (below 0.1% of the
electricity supply World-wide)
The challenge has been represented in a price roadmap, developed by
the European PV Technology Platform [3] and shown in Fig.2.
0
1
2
3
4
5
6
2004 2010 2020 2030 2050
Pric
e BOSModules
€/W
Fig. 2. – Roadmap for the Photovoltaic Sector (www.eupvplatform.org)
The roadmap has been intentionally represented in terms of prices,
because that is what is perceived by the public. This obviously means
the expected costs are much lower. If this is the case, in the period 2010
– 2020 PV electricity will be competitive with retail prices from the grid
(starting from the sunniest regions) and peak load generation. Later, the
electricity can be competitive at wholesale level, that is with all
conventional electricity production today.
From what we know today, crystalline silicon based technology has the
capability to continue following the established price experience curve,
with direct production costs expected to achieve significant reduction to
around 1.00 €/W in 2013 and 0,75 €/W in 2020 and even lower in the
long term. This is true for other technologies as well, which however are
yet less developed, and in the case of thin films need to overcome
limitations such as low efficiency (<10%), stability, the use of toxic or
rare materials, complexity in some cases, the need for expensive
equipment. If this can be done, thin films are for instance well placed to
take advantage of low material usage implying potential low cost,
manufacturing sequences with cell and module at the same time, high
industrial potential and good aesthetical aspect.
This will happen if R&D efforts are directed to address the most critical
issues and the technology areas most likely to allow continued progress
of PV towards full sustainability.
In the following paragraphs, the main pv technologies will be reviewed
with an eye to possible long term developments.
3. Crystalline silicon technology
Crystalline silicon modules are typically produced in a complex and
articulated manufacturing chain, all of which have greatly improved over
the years – and which still have margins for further improvements.
In the first step ingots (mono or multi- crystalline) or ribbons are grown
using pure silicon as the starting material for a melting and crystallization
process which produces crystals of high purity and variable degree of
crystal perfection. The starting material, pure poly silicon is produced by
a complex sequence of energy consuming and waste producing
processes, in large and expensive plants. This material is currently
representing the bottleneck of production expansion, and causing big
tensions on supply and prices. Improvements are expected as new
capacity is being installed, but the large investments required, the long
commissioning times for the installations and the fear of overcapacity or
possible breakthroughs e.g. in solar grade silicon production with lower
prices have postponed the shortage relief. The total silicon consumption
for the PV industry has eventually exceeded that of the electronic
industry for the first time in 2006, with a value of over 20.000 Tons.
Silicon crystals are cut into thin wafers using multi-wire saws, a
technique which was developed specifically for PV and which is now
common in the semiconductor industry as well. A great deal of progress
has been made on equipment and process control aspects, and on
introducing reduced diameter wires several hundred kilometre long for
reduced kerf loss.
This step is evidently not required for ribbons, apart from edge trimming
and cutting the wafers from the sheets. This is considered to be a big
advantage over ingot technology in terms of costs. However other
complications in the technology have prevented a wider spread of
ribbons, which still represent only a few percent of the market.
The production chain from raw material to wafers is sketched in Fig. 3.
IngotIngotBlocksBlocks
WafersWafersFeedstockFeedstock
IngotIngotBlocksBlocks
WafersWafersFeedstockFeedstock
ig. 3 Process flow from silicon feedstock to wafers for the case of
ulticrystalline silicon
he wafers are processed into solar cells, the majority of which have a
iode structure, as sketched in Fig 4, characterized by a thin diffused
oped emitter, screen printed front and back contacts and a front surface
ntireflective coating. Prior to the effective cell manufacturing step, a
rom the wafering step, and provides surface
tructuring which reduces reflectance losses. The cell manufacturing is
F
m
T
d
d
a
chemical treatment of the silicon wafers removes dirt and damage from
the surface coming f
s
therefore rather simple in itself. The major effort devoted to improvement
over the years have been on one hand the introduction of the silicon
nitride antireflective coating, capable of passivating defects in
multicrystalline silicon as well, and the ability of processing thinner,
larger wafers at increasing yield.
Metal contact
n
p
Electroncurrent
hole
P-n junction
Metal contact
Metal contact
n
p
Electroncurrent
hole
P-n junction
Metal contact
Fig 4. Principle of operation of a silicon solar cell
This means the automation of the processing lines has become much
less invasive on the brittle wafers, and handling has become much less
of a trouble. Also, cell processing has had to deal with wafer bowing
because of the different thermal expansion coefficients of silicon and
luminium (the back contact).
ells are then individually sorted and classified according to their
f wafered silicon technology lies in the
omplexity of the manufacturing and supply chain, which involves rather
owever, this is exactly what has happened so far – and
a
C
illuminated electrical parameters and electrically interconnected in
strings, which are then encapsulated to form a module, which is
designed to be weather proof and produce electrical output for more
than 25 years.
The obvious critical aspect o
c
different industry sectors – metallurgy, electronic components, building,
power conditioning. Most sceptical observers also point out the inherent
difficulty of reducing the costs in a cell and module manufacturing
process which need to handle globally a number of wafers in the billion
pieces range. H
those working in the silicon sector are confident it can continue
happening.
The continued success of silicon technology needs a continued progress
in both reduction of material consumption and increase of device
efficiency. Other goals relate to reduced energy content, environment
aspects, standards and manufacturing aspects such as process
automation and control.
The availability of abundant, low price silicon feedstock, in the 10-20
dicated to the solar sector is being carried out in
any different ways. Different processes have been studied and are
precursor
rmation and dissociation, have the potential to substantially reduce
the ingot technology considered. Part of it
an be recycled, at some expense, and part is lost as silicon powder or
€/kg for long term is a very important point for the possibility of silicon
technology to progress as expected in terms of cost reduction.
Development of new, lower energy-intensive techniques for silicon
feedstock preparation de
m
currently under development, all of them with the aim of reducing cost
and complexity while increasing availability. Some processes deal with
the direct purification of metallurgical silicon, with no need for
fo
costs and have not so far reached technical maturity despite
encouraging laboratory results and long lasting research activities. Other
approaches target cost reduction potentials in the existing processes,
and are in part being already utilized for commercial “solar grade silicon”,
which is cheaper than the semiconductor grade poly, without however
fundamental changes. Fluidized bed reactors of various kinds are also
under development for the decomposition of monosilane precursors, and
vapour to liquid approaches.
Besides feedstock prices, another key point is that even considering
internal recycling, as 60% or more of the starting material is lost during
processing.
In fact about 15% of the crystallized silicon ingots doesn’t reach the
wafering stage, depending on
c
unusable scrap. A great deal of work is going into this part of the
process, because of the improvement margins for better silicon
utilization through recycling, and for reduced rejection.
nother rough 40 % of the material is lost as dust and other yield losses
nology, which is
s well below 5%.
ecycling is already being used, with the effect of alleviating the very
g the specific consumption even at
oderately high feedstock prices, to fulfil the cost targets for the long
A
in the wafering process, which is obviously a very delicate point from the
processing, equipment and recycling possibility point of view. Besides
improvement in current wafer technology with more automated, more
controlled equipment and thinner and thinner wafers, a certain focus is
being put into alternative wafering technologies, such as e.g. laser
assisted cutting. This issue does not apply to ribbon tech
in fact seen as one of the potential evolutions of wafer based silicon
technology, especially for long and medium term. Also, wafer substitutes
or equivalents on low cost substrates are seen as a possibility to
overcome ingot/wafer manufacturing limitations, especially given the
increasing challenges to be faced for wafer thickness below 150 μm, in
terms of manufacturability, and optimal cell processing.
Finally, about 10% is lost as broken wafers between wafer handling in
the wafer/ribbon manufacturing stage and the subsequent cell process.
Cell manufacturing needs to improve automation to reduce breakage in
absolute numbers, and in order to allow the introduction of even thinner
wafers, necessary to achieve the cost reduction targets, with the
achievement of manufacturing (mechanical) yields losse
R
heavy losses indicated above.
The whole silicon production chain is expected, by virtue of Research
and Development actions taken to the manufacturing stage to move from
the present 10 Tons/MW consumption figure, to below 3 Tons/MW in the
long term
It is however clear that while the short and probably medium term targets
can be achieved by lowerin
m
term both feedstock price and silicon consumption will have to decrease
substantially.
Another important aspect is cell (and module) efficiency. A great deal of
progress is undergoing in this area. Just as an example, the lab world
nd using vacuum technologies for the deposition of metal
er
erforming equipment, by introducing a back Al layer which provides the
step. This latter step alone has allowed the transition from
rid developed at
oncentrator technology, and now
onverted to large area for flat plate use. All three use single crystalline
record on 1 cm2, 24,7%, is now not so far away, considering the best
commercial cells range in the 22-23% range, on a surface of 225 cm2!
Laboratory cells have been traditionally realized on small areas, in clean
room facilities a
contacts.
Most of the development work in recent years on commercially available
devices, based on screen printing technology for contact formation, has
focussed on improving the manufacturing sequences with high
p
electrical contact and some carrier confinement and, in the case of
multicrystalline silicon, by introducing H passivation in the SiN ARC
formation
about 13% efficient cells to greater than 15% efficiency, had been
demonstrated at lab level long ago, but was only introduced in most
manufacturing facilities when reliable processing PECVD equipment
become available, which was shortly after year 2000.
Current state-of-the-art manufacturing processes are realized in non
cleanroom classified areas. Automation has been introduced in most
manufacturing lines, but substantial progress is needed in view of the
further decrease in wafer thickness.
Only three high efficiency processes have so far been scaled up to
production level, namely the Laser Grooved Buried G
UNSW, Australia and scaled by BP Solar in Spain, the HIT cells
developed by Sanyo by replacing the diffused P doped emitter with an
amorphous silicon layer, and the Back Contact cells developed by
Stanford University for use in c
c
silicon, while the majority of screen printed cells use multicrystalline
silicon wafers.
Commercial module efficiency values (total outer dimensions) are in the
12-14% range for the screen printed modules, and 15-17.5% range for
the best performers.
It is expected that more device designs capable of achieving efficiency
values in the 18+% range will be transferred to production scale.
Promising candidates for such developments are all-rear contacted cells
f different kinds, on both single and multicrystalline substrates, which
ch will influence the cell architecture quite
by this time will have
o
have the added advantage of reducing cell interconnection complexity in
automated sequences. Different contacting schemes will also most likely
be introduced, whi
substantially. As wafers decrease in thickness in fact, the present full
aluminium rear contact of the cell will have to be replaced by local
contacts, both for bow prevention and for reduced recombination at the
metal – silicon interface. An example of different cell structures including
enhanced passivation are the c-Si/a.-Si heterostrucure cells, which are
already at commercial level (Sanyo HIT modules) with best cell
efficiency exceeding 22%. Examples of novel promising structures
include laser fired contact cells. Also, more effective means of contact
passivation will be introduced, and material quality will be enhanced
during processing for lower starting quality materials, and kept as high
as possible for high quality materials. As market size grows and the
consumption of all materials becomes relevant, it will also be necessary
to reduce or avoid totally the use of silver pastes, now consumed at an
average of 80-90 kg/MW, or some 130 Ton/year.
In the long term, it is expected that silicon technology will still play an
important role in the PV sector, although a higher degree of uncertainty
exists in terms of all the numerical parameters identified, and, more
importantly, on the cell and module architecture and component
materials after 2020, when the market size is expected to be in the 30
GW/year range. It is likely that silicon technology
incorporated aspects which are now related to novel or emerging
pply chain. There are three principle
organic thin film technologies, amorphous silicon (in various
onfigurations, including amorphous microcrystalline heterostructures),
Copper indium (gallium) selenide (CIS or CIGS),
ll of which have demonstrated large area, reasonably efficient solar
technologies, and that new materials will also be included in the
processing sequences. Also, the distinction between cells and modules
may not hold any longer, and the wafer or active layer may be so thin
that true distinctions between wafer and thin film technologies may no
longer be appropriate. It is in fact clearly expected that module efficiency
will be able to rise higher than the current lab record. This may only be
possible by incorporating technologies at the periphery of the device
such as up or down converters.
4. – Thin Films
Thin-films are suitable candidates for low-cost photovoltaic modules
because of reduced material consumption and predicted manufacturing
advantages due to a shorter su
in
c
cadmium telluride and
a
modules and which have a number of general principles in common. In
each of the thin film technologies, only very small amounts of
semiconductor materials (typically 0.001 mm thick) are used and the
materials used for encapsulation, such as glass and plastic, are
relatively inexpensive. The availability of large-area deposition
equipment developed in other industry sectors (such as the flat plate
display) and related process technology as well as strong synergies with
the architectural glass industry and the flat panel display industry offer
significant opportunities for high-volume low-cost manufacturing. The
monolithic series connection used for thin film PV simplifies module
assembly when compared to series connection by tabbing and stringing
commonly used with crystalline silicon solar cells. In addition, flexible
lightweight modules can be produced using thin polymer or metal
substrates and roll coating techniques. Currently, the energy pay-back
time of thin-film modules is short, around 1.5 years in Central Europe,
with a long term potential of below 0.5 years.
These features imply that the cost reduction potential for thin-film
technology is very high and it is thus capable in the longer term, of
extending the PV learning curve beyond the point that can be reached
by crystalline silicon technology
At present three competitive inorganic thin-film technologies, based on
thin film amorphous/microcrystalline silicon (TFSi), polycrystalline CdTe
and Cu(In,Ga)(S,Se)2 also known as CIS are under widespread
rea high-volume production lines. This
superstrate, and applying thin metal contacting layers in
ysical vapour deposition methods such as sputtering,
vaporation , plasma – cvd and many other variations. The beauty of
refore
ia
le,
investigations. The high efficiency potential of each technology has
already been proven in the laboratory. Each of these technologies has
demonstrated its capabilities in pilot production lines and is now being or
has been transferred to large-a
transfer is not straightforward since there is a lack of maturity of many of
the required large-area production processes and the related production
equipment.
The thin-film PV industry is taking off and the challenge is now to scale
up fast enough and establish a significant presence in the PV
marketplace.
Thin film modules are generally produced by applying a thin (1-2
microns) layer of active semiconductor material directly on a glass
substrate or
general directly on the glass – but also on patterns on the film itself. The
deposition techniques for all materials are in general under vacuum by
chemical or ph
e
such a technology is, besides a very low material content and the
an inherent possible low cost, the possibility of simultaneously
fabricating cells and modules, by depositing the film and patterning it v
a laser. Handling therefore becomes transporting of large glass sheets –
much less cumbersome than individual brittle wafers. However, the true
advantage of thin films is only just showing up now at commercial sca
despite many decades of intense research work, and for a number of
good reasons. Efficiency of thin film modules, to start with, is nowhere
close to that of crystalline silicon modules. At commercial scale,
areas, average module efficiency is below 10%, and manufacturing
yields not up to the 90%+ reputation of silicon wafer based technology.
As mentioned, however, the trends show thin films growing.
It is clear that production equipment plays a crucial role in the reductio
of cost. Standard equipment with well-defined processes needs to be
developed enabling higher throughput, improved up-times and improved
yield. Equipment manufacturers will play a vital role in this developm
and it is important to exploit synergies with existing industries where
possible. Productivity parameters such as process yield, throu
on large
n
ent
ghput and
vailability of production equipment can be improved by the introduction
e
cted
ion
d
lding up the module.
sses need to
e developed both for recycling during production and for end-of-life
a
of adapted process control and process optimization. To improve both
production yield and efficiency and to assure the quality of the final
products, improved quality assurance procedures and in-line production
monitoring techniques, need to be further developed. Whenever possible
the integration of subsequent production and processing steps into on
line and similar environmental conditions should allow for more efficient
and cheaper production. A recent feature of the thin film sector is the
direct interest of some equipment vendors in stepping in the PV arena
and selling turn key plants – tools and process together. This is expe
to have an impact.
The other main areas of development required to overcome present
limitations are in the efficiency and reliability improvement
At basic research level this implies a better understanding of the relat
between the deposition processes, the electronic material properties an
the resulting device properties, and the improvement in the quality of all
individual layers bui
Finally, as with any new product, dedicated recycling proce
b
recycling. Though the energy payback time is already favourable, a
further reduction to less than 0.5 year is possible.
5. – Other technology related aspects
ent.
f the
ecific consumption of
ilicon, the major cost saving factor of PV technology. An increase of 1%
s fixed, is able to
duce overall costs/W by about 5% (compound growth rate), as shown
Cell and module efficiency directly contribute to the overall €/W cost (and
price) of a PV module, and are historically an area of great developm
Increasing the efficiency of the solar cells and the power density o
modules is, together with the reduction of the sp
s
in efficiency alone, keeping the other cost component
re
in the simulation of Fig 3, in which direct costs have been kept constant,
starting from a 2€/W base case at 15% efficiency.
€/W
1
1,5
2
2,5
dire
ct c
ost
0
0,5
15 17 19 21 23 25 27
efficiency (%)
Fig 3. Sensitivity of cost /W as a function of efficiency.
The consumption of material in general, which directly influences costs
but also availability and environmental issues, needs to decrease
ubstantially. In the silicon wafer or ribbon manufacturing, it is expected
at recycling of silicon scrap and dust will be maximised, together with
cutting phases.
urther, all chemicals for cleaning and etching, will be reduced in terms
s
th
slurry recovery and re-use of silicon powder from the
F
of specific consumption and eventually eliminated, and it is expected that
the module itself, the aluminium frame represents the largest energy
f standardization, energy consumption, and optimised
whole production
hain from crystallization to module assembly.
t base case of 100 MW
ear plant will grow to 500 MW/year in the short term, and probably an
equipment will reduce energy consumption. In the crystallization
process, re-usable crucibles may be an option to reduce a cost which
will have an increasing weight in €/kg, considering the single-use
characteristics of present crucibles.
Energy intensity of the processes contributes to the energy pay back
time of modules. Current silicon feedstock production is energy
intensive, around 150 kWh/kg. Together with the low silicon utilisation,
this leads to a module energy pay-back time between 1.5 and 4 years,
which although much shorter than the module lifetime, needs to
decrease.
In
containing component, 30 €/kg, so long term module development will
need to be frameless or with a non aluminium frame.
Investment costs represent a non negligible part of the cost breakdown
of crystalline modules, and should be reduced while equipment improves
in terms o
production volume. It is expected that specific investment costs will
reduce from the 1-2 M€/MW of current manufacturing facilities to less
than 0.5 M€/MW in the long term, if considering the
c
Scale factors are as important in achieving the required level of progress
than all of the different steps discussed earlier. EU funded studies such
as MUSIC-FM and its recent recalculation have shown the feasibility of
large scale plants up to 500 MW/year, already in times when the total
market was just over 100 MW globally, showing the associated volume
benefits as well. It is expected that the curren
/y
order of magnitude higher in the medium term. Equipment will then be
quite different from the fragmented single-process tools of today, loosely
connected by some custom – made automation. Instead it is likely that
each single line will have multiple processes integrated and that batch
processes will tend to disappear. Module assembly, for instance, will turn
into automated sequences in which the encapsulating materials/sheets
will be fed in on reels and spools, as much as possible. Evidently, major
efforts are needed to reach such progress.
Another important aspect related to both process technology and
equipment design is the need for yield management and process control
techniques embedded in the tools, which will have to provide accurate
and reliable means for avoiding yield losses in manufacturing and
contributing to overall improvement.
From this point of view it is expected that standards in equipment and in
For PV to become widely adopted
t the GWp scale with a large production workforce and components
equipment and the process of manufacture, include the
roduct safety for system installation and most importantly any long term
ltaic technologies are
aining interest and importance.
he main areas of interest are concentrating PV technologies, in
characterization techniques will be developed or implemented if already
available.
Despite the clear focus on cost reduction due regard should also be
given to product and process safety.
a
distributed on millions of commercial and domestic roofs, then safe
systems must be inherent in future products. Safety must start with the
materials,
p
fire and health aspects of unattended PV systems
6. Advanced and emerging technologies: the role of nanotechnology
Besides silicon wafers and thin films, other photovo
g
T
combination with very high efficiency cells, organic and high
efficiency/nanostructured solar cells.
Concentrating solar PV is not a new idea, as it has been under
s are moving towards commercial
h more attractive than in the past.
the potential for very large throughput - reels of kilometre long flexible
dically
ifferent from the planar hetero- or homojunction solar cells. The
generic idea behind these concepts is the existence of nanosized
development since the beginning of research in the sector. However
recently a number of initiative
application. The progress in high efficiency cells, with multijunction III-V
(GaInP/GaInAs/Ge) material based cells above 40% at lab scale, makes
the economics of concentrators muc
Concentrator technology is in principle a simple option, because the
expensive complicated cell manufacturing only needs to address very
small cells, the rest of the work being assigned to lenses which focus the
sunlight on the cell. However, system design and integration is
complicated because the Sun needs to be tracked and alignment
aspects are crucial. System complication and reliability issues have so
far hindered a widespread use of concentrating PV. But this situation
may change as well in the future, as more companies get to the market.
A completely different approach, which may lead to substantial
improvements in widespread diffusion of PV is the use of different (or
new) materials, such as organic compounds, polymers and nanosized
structures, in new kinds of device configuration using new types of
treatments for e.g. light confinement . The obvious source of inspiration
is
plastics, based on the experience of photographic films or other plastic
products - providing an ultimately inexpensive manufacturing option for
PV. In other words, manufacturing technologies which include ink jet
printing, spin coating, rollo to roll printing, which can provide the low
costs and the large volumes required for the Terawatt challenge.
Organic solar cells have been a subject of R&D-efforts already for a long
time because of the potentially very low cost of the active layer material,
the low-cost substrates, the ease of up-scaling and the low energy input.
The breakthrough for solar cells incorporating an organic part in the
active layer came with the advent of concepts which were ra
d
domains resulting in a bulk-distributed interface to increase the exciton
dissociation rate and thereby the collection of photogenerated carriers.
Within this class one can distinguish between the hybrid approach in
which there is still an inorganic component (e.g. the Graetzel cell) and
full-organic approaches (e.g. bulk donor-acceptor heterojunction solar
cells). The main challenges in this field are related to increase of
efficiency, stability improvement and the development of the roll-to-roll
technology. Within this field Europe has built up a world-leading position
both in R&D and first industrial up-scaling efforts. Moreover Europe is in
an excellent position to remain at the cutting edge of these technologies
because of its strong position in related fields like organic electronics
and organic memories.
Most of the other novel PV-technologies suggested so far can be
categorized as high-efficiency approaches, which can be divided
between approaches which are modifying and tailoring the properties of
the active layer to match it better to the solar spectrum versus
approaches which modify the incoming solar spectrum and are applied
at the periphery of the active device (without fundamentally modifying
the active layer properties).
basic relation between output current and
In both cases nanotechnology and nanomaterials are expected to
provide the necessary toolbox to bring about these effects.
Nanotechnology allows introducing features with reduced dimensionality
(quantum wells – quantum wires – quantum dots) in the active layer.
There are three basic ideas behind the use of structures with reduced
dimensionality within the active layer of a photovoltaic device. The first
one aims at decoupling the
output voltage of the device. By introducing quantum wells or quantum
dots consisting of a low-bandgap semiconductor within a host
semiconductor with wider bandgap, the current should increase while
retaining (part of) the higher output voltage of the host semiconductor. A
second approach aims at using the quantum confinement effect to obtain
a material with a higher bandgap. The third approach aims at the
collection of excited carriers before they thermalize to the bottom of the
concerned energy band. The reduced dimensionality of the QD-material
tends to reduce the allowable phonon modes by which this
thermalization process takes place and increases the probability of
harvesting the full energy of the excited carrier. Several groups in
Europe have built up a strong position in the growth, characterization
and application of these nanostructures in various structures (III-V, Si,
Ge) and also on the conceptual level ground-breaking R&D is being
performed (e.g. the metallic intermediate band solar cell).
Tailoring the incoming solar spectrum to the active semiconductor layer
relies on up- and down-conversion layers and plasmonic effects. Again
nanotechnology might play an important role in the achievement of the
required spectral modification. Surface plasmons have been proposed
as a means to increase the photoconversion efficiency in solar cells by
shifting energy in the incoming spectrum towards the wavelength region
where the collection efficiency is maximal or by increasing the
rkshops, projects witnesses the great interest
ido Donegani of Novara, to the study of
absorbance by enhancing the local field intensity. This application of
such effects in photovoltaics is definitely still in a very early stage, but
the fact that these effects can be tailored to shift the limits of existing
solar cell technologies by merely introducing modifications outside the
active layer represents an appreciable asset of these approaches which
would reduce their time-to-market considerably.
It is evident that both modifications to the active layer and application of
the peripheral structures could be combined eventually to obtain the
highest beneficial effects.
Of course the route to optimizing a new, scalable efficient technology is
still long: cell efficiencies in the case of polymer PV are just a few
percent and stability of the materials – and repeatability of realization
techniques all but solved issues.
In any event the whole area of novel and emerging technologies is
gaining momentum in research programmes World-wide: an increasing
number of publications, wo
in developing new features and new technology in PV. At Eni we have
recently started a broad and intense programme on organic and
nanostructured PV, devoting part of one of our research centres, the
Centro di Ricerche Eni Istituto Gu
new energy technologies and establishing important partnerships, such
as the Solar Frontier programme with MIT, and many others in Italy and
Europe.
6. System aspects
Photovoltaic systems can be implemented in a wide range of
applications, sizes and situations and to meet a wide range of power
needs.
At system level requirements are for a reliable, cost-effective and
ttractive solution to energy supply needs.. This means pursuing
osts at the component and/or system level,
crease the overall performance of the system, improve the functionality
ally, PV systems are divided into two major categories
s fed into the grid. It should
e noted however that, whilst most large ground based systems fall into
a
solutions that can reduce c
in
of and the services provided by the system.
Tradition
depending on whether they are connected to the electricity grid system
or are operated in an off-grid configuration. In turn, the grid-connected
systems can be divided into central systems, which feed all the electricity
generated into the grid, or dispersed systems where the electricity goes
to meet local loads first with only the exces
b
the first category, building related systems of all sizes can be operated in
either mode, depending on the financial arrangements. The off-grid, or
stand-alone, systems can also be divided into professional applications
(e.g. telecommunications, remote sensing) and rural development
applications (e.g. irrigation, lighting, electrification of health centres and
schools). Consumer products are a special category in which the PV
cells are integrated into a product to provide the required power supply.
Whilst this has been an important market for PV, especially in terms of
public awareness, the developments in this area are driven by
commercial needs for new product development. These systems are not
considered in this strategic research agenda, which looks at the
research needs for widespread use of PV as a general energy supply
technology.
Because of the wide variation in system applications, it is not possible to
give definitive values for system costs, but indicative values can be
provided as examples. The module has traditionally been the most costly
component in the system, typically accounting for 50-70% of the costs at
system level. However, this varies considerably with application and
system size, since the relative impact of the Balance of Systems (BoS –
ower conditioning, mounting structures, cables, switches etc) and
Wh cost and the Wp
ost would not be feasible here. The target price for the non-module
p
installation costs will vary substantially. In order to meet the cost targets
required for a high penetration of PV technology into the energy supply
market in the 2020-2030 time period, substantial and consistent system
level cost reductions must be made alongside those for the PV module.
The system level costs can be broadly divided into those for BoS
components (whether part of the energy generation and storage system
or components used for control and monitoring) and installation
(including labour). Whilst it can be generally stated that there is scope for
cost reduction at the component level, it is also of major importance to
address installation issues by harmonising, simplifying and integrating
components to reduce the site-specific overheads.
It is usual to express cost targets for PV systems in terms of Wp or kWp
levels. Ultimately, at the system level, the cost comparison must be
made between the unit cost of the electricity generated from the PV
system and from the alternative energy source(s) for that application.
Clearly, both these values will vary with application and system details
and a full treatment of the relationship between the k
c
aspects of a typical PV system has been set in EU-related work [3] at 1
€/Wp for 2010 and <0.5 €/Wp for 2030 and beyond. Taking a reasonable
profit margin of 20%, this results in costs of 0.8 €/Wp and <0.4 €/Wp,
respectively (all excluding VAT). These numbers have to be interpreted
with utmost care since they may vary substantially with system type
(roof-top, building integrated or ground based), with module efficiency
and with the country involved. Taking into account the targets for the
module cost, this implies that the kWh cost of PV generated electricity
will be comparable to the consumer tariff in most of the European
countries in the period 2015-2025 depending on the local irradiation, so
making PV a cost effective alternative. These cost targets for grid-
connected systems provide a useful reference and have been retained in
determining this research agenda, but it should also be recognised that
the condition of cost-effectiveness will be met at other Wp costs for
different applications.
Consideration of typical BoS costs for current systems illustrates the
challenge facing the research in this area. Studies in Germany, the
Netherlands and the UK indicate BoS prices (including components and
installation) of 1.6 – 2.5 €/Wp for building mounted systems on domestic
properties. Lower costs can be obtained for large ground mounted
systems, where the effects of component standardisation can be seen in
e reduction of costs for both mounting systems and labour. Very recent
systems with
2% efficient modules mounted on a frame) to 1.5-2 (in the case of
th
(2006) information from Germany indicates that turn-key systems have
been realized at low BoS-prices between 0.85 and 1.2 €/Wp (for large
ground-based and small roof-top systems, respectively).
The BoS costs are made up of both power related and area related costs
(e.g. the cost of the mounting structure is dependent on the area of the
array). In the latter case, these costs are highly dependent on the
efficiency of the module used and so the cost goals are more
challenging for lower efficiency modules. Currently area related costs are
significant and range from 0.6 (in the case of domestic PV
1
ground-based large area PV systems with 12% efficient modules) times
the power related costs. Increasing module efficiency can, therefore,
help significantly in achieving the system related goals.
The relationship between kWh cost and Wp cost at the system level is a
function not only of the initial capital cost of components and installa
but also of the lifetime of all components, the sustained performance of
the system over its lifetime and of any aspects of multifunctionality or
added value that are realised. Moreover, it is dependent
tion,
on the energy
roduced by the modules per Wp of installed module power (this is
t assisted measures, this allows for strong
arket growth. However, PV electricity costs need to fall even more, for
e technology to be deployed at very large scale – which is not yet the
he main technologies in the field have been revised and the main
g direct costs as shown in Fig 5. Wafer costs are expected to
p
related to the module behaviour under non-standard conditions, such as
higher temperatures, lower light intensities, low angles of light incidence,
spectral variations, etc.).
7. Conclusions
PV technology is improving in performance and reducing its costs. In
turn, together with marke
m
th
case.
T
issues for each one have been addressed.
From the point of view of market leader silicon wafered technology,
technical improvements identified in the previous sections, in connection
with appropriate factory scale-up and integration, are capable of
reducin
decrease up to 50% in the short term, and module costs to become a
fraction of the entire cost in the long term.
However, this is a very aggressive forecast, which will be possible only if
a large effort is put in the activities described previously to reach all the
technical goals, and if the cost of starting material will be brought down
to the 10-20 €/kg levels.
direct costs
2,5
0
0,5
1
1,5
2
2005 2013 2020 2030
€/W
modulecellwafer
Fig. 5 Possible evolution of direct costs for module components.
rom the point of view of thin films, efficiency improvements and
follow
e same curve (with a different breakdown of components, however).
ovel and emerging technologies, including new materials and devices
d
F
reliability issues need to be overcome, for technology to be able to
th
N
structured at the nanoscale to make full use of quantum effects and of
reduce specific material use, have the long tern potential of providing
high efficiency – low cost – highly scalable products, but nee
substantial research effort to reach important results. This category,
which includes organic, polymers and quantum dot or wire approach, is
receiving a great deal of interest, and is also a field in which Eni has
started research programmes in-house and in co-operation with major
centres of excellence such as MIT, the Italian National Research centre
and major universities, and a number of European partners.
The long term solution, at 2030 and further, may be a combination of
existing and novel technologies, but in any event an intense R&D effort
is needed to provide the solutions for photovoltaic electricity to be an
important actor in the future.
References
[1] Photon International, 2008
] IEA-PVPS T10 – 01:2006, pdf version downloadable from
tform.org
[2
www.eupvpla
] Srategic Research Agenda, www.eupvplatform.org [3
“Nanocatalysis for Clean and Sustainable Energy: the design of gold catalysts for the water-gas shift reaction”
Maria Flytzani-Stephanopoulos Department of Chemical and Biological Engineering
Tufts University Medford, MA 02155, USA
Email: [email protected]
Abstract The properties of nanoscale gold on cerium oxide and gold on iron oxide systems are reviewed
here as catalysts for the water-gas shift reaction at low temperatures. A new approach to stabilize
these catalysts in realistic reformate gas streams devised by our group is discussed. We have
found that gold nanoparticles are spectator species in the water-gas shift reaction on Au-CeOx or
Au-FeOx catalysts. The activity resides in [Aun-O-Ce] or [Aun-O-Fe] sites composed of
atomically dispersed gold strongly interacting with the oxide support. The number of these sites
is a function of the properties of the oxide, while their stability depends on the reaction
conditions. A highly reducing gas mixture destabilizes the catalyst via gold cluster formation and
gold particle growth, but oxidation at a temperature of 350-400 oC may be used to redisperse the
metal. This process recovers the initial catalyst activity. Addition of small amounts of gaseous
oxygen assists the water-gas shift reaction, and also keeps the ceria from destabilization during
room temperature shutdown-restart cyclic operation in the presence of condensible water in the
gas mixture. These catalysts and operating conditions are thus suitable for the upgrade of
hydrogen gas streams to be used in PEM fuel cell applications.
Introduction Nanotechnology in heterogeneous catalysis holds promise for the development of practical
catalysts with precise control of the component phases, such that not only their activity, but also
their selectivity for a specific product is optimized. Ultimately, it is envisioned that synthetic
approaches, which have proved so successful for homogeneous catalysts, will also become
available to heterogeneous catalysis, making possible the design, control, and fabrication of
certain structures with an unprecedented degree of precision. Nanocatalyst design has thus
emerged as an important area where catalysis, surface science, new synthesis methods and
characterization tools, and computational chemistry all converge to produce the next generation
of specific-site optimized catalysts.
Nowhere is this effort more apparent than in the relatively new area of catalysis by nanoscale
gold. The inertness of gold disappears as its particle size shrinks to nm scale, and a lot of new
chemistry by gold nanoparticles has been documented over the past two decades, ever since
Haruta first demonstrated the extremely high CO oxidation activity of gold nanoparticles
supported on reducible oxide supports, such as iron oxide1. Whether the preponderance of
coordinatively unsaturated sites on nm-scale gold particles do all the chemistry is still being
debated in the literature, even for the simple CO oxidation reaction. In many reports, the support
oxide has been claimed to be important 1-4, while in others, the support has been found to play a
secondary role, if any5-7. Another facet of the mechanistic debate involves the identification of
the oxidation state of gold that is important for the CO oxidation and the preferential CO
oxidation (PROX) reactions. Positively charged gold8 and metallic gold9 on iron oxide have been
proposed as important. The same is true for gold on cerium oxide (ceria); where cationic gold
has been reported as the active site by some groups10, 11, but metallic gold by others9,12-15. For
other supports, such as titania, metallic gold, especially of a specific size2,16,17 has been proposed,
as well as a cooperative mechanism involving both metallic gold plus cationic gold from the
interface with the support to explain the CO oxidation reaction mechanism3, 18.
In most of the above literature, due to preparation differences, the catalysts have a different
fraction of gold in the nanometer, sub-nanometer, and atomically distributed states; hence their
evolution to the working catalyst state is different with time-on-stream. Gates and co-workers
have taken the approach to start from depositing an organometallic precursor of gold on certain
supports, such as MgO19, Na-Y zeolite 20, or La2O321 and after careful decomposition, to study
the structural evolution of mononuclear gold (III) species by in situ XAS with measurement of
CO conversion during oxidation. Model catalysts, where mass-selected gold clusters of a certain
size are deposited on oxide supports and their structural evolution is followed by suitable in situ
spectroscopy22 and microscopy techniques may become more widely used in the near future to
address the structure sensitivity of various reactions as well as selectivity issues.
In our work, we investigate the reactivity of atomic distributions and metal clusters of Au, Pt, or
Cu stabilized in cerium oxide and iron oxide for a variety of energy-relevant redox reactions.
Starting from the premise that over design and use of precious metal catalysts is both costly and
unsustainable, we set out to seek new catalyst solutions for clean energy production, such as fuel
cells. Large-scale adoption and commercialization of the low-temperature PEM fuel cells is
hampered by the cost of platinum, which amounts to 80% of the fuel cell stack cost23. Promising
solutions include the development of bimetallic and surface alloy cathode catalysts using a
fraction of the amount of Pt with similar or better performance24,25. Fuel processing to upgrade
the hydrogen-rich gas stream produced by steam or autothermal reforming of fuels includes the
steps of water-gas shift (WGS) and PROX reactions upstream of the PEM fuel cell, and the Pt
group metals have emerged as more suitable for fuel cell application than the commercial
Cu/ZnO shift catalysts26. Again, it is not clear whether “we can do more with less”, and succeed
in minimizing if not totally eliminating the platinum metals necessary for the WGS reaction by
proper design of the catalyst. Fundamental knowledge of the nature of the active site is
indispensable in such an effort.
Our approach is based on previously reported work from our lab, where we were first to show
that the Au/CeOx system is an excellent low-temperature WGS catalyst, and that the ceria
properties are critically important for activity27. The Au/CeOx catalyst rivals Pt/CeOx, the well
established low-temperature shift catalyst in the three-way catalytic converter chemistry28. In a
key publication in 2003, it was shown that both gold and platinum catalysts supported on ceria
have active sites for the WGS reaction associated with the support, not the free metal
nanoparticle surface29. Indeed, by leaching away the metal nanoparticles, the residual [Au-O-Ce]
or [Pt-O-Ce] sites, containing a fraction of only 10% of the original metal amount, did the
catalysis equally well29-31. A tremendous opportunity to rationally design active WGS catalysts
presented itself as a result of that work. The importance of the ceria surface properties in
providing binding sites to the metal has since been demonstrated in many papers9, 29-34.
In this presentation, we show how to prepare active and stable water-gas shift catalysts by using
trace amounts of the precious metal in suitable oxide supports to achieve the goal of materials
and energy sustainability in fuel cell applications. As examples we will use Au/CeOx and
Au/FeOx catalysts.
Experimental Au/CeOx samples were prepared by deposition precipitation (DP), as described in detail
elsewhere27. Lanthana-doped ceria was first prepared by the urea-gelation-precipitation (UGC)
method35. Lanthana is used to stabilize the crystal growth of ceria and maintain high surface area
after the high-temperature calcination step. The desired amount of HAuCl4 aqueous solution was
added dropwise into a slurry of ceria under constant stirring at room temperature, keeping the
pH~8 by addition of ammonium carbonate. After aging for 1h, the precipitate was washed with
hot (60-70oC) deionized water three times, dried for 12h at 100oC, heated in air at a heating rate
of 2oC/min and held at 400oC for 10h. Au/Fe2O3, prepared by coprecipitation, was a commonly
used reference material purchased from the World Gold Council (WGC). Leaching of weakly
bound gold from the calcined gold-ceria and gold-iron oxide samples took place in an aqueous
solution of 2% NaCN under O2 gas sparging at room temperature and high pH (≥12). After
washing by deionized.water, the leached catalysts were dried for 12h at 100oC and calcined in air
at 400oC for 2h.
The BET surface areas of the samples were measured by single-point N2 adsorption/desorption
cycles in a Micromeritics Pulse ChemiSorb 2705 flow apparatus. Bulk elemental analysis was
conducted by inductively coupled plasma optical emission spectrometry (ICP-OES, Leeman
Labs Inc.)
A Kratos AXIS Ultra Imaging X-ray Photoelectron Spectrometer (XPS) with a resolution of 0.1
eV was used to determine the atomic metal ratios of the surface region and the oxidation state of
gold in selected catalysts. Samples in powder form were pressed on a double-sided adhesive
copper tape for analysis. An Al Kα X-ray source was used in this work. All binding energies
were adjusted by using C1s as internal standard.
Synchrotron-based X-ray absorption spectroscopy (XAS) was employed to examine the
oxidation state of 0.5AuCL and 0.7AuFe2O3 under different treatments. XAS spectra were
collected using the beamline X19A of the National Synchrotron Light Source (NSLS) at
Brookhaven National Laboratory (BNL). Each catalyst sample was pressed on a Kapton tape as a
thin film and the XAS spectra were taken in the “fluorescence-yield model”. A Ge 13-element
detector was used. The reported data are the averages of three scans (lasting approximately 30
min/scan), and no changes were detected between the first and the last scan.
Steady-state CO oxidation and WGS reaction light off tests and kinetics measurements were
conducted at atmospheric pressure with the catalyst in powder form (<150 µm). A quartz tube
(O.D. = 1 cm) with a porous quartz frit supporting the catalyst was used as a packed-bed flow
reactor. Water was injected into the flowing gas stream by a calibrated syringe pump and
vaporized in the heated gas feed line before entering the reactor in WGS reaction tests. A
condenser filled with ice was installed at the reactor exit to collect water. The feed and product
gas streams were analyzed by a HP-6890 gas chromatograph equipped with a thermal
conductivity detector. The total flow rate was 75ml/min for light off tests and 150ml/min for rate
measurements. The gas composition for WGS light off tests was 2%CO-10.7%H2O-bal. He,
while it was 11%CO-26%H2O-26%H2-7%CO2-bal.He for the kinetics measurements. In kinetic
experiments, the reactor was operated in a differential mode and the typical amount of catalyst
used in the tests varied from 10 to 100mg, with the conversion of CO not exceeding 15%. No
methane was produced in any of the tests described here.
Results and Discussion Figure 1 shows the physical properties of the (as prepared) 4.7at%Au-Ce(La)Ox and (as
received) 2.2at%Au-Fe2O3 parent samples. The leached samples, 0.5at%Au-Ce(La)Ox and
0.7at%Au-Fe2O3 (after air calcination at 400 oC) are also shown. The parent catalysts contain
gold nanoparticles, as shown in the TEM pictures of Fig. 1. However, they also contain sub-nm
clusters and gold atoms, which are not detectable with typical high-resolution microscopy.
Through the use of a new aberration-corrected HREM JEOL 2200 FS at Oak Ridge National
Laboratory, we were recently able to detect gold atoms dispersed on the iron oxide sample36. Of
course, other techniques, such as XPS or XANES/EXAFS have been used to identify the sub-nm
scale gold structures. To study the properties of the sub-nm gold structures in the absence of the
nanoparticles, we have used the leached samples. The leached samples, after washing and air
calcination at 400 oC, were found to contain atomically dispersed gold9,36 fully embedded in the
cerium or iron oxide subsurface layers. The gold was located deeper than the first few sub-
surface layers in the iron oxide, hence it could not be detected by XPS9. However, it was visible
by aberration corrected HREM36, and by XANES/EXAFS9. Gold was initially cationic, as
determined by XANES9. Similar data were collected for the leached 0.5Au-Ce(la)Ox sample,
except that in this case, the cationic gold was detectable by XPS9, 37.
4.7 at%Au-Ce(La)O2 and 2.2 at%Au-Fe2O3(World Gold Council)Deposition-Precipitation (DP); Co-precipitation (CP)Tcalc’n = 400oCAu nanoparticles(2-5nm); Au clusters <1 nm; Au atoms
0.5at%Au-Ce(La)O2 and 0.7at%Au-Fe2O3:by NaCN leaching of the parent catalysts (ionic gold: XPS, XANES; Au atoms: aberration-corrected HREM)
25.6 nm (15-60 by TEM)Fe2O3
5.1 nm (5 by TEM)CeO2
Support particle size by XRD
5%Au-CeO2
2.2%Au-Fe2O3
Fig. 1 Catalyst Preparation and Characterization
The catalytic properties of the four catalyst samples were compared in the water-gas shift
reaction. Figure 2a shows the CO conversion in light off experiments, while Fig. 2b shows an
Arrhenius-type plot of the WGS rates measured in a reformate-type gas mixture over these
catalysts and the Au-free supports. First, we observe that the activity of the parent and leached
gold-ceria and gold-iron oxide samples are the same. Thus, gold nanoparticles of size 2-5 nm,
present in both parent samples are spectators in the WGS reaction. Only the “bound” gold
species, Au-O-Ce and Au-O-Fe participate in the reaction. While this had been shown before for
Au-CeOx catalysts29-31, the case is now made clear for Au-FeOx catalysts9 as well. Hence, these
catalysts can be designed with just enough gold to bind the available surface oxygen of the
support, but no more. Any excess gold will exist as nanoparticles, which do not participate in the
WGS reaction. The second important feature of these catalysts is derived from the data plotted in
Fig. 2b. The reaction rates, normalized with the initial surface area of each support are similar for
gold on either the iron oxide or the ceria support; and the apparent activation energy is the same,
Eapp = 49 +/- 7 kJ/mol. The stability of the Au-FeOx catalyst is very good up to 375 oC9.
Therefore, the operating window for the WGS reaction over gold catalysts can be very wide
indeed: from 150-400 oC; effectively obtaining both a low- and a high- temperature shift catalyst
by optimizing either of the two support systems or their combination.
11%CO-26%H2O-26%H2-7%CO2-He
Fig. 2 WGS reaction activity of gold on two oxide supports
2%CO-10%H2O--He
0.001
0.01
0.1
1
10
1.4 1.6 1.8 2 2.2
1000/T (1/K)
Rat
e (μ
mol
CO
2/m2 /s
)
T (oC)225250275325350375400
CeLaOx
Fe3O4
4.7AuCeOx
0.5AuCeOx
2.2AuFeOx
0.7AuFeOx
0
20
40
60
80
100
0 100 200 300 400Temperature (oC)
CO
Con
vers
ion
(%)
0.5AuCeOx,leached4.7AuCe(La)Ox
Ea=49+/-7 kJ/mol
2.2AuFeOx
0.7AuFeOx
~ 40m2/g
~ 160m2/g
(a) (b)
The reducible surface oxygen of the support oxide is an important design parameter for
supported WGS gold catalysts. We have shown this for ceria from the first paper on the subject27
and in later reports29-31. Thus, nanocrystalline ceria, rich in oxygen defects, is necessary for an
active Au-CeOx shift catalyst27, 29-31, and loss of activity under highly reducing reaction
conditions is due to sintering of gold and ceria31. Recently, we were able to identify a
dependence of the reaction on the morphology and the type of crystal plane exposed in
nanocrystalline ceria used to support gold 34. As shown in Fig. 3, we prepared nanocrystalline
ceria by a hydrothermal technique reported in the literature38. The final shape (polyhedron, rod,
cube) depends on the parameters (temperature, NaOH amount, time) used in preparation. The as
prepared nanoshapes of ceria after air calcination at 400 oC have surface area of ~ 25 m2/g, i.e.
they can be used as realistic catalyst supports. Gold at ~ 1at% was deposited on the ceria
nanorods and nanocubes by the typical deposition-precipitation technique used with ceria
powders34. As can be seen in Fig.3, the {100} surfaces of the nanocubes contained preferentially
gold particles (~3 nm), while gold was fully dispersed and invisible by HREM on the {110}
surfaces of the nanorods. In both cases, the analysis was done after calcination in air at 400 oC.
Leaching of gold hardly affected the amount present on the nanorods, but almost completely
removed all gold from the nanocubes34. The characterization of the samples by XPS, XRD, and
H2-TPR served to corroborate the microscopy and suggested that the nanorod-supported gold
would be significantly more active than the nanocube-supported sample. Catalytic tests
confirmed the anticipated result34. These findings are displayed in Fig. 4. From the XRD data, a
new additional feature of the active {110} surfaces of the ceria nanorods was that they were
much more strained than the {100} surfaces of the nanocubes. How this correlates with retention
of gold and reactivity warrants further detailed investigation.
In the literature, it has been argued that the working Au-CeOx catalyst under WGS reaction
conditions comprises metallic gold nanoparticles39,40, CO adsorbs on the gold particles, and the
Au-CeOx interface plays an important role for the reaction, as ceria supplies its oxygen to the
adsorbed CO40-42. This is the cooperative redox mechanism, already proposed for the Pt-group
metals on ceria28. However, when a multi-structure of gold (particles, clusters, atoms) is present
in the as prepared ceria catalyst39,40, it is difficult, if not impossible, to follow the evolution of all
structures and determine the active one. In other words, there are many states of a “working”
catalyst, but we want to isolate the sites doing the turnover. To this end, starting with a leached
sample, which initially contains only atomically distributed gold9, allows us to follow the
structure evolution of gold with reaction gas and temperature during in situ XAS experiments. If
metallic gold is formed, is the catalyst activated or deactivated in the process?
Preparation of gold on single crystal nanoscale ceria 0.9%Au-CeO2 (DP, 400 °C, air; on ceria nanocrystals made hydrothermally)
TEM TEM
(10 ± 3)×(50 – 200) nm230 ± 11 nm
24 m2/g27 m2/g
Au: ∼ 3 nmNo Au particles
Rod Cube
Fig. 3 CeO2 nanorods stabilize well-dispersed gold, but gold nanoparticles are formed on ceria nanocubes; ref.34.
HRTEM HRTEM
WGS “light-off” (2%CO+10%H2O/He)H2-TPR
XPS (Au 4f)
Au (at%) Microstrain
Rod 0.9 1% {110}
Cube 1.1 0.2% {100}
Solid: 0.9%Au-CeO2 (Parent)Dotted: 0.5%Au-CeO2 (Leached)
Activity much higher for Au on CeO2(110)
Fig. 4 Characterization and activity of Au on ceria nanorods and nanocubes; ref.34
We recently carried out detailed in situ XANES/EXAFS studies37, where the evolution of gold
on ceria was followed with time, temperature, and reaction gas composition. The activity with
time-on-stream was also monitored in microreactor experiments under identical conditions. The
as prepared sample was either the leached 0.5%Au-Ce(La)Ox sample described above, or a
0.75%Au-CeOx prepared by one-pot urea gelation/co-precipitation, also containing only
atomically dispersed cationic gold in the as prepared state37. “As prepared” for both samples
denotes the state after air calcination at 400 oC, 4h. Catalytic stability experiments were
conducted ex situ to complement the XAS studies. The Au-Au coordination number (CN) was
zero at the onset of the EXAFS experiments, while the Au-O CN was 2.7 ± 0.9. It was found that
after 1h-reaction at 100 oC in a CO-rich gas mixture (5%CO-3%H2O), the Au-O CN dropped to
0.4, while the Au-Au CN approached 6.5. A small gold cluster size of 37 atoms fitted the
EXAFS data37. More pronounced growth to a cluster size of 185 gold atoms took place after
reaction at 200 oC37. Reoxidation in 20%O2 –He gas at 150 oC was not effective in reoxidizing
the gold. While the trend was similar, reduction of gold and its subsequent growth (clustering)
was suppressed in a CO-lean gas mixture (1%CO-3%H2O), as followed by XANES37.
Reoxidation at 150 oC was more extensive in this case. Fig. 5 shows the XANES data collected
after various redox treatments of the two catalyst samples.
The stability tests came back negative, i.e. the activity of the partially reduced gold-ceria catalyst
was lower than that of the as prepared sample containing fully dispersed Au-O-Ce species at the
beginning of each test. Thus, it does not take a certain size of gold, above which deactivation
begins due to the loss of gold-ceria interaction, as claimed in ref. 39. We found that deactivation
begins immediately, and the maximum activity is that of the fully dispersed gold in ceria
sample37. To investigate the reoxidation further, we treated the used samples in 20%O2/He gas at
different temperatures. Interestingly, and very importantly, almost complete reoxidation took
place above 350 oC, accompanied by redispersion of gold in ceria37. The catalytic step,
performed ex situ, showed full recovery of the WGS activity, as can be seen in Fig. 6. In H2-TPR
of the 400 oC-reoxidized sample, also shown in Fig.6, it was found that it had recovered the
amount of surface oxygen of the as prepared sample, both of which were higher than in the used
sample (reoxidized at room temperature), again in good agreement with the corresponding
catalyst activity.
11850 11900 11950 12000 12050Energy (eV)
μE (a
.u.)
Au LIII
Au foil
fresh catalyst
100oC WGS
150oC O2
200oC WGS
11850 11900 11950 12000Energy (eV )
μE (a
.u.)
150oC O2
Au foil
0.75AuC eO2 fresh
100C W GS
reoxidation
150C W GS
reoxidation
1%CO-3%H2O-He5%CO-3%H2O-He
Fig. 5 Effect of the reaction gas composition (oxygen potential) on the oxidation state of gold – in situ XANES; ref.37.
0.5%Au-CeOx (leached) 0.75%Au-CeOx (UGC)
0 100 200 300
Temperature (oC)
H2 c
onsu
mpt
ion
(a.u
.)
a--fresh
b--WGS, then RT Helium
c--WGS, then 400C O2
a
b c
0
1
2
3
4
5
0 20 40 60Time (min)
H2
conc
entra
tion
(%) fresh catalyst
reoxidized at 400C
as prepared catalyst
WGS: 200oC5%CO-3%H2O-He
TPR: 20%H2/N2 as prepared catalyst634 μmol/g
reoxidized catalystused catalyst502 μmol/g
reoxidizedcatalyst614 μmol/g
Fig. 6 400oC-oxidation of used 0.5% Au-Ce(La)Ox catalyst (after WGS reaction at 200 oC) redisperses the gold in ceria. Initial activity is recovered; ref. 37.
The structural reversibility found for the gold-ceria system is also present in the gold-iron oxide
samples, as our current work indicates43. In either catalyst, keeping a higher oxidation potential
in the reformate gas mixture stabilizes the gold against sintering. Hence, we can now propose
new reactor designs and operation so that maximum activity and stability of gold catalysts in
WGS reaction is realized over a wide temperature window. In one approach, already outlined in
a previous publication44, small amounts of oxygen can be supplied along the length of the WGS
reactor, with oxygen assisting the WGS activity and stability of the catalyst by preserving the
dispersed oxidized gold state. An additional benefit, specific to ceria, is that oxygen addition has
been found to protect the ceria from forming Ce(III) hydroxycarbonate upon shutdown operation
in the presence of condensing water44. This strategy would work well also for Pt-CeOx44 and
potentially any ceria-based catalyst. Figure 7 shows the cyclic shutdown-restart operation of a
Au-CeOx catalyst, simulating the cyclic operation of a practical fuel cell system. In the presence
of 0.5% O2, the catalyst stability is not compromised44.
0
20
40
60
80
100
0 100 200 300 400 500 600
Tim e (m in)
CO
Con
vers
ion
(%)
300oC full gas with O 2
300oC full gas with O2
Cool down to RT w/o H2O
Cool down to RT in full gas with O 2
300oC full gas with O 2
- Detrimental effect of water on ceria-based catalysts (Au-CeO2; Pt-CeO2; Cu-CeO2) under WGS conditions. - CeCO3OH is formed at low temperatures
11%CO-26%H2O-26%H2-7%CO2-He
Addition of a small amount of oxygen stabilizes the catalyst activity
11%CO-26%H2O-26%H2-7%CO2-He-0.5 %O2
This solution holds true for all ceria-based WGS catalysts
Fig. 7 Stability of Au-CeO2 in realistic shutdown-restart fuel cell operation; ref. 44
Conclusions In this presentation, the aim was to show that new catalyst designs at the nanoscale are possible
for the water-gas shift reaction employing gold dispersed in ceria or iron oxide matrices. Ample
evidence was presented that the embedded gold atoms in the oxide surfaces are the reaction-
relevant sites, and this has guided our thinking and design strategy. To avoid “over design” and
promote sustainable use of precious metals in the emerging, more efficient energy production by
fuel cells, we show here that we can use trace amounts of the metal to activate the surface
oxygen of the support oxide and run the reaction at low temperatures. The importance of using
defect-rich, nanoscale ceria has been demonstrated. For the practical application, it is important
to improve catalyst stability, and we have shown that this can be accomplished by oxygen-
assisted operation at all temperatures.
Acknowledgments The author acknowledges the contributions of several graduate students and postdoctoral
researchers of the Nano Catalysis and Energy Laboratory at Tufts University. Special thanks are
due to postdoctoral fellow Rui Si, former doctoral students Weiling Deng and Qi Fu, and current
doctoral student Yanping Zhai; and to Prof. Howard Saltsburg. The financial support by the
DOE/BES-Hydrogen Fuel Initiative Program, (DE-FG02-05ER15730) and the NSF/NIRT
program (grant # 0304515) is gratefully acknowledged.
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Microalgae as an important source of renewable energy
Giorgio M. Giacometti1 and Giovanni Giacometti2 1Department of Biology, University of Padova, Italy
2Department of Chemical Sciences, University of Padova, Italy Photosynthetic biomass and hydrogen production by microalgae The ability to efficiently harvest solar radiation and use it to drive the synthesis of biomolecules is a unique characteristic of photosynthetic organisms, developed approximately 3 billion years ago, that brought about a real ‘big bang’ in the evolution of life on the earth. All the energy stored in fossil fuels over the eras, which powers now day technology and provides us with the chemical products that make every day life easy and comfortable, comes from the photosynthetic process. The massive exploitation of fossil fuels started only 200 years ago contributing to the exponential development of industry and technology and, at the same time, leading to the depletion of the oilfields, which has now put an end to the ‘cheap oil era’. On top of this, the massive release of carbon dioxide in the atmosphere has recently raised strong concern about the consequences of possible climate changes induced by the green house effect. In previous millennia human activities were based solely on renewable energy sources and the development of new ways, adequate to modern technologies, to exploit these sources, all directly or indirectly linked to the ever present solar radiation, is of primary importance to life on earth and to the health of the environment. The solar energy reaching our planet can be extimated in 100,000 TW which is an enormous amount compared to the total power used by humanity of about 15 TW. Photosynthesis produces annually about 100 Gtons of dry biomass which is approximately equivalent to an annual energy storage corresponding to a power of 100 TW. The secret for a successful exploitation of solar energy is the evolutionary history of the process which took some billion years to tune up its molecular mechanisms for the best performance. Moreover, the row materials and the energy needed to synthesize the biomass -water, carbon dioxide and sunlight - are available in virtually unlimited amount. Indeed, early organisms acquired eventually the capacity of using sunlight to perform the splitting of water into its components: molecular oxygen and hydrogen. Recombination of this simple molecules to give back water releases all the energy necessary to perform the biochemical reactions which drive the life on our planet. However, while the diatomic molecule of oxygen is released in the atmosphere, hydrogen is not released as H2, which would escape lower atmosphere, but is stored in form of hydrogenated organic molecules (Gaffron 1939). Subsequent oxidation of these molecules in the cellular respiration recombines the stored hydrogen to molecular oxygen in a highly efficient and carefully regulated way, so as to minimize entropy production, and provides the cell with metabolic energy (figure 1). Photosynthetic solar energy conversion is a very complex process brought about by plants, algae and cyanobacteria by mean of a molecular apparatus located in a specialized membrane system (the bacterial membrane or the chloroplast thylakoid membrane in the algae and higher plants) where the solar energy is absorbed by chlorophyll and other pigments and transferred very efficiently to the reaction centers where it is converted into chemical free energy. The water splitting reaction occurs by the action of a light-driven enzyme (the oxygen evolving complex, OEC) which is part of photosystem II (PSII, depicted in figure 2), one of the multisubunit integral complexes of the photosynthetic apparatus. In the photosynthetic electron transfer chain, PSII behaves as a water-plastoquinone oxidoreductase which transfers electrons from water to the plastoquinone pool freely diffusing in the lipid phase of the membrane. For each photon absorbed by the antenna system of PSII, a radical pair (P680+ Pheo-) is generated, where P680 is a special chlorophyll a in the ‘reaction center’and Pheo is a pheophytin molecule, also tightly bound on the PSII reaction center. In this charge separation process, most of the photon energy is converted into redox energy where P680+ is a strong oxidant (+1V) and Pheo- (-0.5V) would be a strong enough reductant to bring the water protons to molecular hydrogen. However, evolving hydrogen is not the physiological task of the photosynthetic apparatus. Therefore, while P680+ is neutralized by an electron extracted from a water molecule by the OEC, the electron of Pheo- is not directly donated to a proton H+ , but instead is injected into an electron transport chain which involves the membrane plastoquinone pool, goes through the cytochrome b6/f complex and ends with the reduction of a soluble molecule of plastocyanine (a small soluble copper protein). The energy lost by the electron in the downhill way from Pheo- to plastocyanine is partially converted into a proton gradient across the membrane which will be utilized by the ATPsynthase to phosphorylate ADP to ATP. Another red photon comes into play at this point, which, exciting photosystem I (PSI), promotes the electron of
reduced plastocyanine to the level of ferredoxin (an iron-sulfur soluble protein) that acts as final acceptor of PSI and of the entire photosynthetic linear electron transport chain (figure 3). In normal photosynthetic activity the strong reducing power of the reduced ferredoxin, togheter with the free energy momentarily stored as ATP, drive the fixation of carbon dioxide in a series of reactions known as the Calvin-Benson enzymatic cycle (dark reaction of photosynthesis). All this complex machinery is meant to provide the cell with reducing power in the form of NADPH and free energy in the form of ATP to drive the synthesis of sugars. However, the real core of the process is the light-driven water splitting reaction that occurs at the OEC of photosystem II. The splitting of water into molecular oxygen and reducing equivalents is a four electron process and four absorbed photons are needed:
4 hv 2H2O O2 + 4H+ + 4e-
Only after the fourth electron is extracted form two water molecules the oxygen-oxygen bond can be formed and a dioxygen molecule can be released. The catalytic center performing this job in the PSII consists of a cubane constituted by a Mn3Ca2+O4 cluster with a fourth Mn linked to one oxygen of the cubane (see figure 2B). After each light-driven injection of an electron into the PSII transport chain, an electron is extracted from the Mn cluster which accumulates the oxidizing equivalents necessary to release four protons and one dioxygen molecule. In recent years, the determination of the crystallographic 3D structure of PSII (Ferreira et al. 2004) has revealed the organization of the Mn cluster and all the details of its protein environment. The OEC activity, which, with the help of P680, converts light energy into reducing power extracted from water, is certainly the most promising process for using solar energy, particularly for producing hydrogen, and, although its molecular mechanism is now almost completely understood and several laboratories are working hard to syntesize efficient light driven catalyzers to split the water molecule, no efficient artificial photochemical system has yet been constructed to mimic this reaction. Therefore, for the time being, biotechnology must rely on natural systems. Hydrogen from microalgae The discovery of Gaffron and Rubin (1942) that some green unicellular algae are capable of H2 evolution when illuminated in anaerobic conditions, opened the way to the possibility of exploiting this capability for hydrogen production. Actually at that time the discover was more important as an evidence in support of Van Niel’s general scheme for photosynthesis:
CO2 + 2H2A → [HCOH] + 2A + H2O The mechanism of H2 evolution by algae is now understood in detail and is clearly proven that there are two different pathways for this process. One pathway involves water splitting and electron transport through both PSII and PSI with simultaneous O2 and H2 evolution. The direct source of electrons for H2 production is reduced ferredoxin. The second pathway involves carbohydrate catabolism (Kreuzberg and Martin 1984, Melis and Happe 2001) with electron donation from NAD(P)H to the plastoquinone pool in the thylakoid membrane and continuing, like the first pathway, via PSI and ferredoxin. In both cases electrons ultimately come from water oxidation, but in the second case they are first stored in carbohydrates (figure 4). Here, the critical step is the reduction of protons catalized by a soluble enzyme called hydrogenase (HydA):
2H+ + 2Fdred ↔ H2 + 2Fdox Hydrogenases are a very peculiar class of enzymes (Stephenson and Stickland 1931, Adams 1990). They are metalloenzymes that catalyze the reversible oxidation of hydrogen gas and can be subdivided into two phylogenetically unrelated groups. The first group comprises the [Ni-Fe]-hydrogenases that are mainly found in prokaryotic organisms (e.g. cyanobacteria); characteristic of this group is a dinuclear [Ni-Fe] center in the active site. A second group is that of [Fe-Fe]hydrogenases which contain a dinuclear [Fe-Fe]center linked to a [4Fe-4S] cubane at the active site, also named H-cluster. The [FeFe]hydrogenases are catalytically very efficient, they mainly catalyze the reaction in the forward direction (H2 evolution) and are also found in eukaryotes. Since [FeFe]hydrogenases accept electrons directly from ferredoxin, reduced by PSI, the H2 production pathway competes for electrons with the other electron pathways, first of all that of NADP+ reduction and CO2 fixation. In green microalgae, such as Chlamydomonas reinhardtii, a highly active [FeFe]hydrogenase (HydA1) is present in the chloroplast stroma, codified for by a nuclear gene, which is only expressed in anaerobic conditions . In fact, all
[FeFe]hydrogenases are strongly inhibited by molecular oxygen and this is one of the main problems for the biotechnological exploitation of their activity. Two structures of [FeFe]hydrogenases from Clostridium pasteurianum (Peters et al.1998) and Desulfovibrio desulfuricans (Nicolet et al. 1999) have been resolved by X-ray crystallography showing a structure of the active site which has no eguals in other enzymes (figure 5). The inner core of the active site is constituted by two Fe atoms connected by chemical bonds and surrounded by carbon monoxide and cyanide anion, molecules that are well known poisons, previously considered incompatible with life. The knowledge of the active site 3D structure and the results of several spectroscopic investigations helped organometallic chemists to use these enzymes as models for making synthetic catalists and eventually create stable bimetallic species able to accept electrons from an electrode and send them to reduce protons to molecular hydrogen. Thus, two enzymatic activities are essential for utilizing solar energy to produce hydrogen as an ideal energy vector: that of the PSII OEC and that of [FeFe]hydrogenase. It is only a few years since a clear picture of both of them is available and the road map for a mimetic chemistry of these natural capabilities is open. The most difficult problem of bio-mimetic chemistry in this respect is the one of the water splitting catalyst which must deal with a four electron four protons process. Impressive results in this direction are for instace those recently obtained by the group of Daniel Nocera at MIT (figure 6). Nocera Hopes that in about 10 years, home owners will be able to power their homes in day light through photovoltaic cells, while using excess solar energy to produce hydrogen and oxygen to power their own household fuel cell. Electricity-by-wire from a central source could be a thing of the past. But, even in the case of hydrogenase activity which deals with a only two electron two protons process, no advancements have been produced which can be considered significant from the point of view of their impact on technical application and, once again we can only try, for the moment, to exploit the natural organisms and push them to work for us. Undoubtedly, the unique ability of some algae to photoproduce H2 from water may have significant biotechnological applications in the future. Progress along these lines using intact cells has been made recently but still some unsolved problems must be faced in order that photoproduction of hydrogen may attain a level adequate to industrial exploitation. Hydrogenases of green algae are very sensitive to O2 inhibition and the effective utilization of electrons deriving from water-splitting in H2 production critically depends on the removal of the O2 evolved by the OEC. This problem of mutual incompatibility of O2 and H2 evolution remained unsolved for long time, until a two stage process was proposed by Anastasios Melis based on sulfur deprivation (Melis et al. 2000). This was proven with the unicellular green alga C. reinhardtii, one of the most studied among these organisms, and consists essentially in the temporal separation of two stages. In a first stage, the photosynthetic apparatus is fully active, oxygen is evolved, the algal culture grows and accumulates sugars in the form of starch. In a second stage, characterized by lack of sulfur in the culture broth (sulfur deprivation), PSII is down regulated and the cells fulfill most of their energetic needs by respiration. In these conditions, the oxygen produced by the residual PSII activity is consumed by respiration and the culture medium goes anaerobic. In this stage (see figure 4), the hydrogenase enzyme is induced to work in its active form and the electrons injected in the photosynthetic electron chain by the residual PSII activity and by starch oxidation are utilized by the hydrogenase to reduce protons to H2 (Wykoff et al.1998; Zhang et al., 2002). Sulfur deprivation, however, is a stress condition for the cells and after 3-4 days of H2 production a normal level of sulfur must be restored to allow cells to recover and reconstitute their complete functions by fully active photosynthesis. The process can be repeated for several cycles of hydrogen production. Although production of hydrogen by photosynthetic splitting of water is considered promising for the future, at present several factors contribute to make it still unsuitable for large scale production. First of all, the over all photosynthetic efficiency must be considered. Photosynthesis produces annually more than 100 Gtons of dry biomass which corresponds approximately to a mean annual rate of energy storage of 100 TW. This is really a huge amount of energy if compared to the total energy demand of approximately 14 TW. However, it is a very tiny fraction of the total average light energy incident on the earth. This obviously depend on the fact that only a small fraction of the incident radiation is absorbed by photosynthetic organisms, but also, the transformation efficiency for the absorbed radiation is rather small. There are many sophisticated ways to calculate the quantum yield for energy conversion in the photosynthetic electron transport chain, but we will limit ourselves to a very rough estimation: the average photon flux of photosynthetically active radiation (PAR) on the earth surface can be estimated as 50 mol photons m-2 d-1. The theoretical minimum photon requirement for hydrogen production is 5 mol photons / mol H2. Thus if quantum yield would be one, we would obtain a theorethical maximum yield of hydrogen production of 10 mol H2 m-
2 d-1. In other words, a square meter of an algal colture absorbing all the incident radiation and transforming it without any loss would produce 10 moles of hydrogen per day. But this is only a theoretical upper limit for the transformation efficiency. A more realistic estimation, based on experimental results, is of the order of 10% of this value. This is not surprising as a large fraction of the energy is used in driving the enormous number of reaction that occur in
photosynthetic organisms to maintain their organization and survive. Moreover, natural photosynthesis saturates with increasing light intensity because the maximum rate of electron transport between PSII and PSI limits the amount of optical excitation energy that the photosynthetic apparatus can convert into chemical energy. Consequently, only measurements of conversion efficiencies under strictly light-limiting conditions reveal the inherent maximum capabilities of the photophysical machinery of photosynthesis, independently of the subsequent dark biochemistry. Under non-light-limiting conditions (e.g., incident solar intensities), net conversion efficiencies can be 10–100 times lower, depending on cell concentration, photobioreactor design, antenna content and other parameters. Thus, one of the main problems with the production of hydrogen using green algae can be summarized as follow: when the illumination conditions are limiting (low light) and the culture is scarsely illuminated the conversion efficiency is the highest but the hydrogen production is low, when the light intesity increases the hydrogen production increses as well, but the efficiency decrases because of saturation and an increasing fraction of light energy is dissipated into heat. Moreover, when algae are grown in a photobioreactor, a high cell concentration is needed to ensure good production yield, but in these conditions, due to the high optical density, light can only penetrate few millimetres into the culture. As a consequence, the external cell layers are exposed to high light intensity leading to saturation and energy dissipation, while the more internal layers only see very dim light, unable to sustain photosynthesis. In order to partially overcome this limitation and increase the photobioreactor productivity, an algal strain with reduced antenna size would be necessary. This can be obtained either by using reverse genetics to search for a mutant with these characteristics, or by using molecular biology techniques to build up an engineered strain. Another main limitation for hydrogen production from photosynthetic water splitting by algae is the extreme sensitivity of their hydrogenase to inhibition by oxygen. Several research groups are indeed working hard to construct hydrogenase mutants more tolerant to oxygen as this could significantly improve productivity When these improvement, together with many others essentially based on a deeper understanding of the metabolism of microalgae, will be worked out, the possibility will arise to approach the theoretical yield for hydrogen production based on the photosynthetic splitting of water. Taking into account the above mentioned value of average PAR (Photosynthetically Active Radiation) and that the theoretical minimum photon requirement for hydrogen production is 5 mol photons/mol H2, we have a theoretical max yield of 10 mol H2 m-2 d-1. This means that a single photobioreactor tubular module 20x800 cm, evenly illuminated, would produce approximately 2.2 m3 of hydrogen per day. Although this perspective is very attractive in the framework of a diffuse microgeneration of a clean fuel for local utilization, it does not seem to posses the potential for a significant displacement of fossil fuels and, in any case, the prospects for practical application must be projected in a time period of 10-15 years. Biodiesel from microalgae The analysis and forecast of energy demand in the next 30-40 years is particularly concerned about the availability of transportation fuels at prices reasonable and compatible with ensuring the current mobility levels. In fact, for more than fifty years the transportation system has allowed an independent, fast and inexpensive possibility of moving around, thanks to the simple technology developed for the production, distribution and handling of oil-derived fuels, and to the barrel price, which has remained surprisingly cheap for long time. This situation changed around the year 2000; since then, probably due to the approaching of the oil production peak (both technological and economical), the fuel prices have been steadily increasing and have achieved and passed values unforeseen only ten years ago. Right now, it is reasonable to be afraid that, within a few years, the price of the oil barrel will increase more and more, also due to the fast development of emerging Countries such as China and India. On the other hand, it is quite clear that combustion of fossil-derived fuels for mobility reasons is responsible for a large fraction of the greenhouse gases emissions (mostly CO2), that must be drastically reduced in the shortest time to mitigate phenomena due to global warming. An increase of transportation request will result in more emissions of this type. The only actual possibility to contrast with this trend is to rapidly develop and adopt at a large scale, new technologies capable of delivering large amounts of alternative fuels to the market. These new fuels should be produced starting from renewable raw materials so as to be neutral with respect to CO2 emissions. Under these premises, it looks both scientifically and socially meaningful to invest in research programmes headed to develop biofuel production processes able to sustain large-scale transportation requests. Such a research field is strategically relevant in the present situation as far as both the world fuel market and the quality of our environment are concerned. First-generation biofuel production technologies are based on the availability as raw materials of either vegetal oils (biodiesel) or carbohydrates (bioethanol). Unfortunately, when the amount of biofuel to be produced becomes relevant,
a problem of competition on the use of land will arise, between food and fuel, which is likely to find no solutions with current technologies. More knowledge and ideas must be developed and pursued to allow biofuels take over fossil-derived fuels. One of the most promising and widely recognized potential technology routes is based on microalgae as a potential source of oil for biodiesel production. Differently from present-day biodiesel (obtained from plant and animal oils), microalgae-based biodiesel would not compete for cropping land and would not compromise production of food and other products derived from crops. In addition, a possible cost for a biofuel derived from algae has been recently estimated at about 50 USD per barrel, which makes it already highly competitive at current oil prices. Microalgae, therefore, appear to be the only source of biodiesel that has the potential to completely displace fossil diesel(Chisti 2007, Hu et al. 2008). Last but not least, since algae fix CO2 into biomass, biodiesel derived from them gives an answer to the emerging concern about global warming. Biodiesel production can potentially use CO2 released from power and chemical plants, thus mitigating its emission into the atmosphere. This can contribute to meet the requirements of the Kyoto Protocol for greenhouse gas emissions. According to this idea, CO2 is the carbon source for the process under investigation; other essential nutrients for algae, such as phosphorus and nitrogen, can be derived at no cost from waste water. This makes the growth medium highly inexpensive. Research projects in this field are currently being undertaken, aimed at the development of a new generation biofuel (and chemicals) production system. An ambitious project's goal should assemble, in a strongly interdisciplinary effort, all the competences needed for setting up the design of an industrial plant, able to exploit out-door low-energy photobioreactors where to grow microalgal strains optimized for photosynthetic carbon dioxide fixation and natural oil production, with high throughput per unit volume and low energy consumption per unit of fuel. The photobioreactor should be designed for attaining the highest possible photosynthetic efficiency coupled to the use of an inexpensive CO2 source (such as power or chemical plant emissions) and farming or urban waste water for other nutrients (such as phosphates, nitrates and mineral salts). The concept of coupling a fossil fuel-fired power plant with an algae farm/plant provides an elegant approach to the recycle of CO2 from combustion of fossil fuel into a usable liquid fuel. Technical developments and achievements can also be expected for the conversion of natural oils into biodiesel (new heterogeneous catalysts and upgrade of glycerol as a by-product), the exploitation of the residue of algal biomass after delipidation and the energetic integration and intensification of the production process. Microalgae account for approx. 50% of global CO2 fixation on the planet and many species have been used as a source for natural products and for biotechnological application. In spite of this, the knowledge of their physiology, metabolism, ecology, and the molecular tools for their transformation by genetic engineering are still not fully developed. A research effort directed to increase our understanding of the biology of these organisms could open new possibilities for the exploitation of one of the most important energy gateway of the biosphere. REFERENCES
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FIGURE LEGENDS 1. Carbon and reducing power cycle in the biosphere 2. A) Dimeric photosystem II chrystallographic strucure B) Manganese cluster of the Oxygen Evolving Complex (OEC) 3. Electron transport pathway from water to NADP+ (Z scheme) 4. Hydrogen evolution by the combined effect of photosynthetic and fermentative electron transport chain 5. Christallographic structure of the [Fe-Fe]hydrogenase from Clostridium pasteurianum resolved at 1.8 Å (Peters et al 1998). (On the right)active site (H-cluster) of the enzyme. 6. Daniel D. Nocera in his laboratory at MIT Chemistry Faculty. He propose a simple and inespensive way to store excess photovoltaic energy by a new catalyst, based on cobalt and phosphate, that produces oxygen gas from water. (On the right) oxygen bubbling out from water in Nocera’s apparatus.
Meeting on: Energy crisis, water shortage and climate changes in the Mediterranean area: the involvement of chemistry
Castiglione della Pescaia (Grosseto, Italy), 2-6 may 2008
Hydrogeological and geochemical study of the Pianosa Island aquifer (Tuscan Archipelago, Italy) in relation to the water availability
Marco Doveri1, Roberto Giannecchini2, Mario Mussi1, Irene Nicotra3, Alberto Puccinelli2 (1: IGG-
CNR, Pisa, Italy; 2: University of Pisa, Italy; 3: Province of Livorno, Italy)
Presentation Text
1. Good evening. I’m going to show you our hydrogeological and geochemical study, carried out in Pianosa Island, concerning the relationship between the climatic evolution and the water availability in this area.
2. In this slide we can see the location of the studied area, in Tuscan Archipelago. The island
extension is nearly 10 km2 and shows a very flat morphology.
3. At first we collected data of rainfall and temperature in a period longer than fifty years, in order to analyze the trend.
4. This graph shows the temperature trend since 1951 to 2002 in Pianosa Island. The series is
not complete till today, because of instrumental problems. We can see that the long period linear trend decreases, according to the observations in all Mediterranean area, and not only, because of the global radiation decrease. But the most interesting factor for our context is that you can see that since 1995 to 2002 the global trend in a short period strongly increases. This trend inversion could be probably caused by the evolution of process of Global warming.
5. This graph shows the rainfall trend since 1951 to present. The annual average in this period
is about 480 mm, which indicates a shortage of rainfall in this island. We can see that the global linear trend in the long period is in increase, but in the last period the variations connected at not linear trend is in strongly decreasing. Same explications could be valid in this case, according to the climatic studies already mentioned.
6. Our studies intended to find answers of a lot of questions, but resuming, the aims were:
• study the groundwater circulation, also in relationship to rainfall and pumping rates; • quantitative evaluation of the groundwater budget of the island and of the underground
water resource; • hydro-geochemical classification of the groundwater; • individuation of the origin of the deep water; • analysis of the aquifer vulnerability in relation to the seawater intrusion.
7. The activities carried out were the following: • collection of the exiting data; • processing of the groundwater budget;
1
• carrying out of 4 on-site surveys in the period since December 2005 to May 2007, in order to check-on the water table, to collect samples and to develop geochemical analysis of groundwater;
• collection of the meteoric water aimed at an isotopic control; • data processing.
8. In this slide we can see the hydrogeological setting in a simplified cross section. We can individuate two main hydrogeological units: an upper hydrogeological unit, approximately horizontal, that presents a permeability from medium to medium-high; a lower hydrogeological unit, which presents a succession of impermeable and medium permeable levels, placed in unconformity with the upper one.
9. This slide shows the groundwater monitoring network: we can see the original rain-gauge for collecting meteoric samples, and COMMA-MED weather station that restore meteorological data for processing; then, we can see the springs in the north-western island cost, and the water-wells, which are distinguished in dug-wells (green colour) and drilled-wells (red colour). The dug-wells are twenty-five, while the drilled-wells are only six.
10. With piezometric data we elaborated a water table map that shows the trend of the
isophreatic lines, groundwater divides, drainage axis, stream lines. We can see that in the east part of the island the groundwater level is below the sea level, and forms a large hollow in the piezometrical surface.
11. This simplified cross-section shows the hydrodynamic model that we have processed. We
can see how pumping well determines a depression cone far from the well, due to the hydrogeological structure of the island.
12. This graph shows the evolution of the piezometric level in a period since 1999 to present.
The variation of groundwater level in selected dug-wells shows that complexly water level is uniform, despite the rainfall decreasing.
13. This slide shows better than the last the evolution of the piezometric level, compared with
rainfall and water supply, since 1999 to 2007; we must consider that there were not pumping since 1997, when the prison closed and population suddenly decreased at a few units. The groundwater level trend in some dug-wells in this period increased, although the rainfall complexly decreased. If we compare the not linear trend of rainfall with the water level in others dug-wells, we can see that the trend is almost the same in the first period, but in the last period all the dug wells analysed show a water level increase, although the precipitations decrease. The meaning is that the decrease of pumping allowed the increase of water table, although the precipitations decrease.
14. We also analysed the groundwater budget, using this famous formula.
15. For Pianosa Island we can consider discharge nearly zero, because of the flat morphology
and permeable rocks outcroppings.
16. In order to find the infiltration value, we calculated evapotranspiration with the Turc formula, modified by Santoro (1970). The annual average evapotranspiration in the period analyzed is 385.9 mm per year.
2
17. With some calculations we find the infiltration rate, assessable in about 485,000 m3.
18. With exiting data we elaborated the Thornthwaite water budget in the period analyzed. This slide shows that the infiltration rate is concentrated in a short period of the year, nearly since February to the end of March, because the autumnal and winter rainfall allowed obtaining only the soil restoration of humidity reserves and no restoration of groundwater reserves. The cause is a long arid summer season.
19. During the survey we also carried out geochemistry and isotopic analysis, in situ and in
laboratory: • chemical analyses by Tuscan Region ARPAT laboratories, in order to find the main
chemical compound; • isotopic analyses by CNR-IGG laboratories aimed at evaluating Oxygen-18, Deuterium
and Tritium. The aims of this survey were: • appreciating the water-rock interaction; • evaluating the groundwater origin and residence time; • evaluating the evaporation, seawater intrusion and pollution.
20. This slide shows the Piper-Hill diagram, which allows classifying the kind of natural water on the basis of the main chemical compound. The blue circle represents the position of Pianosa groundwater in the diagram, which indicated a kind of water that associates: • presence of limestone’s elements, due to the flowing of the water in a prevalently
calcareous reservoir; • presence of sea-elements, due to spray-sea occurrence in seaboards region. The diagram shows another important occurrence, as the presence of elements that indicated reducing environment.
21. With stable isotope contents we can note the seawater mixing and/or evaporation phenomena. Some wells show these phenomena; in particular, the wells placed close to the sea present index of seawater mixing. The red circle shows the meteoric water collected. In general, the diagram shows the locally groundwater origin; the aquifer alimentation results from local rainfall.
22. This diagram shows the Tritium contents in the recent samples. The graph allowed:
• evaluating the residence time of the groundwater; • estimating the period of the year when there is a water surplus. According to the Thornthwaite budget estimated, the results of Tritium contents, in most waters, agree with water surplus in February-March.
23. This diagram allowed discriminating the evaporation phenomena and seawater mixing, comparing Oxygen-18 versus Chloride contents. The wells placed inside the two indicated lines, which move in the upper side of the graph, mean seawater mixing, instead of the wells placed outside the lines. The two phenomena can both coexist in different measures.
24. This is a very interesting graph; in fact, it shows the groundwater pollution in some wells,
that present high Nitrate versus Chloride contents. This kind of geochemical element contents is related to human activities.
25. Finally we proposed the followings conclusions:
• from the second half of the Eighties there is a decreasing trend of the rainfall;
3
• in the last 10 years, selected wells (not influenced by pumping) show a generally constant groundwater level. Minimum variation seems to be related to the annual rainfall amount;
• water chemical composition agrees with the local geological structure; • sea-water intrusion is individuated in the eastern part of the island; • Nitrate contents highlight important pollution phenomena, related to human activities; • the estimated infiltration rate could be satisfy a certain tourist presence, but the aquifer is
particularly vulnerable to the pollution.
4
Role of Science and Technology in Solving the Problem of Water Shortage in Mediterranean Countries.
By
V.K. Gouda, Fmr. Minister of Scientific Research, Egypt
1. Introduction Water shortage problem has numerous facets in the Mediterranean countries(MC). Perhaps the availability of water in many countries is the most recognized issue in the last decade. Limited surface water in several MC affects the agricultural land area and hinders the potential expansion to desert areas. In other MC the intensity of rain water precipitation in coastal and sub coastal locations governs almost entirely the intensity, quality and usability of the green cover. Accessibility to affordable reliable water supplies is the second most important issue following to the water availability. The paradoxical situation is related to the inaccessibility in spite of water availability. For instance, it may not be economically feasible at some situations to pump water to remote locations due to techno-economic constrains. Perhaps developing local supplies (eg. by desalination) may be among the most viable means to resolve accessibility. The problem of water quality aggravates water shortage situation due to social acceptability and health risk considerations. Finally, sustainable development requires securing available, accessible, safe and affordable water supplies. For this central objective, science and technology can offer innovative approaches that enable efficient use of current resources, maintaining agreed upon water treatment quality standards while maintaining the affordability for designated consumptive uses. This paper addresses priority interventions of science and technology to accelerate the development of economical non conventional resources of water. . One of the core issues to be addressed is water desalination as a potential resource to counteract the availability, accessibility and acceptability requirements. Improving physico-chemical and biological treatments for instance using adsorption, polymeric flocculation, electrochemical oxidation and bioremediation would enable efficient reuse of municipal, industrial, agricultural drainage water and other marginal quality water for specific consumptive uses. . The paper is concluded with a proposal for international collaboration among MC to improve efficient water treatment and reuse.
1
2. Definitions related to imbalances of water supply and demand Water Shortage A water shortage can be described as any case in which water supply is inadequate to meet demand. The term "water shortage" has the following specific meanings:
• dearth, or absolute shortage, • low levels of water supply relative to minimum levels necessary for basic
needs. It can be measured by annual renewable flows (in cubic meters) per head of population, or its reciprocal. The frequency and/or cause of shortage may indicate the best way to overcome it. Droughts are temporary, but reoccurring. On the other hand, water contamination can put a water supply out of commission permanently. Water shortage caused by inadequate planning or equipment may be overcome by putting attention to equipment design and capital improvements. Shortage resulting solely from increased demand for water resources may be best eliminated through long-term resources management. Water Scarcity Defining scarcity for policy-making purposes is very difficult. The term "water scarcity" has the following specific meanings:
• an imbalance of supply and demand under prevailing institutional arrangements and-or prices,
• an excess of demand over available supply, • a high rate of utilization compared to available supply, especially if the
remaining supply potentials are difficult or costly to tap. The demand for water may be artificially stimulated, so that at a constant rate of supply the water resource becomes "scarce" Water Stress Water stress is generally related to an over-proportionate abstraction of water in relation to the resources available in a particular area. Water stress occurs when the demand for water exceeds the available amount during a certain period or when poor quality restricts its use. It frequently occurs in areas with low rain fall and high population density or in areas where agricultural or industrial activities are intense. Water stress induces deterioration of fresh water resources in terms of quantity and quality. Such deterioration can result in health problems and induce a negative influence on ecosystems.
2
Water demand management: Water demand management refers to the implementation of policies or measures which serve to control or influence the amount of water used. The relationship between water abstraction and water availability has turned into a major stress factor in the exploitation of water resources in Europe. Therefore, it is logical that the investigation of sustainable water use is increasingly concentrating on the possibilities of influencing water demand in favorable way for the water environment. Demand management includes initiatives having the objective of reducing the amount of water used (e.g. the introduction of economic instruments and metering), usually accompanied by information and educational programs to encourage more rational use. According to the EEA, management can be considered as a part of water conservation policy, which is a more general concept, describing initiatives with the aim of protecting the aquatic environment and making a wiser use of water resources. Water conservation: Actually water conservation has many meanings. It means storing, saving, reducing or recycling water. In detail it denotes: For farmers who irrigate:
- Improving application practices via valves, special nozzles on sprinkler systems, soil moisture and crop water needs sensors
- Increasing uniformity of application, thereby allowing less water to be used - Using meteorological data to balance water applications with available soil
moisture and crop water needs - Lining diversion canals and ditches to minimize seepage and leaks - Irrigating with recycled water rather than freshwater that could be used after
treatment. For municipalities:
- Encouraging residents to install and use high efficiency plumbing fixtures and educate them about water-saving habits.
- Reducing Peak demands to avoid the extra-costs of investing in additional pumping and treatment plants.
- Metering water (customers pay for what they use) - Substituting recycled water for non potable application for urban irrigation of
sports facilities and parks - Increasing water shortage through aquifer recharge and recovery so the excess
water in the winter can be stored for summer use.
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For industry:
- Identifying other resource-conserving methods for the production processes - Reusing treated municipal wastewater instead of potable water for processes
and cooling - Reusing water used in manufacturing and cooling
3. Current Situation of water Shortage in Mediterranean Countries The water availability per person in some Mediterranean countries for year 2000 and 2025 as compared to the water poverty line (the red line) of 1000 m3/person/year are shown in figure 1 [1]
0
1000
2000
3000
4000
5000
6000
7000
Greece
Italy
France
Spain
Syria
Leba
non
Turkey
Morocc
oEgy
pt
Tunisi
a
Algeria
Per
Cap
ita S
hare
(m
3/ c
apita
Yea
r)
20002025
Figure (1)
It is clear from figure 1 that most of the southern MC lie below the poverty line. The expected water availability per person for year 2025 as shown is lower than the current one reflecting the severity of the water shortage problem. In case of Egypt, the total available resources are about 63 billion m3 annually of which around 10% extracted from ground water supplies. The different consumptive uses of water in Egypt are shown in table (1) [2]
4
Table 1: Different Consumption Uses of Water in Egypt
Sector Consumption use Billion m3/yr
%
Agriculture 48 76.6 Drinking & Domestic & Municipal
9 14.4
Industry 5.7 9.1 Total 62.7
It is clear that the consumption of agriculture represents about 77% of the total water consumption in Egypt. One of the major challenges that faces Egypt is the fixed quota and the ever increasing population. Consequently, the per capita water availability in year 2025 is expected to reach 576 m3/person as compared to 826 m3/person for year 2007[1]. Another major challenge is the pressure on the water system which causes sever levels of pollution, continual urbanization, the low coverage of sanitary drainage, the modest services of solid waste and the incompliance of industry with effluent treatment, all these low quality waters end back into the drainage system creating intolerable contamination levels in drains which have, in some cases, direct or indirect connections with irrigation canals. Egypt will most probably be hit hard by climate change since parts of the Nile Delta as other low laying lands will be affected by the sea water level rise and the natural flow of the River Nile is expected to be reduced. Future interventions mandate extensive reliance on water reuse technologies for the reclamation of municipal, industrial and agricultural waste waters. Increased reliance on sea water desalination on coastal areas (eg. Red sea and North West zones) reflects the urgency to adopt safe technology measures. It is obvious that we will be facing difficult situations in the near future unless we realize feasible and reliable technological and engineering interventions. The excessive use of water resources by the Egyptians due to the false believe that the water resources are ever lasting. The unawareness of the magnitude of water shortage problem deserves special attention for immediate action.
5
4. Water Resources
Conventional water resources:
The main sources of conventional water are: fresh surface water, rainwater and groundwater. The availability of water resources is determined by a number of factors, including the amount of water received from precipitation, inflow and outflow in rivers and the amount lost by evaporation and transpiration (evaporation of water through plants). The potential for storage in aquifers and bodies of surface water is important in facilitating the exploitation of this resource by humans. These factors depend on geography, geology and climate. It is the fact that the great percentage of the fresh water is directed to agriculture. Thus, it would be reasonable to direct the search efforts for conservation of agricultural feed water. [3,4] A reduction of agricultural withdrawals can be achieved through:
• A reasoning of irrigation with a precise adaptation of the amounts of supplied water: launching of irrigation from an irrigation balance, estimation of the existing cultivations needs, irrigation recording book, etc.
• Leakage limitation by drain, infiltration, evaporation or drift: gravity irrigation suppression localized irrigation development (drop by drop) when possible, equipment adjustment, no irrigation during maximum sunshine or when wind blows over 7 km/hr.
• Collective management of disposable resources for agriculture. • Changing the type of crops: less consuming or differently distributed in time
(winter cultivations instead of spring ones) Non conventional water resources:
With increasing pressure on natural fresh water, other sources of water are growing in importance. These non-conventional sources of water represent complementary supply sources that need intervention of science and technology for development. They include:
• the production of fresh water by desalination of brackish or saltwater (mostly for domestic purposes).
• the reuse of urban or industrial waste alters (with or without treatment), which increases the overall efficiency of the use of water (extracted from primary sources), mostly in agriculture but increasingly also in industrial and domestic sectors. This category also includes agricultral drainage water.
Desalination Initially sea-water desalination technologies were based on distillation; hence energy consumption was very high. The development of more efficient technologies such as
6
Reverse Osmosis has reduced the cost of distillation considerably below 1 €/m). However, the water generated by this technique tends to be considerably more expensive than it from conventional sources (surface and ground water) and need R & D intervention to reduce cost of desalination. This will be dealt with later in the presentation. Rain Water Harvesting For centuries, people have relied on rain water harvesting to supply water for household, landscape, livestock, and agricultural uses. A renewed interest in this approach has emerged due to the escalating environmental and economic costs of providing water by centralized water systems or by well drilling, and the potential cost and energy savings associated to rain water collection systems which are a source of water. Water Reuse Water reuse is the use of waste water or reclaimed water from one application such as municipal wastewater treatment for another application such as landscape watering. The reused water must be employed for a beneficial purpose and in accordance with applicable rules (such as local ordinances governing water reuse). Factors that should be considered in an industrial water reuse program include:
⎯ identification of water reuse opportunities ⎯ determination of the minimum water quality needed for the given use ⎯ identification of wastewater sources that satisfy the water quality requirements ⎯ determination of how the water can be transported to the new use
In terms of quantitative water resources management, the reuse of waste water or reclaimed water is beneficial because it reduces the demand for surface and ground water. The greatest benefit of establishing water reuse programs might be their contribution in delaying or eliminating the need to increase the potable water supply and the capacity of water treatment facilities, and in reducing the costs of long sea outfall pipes to dispose of waste water. Main applications of this technique can be found for irrigation in agriculture, parks, recreational areas, golf courses, etc. Usually simplified water treatment is carried out, in order to guarantee minimum quality standards of the water to be reused. In spite of the numerous endeavors on the use of reclaimed water for agriculture yet further research s needed to assess the long-term effect of irrigation with the treated waste water on soils and agriculture. Case study on drainage water reuse as a mean of fighting water shortage in Egypt The national integrated water resources management plan was initiated by the Ministry of Water Resources and Irrigation (MWRI) to improve supply-demand imbalance. The plan emphasizes coordination between several partners including
7
governmental and NGOs to provide information about quantity and quality of drainage water based on long-term monitoring program. Daily measurements, (31 parameters) are recorded from a network in Nile Delta and Fayoum generated from 140 sites. The parameters included toxicological, microbiological, oxygen budget, ions, elements and others. Database is now available about drainage water in Nile Delta for the last 15 years. The data is linked to Geographical Information System (GIS). The monitoring revealed that an average of 12.5 billion cubic meter of drainage water is discharged annually to the sea. It includes, brackish ground water, municipal industrial discharges. The data were used to develop guidelines for using drainage water for sustainable crop production taking into consideration the potential crop yield reduction and soil salinization when using irrigation water containing different salinity levels. The potential of the soil affected by salinity to remain a suitable medium for plant growth is crucial. The guidelines also include criteria for environment protection and public health preservation. The degree of socio-economic vulnerability of the farmers has been also addressed. The MWRI is now coordinating all effort to meet the water demands through is integrated management approach. [1] 5. Potential Water Treatment Technologies That Need Further R & D for MC: 5.1 Sea Water Desalination Technologies: This technique is used when technically and economically feasible. There are more than 7500 desalting plants in operation worldwide producing several billion gallons of water per day. 57% are in the Middle East and 12% of the world capacity is produced in the Americas, with most of the plants located in the Caribbean and Florida regions. However, as drought conditions continue and concerns over water availability increase, desalinization projects are being proposed at numerous locations. [1] A number of technologies have been developed for desalinization which includes distillation, reverse osmosis (RO), electro dialysis, and vacuum freezing. Two of these technologies, distillation and reverse osmosis RO, are being considered by municipalities, water districts and private companies for the development of sea water desalinization. [5] Desalinization costs are very sensitive to the salinity of the feed water. Desalinization of brackish waters and waters that are mildly saline can be economically justified for some high valued uses such as in tourism. Seawater desalinization remains enormously expensive when all costs are fairly accounted for. There is tendency to promote sea water conversion projects that are joint with power plants. The resulting costs are almost always understated because the power is subsidized and all of the joint costs are allocated to power production. Seawater conversion alone is unlikely to be the solution to water problems except in a few instances where there are no alternative sources of supply and there is considerable wealth to defray the costs of
8
seawater treatment costs vary by the amount of salt removal, cost of energy, size of plants, as well as the type of treatment technology. Desalinization costs are dominated by capital investment, energy and maintenance costs. Reverse osmosis systems, which utilize membrane technology for water treatment, have the lowest cost of operations, especially in the areas with high power cost. While membrane technology advances have resulted in significant cost reductions, energy still accounts for up to 60% of the operating cost. Further improvements in energy efficiency will deliver sustainable reductions in operating cost. Along with improvements in energy efficiency, improvements in membrane performance and membrane life through integrated treatment systems can reduce capital cost and life cycle cost. Membrane-based treatment solutions are essential to create new water sources such as brackish water aquifers, seawater, and even wastewater. Membrane-based desalinization and reuse is a proven solution, but a broader application of these technologies to create meaningful new water sources requires investments to further reduce the energy consumption associated to the operation of membrane systems. The long-term, sustainable solution to produce economical sources of new water lies in developing more advanced, energy-efficient technologies to treat multiple water sources. [1] 5.2 Technologies for water reuse 5.2.1 Treatment Based on Adsorption The main barriers for effective water reuse are those inorganic and organic hazardous pollutants. Reliable low cost adsorbents are suitable. Tables 2 shows the removal efficiency of low cost adsorbents in removal of Altrazine as an example of organic pollutants.[6] Table 3 shows the adsorption capacity of various low cost adsorbents used for chromium (VI) removal as an example of inorganic pollutants. [7,8,9]
Table 2: Removal % of Altrazine using various low cost adsorbents
Adsorbent Removal % Wood charcoal 95.5-97.7 Fly ash 84.1-88.5 Coconut charcoal 92.4-95.2 Saw dust 78.5-80.5 Coconut fiber 85.9-86.3 Baggasse charcoal 76.5-84.6 Activated charcoal 98
9
Table 3: Adsorbent capacity of various low cost adsorbents used for chromium (VI) removal
Adsorbent Maximum Adsorbent
Capacity, qm (mg/g) Activated carbon 57.7 Sawdust 39.7 Palm pressed fibers 15.0 Maize cob 13.8 Sugar cane bagasse 13.4 Tamarind seeds 11.08 Biomass residual slurry 5.87 Waste tee 1.55 Fe (III)/ Cr (III) hydroxide 1.43 Walnut shell 1.33
Removal of acid green 25 dye and acid red 183 dye from waste water by different adsorbents such as shells of almond and hazelnut, and poplar and walnut sawdust were successful[10]. Development of low cost adsorbents from rice straw and cellulosic wastes has been proven. Future adsorbents should be produced based on natural materials (plant residues/ agricultural residues/ food wastes). This would eliminate reliance on synthetic material while enabling efficient resource recovery and conservation.. Promising indicators suggest the importance of capitalizing on these endeavors. Further abundance of natural adsorptive clay materials would enable removal of heavy metals and some hazardous soluble materials. Functional modifications of those natural clays have been attempted and still needed to enhance adsorptive properties. Methods of measurement and control as related adsorption systems should be investigated with emphasize on regeneration of adsorbents. 5.2.2 Treatment Based on Polymeric Flocculants The use of inorganic coagulants has been known since the early beginning of commercial water treatment. Lime, alum and ferric salts are currently being used for water treatment. Polymeric flocculants (anionic, cationic, and nonionic polymers) are used to enhance the efficiency of coagulation process and also for numerous applications in sludge conditioning. Table 4 shows the removal of total suspended solids (TSS) using various commercial polymers. [11]
10
Electrochemical coagulation & flocculation will manifest promising indicators for the treatment of marginal surface water. In addition, electrochemical oxidation is powerful tool for elimination of residual soluble organic and biological contaminants. Future R&D should identify new materials that can be used for flocculants and electrodes. [12] Environmental impact assessment studies should be undertaken following the development of polymeric flocculants to minimize environmental risk. Biodegradable flocculants developed from natural polymers such as cationic starch should be developed to replace expensive synthetic flocculants. Residual monomers after flocculation process should be identified by simple low cost methods. There is a considerable need to develop reliable electrochemical flocculants treatment techniques. Development of efficient, simple and low cost monitoring of flocculants deserves special consideration from the R&D community specially addressing concerns related to the use of complex chemical treatment technologies.
Table 4: Typical removal efficiencies of TSS for using various commercial polymers.
Commercial Polymer
Dosage (mg/l) % Removal with polymer
LT 7991 18
91 93 91
LT 22S 2
74 69 70
CE 1950 20
89 95 94
5.2.3 Treatment based on Cold Plasma Cold plasma treatment process has been developed in recent years. It comprises exposing the contaminated fluid to Glow Discharge Plasma (GDP) generally known as cold plasma. Two electrodes housed in an evacuated reactor under high voltage are able to produce cold plasma between the submerged cathode and the gas phase anode. Active ions, molecules, gases and active water are formed in the liquid medium with subsequent frequent collisions among charged pollutants causing breakdown of organic substances and separation of inorganic substances. Typical operating conditions involve about 15-100 mA, 500-1000 Volt and about 300 K. Pulsed high-voltage electrical discharge processes have been proven to be effective specially for the elimination of toxic organic compounds. [13]
11
The pulsed discharge plasma in water has several modes such as streamer, spark, and spark–streamer mixed mode. The differences in removal efficiency among different modes were considered to be caused by the differences in the physical and chemical processes of each pulsed discharge mode in the water. [14] Table 4 represents a summary of R&D efforts for water treatment conducted by cold plasma technology under various operating conditions.
Table 5: R & D collection of efforts for water treatment conducted by cold plasma
technology under various operating conditions
R&D collection of efforts Reference
Application of cold plasma as a new tool for: • Removal of Fe2+, Cr6+, Ni2+, Mo4+, Co2+, Zn2+, Cd2+, Cu2+,
cyanide, coliphages • disinfection of drinking water • polioviruses inactivation in drinking water
[15],[16]
Decomposition of chloroform using the cold plasma tecnology [17] Development of a tubular high-density plasma reactor for the treatment of methyl tert-butyl ether, benzene, ethylbenzene, toluene, m- and p-xylene, and o-xylene in a dense medium plasma reactor
[18]
Developed a novel non-equilibrium plasma-based water treatment reactor. It was applied to treat low concentrations of methyl orange
[19]
Invented a process and apparatus for purifying a dense dielectric fluid (e.g. carbon dioxide) applying high pressure plasma in a packed bed reactor (US Patent)
[20]
Invented a method for disinfecting water and other dense fluid media containing microorganisms which was carried out in a dense media plasma reactor (US Patent)
[21]
The plasma sparker submersible assembly was used for the removal of antifouling, toxic contaminant destruction, sludge compacting and dewatering of industrial water streams, chemical stabilization, and disinfection of municipal water supplies and degradation of excess organics (BOD or COD).
[22]
Organic contaminant concentrations (benzene, toluene, ethyl benzene, xylene) using dense medium plasma water purification reactor
[14]
Dye decoloration from water solutions by pulsed discharge plasma [13] Pulsed discharge plasma induced Fenton-like reactions were used for the enhancement of the degradation of 4-chlorophenol in water and removal of toxic and biorefractory organic contaminations.
[23]
Degradation of phenol in aqueous solutions using a gas–liquid phase pulsed discharge plasma reactor.
[24]
The method of GDP may be considered as a promising compact technology for calcitrant refractory pollutants. With planned systematic R&D efforts, this technology may be a competitive cost effective technology.
12
Application of low temperature GPD has a number of advantages, such as smaller dimensions of the equipment, opportunity to automate the process and the quality control of processed media, low requirement for human resources, opportunity to use new solutions [15]. In addition it is considered to be environmentally safe, of low operating cost, rapid capital recapture and is expected to be cost effective process.[22] 5.2.4 Treatment Based on Bioremediation of Industrial Waste The elimination of a wide range of pollutants and wastes from the environment is an absolute requirement to promote sustainable development. Bioremediation is a process that uses living organisms (bacteria, fugi and plants) and / or their enzymes to return the natural environment altered by contaminant to its original condition. It may be employed to attack specific soil and water pollutants. Bioremediation technologies can be generally classified as in situ or ex situ. In situ bioremediation involves treating the contaminants at the site, while ex situ involves the removal of the contaminated substrate to be treated elsewhere. The bioremediation technologies have been developed in the recent years to target specific recalcitrant chemicals generated from various industries. There still a great deal of R&D work to do for bioremediation of synthetic organic chemicals widely used in diverse industries everywhere before discharging the wastewater of these industries into the environment. Phenols are commonly employed chemicals in many industries such as coke, refineries, resin manufactures, pharmaceuticals, pesticides, dyes, plastics and herbicides.[25] The residues of phenol , phenolic compounds and synthetic azo-dyes in industrial wastewaters are among the chemicals causing real threat to the ecosystems.. These chemicals also enter the environment as intermediates during the biodegradation of natural polymers containing organic rings such as lignin, tannins and aromatic amines.[26] The microbial biodegradation as strong bioremediation tool has intensified in recent years as man-kind strived to find suitable ways to clean-up contaminated environment. Major methodological breakthroughs in recent years have enabled detailed analyses of environmentally relevant microorganisms and their adaptation to changing environmental conditions. Several trials has been made recently to identify some microbes involved in phenol and azo-dyes biodegradation. Reports indicate the success of microbial bioremediation of toxic chemicals before release into the environment. [27,28,29,30,31,32] There is need for R & D to identity potent microbial strains capable to biodegrade such chemicals. This can allow the reuse of the bioremediated wastewater again in the industry or even in irrigation. This type of eco-friendly bioremediation technology is highly needed for saving the environment from chemical industrial pollutants. The use of genetic engineering to create organisms specifically designed for bioremediation has great potential.
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5. Proposed Project
Development of Innovative Cost Effective Water Treatment Technologies for Mediterranean Countries
Main Objective The main objective of this research initiative is to motivate the R&D community to seek reliable cost effective innovative solutions for the problem of water shortage in the Mediterranean countries. Such research initiative would enable efficient use of current non conventional resources. The suggested priority areas would essentially comprise: membrane desalination, cold plasma treatment and bioremediation. Justification In spite of the successful technical performance related to the three mentioned priority areas, however the cost of treatment is still prohibitive. Further, technical issues merit additional investigations to improve the effectiveness of the stated priority technologies. Collaboration among partners from Europe and other Southern Mediterranean Countries is mandatory for the project in order to integrate experiences, transfer and use technologies and expertise thus increasing geographical applicability of the results. The dissemination of results will be also a special action of the project that will be done through a dedicated web site. By building up this wide and strong co-operation between the participants, solutions to water shortage problem can be achieved.
Technical Program Three main areas are addressed through well planned work packages as follows: Work Package I: RO Desalination Production of low cost desalinated water is still a vital mandate of technology developers. Improving RO-Desalination characteristics comprises the following tasks:
• improving functional and mechanical characteristics of RO membranes • minimization of energy consumption via decrease of pressure drop and
improved module design • optimization of RO pretreatment using Nanofiltration membranes • development of commercially applicable brine managemenet technologies • optimization of solar/hydrogen membrane plants • full fledged techno economic studies for thermal/membrane desalination
plants
14
• development of reliable modeling/simulation and optimization of RO-based desalination sea water.
Work Package II: Cold Plasma Water Treatment Objective: Develop a competitive cost effective treatment based on cold plasma technology. The suggested studies will involve the following activities Development of technology selection and reduction matrices Technology selection matrix will be developed for all cold plasma systems
applicable to water treatment. Every aspect will assume a certain score based on reported actual performance. Thus the selected priorities and the elimination criteria will be adopted for development of a reduced matrix comprising limited number of choices.
Design of the cold plasma water treatment unit
• Modeling, simulation, optimization and design of the following parameters:
• Plasma chamber • Positive and negative electrode assemblies • Dense medium feed system • External/ internal mixing and homogenizing systems • Power unit with associated interfacing and control parameters • Interface/ circulation to intermediate chamber • Measurement and control system
• Design review and modifications
The developed design will be reviewed with emphasis placed upon energy consumption, functional and safety issues.
• Full fledged feasibility study • Construction and testing of experimental unit • Demonstration of plant performance
Work Package III: Bioremediation of Industrial Wastewater The suggested work plan for this activity can be outlined as follows:
• Isolation of microbes capable to utilize several industrial pollutants (phenols and azo-dyes) as sole source of carbon and nitrogen.
15
• Classical and molecular characterization of the most potent strains obtained from industrial sites.
• In depth study on optimization of the process of pollutants biodegradation under different environmental conditions.
• Design small scale bio-reactor to test the capacity of the identified potent strains to remove the pollutants.
16
References
1. Mediterranean Water Scarcity and Drought Report, Technical report on water scarcity and drought management in the Mediterranean and the water framework directive, April 2007
2. Personal communication ,El-Koosi, Diaa El-Dein, Consultant to the Minstry of Water Resources and Agriculture
3. Sorour, M.H., N.M.H. El Defrawy, H.F. Shaalan, "Treatment of agricultural drainage water via lagoon/ systems", Euromed 2002 Conference Proceedings; May 4-6, 2002, Sharm El-Sheikh, Egypt, pp 105-110
4. Taalat, H.A., M.H. Sorour, A.G. Abulnour, "Comparative economics for desalting of agricultural drainage water(ADW)", Euromed 2002 Conference Proceedings; May 4-6, 2002, Sharm El-Sheikh, Egypt, pp 125-130
5. Taalat, H.A., M.H. Sorour, A.G. Abulnour, H.F. Shaalan, "The potential role of brackish water desalinationwithin the Egyptian water supply matrix", Euromed 2002 Conference Proceedings; May 4-6, 2002, Sharm El-Sheikh, Egypt, pp 555-564
6. RK, Sharma, Kumar A, Joseph PE, "Removal of Atrazine from Water by Low Cost Adsorbents Derived from Agricultural and Industrial Waste", Bulletin of environmental contamination and toxicology, 2008
7. Huang, C. P. and Wu, M. H. (1977). “The removal of chromium (VI) from dilute aqueous solution by activated carbon”, Water Research, 11, pp. 673-679.
8. Sharma, D. C. and Forster, C. F. (1994). “A Preliminary examination into the adsorption of hexavalent chromium using Low-cost adsorbents”, Bioresource Technology, 47, pp. 257-264
9. Tan, W. T., Ooi, S. T. and Lee, C. K. (1993). “Removal of chromium (V1) from solution by coconut husk and palm pressed fibres”, Environmental Technology, 14, pp. 277-282
10. Ayden, A.H., Y. Bulut, O. Yavuz, " Acid dyes removal using low cost adsorbents", International Journal of environment and pollution, 2004, vol. 21, no. 1, pp. 97-104
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1
Air quality and climate change in the Mediterranean basin Jos Lelieveld Cyprus Institute, Nicosia Summary The Mediterranean basin is characterized by large climate gradients, and there is concern that climate change will be associated with the intensification of extreme weather conditions. Climate scenario calculations for the 21st century indicate a relatively strong warming in the Mediterranean compared to the rest of Europe, and especially the number of very hot days may increase. Air quality is strongly correlated with the mean temperature through the occurrence of hot and stagnant anticyclonic conditions. The climate scenario calculations also suggest that the distribution and intensity of precipitation may change. However, the models used did not yet account for the effects of aerosol particles on the energy and moisture budgets. The strong aerosol pollution in the Mediterranean basin reduces the surface heating by scattering and absorption of solar radiation. Since the solar energy absorbed by the sea is largely returned to the atmosphere through evaporation, the negative aerosol radiative forcing at the surface can suppress evaporation and precipitation. The abatement of air pollution may reverse this tendency, and it will be necessary to assess the integrated effects of air quality and climate change.
Ozone air pollution It has long been known that atmospheric pollutants can be hazardous to human health and ecosystems. This includes effects from episodic peak levels as well as the long-term exposure to relatively moderate concentration enhancements. Environmental issues related to air pollution include acidification, mostly by the strong acids from sulphur and nitrogen oxides, eutrophication by the deposition of reactive nitrogen compounds, the reduction of air quality by photo-oxidants and particulate matter, and the radiative forcing of climate by increasing greenhouse gases and by aerosol particles. Many air pollutants are photochemically formed within the atmosphere from emissions by traffic, energy generation, industry, the burning of wastes and forest fires.
The Mediterranean basin in summer is largely cloud-free, and the relatively intense solar radiation promotes the photochemical formation of ozone (O3), being health hazardous at levels in excess of about 100 µg/m3. Ozone is formed in the lower atmosphere as a by-product in the oxidation of reactive carbon compounds such as carbon monoxide (CO) and volatile organic compounds, catalysed by nitrogen oxides (NOx ≡ NO+NO2). In summer transport pathways of air pollution near the earth’s surface are typically determined by northerly winds, carrying photo-oxidants and aerosol particles from Europe into the basin.
It appears that O3 levels exceed the European Union eight-hourly air quality limit of 110 µg/m3 on a basin scale throughout most of the summer, being caused by European air pollution. In several parts of the basin, for example in the northeast of Spain and central Italy, the EU plant protection threshold (80 µg/m) is exceeded more than 80% of the time. It is difficult to locally control the ozone smog, notably in the populated areas along the coast, since urban emissions add to the already high background O3 mixing ratios. Based on scenario simulations for the year 2025 it may be expected that tropospheric O3 will further increase,
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and that the Mediterranean region will remain to be one of the ozone “hot spots” in the northern hemisphere.
Widespread aerosol haze Aerosol particles with a diameter of less than ~10 µm (PM10) can have adverse health effects at a concentration of about 30 µg/m3 or higher. The fine mode aerosol particles (< 2 µm diameter) are mostly composed of sulphates and particulate organic matter (POM), whereas the coarse mode particles (≥ 2µm) often contain substantial amounts of sea salt, nitrate, Saharan desert dust and other mineral components.
The aerosols can form a widespread haze that scatters and absorbs solar radiation, thus reducing downward energy transfer and surface heating. Increased aerosol scattering causes a negative radiative forcing of climate (cooling tendency), which can regionally mask the positive radiative forcing (warming tendency) by increasing greenhouse gases such as carbon dioxide (CO2), methane (CH4) and tropospheric ozone.
Based on satellite measurements, the Mediterranean Sea has been identified as one of the maritime regions in the world with the highest aerosol optical depths. Measurements indicate relatively high concentrations of sulphate and nitrate, mostly caused by long-distance transport of air pollution. Upwind of the eastern Mediterranean high levels of sulphur dioxide have been observed, attributed to coal burning in Central and East Europe.
Furthermore, desert dust intrusions from Africa, and additional transports of mineral dust from the Near- and Middle-East substantially contribute to the aerosol column. Over Africa, the dust is often lifted to altitudes well above the Mediterranean boundary layer in synoptic weather disturbances. Hence, after its northerly transport from Africa it can entrain into the westerly flow over the Mediterranean in the free troposphere and descend over the Mediterranean region.
The mixture of natural and human-made particles gives rise to an extensive haze in the Mediterranean basin which can clearly be discerned in satellite images. Often the visibility is limited, even on distant islands. The Mediterranean islands represent the southernmost part of Europe, remote from pollution emissions on the continent, and the local aerosol concentrations are nevertheless close to the European Union air quality standard for particulate matter (PM10) of 55 µg/m3. This concentration is not allowed to be exceeded for more than 35 days per year. The high concentrations over the Mediterranean Sea may be considered indicative for stronger violations of the air quality standards further upwind.
Air pollution control In Europe the abatement of air pollution has been promoted by the UN Convention on Long-Range Transport of Air Pollution (LRTAP), which was signed in 1979 and entered into force in 1983. Since 1980 the emissions of air pollutants in Europe have indeed decreased. Substantial emission reductions have been achieved, for example, nearly 50% for CO and more than 75% for SO2. Nevertheless, the emissions have decreased relatively less in the Mediterranean member states of the European Union (EU). In Greece, Portugal and Spain the anthropogenic emissions of NMVOC and NOx have actually increased and those of sulphur dioxide (SO2) have hardly decreased during this period. In fact, five Mediterranean EU countries contribute nearly 50% to the EU25 air pollution emissions.
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Radiative forcing of climate Based on radiometric measurements it has been shown that the 24-hour average shortwave radiative forcing at the surface by aerosol particles is nearly 18 W/m2 (see figure below). This is mostly caused by solar radiation scattering and absorption by particles in the fine mode aerosol, substantially reducing the surface heating. The radiative forcing at the surface compares to a negative forcing of about 6.6 W/m2 at the top of the atmosphere (TOA), the latter representing the overall loss of solar energy to space through radiation backscattering by aerosol particles. The difference between the TOA and the surface forcing corresponds to an atmospheric heating in excess of 11 W/m2, caused by the absorption of solar radiation mostly by black carbon (soot).
The above figure shows the diel mean radiative forcing of climate (∆Q) over the eastern Mediterranean measured in August 2001. It contrasts the negative aerosol forcing with the positive radiative forcing over the Mediterranean exerted by long-lived greenhouse gases (GHG) and tropospheric ozone. Obviously, these strong radiative perturbations may be expected to influence the Mediterranean atmospheric heating profile and the moisture budget through changes in evaporation and cloudiness.
Note that the radiative forcing by aerosol particles and ozone is mostly regional in nature because the lifetime of these compounds is relatively short (days-weeks). Conversely, the long-lived greenhouse gases CO2 and CH4 (years-centuries) are mixed more or less homogenously through the atmosphere on a global scale. This has the important implication that air quality control measures, e.g. reducing sulphate particles, have near-instantaneous regional effects on climate forcing, whereas control measures aimed at CO2 have a much delayed response. Since the regional cooling tendency by aerosol scattering can mask the enhanced greenhouse effect by CO2, air pollution emission controls can have a complex and possibly unanticipated outcome.
Air quality and climate change The Mediterranean basin is characterized by large climate gradients, and there is concern that climate change will be associated with the intensification of extreme weather conditions and a general drying tendency. Regional European climate scenario calculations for the 21st century
4
indicate a relatively strong warming as compared to the rest of Europe, and especially the number of very hot days is expected to increase. Air quality is strongly correlated with the mean temperature through the occurrence of hot and stagnant anticyclonic conditions, which will likely increase in future. In addition, the hemispheric background level of air pollution may increase, e.g. through long-distance transport of emissions from Asia.
Climate scenario calculations also indicate that precipitation may increase in the western and northern parts of the basin, more often released in torrential rain events, while in the dry southern and eastern parts precipitation is expected to decrease even further. However, the models used did not yet account for the effects of aerosol particles on the energy and moisture budgets. As indicated above, the strong aerosol scattering and absorption in the Mediterranean basin reduces the surface heating and thus the sea surface temperature (SST). Since the solar energy absorbed by the sea is largely returned to the atmosphere through evaporation, the negative radiative forcing at the surface, caused by sulphates and other particulate matter, suppresses evaporation and atmospheric moisture transports. Further studies will be needed to substantiate these links between aerosol pollution, SST anomalies and perturbations of the water cycle.
Advanced investigations will also be necessary to better understand several additional effects that aerosol particles can have on clouds and climate. For example, the solar radiation absorption by black carbon, which heats and thus stabilizes the aerosol pollution layer, could lead to the evaporation of clouds. Indirect aerosol effects on clouds also include the precipitation efficiency; for example, a high particle abundance may inhibit rainfall or suppress “warm” rain formation in convective clouds. The latter effect can extend the vertical development of deep convective clouds, which promotes ice and hail formation and lightning so that some of these clouds may invigorate into heavy thunderstorms that produce torrential rain.
How important these interactions between air pollution, clouds and climate are for the Mediterranean basin needs to be determined through coordinated research programmes. Global, regional and local aspects influence both air pollution and climate, and mitigation or adaptation strategies should be based upon integrated problem assessments that also account for land-use and soil hydrology changes. The largest risk lies in the possibility that some of these aspects combine into destabilizing (positive) feedback mechanisms with potentially large consequences for the region, shown to be vulnerable to changes in air quality, climate and the water cycle.
The role of science and technology in the soft path to solving conflicts over water1
MANUEL RAMON LLAMAS2 AND ELENA LOPEZ-GUNN3
Abstract.
Today most water resources experts admit that water conflicts are not caused by the physical scarcity of
water but are mainly due to poor water management. However, scientific and technological advances
that have occurred in the last fifty years open new paths to solving many water related conflicts, often
with tools that a few decades ago seemed unthinkable. Four of them are discussed in this paper: a) salt
water desalination; b) the concept of virtual water (i.e. water embedded in food trade on a global scale);
c) the “silent revolution” in groundwater abstraction taking place in most arid and semiarid countries; d)
how the use of remote sensing and GIS. Together these advances are changing the concepts of water
and food security that have been predominant during centuries in the minds of most water decision-
makers.
Key-words: blue water, green water, virtual water, desalination, intensive use of groundwater, water
footprint, water conflicts, remote sensing, GIS and Internet in water governance.
1. Introduction
This paper aims to discuss how recent advances in science and technology coupled with new concepts
can shift our perceptions on the ‘looming water crisis’ repeatedly forecasted in the media and in
academic circles. It tries to offer alternatives to doom and gloom scenarios by looking at the facts on
water use globally and in particular by looking at cheap and feasible options which currently exist to
address this water crisis.
This paper emphasizes that the current crisis is less due to water scarcity than to a crisis in water
governance and management. Thus the solutions have to be found elsewhere. It proposes a shift away
from pure technological fixes, predominant in the past or so called the hard path, which relied mainly
on the construction of infrastructure like dams, pipelines or aqueducts (Wolff and Gleick 2002; Gleick
2003) towards a soft path in water governance.
1 A previous version of this paper was presented at the Areces Foundation Scientifric meeting on Water Management: technology, economics and environment , Madrid 19th and 20th January 2007 2 Real Academia de Ciencias, Universidad Complutense, Madrid e-mail: [email protected] 3 Centre for Environmental Policy and Governance London School of Economics (UK), Houghton Street, London WC2 2Ae-mail: [email protected] and Observatorio de Tendencies Hidricas, (Fundacion Botin, Madrid, Spain)
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As Gleick (2003) emphasizes: A transition is underway to a "soft path" that complements centralized
physical infrastructure with lower cost community-scale systems, decentralized and open decision-
making, water markets and equitable pricing, application of efficient technology, and environmental
protection
The scope of this paper is to focus on four concrete options to address this water ‘crisis’, which are
cheap, feasible and most important, already available; first, it looks at water use globally and, in
particular the potential offered by yellow water or desalination, second, it looks at the silent revolution
of groundwater use, third, it emphasizes the key strategic relevance –of virtual water particularly for
arid countries and a country’s water footprint, and finally- although briefly- the potential of new
technologies from the information age, like remote sensing, GIS and internet.
As a case study it focuses mostly on Spain because of the interesting lessons that this country can offer
to other countries and regions in the world. This is for a number of reasons; first. Spain is now part of
the European Union, and has a developed economy- yet only 50 years ago it was a relatively isolated
country, with a predominantly rural economy. Spain therefore offers an interesting example to
developing countries due to its recent economic transformation. Second, Spain is mainly an semiarid
country, and other countries can learn from its both positive and negative experiences in relation to
water governance.
The paper also focuses mainly in the agricultural sector, since irrigation is the main water user
globally, accounting for more than 80% of the global water budget. Therefore, if we address key
questions in relation to water use by irrigation, by definition we will be focusing on 80% of the
world’s water use. Any advances made in irrigation will translate in gains by other sectors – which
often have higher economic returns or added value like industry, public water supply and sanitation or
environmental services- which at present are not benefiting globally from water captured by irrigation.
There is increased agreement globally that the water crisis is not due to water scarcity but is a crisis of
governance (Rogers, 2006). The last UN report on Human Development clearly states this point of
view (United Nations, 2006). This change in perception offers new opportunities on how to address
this governance crisis. The paper revisits traditional concepts of water and food security by looking at
new concepts and ideas, and how these are helping to re-shape old water paradigms. It particular it
discusses the different water aspects, and opportunities provided by virtual water and its potential
impact on softening the physical water scarcity of humanity at the global, regional and local level.
Traditionally, water played a key role throughout history in helping communities settle geographically,
allowing civilization to develop from largely nomadic tribes towards communities centered on cities.
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This started, through water infrastructure for irrigation developed in Egypt and Mesopotamia, through
to Roman aqueducts for public water supply, to canals for transport of goods and more recently for
industrial development and hydroelectric power.
These first civilizations have been known as ‘hydraulic civilizations’ (Wittfogel 1957). These
civilizations were born in the valleys of arid areas about 50 or 60 centuries ago. In these valleys hunter
and gathering societies settled into the land thanks to small irrigation infrastructure that could
guarantee the regularity of crops. This required a collective effort, which facilitated the settlement of
tribes, and led to the creation of ‘civis’ or small urban centers. This tradition of collective effort for the
creation and operation of water infrastructure has continued. These so called ‘hydraulic societies’
relied heavily on ‘hard infrastructure’ and often economies of scale to re-organize land use planning,
whilst facilitating the strengthening of the central state as funder and coordinator of infrastructure.
With few exceptions, most of the large water infrastructure built in the last 100 yeas has been due to
collective action on the part of the state, funded and controlled by the state administration.
However, this ‘hard’ path to water is now under duress and increasingly an alternative ‘softer’ path to
water is being advocated. It partly coincides with the shift from government to governance and the fact
that water policy is highly complex. To address water issues in the 21st century, the government alone
will be unable to deliver. In the shift from government to governance, new power dynamics are being
re-drawn and new concepts being developed to re-structure our understanding of the problem.
Old paradigms, based on the predominance of hydraulic societies, remain set in their obsession with
both water and food security, and the key role of the central states in providing these, as a way of
legitimizing their power vis-a-vis their citizens. Yet, the concept of water and food security are being
re-defined by the concepts of human security (CSGG, 2003 and 2007) and environmental security
(Tuchman Mathews 1989), which by definition it is not state centered and rather turns on networks of
governance, and not the dominance of the sovereign state. The notion of environmental security
challenges the foundations of water and food security, because in contrast to food and water security,
it is inherently accepting that environmental problems know no frontiers and therefore solutions have
to be global. This shift to water governance will be exemplified below by reference to aspects of
water.
2. The different shades of water
The basic functioning of the hydrological cycle is well known, and its quantitative evaluation
calculated about forty years ago. In summary, total rainfall on land is calculated at 115,000 Mm3, of
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which 45,000 make up the flow of rivers and aquifers, and 70,000 Mm3 evaporate from soil or
evapotranspirate from vegetation (United Nations 2003, pp 77 and 84)
Blue Water
Blue water is the water in the hydrological cycle from surface water runoff or groundwater recharge. It
is also the part of the hydrological cycle that humans have used beneficially for their own use through
the construction of water infrastructure, like canals and reservoirs. More recently blue water has also
included the spectacular rise in the use of groundwater. According to the United Nations, the amount
of water used for irrigation is about 2,000 to 2,500 Mm3, to irrigate 250 million hectares. Shah (2005)
estimates that out of the 2,000 to 2,500 Mm3 of water used, 800 Mm3 come from groundwater. In
terms of efficiency of water use, irrigation - when efficient - is the prime example of a consumptive
use, since 80-90% of water evapotranspirates. Yet, in most traditional irrigation (e.g. flood irrigation)
water use efficiency is normally lower than 50%. Meanwhile in urban use, it is calculated that at least
20% is lost through leaky pipes. Increasingly it has to be taken into account when discussing ‘blue’
water is the fact that there is a range of shades of blue, from pale blue of drinking water to dark blue of
water polluted by sewage or industrial use. However, in theory water, if treated, is a renewable
resource and will return to the water cycle.
Green Water
Two decades ago the term ‘green’ water started to be used. Green water is the name given to soil
water. It is the water in the soil that allows the growth and development of natural vegetation (forests,
pasture lands, tundra, bush land,…) as well as rain-fed agriculture. This water evaporates directly from
the soil or through evapotranspiration from vegetation. Soil water has only recently started to be taken
into account quantitatively, since its measurement and monetary valuation is still highly complex. It is
calculated at 70,000 Mm3/year, of which about 3,000 to 4,000 Mm3 are used by rain-fed agriculture. In
most water and agricultural statistics green water is not included. This is the case of the FAO-
AQUASTAT (FAO 2003), which only refers to blue water, even when in many countries –
particularly in the developing world- most crops are rain-fed. Its analysis has led to the concept
(discussed below) of water footprint.
3. The silent revolution: the intensive use of groundwater
Groundwater use until relatively recently was only undertaken on a small scale, with basic technology,
generating low flows and irrigating small areas to supply small villages and urban centers, organized
by small collectivities or individuals. Groundwater’s origin, location and movement were shrouded in
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secrecy, with little realization of cause and effect. This has changed dramatically in the last 50 years,
mainly due to technological advances, like well drilling and the invention of the multistage or turbine
pump. These have substantially reduced the cost and difficulty in accessing groundwater, which has
led to a spectacular rise in intensive groundwater use (Llamas and Martinez-Santos, 2005b). In the last
50 years in practically all arid or semi-arid regions across the world, from California, to a large part of
India, or Spain and Mexico, a silent revolution has taken place through the intensive use of
groundwater (Llamas and Custodio 2003; Fornés et al. 2005a; Llamas and Martínez-Santos 2005b). It
is called a revolution because it has led to dramatic changes in water use and food policy in these
regions. It is also called ‘silent’ because it has been mainly undertaken by millions of small farmers,
with little control and planning on the part of the government administration (Fornés et al. 2005;
Llamas and Martínez-Santos 2005b; Llamas 2006b). The most spectacular example globally is the
case of India, where population has more than doubled in the last 40 years, from 600 million to 1,100
million, changing from a net importer of cereals to becoming an important exporter in the global trade
of cereals. This has been achieved mainly through the abstraction of 200 Mm3/yr, from about 20
million wells to irrigate 60% of land, about 50 million hectares (Shah 2005). In a recent report of the
World Bank this situation has been described as a ‘quiet revolution’ (Briscoe 2005). These efforts
have been mainly undertaken and financed by small farmers or small municipalities, and the pattern
extends to most of South East Asia, including Pakistan and Bangladesh (Shah et al. 2006).
It is such a new social and technological phenomenon, that it is largely ignored or misunderstood by
most international organizations that deal with water issues. More recently, groundwater has been
raising in status in the global water agenda, first featuring in the 3rd World Water Forum in Osaka (18th
march 2003), and in the World Water Week in Marseilles (March 2005), and more recently the World
Water Forum in Mexico (March 2006) . The fact that the use of groundwater is so economically
salient, yet politically difficult to address has led to some serious unintended consequences due to lack
of groundwater planning and control. The monitoring of groundwater use globally has been minimal,
with most government and water agencies taking little or no action to assess and control groundwater
use. This attitude, which has tended to ignore or disregard groundwater use in water planning has been
called ‘hydroschizophrenia’, where groundwater management was considered as totally separate from
surface water, thus practically ignoring the concept of the hydrological cycle. The dominant view
therefore extended amongst the majority of the public is the ‘hydromyth’ that groundwater is a fragile
resource (López-Gunn and Llamas 2000; Custodio 2002).
In the case of Spain, the silent or quiet revolution is estimated involves hundreds of thousands of
farmers, abstracting about 4 or 5 Mm3/yr. However, increasingly these costs which until now were
mainly external are now starting to impact directly on farmers due to the drastic lowering of water
levels, to levels of 500m in some small aquifers in Alicante and Murcia (Garrido et al, 2006). The
5
main reason why groundwater has been so attractive to farmers has been its low cost, which is a
fraction of the crop value. Additionally, except in the case of small or low-permeability aquifers,
farmers are cushioned from drought, since aquifers provide a highly reliable source of water,
particularly in times of low rainfall due to the time lag built into the system which provides a reliable
supply of good quality water. Additionally, at present, as discussed above the cost does not include
negative externalities like pollution or ecological impacts.
The first quantitative assessment of groundwater resources in Spain was undertaken in 1966 for the
area of Rios Besos and Low Llobregat near Barcelona (Llamas 2006a). At the time, it was also
suggested that similar studies should be undertaken for all basins in Spain, and particularly in the case
of the Segura basin, where groundwater use was booming and there was already suggestions for an
interbasin water transfer from the Ebro. There was a lack of control on groundwater use, and often the
water authority would argue the difficulty in controlling groundwater use in the region due to the fact
that water rights were private (Díaz Mora 2002). However, this is the case in many other countries
across the world, in particular some states in the USA, where groundwater is private. Increasingly all
the evidence points that it is not whether water rights are private or public, this is a political choice to
be decided by society; the issue is whether water rights, either privately or publicly owned are
properly regulated, though a clear programme of monitoring and sanctioning to ensure the sustainable
management of a common good resource like groundwater.
This lack of enforcement and implementation of the existing regulation has continued and has had
some unintended side- effects on water planning for the whole of Spain. According to then Head of the
Groundwater Department in the Ministry of Environment, one of the main reasons the government
pursued the Ebro water transfer was due to the uncontrolled groundwater over-exploitation in the
Segura basin (Sánchez 2003).
In the case of the Segura basin, the answer by the Government to such a colossal chaos was to supply
1 km3 per year via a water transfer from the Ebro to help recover these aquifers. It was politically
easier to continue with a supply management policy, based on bringing additional resources to the
Segura basin through an inter-basin transfer, than to pursue demand management and tackle the
politically difficult question of controlling illegal abstractions. The Ebro River water transfer,
approved by a Conservative government in 2001, was cancelled in 2004 by a socialist government.
The new solution was to build about twenty large desalination plants. This solution was opposed by
several members of the Spanish National Water Council, the highest consultative body for water
planning in Spain (Sahuquillo et al. 2004) since they considered that this was also a water supply
approach based in "perverse subsidies" (Myers and Kent, 1998) and against the water demand
approach required by the EU Water Framework Directive.
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In the case of the Guadiana basin, the Spanish parliament requested a Plan for the Upper Guadiana
basin, when the Spanish National Water Plan was originally passed as law in 2001. The request for
this plan was re-instated in the year 2005, in the new Law for the new Spanish water plan. There have
been 20 draft versions of this Plan, which was finally presented in 2008 (CHG, 2008).
The situation described in Spain is similar to other arid and semiarid regions in the world. The
intensive use of groundwater has triggered an economic revolution; however, government policy has
not kept pace with this economic miracle. In many countries regulatory frameworks in relation to
groundwater are either non existent or rarely implemented. This is due to two main reasons: the first is
the fact that the implementation of these laws is often politically unpopular, the second is due to the
power or hydrohegemony of the farmer lobby in most of these countries, which sometimes capture the
water authorities or develop a clientelistic relationship. Two very different examples can be briefly
discussed to highlight these issues. In Spain, in the year 2002 the Ministry of Environment initiated the
ALBERCA Plan (Ferrer et al , 2004; Yagüe 2006). This plan aims to bring up to date the register on
water uses and rights. This plan will end in the year 2008. However, some authors have argued that
this plan will be insufficient to register even half of all the current abstractions. Two new initiatives
have followed on the footsteps of the Plan ALBERCA. The first relates to a program of sanctions for
illegal wells. The second is the modification of the Spanish Water Law to address the problem of
illegal wells.
The initiative to sanction illegal wells could potentially be very effective since most academic
literature and evidence points to the need to penalize free riders in healthy self governing systems to
manage common property resources like groundwater (Ostrom 1990; Lopez-Gunn 2003). In October
2005 the administration initiated 2,000 legal fines to both illegal wells and illegal water abstraction
above the water rights registered in either the Water Register of the Water Catalogue. However, it is
estimated that currently there are about 2 million illegal water wells or wells abstracting more water
than entitled to. This means that only one per thousand illegal wells is sanctioned. However, the
implementation of this sanctioning regime is very difficult. Many of these sanctions when they get to
court have either prescribed or are cancelled by the courts, since the legal system in Spain is currently
overburdened with pending cases on water rights. Second, due to lobbying pressure from the farmer
unions, the political will of the Ministry of Environment to ‘name and shame’ is wilting. A month
after the announcement was made on the intention to issue 2,000 sanctions, the Minister for
Environment announced an amnesty or delay with the enforcement for some farmers in the region of
Castilla- La Mancha one of the regions with the largest number of illegal wells as ‘social protection’
due to the ongoing drought (Llamas, 2006a).
7
The silent revolution however, is now global in scale, and many of the problems discussed in Spain
are similar in many countries across the world, particularly those related to the ineffective
implementation of the regulatory framework to control and rationalize groundwater use. This fact is
mainly due to the lack of educated participation in the process by farmers who tend to be the main
stakeholders. One of the most spectacular cases is happening in the United States of America, in the
Ogalla aquifer.
The Ogallala aquifer, also known as the High Plains aquifer, has a surface area of more than 500,000
km2, i.e. the size of Spain. Some areas of the aquifer, like Texas, have intensively used groundwater
for the last 60 years. This Texan ‘water mining’ has meant that an annual volume of 6 km3 per year
has been taken out, which is 10 times the annual recharge. Therefore, water that was stored in this
massive aquifer over millennia has now been reduced to 2/3 of its original volume (Terrell et al.
2002). This groundwater, abstracted relatively cheaply has been used mainly for the production of
cotton, cereals and animal fodder, i.e. crops with little economic value. However, meat production and
meat products generate more than 6 billion dollars per year, part of which has been exported as virtual
water (see below), since the USA is the first global exporter of agricultural products, including meat.
Groundwater in Texas is private property (Peck in press). Therefore, the state government of Texas
has to persuade the powerful lobby of Texan farmers that this groundwater abstraction is not
sustainable and that abstractions should be curtailed. However, it would be interesting to know to what
extent the intensive use of non renewable groundwater has contributed to the hegemony of the US in
global food trade.
Grey water
The last color of water, and often the one most often overlooked is grey water. This water color is
frequently used to describe water from urban and industrial water supplies. In this grey water, there are
also different shades. The most obvious use of this treated grey water is its introduction in some parts
of the water systems.. Adopting a ‘soft path to water’ would mean that what is being met are water
needs, not demand (Wolff and Gleick 2002; Gleick 2003). For example, cities like Murcia and more
recently in Madrid and Bardelona in Spain already operate dual public water supply networks, one
with drinking water and a second for watering gardens, cleaning streets, etc.
However, another much deeper understanding of grey water is that of the grey matter in our brain
(Shamir 2000). The relative scarcity of water (blue or green) will sharpen human innovation (grey
water)(Ramírez-Vallejo 2006), and will trigger positive technological change. The fact that Malthus’s
catastrophic predictions never came to fruition is proof of the ingenuity of human kind and the fact
that necessity is the mother of invention (Boserup 1965; Llamas 2006b).
8
4. Desalination’ potential and limitations
Shamir (2000) refers to water with either a high saline context or toxic load, which can be transformed
into drinking water via chemical processes as yellow water. In recent years there have been relevant
technological advances, due to progress in chemical engineering such as membrane technology
(Reverse Osmosis), which has allowed the removal of all impurities from water at a reasonable (and
decreasing) cost. The total cost of desalination by Reverse Osmosis has reduced dramatically in the
last few years. The cost for desalinating sea water is now estimated at 0.5 €/m3. This is generally the
case for large desalination plans, with no hidden subsidies. The price is lower if desalinating brackish
groundwater. Desalination of water through thermal solar energy may be an important technology for
the future (Blanco et al. 2006), although at present it is still not economically viable.
A recent study by the Pacific Institute (Cooley et al. 2006) gives an overview of desalination on a
global scale, with special emphasis in California, very wealthy a water scarce region. It is therefore
significant that in California only 1% of desalinated water is used for irrigation, even more telling is
the fact that the desalination plant in the city of Santa Barbara is being decommissioned for economic
reasons.
In Spain, some authors have estimated that there are 900 desalination plans, which could produce
about 500 Mm3 per year (Llamas 2006c). However, the beneficial use of this desalinated water is less
clear. For example, it is not clear whether desalinated water will be used for irrigation, since there is
not much reliable data on the amount of desalinated water currently being used for irrigation. Olcina
(2002) estimated that for the year 2001, 255 Mm3 were desalinated in Spain, of which only 5 Mm3
were used for irrigation. Meanwhile, Medina (2005) estimated up to the year 2000 the total capacity of
desalination plants for irrigation oscillated between approximately 8 to 15 Mm3/yr, of which 60% was
from brackish water and 40% from sea water. Medina (ibid) - gives more up to date figures for 2005,
which estimates 600 Mm3 were being desalinated, of which 55% came from sea water and 45% from
brackish water, presumably from groundwater Agriculture used 210 Mm3 of this total amount, mainly
generated by small plants, with a capacity of 100 to 5,000 m3/day operated by private farmers. The
cost per m3 in the large plants operating with Revere Osmosis, is estimated at 0.45 to 0.71€/m3.
Irrigation accounts for 25,000 Mm3 per year of the water used in Spain (MIMAM 2000) or 80% of
total water use. Desalination from seawater was only 5 to 10 Mm3 in the year 2000; desalination from
brackish groundwater water may perhaps be in the order of 200 Mm3 and is performed mainly by
private farmers. In any case this would only represent less than 1% of the total water used for
irrigation.
9
As previously mentioned, the Law on the National Water Plan of 2001 (Plan Hidrologico Nacional)
included the Ebro River water transfer. A New Decree revoked the Ebro transfer in 2004 and a year
later, in 2005, the Plan A.G.U.A. substituted the planned Ebro water transfer with about 20 new large
seawater desalination plants. According to Albiac et al (2006), this project has a public investment
budget of 1,200 million € to build the new seawater desalination plants, to generate 600 Mm3, of
which 50% or 300 Mm3 are used for irrigation. The estimated cost will be 0.5 €/m3. However, the real
price would probably be more in the region of 1€/m3. The price for this desalinated seawater offered
by the government to farmers is I the order of 0.4 €/m3. Therefore, it will be necessary to give a
subsidy covering 50% of the real cost. However, in the long term, this subsidy will probably have to
be phased out due to the Water Framework Directive, and the fact that beneficiaries of any water
infrastructure- due to the principle of full cost recovery- will have to pay the real cost. The farmers
seem to be aware of this and are reluctant to accept the government conditions.
Therefore, it could be argued that the use of 300 Mm3 of desalinated water for public water supply for
new tourist resorts and for use in golf courses in the Mediterranean coast could be a sensible option.
However, an economic analysis should be undertaken on the desalination plants in Marbella and
Almeria. The reason appears to be cost, since it is cheaper for the municipality to buy groundwater
than to produce desalinated water in the existing plant. This is a despite the fact that the investment for
the desalination plant was paid from central Spanish and European funds.
It is also not clear whether demand will exist from the farming population due a number of reasons
(Llamas 2005a; Llamas 2006a). First, farmers at present are not paying for the externalities of
groundwater abstraction (e.g. pollution, damage to wetlands, land subsidence); second, farmers are
presently not paying for the use of groundwater, but only for the capital and of energy costs; third, at
present there is little monitoring and sanctioning (as it will be discussed below) on the amount of
water abstracted and how these correlate with their water rights. In many cases, farmers are either
abstracting more water than entitled to in their water right –independent of whether this right is public
or private- or are abstracting water illegally, with no entitlement to water abstraction. At present
farmers are paying 0,1 y 0,2 €/m3 for groundwater. The price for desalinated seawater used for
irrigation offered by government in the A.G.U.A. programme will more than double the formal or
informal market price. This clearly explains the general reluctance of farmers towards the A.G:U.A
programme.
In some coastal regions, as will be discussed below farmers could pay a higher price for water, due to
the high value of crops produced. However, farmers as rational economic agents will obviously prefer
to pay the lowest possible price, free riding on the lack of action on the part of the authorities in
10
relation to controlling groundwater abstractions. Therefore, in order for farmers to pay this new higher
price two things have to take place; first, the administration must seize the opportunity provided by the
concept of full cost recovery introduced by the new Water Framework Directive and second, the
current water legislation (and limits on abstraction e.g. in over abstracted aquifers) must be enforced
(Albiac et al, 2006). Similarly unless groundwater abstraction is regulated, farmers will find it easier
and cheaper to continue groundwater abstraction- than pay for new desalinated water, even if this is
highly subsidized by the government.
Therefore in both the case of desalinated water for irrigation and for public water supply and tourism,
it appears that due to hidden subsidies and perverse incentives, desalination will only provide part of
the answer. It is still part of the hard path to water, based on new infrastructure rather than tackling the
softer path to water which requires tackling the much more politically difficult question of water
allocation and re-allocation. i.e. who gets what, why and at what cost.
5. Virtual reality? Virtual water and water footprint
‘Virtual water’ is the water needed to produce a good or service (agricultural, industrial,…). It was a
concept developed by in the late 1990s by Tony Allan (Allan 2003; Allan 2006; Allan in press ). If a
country exports a product that requires a high amount of water for its production, this country is
effectively exporting virtual water, i.e. water embodied in the production of the corresponding good.
However, this also means that due to opportunity costs, this water will not be available for other uses
in the exporting country. Importing virtual water is allowing countries that are poor in water resources
to achieve food and water security. Arid countries for example can put their limited water resources to
a more profitable use, like tourism, public water supply, or the production of high value crops, instead
of using this water to produce staple food, that have high water consumption and yet have low
economic value.
A country which exports a product that needs a lot of water to be produced is effectively exporting
water, embodied in the product, and equally the country importing that good is saving water by not
using its own water to produce that good.
There has been agricultural trade for centuries, even millennia, like the example in Chapter 42, in the
Book of Genesis on the story of Joseph. Thus, virtual water trade is allowing water scarce countries, to
achieve water and food security thanks to virtual water trade. However, what is new is its growth due
to the increased production thanks both to technological advances and cheap transport – particularly
by sea- which has facilitated trade. For instance, it is now possible to purchase kiwis in Spain
11
produced in New Zealand. The cost per tonne of product transported by sea is about 1 euro per tonne
or one 0.1 euro cent per kg. It is easier- and cheaper- to transport 1,000 tones of wheat, than the 1
million m3 needed to produce that same wheat (see below Table 1). This is different for poor countries,
where the road infrastructure is not very developed. For example, in South Africa it is physically
difficult and costly to transport goods imported by sea to the interior of the country (Hofwegen 2004).
In general trade in virtual water is often an implicit rather than an explicit choice, yet it has
substantially ameliorated the problems of water and/or food security in many arid and semi-arid
countries. Thanks to virtual water many water scarce countries have avoided a crisis, particularly in
politically unstable regions like North Africa and the Middle East. The only pre-requisite is that these
countries are developed enough to have the purchasing power needed in international markets. If these
countries are wealthy enough they can buy food embodying virtual water. As will be discussed below,
most of these products are staple products like cereals, or fodder, whose value per tonne (or m3 of
virtual water) is relatively low (see Table 1 and 2 below). Most countries import and export virtual
water, although the trade balance in virtual water can be very different depending on the individual
country.
For example, Canada exports large amounts of virtual water when it exports cereals, yet imports
virtual water when it imports flowers and fruit from Central America. Equally, Jordan imports virtual
water when it buys cereals (of low economic value) yet exports virtual water in high value crops like
citrus fruit and horticultural products, well suited to its climate.
Table 1: Comparative table on the amount of water (in ml) needed to produce 1 unit of specific
products
Product Water (in 1000ml) necessary for production
Bottle of Beer (250ml) 75
Glass of Milk (200ml) 200
Bread Slice (30 gr) 40
Cotton T-shirt (500 gr) 4,100
A4 sheet of paper (80gr/m2) 10
Beef Hamburger (150gr) 2,400
Pair of leather shoes 8,000
Beef meat (1 kg) 15,000
Lamb Meat (1 kg) 10,000
Cereals (1 kg) 1,500
Chicken Meat 6,000
Source: (Llamas 2005a) from (Chapagain et al. 2005)
12
There is still some data however, which has to be analyzed further, because of its potential
implications. First, it is important to explore further the geographical variations in the productivity of
virtual water. For example, Chapagain and Hoekstra (2004) show that in Italy a tonne of wheat
requires 2,400 m3, yet in Spain it only needs 1,227 m3, i.e. about half the amount of virtual water. This
would imply that the productivity of virtual water in Spain is twice as much as Italy. Second, strategic
choices have to be made by different countries on whether water is used to grow high value crops, or
low value crops like cereals or alfalfa (see below Table 2).
Table 2: Average value of some vegetable produce (in $/tonne)
Product Average value ( in $/tonne)
Wheat 125-150
Barley 134
Corn 125
Tomatoes 856
Horticultural products 757
Sunflower 294
Virgin olive oil 2,036
Coffee 2,118
Fresh grapes 1,160
Source: after Appendix IV in Chapagain and Hoekstra (2004)
There is a growing realization that economic and social factors tend to be the drivers in virtual water
trade, through trade in agricultural and processed food products. Estimates on the amount of water
required for the production of each good are complex, and are being developed at the moment
(Chapagain et al. 2005). Meanwhile estimates on virtual water for food or industrial products are still
in its infancy. Zimmer and Renault (2003) have calculated that the total amount of water (blue and
green) globally to produce food is 5,200 km3. This is a similar amount in magnitude to the 6,000 km3
estimated by the United Nations (United Nations 2003), as the water needed to produce food for 6,000
million people in the planet. Yet, it is important to remember that the total amount of water in the
hydrological cycle is 115,000 Mm3, and humankind at present uses below 10% of annual rainfall, i.e.
of blue and green water.
According to Zimmer and Renault (2003), 29% of water is used to produce meat, 17% to produce
meat products, and cereals only account for 23%. It has to be taken into account that the calculation
for meat and processed livestock products includes animal feeds. However, from an energy point of
13
view, the situation is quite different; cereals represent 51% of energy value and meat and livestock
products only 15%
Meat Livestock Cereals
Global Water Use 29% 17% 23%
Global energy use 15% 51%
In the case of Spain, Chapagain and Hoekstra (2003) calculate that the total green and blue water
needs in Spain amount to 100 Mm3/yr. Spain imports 45 Mm3/yr in virtual water and export 31
Mm3/yr, i.e. the balance is negative since Spain imports more virtual water than it exports. Yet 80% of
the 100 Mm3 of Spain’s footprint is for food, 2/3 with water from Spain and 1/3 with imported virtual
water, 15% for industrial water use (of which ½ corresponds to imported products) and 5% is for
public water supply. This highlights the key importance that the agricultural sector represents for any
arid country in calculating is water budget and demand, and therefore its water policy4.
These figures are in line with those of the Spanish Ministry of Environment in relation to urban and
industrial use (i.e. 5% and 15%), however, there is a marked difference in the case of agriculture. The
Green Paper on Water or Libro Blanco de las Aguas (MIMAM 2000) calculates that the amount used
by agriculture is 25 Mm3/yr, whereas Chapagain and Hoekstra (2003) calculate it at 51 Mm3 for
national production and 17 Mm3 for export. This difference might be explained by the fact that
Chapagain and Hoekstra also include green water in the calculation, which might account for the 35
Mm3/yr in green water (pastures, dryland agriculture, forests).
Water footprint
The sum of all water (blue and green) and all imported water (i.e. virtual water) required to meet the
needs for goods and services for a specific area or collectivity is known as the ‘water footprint’5. This
concept was developed by Hoekstra and Hung (2002) and it is used as an indicator of water use by an
individual, a collectivity or a country. It can be defined as the volume necessary for the production of
goods and services that are used by one person or group of people. Obviously, this concept is
intimately tied up with the concept of virtual water.
4 Virtual water only affects energy consumption indirectly, mainly through its impact on transport, particularly by sea.
However, at this stage more studies need to be undertaken in order to evaluate the primary energy consumption due to the import and export of virtual water. The impact is likely to be however, fairly high if goods are transported by air, as compared to by sea.
5This concept is linked conceptually to the concept of ecological footprint (Rees 1996)
14
When the inhabitants of a region import goods and services from a different region, they are obviously
importing virtual water that was needed to produce those goods and services. The total use of blue and
green water that is used by a specific region for a social collectivity would be incomplete if imported
and exported virtual water was not included.
The sum of national water (blue and green) and net imported water is defined as the ‘water footprint’
of that country or group. In the concept of virtual water used by Chapagain and Hoekstra (2004)
virtual water that is exported in agricultural or industrial products are not subtracted. Possibly these
authors consider that exports are not vital from the point of view of the country or group. Yet, exports
can play a vital role for the economy of that country or group, amongst other reasons because it allows
the generation of capital that allows this country or group to import virtual water as agricultural or
industrial products.
Chapagain and Hoekstra (2004) calculate that the current total global water footprint for humanity is
7,500 Mm3, although this figure is likely to increase in the coming years. This difference of about
1,500 Mm3 –compared to the previously mentioned water used to produce food – is because it includes
public water supply and industrial use. In any case it is important to remember that the total amount of
rainfall in the land surface, i.e. the sum of blue and green water is about 115,000 Mm3. In other words,
the water demand from the whole of humanity is well below 10% of annual precipitation. In Llamas
(2005a) it was shown that the water footprint of Spain, Italy and the USA is similar – approximately
2,300 m3/person/yr, whilst India’s water footprint is less than 1,000 m3/person/yr. This is mainly due
to the vegetarian diet in India6 and its lower level of industrialization. Meanwhile China’s water
footprint currently is even lower, at 700 m3/per capita/yr, although this is likely to increase
substantially in the coming years.
Food trade is regulated by the World Trade organization (or WTO). Thus, trade in virtual water is
much more dependent on global trade policy than national water policy. Authors like Garrido (2005)
and Wilchems (2004) believe that the concept of virtual water is useful to help describe- and define-
agricultural policy and to develop water and food security. However, the concept does not internalize
shifts in technology and opportunity costs. Therefore the use of competitive advantage is necessary to
define optimal trade and production policies. What is important however is to emphasize the need to
integrate agricultural ministries in defining water policy since most water used globally is for
agriculture and also the need to study key strategic decisions like whether it is best to irrigate or
instead import virtual water.
6 See Table 1 for amount of water needed to produce 1 kg of cereal vs. 1 tonne of meat.
15
Ramirez Vallejo (2006) argues that it is not sensible to apply pure economic theory to explain virtual
water trade. Many factors influence water trade, like bilateral trade agreements, direct or indirect
subsidies, technological innovation, or the macroeconomic polices of exporting and importing
countries. It is crucial to remember that most trade in virtual water is not explicitly or directly
motivated by lack of water or food security. For example, for the period 1993-1998, 75% of trade in
virtual water was between OECD countries.
Trade in virtual water depends largely in WTO rules, which are in the process of being settled. These
rules will have important geopolitical consequences, e.g. in terms of power shifts and some
politicians- particularly in developing countries- are uneasy about trade in virtual water since it could
lead to increased dependency towards exporting countries or large multinational companies, which
could develop monopolies on global food trade.
The prices of agricultural products are largely dependent on climatic and technological conditions.
However, these prices are probably influenced just as much or more by hidden subsidies and tariffs to
farmers in the USA, the European Union and Japan. For example, Rogers and Ramirez Vallejo (2003)
in the OECD farmers subsidies are estimated as 1,000 M $ per day, which has a substantial negative
impact to farmers in developing countries. According to these authors, more than a third of the income
of farmers from OECD countries comes from government subsidies. These subsidies are five times
higher than all the aid received by developing countries, and twice higher than the agricultural export
from developing countries. For example, a cow in the European Union receives a subsidy of two
dollars per day, yet about 2,500 million people live on less than 2 dollars per day (United Nations
2005).
Rogers and Ramirez-Vallejo (2003) have made a forecast of the potential evolution of the virtual
water market for the year 2020, in case of market liberalization under the WTO. The dominance of the
USA would be even greater under market liberalization scenarios, whilst the role of Latin America
would also increase substantially. A key element in all these future predictions will be the price of
water, which at present is generally well below its real cost. Therefore reducing the gap between the
price and real cost of water as demanded by the concept of full cost recovery embodied in the
European Water Framework Directive, could have a substantial impact on virtual water trade.
However, it is a difficult and widespread problem in the world, to eliminate so called ‘perverse’
subsidies, i.e. those that are bad for the economy and the environment (Myers and Kent 1998).
16
6. The role of GIS and remote sensing in increasing transparency and participation
In this last section on key advances and science and technology the role of remote sensing and GIS
will be briefly discussed. These play an indirect- but crucial role in addressing water problems.
(Chuvieco, 2002; Bosque, 1997; Schulz et al., 2000; Gurnell and Montgomery (2000). Remote sensing
can help planning for land use change. Nowadays, the use of remote sensing is relatively cheap and
allows us to measure with increased precision irrigated areas and the type of crop. This is essential in
order to plan water policy for irrigation use, which as stated above, represents 80 to 90% of
consumptive water use.
However, most water authorities, and Water Departments in the Regional Governments in Spain
(except in the region of Andalusia (Vives, 2000), either do nota hve or do not use data on irrigation
water use. This is despite the fact that obtaining this data is relatively quick and cheap, as
demonstrated by the Andalusia regional government 10 years ago. (Vives, 2003).
The other great technological advancement are Geographical Information Systems (or GIS), which
greatly increase the potential transparency in information at a user level and in a user friendly format.
Increasingly it is clear that the availability of good information is basic for negotiations over water use
in many conflictive areas. A good example is currently implemented in the Mancha region in Spain,
where satellite information is being directly used by farmers though an Irrigation Advisory service,
which integrates real time data to help farmers improve water use by different crops, whilst optimizing
production (Calera et al, 1999; Calera et al 2005; Martin de Santa Olalla et al, 2003). Data and
information transparency are the foundation stones on solving any potential water conflicts. Both GIS
and remote sensing offer a relatively cheap and quick way of opening up decision making processes
by allowing civic society to participate though information transparency. In the case of water, GIS is
making huge strides in the range of ways it can be utilized to support and inform policy making
(Gurnell and Montgomery, 2000; Chuvieco, 2002). Technologies like GIS and remote sensing can
bring about transparency and participation, which in the information economy (Stiglitz 2006) foster
innovation and adaptation essential to good management. Equally participation can prevent corruption,
clientelism and inertia, whilst facilitating taking decisions that sometimes are politically difficult yet
necessary. It brings about deliberative democracy in water management, essential to achieving sound
water governance (Innes and Boother 2000; Lowndess et al. 2001; Bulkeley and Mol 2003).
7. Constructive realism in science and technology?
Often water has been portrayed a tragedy of the global commons, (Hardin, 1968), where water is
inescapably doomed to over-use, particularly in the case of groundwater. Only two options were
17
offered, to centralize management under strong government control or to privatize resources allocating
private water rights. Yet, more recently a third way is available, which has shown that contrary to
predictions of over abstraction, self-governance by water users themselves, can help guarantee the
sustainable management of the commons (Dietz et al. 2003; Lopez-Gunn, 2003).
Equally, there is a realization that neither optimism nor pessimism should dominate forecasts on water
governance; instead the focus should be on constructive realism. For example, concern over
population growth goes back a long time. For example, Guerra (Guerra 1989) discusses how Aristotle
and other Greek philosophers in the IV century BC advised abortion in order to control population
growth by slaves, since they outnumbered Athens citizens on a ratio of 1 x 20 in the year 313 BC; they
also argued that such “overpopulaion” was threatening food security. Malthus, more than 200 years
ago made predictions that now bear little resemblance to reality (Heap 2000; Heap and Comim 2007).
World population is now six times larger than in Malthus‘s time, and most people have greater food
availability and life expectancy than in Malthus’s time.
Julian Simon (1996) showed that predictions on the problem of overpopulation and exhaustion of
resources were wrong, thanks in great part to technological advances and human ingenuity.
Aguirre(2006) has a similar point of view. Instead of blaming the current ecological crisis on
population overgrowth, more emphasis should be placed on sustainable consumption; since the
ecological footprint of e.g. the UK in terms of CO2 emissions is twice that of Bangladesh, yet the
population growth in the UK is 120,000 per year compared to 2.4 million in Bangladesh.
It is increasingly clear that in order to solve the global water crisis simple scientific reasoning will not
be sufficient. Many of the choices faced by society inherently imply key ethical questions, where
increasingly a balance will have to be struck between pure utilitarian values on water e.g. as a market
good, and other intangibles, like cultural, ecological and religious values (Llamas and Delli Priscoli
2000). Economic man as defined by the dominance of neo-classical economics and rational choice
theory, where men are understood as self interested individuals and their bounded rationality, have to
be expanded to view men and women as part of humanity and capable of altruistic behavior, with an
expanded understanding on human rationality and self interested behavior. These new ethical issues
and emphasis on the moral norms and value of water have increasingly been recognized, for example
by international organizations like UNESCO, in its series on Water and Ethics (Delli Priscoli et al.
2004), and by the World Commission on The Ethics of Science and Technology (or
COMEST)(Selborne 2001) (Llamas et al in press)
The starting point to current debates in water policy is that the crisis is not due to scarcity and water
stress but to governance. That is, the diagnosis on the cause is different, and this leads to different
18
solutions to those currently pursued by international organizations like the Food and Agricultural
Organization (FAO) and the International Water management Institute (IWMI) which are still mainly
focused on water and food security, by concentrating on the expansion of irrigated areas and greater
use of both surface and groundwater. At present the solutions proposed are ‘hydrocentric’ based on the
watershed (Brichieri-Colombi 2004). However, as it was discussed above decisions on the type of crop
or on food trade would have a much higher impact than any decisions to build new large water
infrastructure. This leads towards a re-definition on the unit of analysis away from a pure water shed
towards the concept of the ‘problemshed’ – as defined by Allan (2006). That is, taking into account
that globally approximately 70% of water is used for agriculture, the decisions on which crops are
grown (and its embodied water use), and which foods are imported as virtual water, have a much
substantial impact on the country’s or catchment’s water budget.
The soft path to water
The soft path to water requires innovative solutions to old problems, this translates in a portfolio of
appropriate solutions to specific problems, instead of the old mentality where one size fits all, i.e. the
hard path to water centered on water infrastructure as the only solution to the ‘problem’ of water
scarcity’
Once again, as stated above, if the diagnosis of the water problem looks at the causes of the current
water crisis –i.e. the lack of effective, efficient and equitable water governance, rather than the
symptoms, i.e. physical water scarcity- then the course treatment will surely have to be re-assessed and
modified on a case by case basis. The sections below re-visit some classic concepts and provide and
alternative explanation in order to highlight that appropriate solutions are within reach in the soft path
to water governance.
Many countries, particularly in the developing world still have to address questions related to food
security, and particularly so in arid and semi arid regions, where droughts can trigger hunger and also
potentially destabilize or even topple governments in power. However, often these mass starvations
have more often a political origin than a physical cause, as highlighted by Brunel (1989). Food
security can often be ensured either though self sufficiency in food production, or a mixture of own
production and imports from other countries. This political choice, i.e. whether to opt for self
sufficiency or an open trade approach has substantial implications in terms of need for water
infrastructure, rainfed agriculture and trade in agricultural products. Often geography partly dictates
the choice made, for example large countries like China or India can opt for self sufficiency, whereas
arid countries prefer to guarantee enough income to be able to guarantee food imports. In very poor
19
countries, food security is heavily compromised and conditioned by poverty. Their population tends to
be mainly rural and relies on subsistence agriculture. Due to their lack of capital, authors like
Hofwegen (2004) suggest that their safest bet to ensure food security is to improve the productivity of
rain fed agriculture- or green water as discussed above-, since their poverty leaves the choice of
building large irrigation infrastructure and/or agricultural trade beyond their reach. In other countries
food security is slowly happening due to the silent revolution in groundwater use. In extremely poor
countries, with less than 1$/per capita/per day, where 500 million people live, the NGO International
Development Enterprise (or IDE) developed in the last 20 years a simple pedal operated pump (Polak
2005), which has allowed these areas to evolve in a relatively short space of time to a diesel or electric
pump. Meanwhile, in mid range countries, a potential initial solution will be the intensive use of
groundwater (Llamas 2005b; Allan in press).
Economies of scope and civic participation
Yet in many countries the idea still predominates that economies of scale of large water infrastructure
is the suit that fits all, in order to guarantee food security. Yet the evidence cited above shows the key
role of virtual water or the silent revolution of groundwater use, and offers the alternative concept of
economies of scope, which looks for the most appropriate solution suited on a case by case basis.
In many countries there is a marked shift in the active population in different economic sectors. In
general the shift is away from rural towards urban. For example, in the case of Spain, rural population
-in the agricultural and livestock sectors - is less than 6%, when half a century ago it was 50%. This
varies internally between less than 2% in the Balearic Islands to more than 10% in Andalusia or
Extremadura. However, it is quite probable that the proportion of people employed by the agricultural
sector will continue to reduce not only in Spain, but globally.
Some regions in the world live in conditions of extreme poverty, on less than 1$ per day. In these
countries the majority of the population tends to be rural and depends on subsistence farming. In these
regions virtual water or importing food without giving due consideration to the staple diet of the
country and to the potential impact on local agricultural markets could do more harm than good. The
combination of high production costs due to lack of technology and the potential flooding by cheap-
and often subsidized products from global trade could substantially harm local, subsistence markets.
Meanwhile, in developed countries, importing food could have impacts if certain protectionist tariffs
and/ or subsidies are removed. For example this is the case of Spain and the current review of the
European Union Common Agricultural Policy, which is likely to reduce both subsidies and tariffs for
products like cereals, rice, sugar beet and many other products typical of continental style agriculture.
20
In countries like Spain, these types of products often need to be irrigated in order to be able to compete
with other Northern European Union countries, with a wetter climate. Once subsidies for these
products are removed, and even if water tariffs are not adjusted to account for the price of water many
of these products may cease to be profitable in Spain.
Many authors consider that Spain should concentrate on typical agricultural products like horticulture,
citric fruit, olive oil, and others, which at present have low subsidies from the European Union, and
where Spain due to its climate has a competitive advantage. Many farmers are following this economic
logic and are shifting away from agricultural products which are water intensive, like corn or alfalfa,
towards Mediterranean products like vineyards or olive trees. Spain however will have to prove
competitive once the WTO - or the EU itself through bilateral agreements - opens up the European
markets to products from North Africa or Turkey.
Increasingly it is a vital question for Spain, and other arid countries to evaluate the value per type of
crop and the use of green and blue water required to grow different crops. For example, Albiac et al
(2006) (see below table 3) undertook a study on the different crops that would be irrigated by the
planned Ebor transfer, and found that the value ranged from 900 euros per ha for cereals to more than
40,000 euros for greenhouse crops. These figures were similar to those generated by the Andalusia
irrigation inventory produced ten years ago and updated three years ago (Vives 2003). Therefore the
gross value per crop and m3 from irrigation oscillates from 0.1 euro to 11 euros.
Table 3: Area, water use and income in the Spanish south east river basins (2001)
River Basins Total Cereals,
alfalfa
and
sunflower
Fruit trees Horticultural
product
Horticultural
product (in
green
houses)
Area (1.000 ha) 212,7 18,5 173,6 19,5 1,1
Irrigation water
(Mm3) 1.450,7 242,7 1.081,7 121,7 6,7
Income (millions €) 1.196,7 39,7 957,7 167,7 33,7
Segura basin
Area (1.000 ha) 154,9 8,1 107,7 34,2 4,9
Irrigation Water (Mm 863,7 62,7 654,7 125,7 22,7
Income(millions €) 1.070,7 6,7 7 485,7 336,7 243,7
Sur basin
Area (1.000 ha) 54,5 1,1 18,7 6,5 28,1
21
Irrigation Water (Mm 232,7 7 10,7 96,7 24,7 102,7
Income (millions €) 1.124,7 1,7 67,7 ,7 87,7 969,7
Source: Table 5 in Albiac et al 2005
Ecological impacts
Often the economic use of a natural resource has an ecological impact. It is a delicate question to
achieve a balance between economic benefit and environmental costs. However, the valuation of these
ecological costs is not straightforward, and is partly dependent on both the cultural and the economic
situation in each country.
Environmental awareness is often conditioned by the so called Kuznets curve, which effectively links
environmental awareness with income per capita. Poor countries are generally reliant on nature due to
an agricultural subsistence economy. Their inhabitants are normally integrated in their local
environment and have no means to over use or damage their local ecology. The main concern in these
countries is to increase the standard of living, though economic growth, whether sustainable or not.
Ecological or environmental awareness develops once the country reaches a certain level. Civil society
seems to mature, environmental NGOS develop and in general environmental awareness grows. This
awareness continues to develop as the standard of living increases. Mukherji (2006) has shown
recently how the Kuznets curve also applies to many regions in the world in relation to water
resources.
However, Hofwegen (2004) calculates that the liberalization of trade in agricultural products (and
therefore virtual water) will have negative effects on the environment. This would happen if countries
used- or overused - water resources in order to produce agricultural products in an unsustainable
manner, in order to be able to sell these products to other countries. This seems to have already
happened in one of the most developed countries in the world, in the USA, and one of the largest
aquifers, the Texan Ogallala or High Plains aquifer (see above).
8. Conclusions
The introduction of key concepts like virtual water and water footprint can provide new ways of
looking at old problems, like the traditional concept of food and water security, and the concern that
humanity will shortly be ‘water stressed’.
22
Virtual water trade and the concept of water footprint are relatively new concepts, although their basis
has been around for centuries, as agricultural trade, based on the law of competitive advantage. The
quantitative data in relation to both concepts are at present a first approximation. It is therefore
fundamental to improve methodologies to calculate the virtual water needed, not only to generate food
products, but also industrial products and other services. It is therefore crucial to ensure that the basic
data on green and blue water available is of the best quality. The concept of virtual water is helping to
generate much more sophisticated water budgets, more thorough, and based on the water needs (and
water footprint) of each country. In particular, it has also helped to highlight the key role played by
green (or soil) water in the production of food products. The concept of water footprint emphasizes
that in most arid and semi arid countries, water policy is heavily dependent and conditioned by
agricultural policy. This is particularly true in a country like Spain where the sum of green and blue
water to meet the demand of both agriculture and livestock represents almost 90% of the Spanish
water footprint.
Trade in virtual water constitutes a key element in helping to eliminate or at least soften the global
water crisis. However, it is not a panacea, methods have to be further developed (Aldaya and Llamas,
2008), data has to be improved and the side effects or unintended consequences- economic, social,
geopolitical and ecological, better studied.
Cases of extreme poverty, people with less than 1 dollar per day- normally reliant on subsistence
agriculture, deserve a special mention. These countries represent 10% of the global population.
According to the Johannesburg conference on Sustainable Development, the great ecological crisis is
extreme poverty. It is also an imperative ethical question, which requires fewer words and more
imaginative, cheap and feasible solutions, like paying for environmental services offered by green
water as e.g. green water credits (Grieg-Gran et al. 2006).
This paper has shown that there are already two politically silent events, which are helping to prevent
the often quoted ‘water crisis’, these are virtual water and groundwater. Both are politically silent yet
are allowing countries, particularly in arid and semi arid regions to sidestep the problem of water
scarcity. However, this paper has also highlighted that these ‘revolutions’ generated thanks to
scientific and technological advances should not occur in a vacuum and it is the responsibility of states
to carefully assess their full potential and limitations. Science and technology have shown an
alternative path, a soft path to water, where solutions are targeted to specific situations, supported by
public participation and information transparency. This path offers an alternative to the traditional
doom and gloom hard path, which concentrates on a one size fits all of new water infrastructure. There
are currently cheap, feasible and real solutions to the current water crisis, but their Achilles heel once
again is addressing pending- and politically difficult questions- on good water governance.
23
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29
Future Trends in the Oil & Gas Industry:
New Production and Upgrading Technologies
Ugo Romano
Eni SpA
Chief Scientific Advisor
Alberto Delbianco
Eni E&P Division
Energy and economy
The demand for energy is increasing on a worldwide scale forced by demographic
growth and economic development.
Over 70% of the new energy demand is due to developing countries [China, India,
Middle East, Latin America] [fig. 1] and most of the growth will be in electric
generation [50%] whereas a significant part will be absorbed by the field of
transport (20%) and the remaining percentage distributed among between
industry, services, residential use.
Fossil resources will remain dominant (80%) within the long-term scenario
[2030].
The quotient attributed to petroleum will decrease over the next twenty-year
period even if oil will remain the main fuel.
At the same time, unconventional resources of hydrocarbons, natural gas and
coal will play take on an increasing role and will balance the lesser availability of
oil.
Evolution of primary hydrocarbon resources
The production models of liquid hydrocarbons are following curves of the type
indicated in fig. 2 where the growth and exhaustion of various sources are
combined to form an overall model which indicates a decline after 2050.
2
A more recent estimation of conventional oil resources, on the basis of the work of
the US Geological Survey indicates an estimate of 2,600 MLD Giga barrels (Gb) of
which about 1,100 are proved reserves, already economically recoverable. The
remaining amount consists of resources which have been discovered but not
exploited, resources deriving from a possible increase in the recovery factor, the
contribution of reservoirs which have not yet been found.
The greatest challenges which arise in the development and production of
hydrocarbon resources are: an increase in the recovery factor of oil fields, a
reduction in production costs, the development of unconventional resources.
The overall outlook of potential resources is extremely wide even if there is
inevitably a considerable difference in the cost of hydrocarbons deriving from
various sources [fig. 3].
In the present state, only 30% of the conventional oil found is extracted, the
application and optimization of Enhanced Oil Recovery processes could bring the
recovery factor to over 60%.
Every reservoir is a candidate for the application of the Enhances Oil Recovery
technology, but the recovery degree and cost of the relative extraction process
depend on the characteristics of the reservoir and type of technology applied [fig.
4].
Unconventional Resources; Size & Distribution
3
There are important oil reserves in the world which are known as
“unconventional”, i.e. heavy crude oils and bitumens which can be recovered
from oil shales and sands which form additional strategic reserves with respect to
the crude oils which are generally known. Even if there is no universally
recognized definition, these fossil sources are normally classified on the basis of
the density and viscosity values under the reservoir conditions (Table 1).
According to this classification, oils having an API density lower than 25 are
defined as heavy oils. Among these, those having a viscosity higher than 10,000
mPa.s are classified as extra-heavy; their density is generally lower than 10° API,
which means that they are heavier than water. Bitumens extracted from
bituminous sands, better known as oil or tar sands, as well as oils produced by
the thermal treatment of oil shales, are also included in this latter category.
From a geological point of view, most heavy oils derive from mature oils which,
after being expelled from the mother rock, have migrated to permeable rock layers
where they may have undergone a series of degradative processes such as the
attack of micro-organisms, evaporation or washing away of the light fractions,
which have concentrated the heaviest and aromatic component of the oil (Fig. 5).
Consequently, in addition to a high density, heavy crude oils are generally
characterized by significant quantities of sulfur [up to 6-8% by weight], metals
[various hundreds of ppm of nickel and vanadium which in the case of
4
Venezuelan heavy oils can reach record values of 700-800 ppm) and above all
asphaltenes, to the extent that they often form a real oil component as they can
reach concentrations of 35 % by weight. A characteristic common to most heavy
oils is their presence in relatively superficial fluvial basins such as in the case of
the Orinoco belt in Venezuela.
In a recent Multiclient Report of 2007, WoodMackenzie estimates that the world
reserves of heavy crude oils and oil sands amount to approximately 4,600 Gb (Fig.
6). Even considering that the percentage of “technically recoverable” oil is 15-
20 %, it is evident that we are talking about enormous quantities if one takes into
account that the whole that these are enormous quantities considering that the
whole of the Middle East has reserves for 2,000 Gb, of which 743 are considered
recoverable. Most of these reserves are concentrated in Canada in the state of
Alberta and, as previously mentioned, in Venezuela in the so-called Orinoco Belt.
A third country rich in unconventional oils is Russia, even if in this case the data
on the quantity of reserves and type of oils are much more uncertain.
Oil shales are sedimentary rocks, generally silicates and carbonates, containing
large quantities of insoluble organic material which can be recovered by pyrolitic
distillation, a process better known as retorting. In rocks of potential commercial
interest, the quantity of organic material must be higher than 10 gal/t (> 45 l/t)
even if in richer formations, this value normally ranges from 30 to 40 gal/t [it
5
should be remembered that the Canadian Athabasca bitumen is around 22 gal/t).
The productivity of one of the most important reservoirs (for example Colorado oil
shale] can in fact reach values of up to 0,73 bbl of oil per ton of material
recovered. Moreover, deposits of oil shales can extend for thousands of square km
for thicknesses which can reach 700 m so that the quantity of oil which can be
potentially recovered per surface unit is about one order of magnitude higher with
respect to what is the case for Canadian oil sands.
The organic component of oil shales consists of complex hydrocarbon molecules
similar to kerogen from which oil derives, containing large quantities of oxygen [5-
6% by weight] and, to a lesser extent, sulfur and nitrogen. The hydrogen content
of the oil shale kerogen as such is much higher than that of coal with an H/C
ratio of 1.5-1.6 with respect to values of approximately 0.8-0.9 for bituminous
coals.
The world reserves of oil shales are in the order of 2,800 Gb (WoodMackenzie
source, 2007]; of these, about 1,900 Gb are on United States territory and in
particular in the formation called Green River [Colorado]. Other important
reserves are present in various countries among which Brazil, Australia, China,
Russia, Congo, etc., as indicated in Fig. 7.
From a strategic point of view, the upgrading of unconventional oils is extremely
important as it allows certain reserves to be increased without having to resort to
6
new exploration investments. They also contribute to diversifying the supplies
and, as a result of their geographical distribution which is mainly located in areas
other than the Middle East, to eliminating the geopolitical risk which has always
characterized oil markets.
These considerations are favouring a whole series of industrial initiatives which,
within the next few decades, will bring significant quantities of synthetic crude oil
and/or distillates from unconventional sources onto the market, also as a result
of a progressive reduction in the production costs associated with the
development/optimization of new technologies, both upstream and downstream
[Table 2]. In addition to the technological aspects, it should be noted, however,
that a limit to the exploitation of unconventional oils could derive from
environmental aspects, as their production and upgrading require energy
consumptions from 3 to 5 times higher than those associated with the production
and upgrading of traditional crude oil. Also for this reason, it will therefore be
necessary to develop processes with greater energy efficiency and/or integrate
them with carbon-sequestration technologies.
Production & Upgrading Processes
Extra-heavy crude oils and bitumens
7
The production of extra-heavy crude oils and bitumens very often requires the
use of particular technologies specifically developed for treating highly viscous
products or, as in the case of bitumens, dispersed inside sandy mineral matrixes
to a degree of 7-15% by weight.
The recovery techniques of bitumens, mainly used in Canada in the region of
Alberta, vary according to the depth of the deposit. For depths less than 75m,
extraction techniques such as mining are normally adopted. Open pit mines are
like extensive terrace excavations, more or less circular, from which the material
removed from the excavation is loaded onto large trucks by means of enormous
electric or hydraulic spoon excavators. The material is then unloaded directly
onto a moveable crushing plant, connected with a conveyor belt which sends the
material to the treatment plant, where the material is mixed with hot water to
form a slurry from which, by means of large separation plants, the bitumen is
recovered from the sand and sent via pipelines to the treatment plant [upgrader
and refinery].
If the formation is at a depth greater than 75 m, on the other hand, the bitumen
can be recovered by applying in-situ thermal recovery technologies such as Steam
Assisted Gravity Drainage (SAGD) and Cyclic Steam Stimulation (CSS) or the
more recent Toe-to-Heel Air Injection (THAI).
8
The success of these technologies, and in particular SAGD, has become possible
thanks to the development of horizontal drilling techniques. SAGD, in fact,
envisages the drilling of 2 horizontal wells superimposed by a few metres: the
upper well is a vapour injector, the lower well is the producer. The injected
vapour heats the oil reducing its viscosity and at the same time creates a vapour
chamber which extends upwards. At the vapour/oil interface, part of the vapour
condenses and is drained gravitationally together with the hot oil to the lower
well.
The CSS technology [also known as huff and puff], on the contrary, requires a
single horizontal well which acts as both injector and producer and the
production of the bitumen takes place in 2 phases forming a single cycle which is
repeated various times. In the first phase, vapour is injected for several weeks to
heat and mobilize the bitumen. In the second phase, the flow is inverted and
bitumen is produced, for a certain period of time (typically several months], by
the same injector well.
Both of these two technologies require enormous quantities of vapour and
consequently of natural gas for its production. To avoid the importation of natural
gas, the THAI technology is being developed, which is based on the concept of the
in-situ combustion of part of the oil by air injection from an injector well. In this
9
way, the reservoir is appropriately heated and the oil can be recovered through a
producer well.
The use of these technologies has allowed the incidence of the production cost on
the total cost for the preparation of syncrude, to be significantly reduced with
time, for example, in the case of Canadian bitumen, production costs are
estimated at approximately 20 $/bbl.
The bitumen extracted, either by mining or by applying in-situ technologies, can
be upgraded to allow it to be processed in refineries or mixed with a solvent
[naphtha gas oil] and sold as such [Fig. 8].
Conversion processes of extra-heavy oils and bitumens have the purpose of
transforming a substrate consisting of high-molecular-weight, viscous
hydrocarbons, rich in toxic components and metals, into more fluid and lighter
products comparable to a traditional crude oil [syncrude], or even better into
distillates which can be directly upgraded to transportation fuel and gas oil for
motor vehicles. From a chemical point of view, the molecular weight of the
hydrocarbon structures forming the substrate must be reduced [cracking
reactions] and the H/C ratio increased by means of carbon removal reactions [C-
rejection processes] or hydrogen addition processes, as illustrated in Fig. 9.
C-rejection processes are thermal processes through which the heavy
hydrocarbons of the feedstock are disproportioned generating distillates with a
10
higher H/C ratio and releasing a highly aromatic residue [tar or coke]. The
process involves the is of the radical type and envisages the homolytic breakage of
C-C and C-heteroatom bonds followed by β-scission reactions whereby, as the
reaction proceeds, increasingly lighter hydrocarbons are produced generating
distillates and gas.
The aromatic radicals produced by dealkylation tend however to react with each
other forming highly condensed polynuclear structures which become
increasingly less soluble in the reaction mixture and which, over a certain level,
lead to the formation of mesophase and therefore coke.
Thermal processes are generally not very selective towards the production of
distillates in that, as the severity of the process increases, so does the yield to gas
and problems of stability arise on the reaction products. The quality of the
distillates is poor mediocre as thermal cracking alone is not capable of
significantly removing the hetero-atoms present in the heavy feedstocks. In
addition, naphtha and gasoil are rich in olefins and dienes and must
consequently be stabilized by means of hydrotreatment.
The most widely-used thermal process in upgrading complexes of heavy oils and
bitumens is Delayed Coking. This is a semi-continuous process operating at
temperatures of about 500°C in which the feedstock is confined in particular
coking drums, where it remains, under specific temperature and pressure
11
conditions, until the coking reaction has been completed. The liquid and gaseous
products obtained pass to the fractionator for separation; the coke is deposited in
the same drums, from where, in order to be removed, it is hydraulically crushed
into large pieces. Alternatively, the Coking process can be carried out in
continuous using processes called Fluid CokingTM and FlexicokingTM , in which
the coke is generated by thermal cracking as a reaction medium and heat carrier.
The Coking process is generally able to convert over 80% of the feedstock into
light products.
In H-addition processes, the conversion of the heavy feedstocks to distillates is
obtained through the combined action of cracking and catalytic hydrogenation
reactions of reactive fragments. In this way, it is possible to more effectively
control the propagation of radical reactions mainly with respect to the aromatic
compounds condensation processes of aromatic compounds and consequently
reduce the problem of fouling and coke formation. Depending on the reaction
conditions and type of catalyst used, hydrogen can also be added to the products,
saturating the aromatic structures and favouring the elimination of the hetero-
atoms. For this reason, the quality of the distillates, but also of the non-converted
residue obtained from hydrocracking processes is much higher than that
obtained from thermal processes.
12
These processes generally operate at temperatures ranging from 390 to 430°C to
promote the thermal cracking and at partial hydrogen pressures higher than 90-
120 atm.
The most active catalytic species for these reactions are various sulfides of
transition heavy metals such as, in particular, Mo, Ni, Co, W, Rh, often used in
pairs (NiMo, CoMo, NiW) and supported deposited on suitable porous carriers
[preferably alumina] or mixed with the feedstock in the form of powder [catalysis
in slurry phase].
The hydro-conversion plants that use supported catalysts can be divided into two
categories, based on the technology used: those with fixed bed reactors and those
with expanded (or ebullated) bed reactor. The hydroconversion plants which use
supported catalysts can be divided, on the basis of the technology used, into two
categories: 1) plants with fixed bed reactors and, 2) plants with ebullated bed
reactors.
The plant configuration using fixed bed reactors generally consists of three or
more reactors in series and a fractionation section where the effluents are
separated by both atmospheric and vacuum distillation.
A particular innovation developed by Chevron for the fixed bed technology is the
insertion of the so-called Onstream Catalyst Replacement System (OCR) which
allows the substitution of part of the catalyst while the plant is still running.
13
Analogously to fixed bed hydrocracking, the process scheme with ebullated bed
reactors generally consists of two or three reactors in series and a fractionation
section where the effluents are separated by both atmospheric and vacuum
distillation. Also in this scheme, the liquid feedstock and hydrogen are heated
separately up to the reaction temperature and the flow through the reactors is of
the upward type. The liquid flow is ensured by a pump which recirculates part of
the liquid collected in the upper part of the reactor. The recycling pump can be
installed on the lower bottom of the reactor or outside the reactor.
Part of the catalyst contained in the reactors is substituted on a daily basis in
order to keep its activity unchanged.
Unlike the fixed bed technology, the ebullated bed technology is suitable for
treating feedstocks with a high content of contaminants and as such is used for
processing the vacuum residue from feedstocks which can also be particularly
heavy. This solution, moreover, has a high flexibility with respect to feedstocks
coming from different crude oils, it provides almost constant yields and product
quality and has a high operative flexibility.
In the field of H-addition processes of extra-heavy feedstocks, an important role
can be played by slurry technologies. These hydrotreatment technologies are
characterized by using non-supported hydrogenation catalysts, finely dispersed
in the substrate to be hydrogenated. These catalysts are not particularly sensitive
14
to poisons and consequently do not create problems of deactivation due to the
deposition of coke and metals on the pores of the carrier, making them
particularly interesting for the treatment of feedstocks which are characterized by
an extremely high concentration of metals, sulfur, nitrogen and asphaltenes.
There are currently no slurry processes which have been developed as far as a
commercial level; attention is being paid to the development of these technologies
however by numerous companies among which, in particular, Eni, whose Eni
Slurry Technology [EST] represents the most advanced version in this field.
Oil Shales
Traditional technologies for the exploitation of oil shales envisages three main
phases:
recovery of the mineral in the mine;
thermal treatment for the production of gas and crude oil;
hydrotreatment (upgrading) of the liquids up to the production of distillates for
the fuel market
The recovery of oil from the rock containing it then passes through high-
temperature pyrolysis treatment for which various technological solutions have
been developed over the years.
15
The process which, as already mentioned, is known as retorting, starts at 200°C,
and is completed at higher temperatures [500-600°C] and is effected in reactors
called retorts. The main objective in projecting the retorts is to effect low-cost
heating using as little energy as possible.
The product generated with the retorting of oil shales is a dark viscous liquid
(shale oil) having a high content of hetero-atoms and unsaturated compounds
produced during the pyrolysis. With respect to heavy oils or bitumens, the liquids
from shale oils have a high concentration of hydrocarbon structures with a high
H/C ratio due to the fact that the starting kerogen contains a high percentage of
paraffinic structures.
An alternative solution to retorting is represented by the so-called in-situ
conversion.. This technology was initially proposed in the USA in the sixties’ by
various mining companies and envisages injecting air and vapour into the
reservoir causing the partial combustion of organic material and subsequently
heating the formation reaching temperatures of 700-800°CC. In this way, the
pyrolysis process is carried out directly in the reservoir from which the conversion
products can then be recovered using suitable producer wells.
A different approach is currently being evaluated, which envisages the production
of a series of vertical wells in the oil shale reservoir which are then heated
electrically, or by means of overheated vapour or again using the hot gases
16
produced by the partial combustion of organic material. In this way, the
formation is brought to a temperature in the order of several hundreds of
centigrade degrees and maintained under these conditions for various years. The
high temperature accelerates the natural degradation process of the kerogen to
oil as represented in Fig. 10, which can then be extracted as a traditional crude
oil from a producer well. The conversion yields are lower than what can be
obtained with traditional retorting [approximately 20% by weight with respect to
the organic material], but the quality of the oil produced is much higher and
above all environmental problems associated with the recovery of the mineral and
disposal of the processing residues are significantly reduced. Of particular
importance is the work carried out by Shell relating to the development of the ICP
technology (In-situ Conversion Process) in an advanced experimental phase in the
Piceance Creek basin in Colorado.
The development of these technologies (Unconventional Oil, 2008) could favour
an acceleration in the industrial exploitation process of oil shales, for which a
production cost of 70-95 $/bbl is currently estimated.
17
Natural gas: a highly available resource
Development and upgrading of natural gas
Natural gas is an abundant resource which is versatile in use and also enables
uses with reduced local environmental impact. The consumption of natural gas is
currently estimated at around 3,000 billion m3 (bcm) per year. The overall
demand is increasing at an average of 2% per year until it will reach, according to
current growth models, approximately 4,800 bcm in 2030, exceeding the
production of liquid hydrocarbons [fig. 11].
Proved reserves are 182 trillion billion m3 and on the basis of the consumption
projection, according to current models, they should be sufficient for supplying
the markets for over 60 years [fig.11]. Most of the gas production derives from
exploration activities aimed at finding liquid hydrocarbons. Only recently has a
specific research activity been developed together with a review of the reserves
discovered in the past and not exploited.
Unconventional gas
Together with large gas reservoirs, there are also huge reserves of natural gas
which can be found in nature in very particular geological formations which
require specific development techniques [fig. 12].
18
The coalbed methane (CBM) is substantially methane adsorbed in coal reservoirs
during the geological formation process. These are molecular layers of methane
which remain bound to the surface of the coal matrix at the high pressures of
deep deposits.
The exploration of coalbed methane is associated with the discovery of coal mines
characterized by high pressures and low temperatures, conditions which allow
the retention of considerable quantities of gas. Large quantities of water are
generally present in the reservoir, together with the gas, which must be removed
by means of drainage processes. In order to obtain an effective desorption,
stimulation techniques must be effected, which depend on the specific
characteristics of the reservoir.
Apart from the more conventional depressurization of the reservoir, one of the
most effective processes which are becoming increasingly more widespread,
consists in the injection of CO2 to relocate the adsorbed methane (Enhanced
CBM). In this way, it is possible to recover up to 90% of the gas originally present
(OGIP) [fig. 13]. In the last fifteen years in the USA, a total of approximately 350
billion cubic metres of CBM have been produced. Methane associated with large
coal reservoirs has also been put into production in Australia for several years.
China and Russia, two of the countries which are probably the richest in CBM,
have not activated production, probably due to the lack of infrastructures. Under
19
the most favourable conditions, CBM has reached competitive production costs
with respect to conventional gas.
Deep Gas
Accumulations of natural gas present in very deep (over 4,500 metres) and high-
temperature reservoirs, are classified as Deep Gas and, due to the high risks and
exploration and drilling costs associated with their development, they are
classified as unconventional..
At present, these reservoirs are only exploited in the USA and Canada where
there is a favourable combination of gas supply, low costs for technologically
advanced field services and the presence of infrastructures for the treatment and
distribution of the gas produced.
The limited development activities make an estimation of the abundance of this
resource still extremely uncertain. The debate underway on the nature of the
accumulations of deep gas and on the generation potential of hydrocarbons at
great depths leads to important estimates on technically recoverable deep gas
[700 billion cubic metres]. The recent discovery of deep gas accumulations in the
low basins of the Gulf of Mexico have led to a growing interest in the development
of these fields. Drillings at depths greater than 7,500 metres have also been
activated, with the expectation of discovering important reservoirs at these levels.
20
Tight gas
These are formations containing natural gas characterized by permeabilities lower
than 0,1 millidarcy. Two main types can be distinguished: tight gas when the
reservoir consists of carbonate or sandy matrixes and shale gas when it consists
of schist matrixes [clays].
These formations have been the object of accurate studies and are currently
under production mainly in the USA and Canada. The estimate of tight gas which
can be produced in the USA exceeds the conventional reserves and in 2004 the
production was 130 billion cubic metres.
The world scale has never been characterized, but it is presumed to be abundant
and present in most oil regions.
In relation to the low permeability of the reservoir rock, particular production
technologies are required [horizontal wells and multiple fracturing of the
formation] to favour the gas inlet into the production well and obtain
economically favourable productivities [fig.14].
A strong potential growth is expected which will be influenced however by the
local market and a decline in conventional gas resources.
21
Gas hydrates
The first evidence of the presence of methane hydrates in natural deposits goes
back to 1965, when the first samples were observed in the Siberian permafrost
followed by analogous indications in the Arctic areas of Canada and Alaska.
As the hydrates tend to be stable at low temperatures and high pressures [for
example at 4°C e 39 bar), the conditions under which they can exist naturally in
a crystalline phase are widely present in many areas of the planet.
There is considerable uncertainty as to the estimation of the possible dimensions
of these resources, however, due to a limited knowledge of their properties and to
reduced exploration.
Estimations effected at the end of the eighties’ were based on the assumption that
the hydrates are concentrated in continental margins where formations
containing organic material destined to being transformed with time into
methane, seem to be preferably localized.
The most problematic aspect linked to their presence is that the same structural
stability of the beds greatly depends on the properties of the hydrates.
Knowledge of the possible production mechanisms is still at an initial stage.
Energy must be supplied for producing the methane contained in hydrates, there
is an extremely positive balance, however, between the combustion energy of
22
methane and that necessary for releasing it from the crystalline structure of the
hydrate containing it [fig. 15].
The production processes currently being evaluated are:
depressurization of the reservoir by production of the free gas beneath the
hydrate formation;
heating by vapour or hot water injection;
injection of defrosting additives (methanol, glycols);
destabilization of methane hydrates by CO2 injection and with the
contemporaneous formation of CO2 hydrates;
mining extraction with conventional techniques.
23
Mediterranean climate change
Jos Lelieveld Cyprus Institute, Nicosia, Cyprus
The XIV International Conference “Energy Crisis, Water Shortage and Climate Changes in Mediterranean Area: the Involvement of Chemistry”, held in Castiglione della Pescaia, in the coast of Tuscany , Italy, May 2-6 2008, under the auspices of the Accademia Nazionale dei Lincei, Fondazione Alessandro Volta, addressed several key aspects of climate change:
- Global climate change: natural and anthropogenic causes; - Mechanisms of climate change; - Measurement techniques to detect atmospheric change; - Climate change aspects related to the energy and water crises; - Past and future climate changes in the Mediterranean region; - Storm activity and precipitation; - Effects of desert dust and pollutant aerosol particles; - Chemistry and transport of toxic air pollutants.
A summary of these issues is presented in the following.
1. Climate and meteorology The Mediterranean climate is characterized by humid winters with cyclonic storms, and warm, dry summers, with occasional extended drought periods. The average north-south temperature gradient across the basin, from the Alps to North Africa, is remarkably large, about 25°C. In some locations, e.g. along the Adriatic coast, precipitation is among the highest in Europe (~1000 mm/a) and in the mountains of the Balkan Peninsula it is typically in excess of 2000 mm/a, whereas in North Africa this can be more than an order of magnitude less.
The Mediterranean weather is strongly influenced by the geographical positions of the Azores high and the Icelandic low, which can modify the mean westerly flow. When the high and the low are strongly developed, and therefore the meridional pressure gradient is strong, relatively moist air masses are transported to Europe. In the alternate case, the zonal flow is weak, and blocking weather systems prevail over central Europe. The interannually varying pressure gradient between the Icelandic low and the Azores high pressure systems is known as the North Atlantic Oscillation (NAO), an indicator of the intensity of synoptic weather systems over the North Atlantic Ocean.
Even though the NAO is a natural mode of climate variability, it can be influenced by anthropogenic climate change. It is linked to the general atmospheric and oceanic circulation systems, the latter being affected by the formation of cold bottom water in the Arctic Ocean and the influx of salty water from the Mediterranean Sea through the Strait of Gibraltar. By definition, a relatively strong pressure gradient between the Azores high and the Icelandic low yields a positive NAO index, a relatively weak gradient a negative NAO index. Although its influence has been studied primarily for the winter season, the NAO is associated with considerable monthly and interannual variability, and effects have been identified for all seasons.
1
In summer, the InterTropical Convergence Zone (ITCZ) and the Azores high shift to higher latitudes. The Azores anticyclone in combination with eastward moving low pressure systems over central Europe lead to westerly flow in the lower and middle troposphere toward the Mediterranean basin. Spreading of the high pressure across central Europe in summer weakens the westerly flow, and European air is mostly transported to the basin by northerly winds, at right angles with the strong east-west pressure gradient near the surface. In the upper troposphere, air masses are transported in the westerlies from the North Atlantic Ocean.
During summer the Mediterranean basin is directly under the descending branch of the Hadley circulation, driven by deep convection in the ITCZ. As a result of subsidence, the region is characterised by dry and cloud free conditions with high solar radiation intensity. Recent research indicates that the ITCZ is intensifying as a result of climate change, leading to enhanced drying over the Mediterranean. Over land, convection can develop, which is generally not very deep at coastal locations. The air near the surface travels to the equatorial region as the synoptic northerly flow combines with the trade winds, carrying moisture evaporated from the Mediterranean Sea southward.
Atmospheric teleconnections between the Mediterranean region, the Indian monsoon and the Sahel rainfall regimes can be important, varying on an interannual time scale. The atmospheric pressure at sea level in the eastern Mediterranean is anticorrelated with that in the Indian monsoon, mainly in the July-September period, while that in the western Mediterranean is positively correlated, with a maximum during September-November. The meridional wind component over the central and eastern Mediterranean basin is anticorrelated with that in the Indian monsoon. This means that a more active monsoon is connected with lower atmospheric pressure at sea level over the eastern part of the basin and higher pressure over the western basin.
2. Extensive aerosol haze Based on satellite measurements, the Mediterranean Sea has been identified as one of the maritime regions in the world with the highest aerosol optical depths. The earliest atmospheric chemistry measurements on Crete indicated relatively high concentrations of sulphate and nitrate, attributed to long-distance transport of air pollution. Upwind in northern Greece high levels of SO2 have been observed, attributed to coal burning in Central and East Europe. A small though significant fraction of 5-25% of the sulphate, however, originates from natural dimethyl sulphide (DMS) emissions by marine phytoplankton.
Furthermore, desert dust intrusions from Africa, and additional transports of mineral dust from the Near- and Middle-East substantially contribute to the aerosol column. Over Africa, the dust is often lifted to altitudes well above the Mediterranean boundary layer in synoptic disturbances. Hence, after its northerly transport from Africa it can entrain into the westerly flow over the Mediterranean in the free troposphere. It appears that the inter-annual variability of aerosol optical depth over the Mediterranean is strongly affected by the atmospheric column abundance of mineral dust, which correlates with the phase of the NAO which influences the atmospheric transport regime.
Generally, the fine aerosol mass consisted for more than one third of sulphate and nearly one third of particulate organic matter (POM), and it includes substantial fractions of ammonium, black carbon and other compounds. The sulphate is not fully neutralised, mostly present as ammonium bisulphate. The coarse aerosol fraction mostly consists of mineral dust and sea salt, including significant fractions of nitrate and sulphate. It has been estimated that
2
the fine aerosol particle mass was about 80-90% anthropogenic, whereas about 60-80% of the coarse mode particle mass is of natural origin.
The pollutant aerosol sources include urban, industrial, agricultural and forest fire emissions. Fire maps from the MODIS satellite instrument show that during summer around the Black Sea and in several Mediterranean countries extensive biomass burning can occur. The emissions reach the eastern Mediterranean area within several days and North Africa within about one week. In general, agricultural burning and forest fires – mostly anthropogenically ignited – in the Mediterranean region contribute strongly to the aerosol burden, especially during dry spells.
Black carbon can originate both from biomass and fossil fuel combustion. It has been estimated that more than half the black carbon originates from fossil fuel use and the remainder from biomass burning. The relatively large mass of POM, on the other hand, includes many oxygenated hydrocarbons, indicative of aged photochemically processed air pollution and biomass burning aerosol. Only a small part of the POM appears to be related to natural emissions, discernable in the particles as formate, acetate and ≥C9 compounds, which are only present in very small concentrations. In the Mediterranean region aerosol concentrations often exceed the European Union air quality standard for particulate matter (PM10) of 55 µg/m3. This concentration is not allowed to be exceeded for more than 35 days per year.
Altitude resolved radiometric measurements show that the diurnally averaged shortwave radiative forcing at the surface by aerosol particles can be nearly 20 W/m2. This is mostly caused by solar radiation scattering and absorption by particles in the fine mode aerosol, substantially reducing the surface heating. The radiative forcing at the surface compares to a forcing of only about 7 W/m2 at the top of the atmosphere (TOA), the latter representing the overall loss of solar energy to space through aerosol radiation backscattering. The difference between the TOA and the surface forcing corresponds to an atmospheric heating of about 12 W/m2, caused by the absorption of solar radiation, in which black carbon plays a key role. These strong radiative perturbations influence the Mediterranean atmospheric heating profile and the moisture budget through changes in evaporation and cloudiness.
3. Air quality, climate and the water cycle The solar radiation energy input into the Mediterranean Sea, as reduced by aerosol particles, constitutes a major driving force of the oceanic thermohaline circulation. Indeed, substantial changes in Mediterranean deep water formation have been observed, possibly affecting salinity transports to the North Atlantic Ocean through the Strait of Gibraltar. It should be further investigated to what extent these changes have been caused by surface radiative forcings of aerosol pollution, regional rainfall anomalies and how they link to global climate change, e.g. through the NAO.
The Mediterranean basin is characterized by large climate gradients, and there is concern that climate change will be associated with the intensification of extreme weather conditions. Regional European climate scenario calculations for the 21st century indicate a relatively strong warming as compared to the rest of Europe, and especially the number of very hot days may increase. Air quality is strongly correlated with the mean temperature through the occurrence of hot and stagnant anticyclonic conditions, which are expected to increase in future. In addition, the hemispheric background level of air pollution may increase, e.g. through long-distance transport of emissions from Asia. Furthermore, since a positive phase
3
of the NAO correlates with increased transatlantic air pollution transport, a possible future change in the NAO may have consequences for air quality both in North America and Europe.
Climate scenario calculations furthermore indicate that precipitation may increase in the western and northern parts of the basin, more often released in torrential rain events, while in the dry southern and eastern parts precipitation is expected to decrease even further. However, the models used did not yet account for the effects of aerosol particles on the energy and moisture budgets. As indicated above, the strong aerosol scattering and absorption in the Mediterranean basin reduces the surface heating and thus the sea surface temperature (SST). Climate model calculations show that the long-term SST variability, as influenced by the NAO, was relatively regular in the period 1930-1970. Subsequently a strong cooling phase occurred, which correlates with sulphate aerosol pollution over the Mediterranean Sea. Since the solar energy absorbed by the sea is largely returned to the atmosphere through evaporation, the negative radiative forcing at the surface, caused by sulphates and other particulate matter, suppresses evaporation and atmospheric moisture transports.
To assess the possible consequences of this aerosol effect on the regional water cycle, a sensitivity study was performed by prescribing observed low and high SSTs as boundary conditions to a general circulation model. The results demonstrate that the Mediterranean SST sensitively influences the amount of precipitation downwind, e.g. in the Middle East and the Eastern Sahel zone. Firstly, the negative SST anomalies appear to correspond to drought periods in northern Africa in the 1970s. Secondly, the positive SST anomalies in the 1990s correlate to a recovery from these spells in the same period, coincident with decreasing sulphate concentrations. It is expected that future climate warming will be associated with increased rainfall in the Sahel region. Further studies will be needed to substantiate the links between aerosol pollution, SST anomalies and perturbations of the water cycle.
There are several additional though poorly quantified effects that aerosol particles can have on clouds and climate. For example, the solar radiation absorption by black carbon, which heats and thus stabilizes the aerosol pollution layer, could lead to the evaporation of clouds. Indirect aerosol effects on clouds also include the precipitation efficiency; for example, a high particle abundance may inhibit rainfall or suppress “warm” rain formation in convective clouds. The latter effect can extend the vertical development of deep convective clouds, which promotes ice and hail formation and lightning so that some of these clouds may invigorate into heavy thunderstorms that produce torrential rain.
To what degree these interactions between air pollution, clouds and climate are relevant for the Mediterranean basin needs to be determined through coordinated research programmes. Global, regional and local aspects influence both air pollution and climate, and mitigation or adaptation strategies should be based upon integrated problem assessments that also account for land-use and soil hydrology changes. The largest risk lies in the possibility that some of these aspects combine into destabilizing (positive) feedback mechanisms with potentially large consequences for the region, shown to be vulnerable to changes in air quality, climate and the water cycle.
4
Appendix: Conference program related to climate FRIDAY MAY 2nd Afternoon session: Climate changes I 16.00 Welcome addresses 16.20 Costas PAPANICOLAS: Climate Change, Energy and Water Crisis: Manifestations of the physical basis of globalization 17.10 Sylvie JOUSSAUME: Past and future climate changes with a focus on the Mediterranean Region Chair: Venice K. Gouda 18.20 José Luis SANCHEZ GOMEZ: Storm activity and precipitation from different points of view: microphysics, radar meteorology, mesoscale modeling, hail climatology and trends 19.10 Franco PRODI: Climate changes: natural and anthropic causes Chair: Manuel R. Llamas SATURDAY MAY 3rd Morning session: Climate changes II 09.00 Hervé LE TREUT: The mechanism of climate science in response to greenhouse increase and the associated uncertainties 09.50 HRH Princess Sumaya BINT EL HASSAN: El Hassan Science City; making a change to adapt for climate change 10.30 Euripides STEPHANOU: Eastern Mediterranean: a crossroad of toxic pollutants Chair: Sylvie Joussaume 11.20 Coffee Break 11.40 Giorgio FIOCCO: Brief survey of modern instruments for the study of the atmosphere 12.20 Tatiana DI IORIO: Transport of desert dust in the Mediterranean basin 12.40 Alcide G. DI SARRA: Radiative effects of desert dust Chair: Hervé Le Treut Afternoon Session: Climate changes III - Water shortage I 15.00 Jos LELIEVELD: Air quality and climate change in the Mediterranean basin 15.50 Gideon DAGAN: Modelling of Water flow and pollutant transport by groundwater Chair: Costas Papanicolas 17.00 Andrea RINALDO: River networks and ecological corridors 17.50 Guido VISCONTI: Hydrological and meteorological changes related to the land uses variations in the Mediterranean Region Chair: Franco Prodi 18.30 ROUND TABLE - CLIMATE: Joshua Jortner, Sylvie Joussaume, Franco Prodi, Costas Papanicolas, Jos Lelieveld, Dweik Hasan Salah
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POTENTIAL AND TECHNOLOGICAL CHALLENGES FOR THE CONVERSION OF RENEWABLE BIOMASS TO LIQUID TRANSPORTATION FUELS
Gregory Stephanopoulos
W.H. Dow Professor of Chemical Engineering and Biotechnology Massachusetts Institute of Technology
Cambridge, MA 02139
1.0 Summary-take away messages This paper examines the potential of renewable biomass to supply a sizable fraction of the liquid fuels presently used for transportation. The main thesis is that renewable sources of biomass can supply approximately 1/3 of the liquid transportation fuels in the US and, by extension, other geographical regions. Biofuels, (i.e., fuels produced from renewable resources), however, will have to be produced in a way that avoids competition with food, either directly for grains that are used for food or animal feed, or, indirectly, for land and other resources required for the production of either. This is possible by converting to liquid fuels cellulosic biomass produced either as agricultural residue, forest products or in marginal lands. Possible biofuels include alcohols, oils and higher hydrocarbons. One can now envision cost effective processes for converting biomass to biofuels thanks mainly to the advent of the new biology, metabolic engineering and cost-effective enzyme production. However, challenges still remain and are briefly outlined.
2.0 Corn is not the answer In 2006, approximately 5B gallons of ethanol were produced in the US from approximately 130 plants for use as liquid fuel. Another 2.2 B gallons/yr capacity was at the construction stage. This ethanol demand was driven by the use of ethanol as MTBE substitute, a $0.51/gallon excise credit, and the increasing oil and gasoline prices that made ethanol production very profitable in 2006. One would think that the 5B gallons of ethanol would displace an equal volume of liquid fossil fuels, however, the reality is much different. First, the energy content of ethanol is 2/3 that of gasoline, so the above volume is equivalent to ~3.8 B gallons/yr of gasoline. Additionally, if one considers that it takes ~0.75 units of fossil energy to produce 1 unit of energy contained in ethanol (1), the 3.8B gallons of ethanol actually represent only ¼ of net energy production, which is only ~0.95B gallons, or less than 1% of the annual demand in the US. If one further considers that the production of the above amount of ethanol absorbed approximately 16% of the corn production in 2006, it is clear that, even if all of the US corn were used for ethanol fuel production, it would be able to displace no more than 4% of the liquid fossil fuels used for transportation. The
G. Stephanopoulos, MIT - Potential and challenges for biomass conversion to liquid fuels July 25, 2008 Conference on Energy and Water Crisis in the Mediterranean, Castiglione della Pescaia, May 2-6, 2008
conclusion is that, although ethanol produced from corn starch has played an important role in paving the way for the introduction of renewable fuels in the liquid fuel market, its potential for production of a significant fraction of the current consumption of liquid fuels is quite limited. In assessing the role of ethanol in advancing biofuels and the food versus fuel question, it is also important to note that approximately 1/3 of the corn consumed for ethanol production ends up as animal feed in the form of DDGS (see below). 3.0 Potential of biomass Figure 1 depicts the various types of energy consumed for the production of ethanol fuel. Clearly a substantial fraction (between 25-30%) is required for the production of the corn grain. In addition, more than 55% of the energy consumption is for distillation of ethanol from the ethanol-water mixture and the drying of the Distillers Dry Grain Solids (DDGS), a substantial byproduct used as animal feed. If one were to use cellulosic biomass as feedstock for ethanol or other biofuel production, there would be no need for expending the amount of energy used for corn production. Furthermore, the steam required for distillation of ethanol could be supplied by burning the lignin fraction of biomass, which is, for most feedstocks, sufficient to also supply the power needs of an ethanol plant. As a result, the energy balance in the production of ethanol from cellulosic feedstocks is much more positive compared to that of ethanol from corn starch. Estimates range from 4-7 units of energy produced per unit of fossil energy consumed. In addition one must consider the fact that, while ethanol is a liquid fuel, the energy required for its production can be supplied in many different forms such as from coal, wood or natural gas which constitute (the first two) lower grades of energy. As a result, cellulosic biomass is a promising source of liquid biofuels.
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Figure 1: Energy utilization in ethanol production from corn (source: J. Johnson thesis, MIT)
A recent study of the US Department of Energy assessed the total amount of
biomass available for biofuel production on a sustainable basis (2). This study, usually referred to as the Billion Ton Study, included agricultural residues, forest products, pulp and paper wastes, and new energy crops as biomass sources and estimated that the total amount of available biomass on a sustainable basis to be ~1.3B tons per year. A more recent study of the National Academy estimates the amount of available biomass to 400-600 M tons/year (3). The difference is due to the fact that only lands in the CRP (Conservation Reserve Program) are considered for
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production of energy crops, and only a fraction of the total agricultural residues can be used for biofuel production, as a significant fraction must be left on the field to ensure adequate recycle of agricultural nutrients. Even if one considers the lower, more conservative estimate, this amount of biomass is sufficient to produce between 30-55B gallons/yr of ethanol, which is between 20-35% of the annual US consumption of liquid fuels.
Figure 2 depicts a schematic flowsheet of the envisioned biomass-to-biofuels (B2B) conversion process. There are a lot of similarities between the cellulosic and corn-ethanol manufacturing processes, as they share at least 5 basic and identical unit operations. These are size reduction, saccharification, fermentation, distillation, and solids separation (centrifugation). In some plant configurations, however,
saccharification is attempted simultaneously with the fermentation, but this design is somewhat independent of whether corn or cellulosic biomass is used as feedstock. Both systems also share the need of some form of solids feedstock handling and storage, but one can envision a variety of alternatives for this front-end process; maybe the simplest is a single storage bin.
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The main difference between these two ethanol manufacturing alternatives lies in the initial pretreatment of the feedstock after size reduction (grinding or chopping), for the preparation of the mesh to be saccharified and fermented in the subsequent step(s). This is due to the difference in resilience to ‘liquefaction’ or ‘softening’ of the feedstock. In the case of the cellulosic biomass process there are a few alternatives to pre-treat the lignocellulosic material to make the glucan and xylan or arabinan fibers available to enzyme degradation into monomers in the saccharification step. These are steam pretreatment, weak acid pretreatment at higher temperature, or ammonia explosion. They all have advantages and disadvantages regarding the type and amount of sugars released for subsequent fermentation. The pretreatment step is also quite important in the type of toxic byproducts released in the medium that
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may limit the ability of microorganisms to convert simple sugars to ethanol or other biofuel in the subsequent fermentation step.
The second main difference has to do with the resulting byproducts of the process. More work and energy is used in the dry grind corn-based case to produce adequate quality DDGS, requiring both an evaporator and a drying step. In the case of the cellulosic alternative, only a dryer is needed to retrieve the residual solids – rich in lignin – that are then burned in a boiler to cover the steam and power requirements of the biofuels plant. Some designs, such as that of a 2002 NREL study for example, even avoid this drying step altogether thereby reducing even further the capital cost, but, this may come at the cost of being more dependent on external sources of energy for the plants heating and electricity needs (3).
Finally, the third major difference is the inclusion in the cellulosic plant design of a lignin based burner and boiler for the generation of steam, as well as a steam turbine for the generation of electricity. These are included in the design to take advantage of the relatively high content of lignin in the feedstock as well as the ease by which the lignin in the residual solids can be combusted by simply providing air, together with the high amount of energy contained in the lignin: 11.5 Kbtus/lb (26.7 KJ/g). It should be noted, however, that the capital cost of a lignin burner and steam turbine generator may increase by as much as 35-45% the capital cost of a cellulosic ethanol plant. The main justification for such an expense is to improve the energy balance and, by extension, the CO2 emissions of the B2B conversion process. This expense is only marginally justifiable from an economic standpoint. Therefore, such process designs that minimize CO2 emissions can be encouraged by giving proper credit to plants with reduced carbon emissions. 4.0 What is different now? This is not the first time that biomass is being considered for biofuel production. A very strong R&D activity for bioethanol production from biomass had similarly been initiated in the decade of the 70’s in response to another energy crisis at that time. That effort did not lead to any commercial process and subsequently subsided as oil prices headed to drastically lower levels in the interim period.
There are three major differences, however, between the present situation and that of 30 years ago. First, the cost of cellulolytic enzymes has been drastically reduced. While the enzyme cost was estimated between $1.20-2.50 per gallon of produced ethanol then, now, thanks to coordinated efforts of enzyme producers and the Department of Energy, that cost has been reduced to between $0.15-0.40/gallon of ethanol depending on enzyme manufacturer and whether the enzyme plant is co-located with the ethanol plant. This enzyme cost reduction allows more optimism about the eventual commercialization of B2B conversion processes.
The second difference is the Billion Ton Study that has now substantiated the sustainable availability of biomass for the production of a sizable fraction of the US liquid fuel demand. There may be disagreement with regards to the exact total
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amount of available biomass, however, the main point is that the total is not trivial and sufficient for the displacement of a substantial amount of liquid fossil fuels.
The third important difference is the New Biology as embodied in the field of Metabolic Engineering. This is simply the unprecedented ability to transfer, express and regulate genes of various origins in host microbes for the overproduction of chemicals and fuels. As such, Metabolic Engineering has become the enabling technology for biofuels production. It emerged 15-20 years ago and in a short period of time developed a deep intellectual content and rich portofolio of successful applications of microbe engineering for the overproduction of biochemical products. These molecular and biotechnological capabilities allow optimism regarding the ability of current research to engineer and optimize pathways for the production of existing and new biofuels in microorganisms at rates and yields competitive with those achievable by chemical means.
5.0 Is biomass the answer to the production of liquid transportation fuels? Figure 3 shows a schematic of the fraction of the US land required to displace 25% of petroleum used today for three types of bioethanol feedstock. Clearly, the potential of biomass is very significant. However, whether this industry will eventually materialize will depend on at least 3 additional factors: concentration of cellulosic biomass, cost of biomass, and satisfactory resolution of various technological issues associated with B2B conversion.
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Figure 3: Land requirement for displacing 25% of petroleum used in the US for the case of corn, switchgrass or advanced energy crop used as fuel feedstock (from J. Johnson thesis, MIT, 2007).
Figure 4 shows the distribution of various types of biomass feedstock in the US. Clearly, there is a significant non-uniformity in the capacity of various regions to produce biomass. Furthermore, transportation and basic infrastructure considerations limit the amount of biomass that can be processed in each biorefinery to approximately 2-3,000 tons of biomass per day. This would be sufficient for an annual ethanol production of the order of 40-50M gallons/yr. As a result, future
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bioethanol plants will not benefit significantly from cost reduction typically expected of large plants and brought about by usual benefits from economies of scale.
Furthermore, many unresolved issues remain regarding the collection, baling, storage and transportation of biomass required for the needs of a biorefinery of the above size. Perhaps the prevailing model of biomass collection and handling that is based on transportation by trucks to a central processing facility needs to be replaced by a more distributed scheme, whereby biomass is collected at many different satellite stations where it is preprocessed and stabilized in order to be transported by pipelines to the central facility where saccharification, fermentation and product isolation takes place. In a variation of this scheme, cellulosic biomass properly pretreated may be contacted with cellulolytic enzymes before pumped in the pipeline to the central facility. In such a process, the long residence time required for cellulose hydrolysis would occur while biomass, in the form of a slurry, is being pumped from the satellite stations to the central processing facility. Figure 5 depicts such a scheme. Additional advantages of such a model also include the ability to handle various types of cellulosic feedstock (such as different energy crops, and agricultural resides), increased robustness of the overall plant against local variations in production resulting from plant disease, water conditions or other unpredictable situations, crop rotation and year-round operation utilizing stored and properly stabilized feedstocks.
Figure 4: Geographic distribution of cellulosic feedstock in the US
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Figure 5: Schematic of a biorefinery with distributed network for the collection, pretreatment and pumping of biomass feedstock to a central processing facility via pipeline.
The second important issue is biomass
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cost. Initially, it had been assumed that biomass could be had for biofuel production at a very low, perhaps even negative, cost. As the demand for fuel intensifies it is becoming abundantly clear that the above assumption was wrong and biomass cost emerges as the most important factor in determining the cost of future biofuels. The recent dramatic climb in the cost of corn from $2.25 to over $7 per bushel underlines this trend.
There are various economic models for predicting the minimum price acceptable to farmers and the maximum cost that a processor will be willing to pay for a steady biomass supply. These models suggest that the minimum price that a producer will be willing to accept ranges between $100-120 per ton. Key factors contributing to this estimate are transportation and storage (currently accounting for $50-100/ton), yield of biomass per acre and land opportunity costs (estimated at $250-400/acre). The latter increase in significance as one becomes cognizant of the constraint that biofuel production should not compete with food production. Additionally, costs for establishment of new energy crops must be considered.
The maximum price a processor is willing to pay ranges between $80-110/ton of biomass. Significant parameters in the determination of this estimate are, first the price of oil and then the yield of ethanol (or other biofuel) per ton of biomass, and the energy content of the produced biofuel. At a present price of oil in the range of ~130/barrel, a processor is willing to pay an even higher price per ton of biomass than the estimate indicated above. However, these calculations must be based on a long-term average. On the other hand, engineering microbes for production of biofuels with higher energy content than that of ethanol (such as hydrocarbons, for example), or increasing the yield of biofuel production per ton of biomass can have a very significant impact on the overall process economics. For example, the energy content of a biofuel can range from a low of 2/3 (for ethanol) to close to 1 for higher alcohols and hydrocarbons. Similarly, the amount of biofuel that can be obtained from a ton of biomass ranges between 60-110 gallons. The exact numbers will depend on the type of biomass (in particular its lignin content), and the particular process employed for biofuel production and will impact in a profound way the cost-effectiveness of the B2B process. Both are subjects of microbe engineering as discussed below.
Clearly, the use of biomass for biofuel production is a feasible possibility based on a value proposition. Absent in the above calculations are the additional societal and environmental benefits that will be obtained from the use of renewable resources for the production of liquid fuels. These are definitely non-trivial and are likely to tip the balance and provide the additional incentive needed to drive further B2B process development for commercial application at scale.
6.0 Technological challenges We discuss in this section the technological challenges in materializing a B2B conversion process. Pretreatment and enzyme hydrolysis, although very important enabling technologies, are no longer critical factors in the overall cost. Enzymes
G. Stephanopoulos, MIT - Potential and challenges for biomass conversion to liquid fuels, July 25, 2008 Conference on Energy and Water Crisis in the Mediterranean, Castiglione della Pescaia, May 2-6, ‘08 7
contribute no more than 40 cents per gallon in overall cost and their cost is continuously decreasing. Pretreatment is a significant part of the process in that it determines the level of solids loading that can be handled. This has important implications in the overall process efficiency, however, it is not a cost-determining step by itself.
Corn ethanol is produced by fermentation as a 12-15% (weight by volume, w/v) aqueous solution from which it is separated by distillation. Both the distillation cost and the overall plant cost would benefit significantly from a higher ethanol concentration. However, ethanol toxicity of the microorganisms (yeast cells) producing the product limits the concentration of ethanol that can be so produced.
Without exception, all envisioned biomass-to-biofuels (B2B) processes will produce a product stream of 4-4.5% (w/v) ethanol concentration. Besides a more challenging and costly ethanol separation step, the low ethanol concentration makes cellulosic ethanol plants 3 times larger than corn ethanol plants of equivalent annual production. The greater capital cost of a plant producing a dilute ethanol product contributes 30-40 cents per gallon of ethanol produced (5). This is far greater than any other major component of manufacturing cost after the feedstock cost.
The main reason for the low ethanol concentration produced in the fermentor of a
cellulosic ethanol plant is the toxicity of both the product as well as the fermentation medium. The latter is biomass hydrolysate comprising, besides sugars, aromatics, furfural, acetic acid and other very inhibitory compounds. To reduce the toxicity, current practices call for a low solids loading eventually yielding product with low ethanol concentration. There have been many attempts to engineer microorganisms with enhanced tolerance to toxicity over the past 25 years. These attempts have followed outdated paradigms, either looking for “ethanol tolerance” gene(s) or employing standard mutation/selection strategies in order to generate mutants with enhanced tolerance. These efforts have all failed in their goal.
One can conclude that the most significant challenge in the development of cost-
effective cellulosic biofuel processes is increasing the concentration of the fuel product stream produced in the fermentation step. However, there is presently no yeast strain that can ferment biomass hydrolysates to produce ethanol at sufficiently high concentrations for an economical process.
It is clear from the above that overcoming toxicity in the production of ethanol from corn, and well as cellulosic feedstocks, is a key challenge in achieving higher efficiencies in ethanol production.
The last challenge in engineering microbes for biofuel production is the optimization of the biofuel producing pathway. Unforeseen issues do arise occasionally in the construction of new pathways in microbial host cells, such as the functional expression of heterologous genes of various origins in yeast and bacteria. However, the most critical challenge in engineering microbes to overproduce fuels is not in stitching a series of genes together to form a pathway but doing so optimally and in a cost-effective manner. This means that the so constructed pathways must
G. Stephanopoulos, MIT - Potential and challenges for biomass conversion to liquid fuels, July 25, 2008 Conference on Energy and Water Crisis in the Mediterranean, Castiglione della Pescaia, May 2-6, ‘08 8
produce the product of interest at high yields and productivities. This is the main challenge in metabolic engineering for biofuels production.
High yield means, (a) selecting a pathway that has the maximum theoretical yield compared to other possible pathways that do the same conversion but at lower overall yields, and (b) pruning unwanted reactions in order to maximize the actual product yield. High productivity is important for maximizing throughput and thus minimizing the plant capital cost. To achieve this, rate-controlling steps must be identified and amplified. These tasks are key objectives of Metabolic Engineering and various technologies have been developed to this end.
7.0 Closure The production of biofuels from biomass is a complex issue with many technological, economical and societal dimensions. After many years of research, it is now becoming clear that this vision is feasible from both a technological and economic standpoint. The upside potential from materializing such a vision is easy to estimate and ranges in the hundreds of billions of dollars annually in the form of new domestic income generated by such processes. There is little if any downside. The cost for overcoming the few remaining hurdles is trivial in comparison to the expected benefit. It is therefore very clear that the time has come to mount the R&D effort required to allow us to move into a more sustainable future by increasing our reliance on renewable resources and limiting the use of irreplaceable fossil fuels to the more demanding tasks of our economic activity.
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References 1. Johnson, Jeremy C. , “Technology assessment of biomass ethanol : a multi-objective,
life cycle approach under uncertainty,” MIT Thesis, published 2006. Online Ed. URL http://dspace.mit.edu/handle/1721.1/35132
2. "Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply", USDOE, USDA, April 2005. http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf
3. "Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis for Corn Stover,” A. Aden, M. Ruth, K. Ibsen, J. Jechura, K. Neeves, J. Sheehan, and B. Wallace; National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401-3393, June 2002 ? NREL/TP-510-32438
4. “Biomass availability for biofuel production.” NRC study on Alternative Fuels to be completed July 2008. Out for review in July-September with target publication date before the end of 2008. Professor Stephanopoulos is an NRC panel member. The Alternative Fuels panel is part of a larger study titled: Energy in America’s Future (EAF).
5. “Bioprocess design and economics for biomass conversion to biofuels.” NRC study on Alternative Fuels to be completed July 2008. Out for review in July-September with target publication date before the end of 2008. Professor Stephanopoulos is an NRC panel member. The Alternative Fuels panel is part of a larger study titled: Energy in America’s Future (EAF).
G. Stephanopoulos, MIT - Potential and challenges for biomass conversion to liquid fuels, July 25, 2008 Conference on Energy and Water Crisis in the Mediterranean, Castiglione della Pescaia, May 2-6, ‘08 10
EASTERN MEDITERRANEAN: A CROSSROAD OF TOXIC POLLUTANTS AND MICROORGANISMS
Euripides G. Stephanou
Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry,University of Crete, GR-71409 Heraklion, Greece
Introduction Although the production and use of polychlorobiphenyls (PCBs) were
banned by the mid-1970s, these chemicals are ubiquitous pollutants in nearly all environmental compartments. PCBs are still released into the atmosphere by primary and secondary emission sources. Previous studies suggested that warm temperatures favor the volatilization of PCBs, from contaminated earth surfaces, which are subsequently transported and condensed to areas permanently or seasonally cold. Because of their high persistence and toxicity PCBs can pose toxic effects, on animals and humans, decades after their release into the environment. Atmospheric PCBs tend to partition between the gas and particulate phase of the atmosphere [1] and they are transported away from the release sources through the movement of air masses. Several studies have shown that atmospheric transport and deposition is a major mechanism by which PCBs and other semi-volatile organic compounds may enter the aquatic ecosystems [2] and contribute to biota contamination. In the aquatic environment, these compounds can be dissolved in the water phase or associated with particles depending on their hydrophobicity and organic carbon-water partition coefficients. Particle-bound PCBs are subsequently removed from the water column by vertical transport of sinking particles [3]. Land based sources (e.g. refineries, sewage treatment plants, river runoff), tanker oil transportation, shipping, and atmospheric deposition are the most important sources of polycyclic aromatic hydrocarbons (PAHs) in the marine environment. Atmospheric deposition was referred to as a significant nonpoint source of PAHs in open sea and remote Eastern Mediterranean coastal areas [4-8]. However, the atmospheric deposition of PAHs in the Mediterranean Sea was evaluated in relatively few studies, most of which were carried out in the western basin [6,8]. Measurement of dry and wet deposition was the focus of these studies, whereas fluxes of PAHs resulting from air-sea exchange were not studied. Air-water exchange of semivolatile organic compounds (SOCs) is an important process controlling inflow of these compounds in large aquatic ecosystems. PAHs introduced into marine ecosystems are buried in sediments and bioconcentrate in marine flora and fauna through various processes [5]. In the last decade, increase of desertification resulted in a concomitant intensification of atmospheric dust loadings [9]. Furthermore, El Nino events have coincided with increased flux of Saharan dust across the Atlantic [10]. It has been estimated that dust flux from the Saharan-Sahel region to the atmosphere
approximates 1 billion tons per year [11]. In addition to their effect on visibility and Earth’s climate through the atmospheric radiation balance, photochemistry, and cloud formation processes, airborne dust can also exert a direct impact on human health. The World Health Organization has identified drought and dust storm activity in the sub-Saharan region of Africa as causing regional outbreaks of meningococcal meningitis (in 1996 there were ~ 250,000 cases and 25,000 deaths) [12]. Only recently it has been shown that dust events can also introduce a significant pulse of microorganisms [12]. Traditionally, the detection and enumeration of airborne microorganisms has been conducted using light microscopy and/or culture-based methods. However, these analyses are time-consuming, laborious, lack sensitivity and specificity [13], and offer just a glimpse of the biological agents present (less than 1% of environmental bacteria can be cultivated) [14]. The development of various techniques based on community molecular analysis has freed researchers from culturing biases and allowed characterization of community structure (e.g. 16S and 18S rRNA genes for bacteria and microeukaryotes, respectively; [14]).
The extent, to which the atmosphere constitutes an important pathway for toxic organic pollutants and microorganisms from Europe and North Africa to the Eastern Mediterranean Sea, remains largely unknown. A number of studies were carried out by the Environmental Chemical Processes Laboratory (ECPL) [15-22] in order to fill this gap. These studies aimed i) to assess the physicochemical and deposition processes of PCBs and PAHs in the atmosphere and the water column of the Eastern Mediterranean, and ii) to combine the obtained results in order to construct a mass balance which described the behavior of PCBs and PAHs in this region. In addition, we studied the microbial components of bioaerosol samples collected from the atmosphere, during intense Saharan dust storm events with culture-independent methods [22]. The later study [22] aimed to investigate the microbial quality of size distributed aerosol particles by using a high volume pump equipped with a five-stage cascade impactor for efficient genomic DNA extraction. Cloning and sequencing the 16S rRNA genes were used to determine the composition of the airborne microorganisms.
Sampling and Experimental
Air and deposition samples for PCB and PAHs analysis were collected at the marine background sampling station of ECPL at Finokalia (35o 20' N, 25o 40' E; Island of Crete, Greece). Details on sampling and analysis of PCBs and PAHs are reported elsewhere [15-21]. Sediments traps were deployed at three different depths (186, 1426, 2837 m) in southern Ionian Sea (35o 10' N, 20o 51' E). Total mass fluxes were measured every 15 days. Surface seawater at a coastal area close to Finokalia station was also collected and analyzed [7]. Air sampling for the analysis and size distribution of microorganisms was carried out in the coastal city of Heraklion (25o11´N, 35o19´E) in Eastern
Mediterranean Sea during a strong Saharan dust event. Details on sampling and analysis of microorganisms are reported in [22].
Results and Discussion
I. Study of PCBs The average concentrations of total PCB congeners (∑PCBs) in the gas and
particulate phase of the atmosphere were 68.1±28.8 pg/m3 and 2.3±1.8 pg/m3, respectively. The lack of seasonal variation for the atmospheric concentration of individual congeners and ∑PCBs and the shallow slopes obtained from the Clausius-Clapeyron plots for several PCB congeners indicated that long-range transport is the main factor controlling the atmospheric levels of PCBs in this area. Most of the episodes with elevated concentrations of ∑PCBs concurred with air transport from Western and Central Europe [15].
The variation of PCB total concentration, during the intensive measurement campaign in Finokalia, showed a diurnal pattern inversely related to that of OH. The diurnal variation of PCBs observed in our study, suggested that the daytime depletion observed for the PCBs should be attributed to their reaction with OH radicals [16]. Based on laboratory-derived rate constants [23], Anderson and Hites suggested that the reaction with OH radicals should be the major permanent loss process of PCBs from the atmosphere. In our study, the destruction of PCBs was assessed for each of the four seasons by using a one-box approach. Our results showed that the destruction of total PCBs (54 congeners) should be about 8 times higher in the summer (3300 kg) than in the winter (400 kg), while similar amounts of PCBs should be destructed during spring (1700 kg) and fall (1250 kg). Regardless of the season, the congeners having 2 to 4 chlorines accounted for 86% of the total destruction, with trichlorinated congeners exhibiting the highest contribution (about 40%) to this process. The estimated annual destruction of PCBs in the atmosphere overlying the Eastern Mediterranean Sea should approach 6650 kg yr-1 and this loss process is remarkably higher than the corresponding fluxes of dry and wet deposition.
The dry deposition flux of PCBs was determined for each one of the twelve sampling periods. The flux of ΣPCB ranged from 0.1 to 1.1 ng m-2 day-1, while the estimated annual dry deposition flux as 180± 110 ng m-2 yr-1 [19]. Based on this result, the input of PCBs in the Eastern Mediterranean due to dry deposition should be 0.3 t yr-1. In consistence with the sediment traps samples collected from southern Ionian Sea and analyzed in the current study, PCBs 28, 31, 18 and 33+20 were also the predominant congeners in dry deposition samples. Tri- plus tetra-chlorobiphenyls constituted 50 to 70% of the total PCB mass, while congeners having seven or eight chlorines provided the minimum contributions (about 2% each). The average pattern of PCB homologues in dry
particle deposition was very well correlated (R2>0.97, p<0.001) with the corresponding pattern in the sediment traps and those observed in precipitation samples and the atmospheric particulate matter.
Wet deposition of PCBs is a process that has been poorly studied in the broader region of Mediterranean Sea. The concentration of ΣPCB in precipitation samples (particles plus dissolved phase) collected from Finokalia ranged between 1.0 and 3.6 ng l-1, with an average value of 1.9 ± 0.9 ng l-1 [17]. The volume-weighted mean (VWM) concentration of ΣPCB was 1.8 ± 0.4 ng l-1. Based on the precipitation rate and the VWM concentration of PCBs in rainwater the estimated annual wet deposition flux of PCBs should approach 820 ng m-2 yr-
1. By taking into account the total surface area of Eastern Mediterranean basin, the total input of PCBs in this area should be ca. 1.3 t yr-1.
Diffusive gas exchange across the air-sea interface (volatilization/absorption) has been recognized as an import process for the delivery or the removal of PCBs from natural waters. In order to estimate the net vapor flux of PCBs (volatilization minus absorption) in the Eastern Mediterranean Sea a modified two-film, gas exchange model was applied [18]. The presence of PCBs in seawater of the Mediterranean basin has also been investigated [24]. The average values calculated from these results were subsequently used in our model. The fluxes of all individual congeners were positive (net volatilization) and ranged from +0.5 to +157 ng m-2 yr-1. By summing up the fluxes of the congeners (18 chromatographic peaks) whose concentrations were available in both seawater and air, the flux of PCBs was +940 ng m-2 yr-1. Since, these congeners normally account for about 58% of ΣPCB (54 congeners) measured in different types of samples from the region of Eastern Mediterranean (e.g. aerosols1, precipitation, dry deposition and sediment trap samples), the gas-exchange flux of ΣPCB should approach +1600 ng m-2 yr-1. By considering the surface area of the Eastern Mediterranean Sea, we estimated that the annual evaporation of PCBs should be 3150 kg yr-1. However, the estimated air-sea exchange flux should include a high uncertainty due to the assumptions used and thus this flux should be considered more as approximate estimation rather than exact value [18].
For all three sediment traps, the total mass flux exhibited a clear seasonal variation with the maximum values occurring during spring and summer and the lowest ones during autumn and winter months [18]. At the upper sediment trap (186 m water depth), the mass flux ranged between 8 and 220 mg m-2 day-1, with an average value of 48 ± 65 mg m-2 day-1. Although similar values were observed at 1426 (4 to 300 mg m-2 day-1) and 2837 m water depth (6 to 259 mg m-2 day-1), the flux at the upper sediment trap was relatively higher throughout the spring. The concentration of ΣPCB in settling solids varied between 3.3 and 19.0 ng g-1 (dry weight; dw) with an average value of 7.0 ± 5.5 ng g-1 dw. For all sediment traps, the levels of PCBs were generally higher during summer than spring samples. Congeners 18, 8+5, 28, 31 and 20+33 were the most abundant and the concentration of each one ranged between 0.2 and 1.8 ng g-1 dw. For both sampling periods and especially during summer, the concentration of PCBs
exhibited a decline with depth in the water column. In particular, the concentration of ΣPCB at the upper sediment trap ranged from 5.0 to 19.0 ng g-1 dw and it was substantially higher than those observed at the middle (4.5 to 7.4 ng g-1 dw) and near-bottom sediment trap (3.3 to 5.8 ng g-1 dw). For all depths, tetra- and tri-chlorinated congeners dominated the PCB pattern and accounted for 38 ± 5% and 22% ± 5% of the total PCB, respectively. For all traps deployed, the derived depositional flux of ΣPCB varied between 0.18 and 1.04 ng m-2 day-1, with the upper and near-bottom sediment traps providing the highest and the lowest values, respectively. The arithmetic average flux of PCBs was 0.63 ± 0.34 ng m-2 day-1, while the corresponding time-weighted average flux approached 0.45 ng m-2 day-1. The estimated annual settling flux of PCBs below the euphotic zone (186 m water depth) approached 214 ng m-2 yr-1, while the corresponding fluxes at 1426 and 2837 m were 87 and 81 ng m-2 yr-1, respectively. By taking into account the surface area of the Eastern Mediterranean Sea (1.65 million km2), it was roughly estimated that the annual export of PCBs out from the euphotic zone should be around 350 kg yr-1, while only 40% of that amount (about 135 kg yr-1) will finally reach deeper waters.
The mass balance is completed by assembling all of the fluxes reported above (Figure 1). The estimated pools of all PCBs in the atmosphere were clearly much lower than those in surface seawaters, and that was especially evident for the more chlorinated congeners. The atmospheric burden of ΣPCB approached 160 kg, while the corresponding burden in the euphotic zone should be 84 t. Particle-bound PCBs accounted for only 1% of the atmospheric pool, though about 97% of these chemicals in the euphotic zone should be associated with suspended particles. The atmospheric input of PCBs in the Eastern Mediterranean Sea through dry and wet deposition was estimated to be 0.3 and 1.3 t yr-1, respectively. The total atmospheric input estimated in the present study (1.6 t yr-1) is about 8 times lower that the input previously reported for the western part of the Mediterranean (24 t yr-1)2, which covers an area of 840000 km2. The volatilization flux of ΣPCB from the Eastern Mediterranean Sea due to air-sea exchange should be 3.15 t yr-1 and overall it should offset the input from wet and dry deposition (1.3 plus 0.3 t yr-1). In general, the Eastern Mediterranean Sea should act as a net source of PCBs to the atmosphere (volatilization minus wet and dry deposition) mainly due to the higher evaporation fluxes of the less chlorinated congeners (such as PCB 18 and 52). However, the opposite situation was apparent for some individual congeners such as PCB 28, 70, 110 and 180, whose evaporation fluxes were relatively lower than their inputs through atmospheric deposition. In addition, PCBs are removed from the euphotic zone with a settling flux of 350 kg yr-1. Assuming steady-state conditions for the surface waters, an additional inflow of PCBs should be required. The discharge of urban and industrial sewage, riverine input and the transport of more polluted surface waters from western to Eastern Mediterranean could justify such an inflow. The estimated destruction of ΣPCB by OH radicals (6.65 t yr-1) was approximately four times higher than the export flux due to atmospheric deposition (wet plus dry deposition). By subtracting inflows (volatilization) from
outflows (destruction and deposition), a net loss of 5.1 t yr-1 is predicted for ΣPCB, implying that the whole burden of these chemicals should be vanished from the atmosphere in 9 to 11 days. If a steady-state situation is assumed, a considerable continuous inflow is required to balance the net loss. We suggest that long or short-range transport of PCBs from contaminated terrestrial surfaces is likely an additional pathway, which introduces significant amounts of PCBs into the atmosphere of this region.
The current mass budget indicates that the destruction by OH radicals is of major importance for the fate of PCBs in this region but further research effort is required to better understand and evaluate the precise magnitude of this loss process. In addition, our calculations for the air-sea exchange of PCBs indicated that this process might also play an important role. More accurate estimates for the air-sea exchange flux of PCBs should further improve our knowledge regarding the mobility of these contaminants between the atmospheric and aquatic compartments [18]. Figure 1: Mass balance of ΣPCB in the Eastern Mediterranean Sea ([18])
Atmosphere Gas: 160 kg Particles: 2 kg
Dry Deposition 300 kg yr-1
Wet Deposition 1300 kg yr-1
Air-Sea Exchange 3150 kg yr-1
Settling 350 kg yr-1
OH Reaction 6650 kg yr-1
Euphotic Zone Dissolved: 2500 kg Particles: 81500 kg
Input? 5100 kg yr-1
Input? 1900 kg yr-1
II. Study of PAHs Total atmospheric concentration of PAHs in Finokalia, varied form 4.14 to
57.16 ng m-3 and gas phase PAHs contribute 90% or more of total atmospheric levels. Long-range transport is a major source of PAHs in the Eastern Mediterranean atmosphere. Atmospheric samples with highest concentrations of PAHs originated in Eastern and central Europe. Concentration of gas phase PAHs was equally distributed over the Eastern Mediterranean Sea while particulate phase was significantly higher close to urban areas [19].
Gas phase reaction of PAHs with OH radicals, is an important production process of the highly mutagenic and carcinogenic nitro-PAHs [20]. During a three days intensive measurement campaign in Finokalia, the concentration of 2-NF
and 2-NP varied from 3.35 to 78.88 pg m-3 and from 2.22 to 21.98 pg m-3 respectively. The highest concentrations were determined during noon hours, characteristic of reactions between gas PAHs with OH radicals. However this process is not considered as an important PAH sink in the area [20].
Average concentration in rain was 343.2 ng L-1, whereas maximum and minimum concentrations were 321.8 and 366.2 ng L-1 respectively [21]. The lowest concentration (321.8 ng L-1), was measured in February and the highest (366.2 ng L-1) in May. The highest flux, (1.1 μg m-2 d-1) occurred in January (rainfall 92.9 mm) whereas the lowest (0.01 μg m-2 d-1) in August (rainfall 0.74 mm). The mean wet deposition flux of Σ35PAHs was 0.45 μg m-2 d-1 (0.42 - 0.48 μg m-2 d-1) [21]. Despite the low rainfall and the absence of local PAHs emission sources in the study area, the observed wet deposition flux is similar to corresponding fluxes measured in other non-urban areas [5].
ΣPAHs dry deposition rates in this study ranged from 0.025 to 0.484 μg m-2 d-1 and averaged 0.176 μg m-2 d-1 [21]. Relatively few studies have been published reporting dry deposition fluxes in the Mediterranean. The calculated dry deposition PAH (Σ11-PAH) fluxes in western Mediterranean ranged from 0.033 to 0.081 and from 0.026 to 0.081 μg m-2 d-1 [8].
Phenanthrene was the most abundant PAH member both in gas and dissolved phase, ranging from 1.75 to 7.78 ng m-3 (gas) and from 230 to 720 ng m-3 (dissolved) [21]. Gas exchange rates were calculated for 8 PAH members in five samples. Negative values for the flux indicate that PAH absorption into the water column is the dominant exchange process. In this study, total exchange flux of gaseous PAHs varied from –870 (ng m-2 d-1), to -3580 (ng m-2 d-1) while the mean flux was -1940 (ng m-2 d-1). The magnitude of ΣPAHs fluxes varied on a seasonal scale. Wind speed, surface skin temperature and the air-water concentration gradient strongly influenced the direction and magnitude of PAHs fluxes. Even though high surface skin temperature induces evaporation from the sea to the atmosphere, we observed the largest net absorption rates in September and in April and July. Conversely, lower fluxes were observed in October and February.
Average total annual flux of wet deposition, dry deposition and air/sea exchange were 162.7, 64.2 and -706.4 μg m-2 y-1 respectively. Over the western Mediterranean Sea [8] reported PAH wet deposition flux was 2.6 times higher than dry deposition. Sea water absorption of PAH gases is the most important inflow process in the Eastern Mediterranean marine ecosystem, introducing 4 and 11 times the corresponding quantity introduced through wet and dry deposition, respectively. PAHs with low molecular weight are deposited in the marine environment primarily through absorption. Thus, gas phase absorption of fluorene, phenanthrene and chrysene contributed 85.9, 90.7 and 22.9% to the total flux, respectively. Conversely, PAHs with high molecular weight are introduced in the marine environment primarily through dry and wet deposition.
As PAHs enter the marine ecosystem, they are sorbed onto particles rich in organic matter (e.g plankton, faeces and colloids), this property is attributed to their low solubility (high KOW values). Total Σ35-PAHs concentration in
sedimentary material at 250 and 1440 m depth was 467.9 and 259.1 ng g-1 (dry weight) respectively. Total Σ35PAHs fluxes at the two depths (250 and 1440m) were 28.2 ng m-2 d-1 and 22.7 ng m-2 d-1 respectively [21].
PAHs with two or three aromatic rings were the dominant species in gas phase, dissolved seawater and settling material samples. Contribution of species with four or more aromatic rings was significant for the particulate phase and wet and dry deposition samples. The coupling between compartments was studied through the calculation of correlation coefficients among PAH concentration profiles of atmospheric particles, gas phase, dissolved phase in seawater, sinking material and wet and dry deposition. The correlation between gas and dissolved concentration profiles was statistically significant (R2=0.94, p<0.0001) indicating that the air and water compartments are closely coupled. Gas phase and sedimentation PAH profiles were also significantly correlated (R2=0.94, p<0.0001) confirming that air-sea exchange is a significant factor of PAH transport to deep-sea ecosystems. The gas phase PAH profile was also statistically correlated with the wet deposition PAHs concentration profile (R2=0.65, p<0.001), suggesting the occurrence of a below cloud vapor scavenging mechanism. Atmospheric particles PAH profiles were significantly correlated with those of wet (R2=0.77, p<0.0001) and dry (R2=0.84, p<0.0001) deposition, implying particle scavenging is significant. A strong correlation was also observed between PAH profiles in the dissolved phase and in settling material (R2=0.90, p<0.0001) [21].
In Figure 2 is presented a mass balance approach of PAHs in the Eastern Mediterranean [21]. Total annual average (min–max) dry and wet deposition was 64 (9.1-177.0) μg m-2 y-1 and 165 (154.7-176.0) μg m-2 y-1, respectively. The air/sea exchange was 706 μg m-2 y-1 (318-1310 6 μg m-2 y-1). It must be noted that this process primarily introduces PAHs of lower molecular weight, whereas dry and wet atmospheric deposition introduce members with five or more aromatic rings. The total atmospheric deposition of Σ35-PAH in the Eastern Mediterranean was 959 μg m-2 y-1. PAH sedimentary fluxes were considerably lower within the water column: At 250 m the sedimentation flux was 10 μg m-2 y-1, corresponding to the 1.1% of total atmospheric deposition, and at 1440 m the flux was 8 μg m-2 y-1 corresponding to the 0.7% of the total atmospheric deposition. These data imply that the majority of atmospheric PAHs introduced to the marine environment remains in the euphotic zone. Dachs et al., [6] measured total sedimentation flux of PAHs ranging from 80.3 to 87.6 μg m-2 y-1 using sediment trap data. Atmospheric deposition fluxes in the same area ranged from 1.83 to 10.22 μg m-2 y-1 [8]. However, it should be noted that air/sea exchange was not considered in Dachs et al. study [6].
Transport of persistent organic pollutants to deeper layers of the water column is largely determined by biological characteristics of marine ecosystems. Flux of organic matter in deeper layers has been observed to be higher in eutrophic areas relative to oligotrophic areas. Being a well-layered oligotrophic system, the Eastern Mediterranean is characterized from a trophic chain composed of picoplankton and a potentially dominant microbial loop. This has a
negative effect on energy transport in deeper water layers and benthos. Tselepides et al. [25] used carbon fluxes, calculated from sediment traps deployed in the same area, and reported that approximately only 2.8-4.8% of primary production found its way into the particulate organic carbon (POC) flux. These observations confirm the low PAHs percentage transported to deep marine ecosystems, determined in our study. A major fraction of PAHs introduced in the marine ecosystem might bioconcentrate on the food web or might be biodegraded or photo-chemically oxidised. However data on these processes are limited at present.
Figure 2: Estimated ΣPAHs fluxes in the Eastern Mediterranean ([21]
III. Study of microorganisms Over the last few decades the increase in the amount of African dust flux has
been attributed to the ongoing drought in North Africa that began in the 1970’s [10]. Satellite images show that African dust is transported across the Mediterranean to Europe and crosses the Atlantic Ocean affecting distant areas. Outbreaks of Saharan dust over the Eastern Mediterranean region are very frequent in winter and transitional seasons (October-May) and minimal during the summer [26]. Trajectories indicate that the major source of dust pulses to the Eastern Mediterranean originate from North-West Africa. Recently, Kellogg et al. [27] identified aerosolized microbes cultured from dust events in Mali, West Africa.
250m
1440m
10 g m-2 y-1
8 g m-2 y-1
1.1 %
0.7 %
Bioconcentration in Food Web?
Photochemical Oxidation?
Biodegradation?
100 %
Dry deposition 64 (9-177) g m-2 y-1
Wet deposition 165 (155-176) g m-2 y-1
Air/Sea exchange 706 (318-1310) g m-2 y-1
We studied the composition of airborne bacteria in the atmosphere of the Eastern Mediterranean, during a strong Saharan dust storm, using air particle size distribution sampling and a culture-independent approach [22]. Despite the extremely high aerosol mass concentration experienced during that event, we cannot exclude the possibility that some of the detected microorganisms could have been derived from sources other than the Saharan region. In a recent study Prospero et al. [28] indicated that the concentrations of viable (colony-forming) bacteria and fungi in the atmosphere of the Caribbean were essentially uncorrelated with the levels of transported dust from Africa, implying that Saharan dust was not the sole source of airborne microbes. The microbial content of Saharan dust particles collected in Crete could have been mixed with soil particles deflated from land surfaces of Northern Africa and Crete along the advection of southerly air masses to the sampling site. However, the sampling technique we have used indicated that microorganisms were mostly concentrated in aerosol particle sizes < 7.9 µm and especially in sizes <3.3 µm [22]. Particles sizes extending from 0.1 to 2.5 µm diameter (accumulation mode) tend to have considerably longer atmospheric residence times implicating a larger long range transport potential also for the microorganism which are associated to them. Prospero et al. [28] suggested that wind transport is possible for some organisms over long distance.
We observed diverse bacterial phylotypes commonly found in soil and marine ecosystems as well as on human skin. The majority of the bacteria identified were gram positives accounting for 58% of the total sequenced clones. Most clones were closely related to the bacterial strains, which have been detected in Mali [27]. By constructing large clone libraries we were able to identify bacteria that are missed when using culture-dependent approaches. Recently, Brodie et al. [29], using clone libraries and high-density DNA microarrays, detected a diverse bacterial community in the urban aerosols of two large U.S. cities. However they did not attempt to investigate the particle size distribution of the detected microorganisms.
Phylogenetic analyses in our study [22] revealed that the atmospheric microbial community structure depends on particle size. Spore-forming bacteria such as Firmicutes were found to dominate large particle sizes whereas clones affiliated with Actinobacteria (found commonly in soil) and Bacteroidetes (widely distributed in the environment) gradually increased their abundance in aerosol particles of reduced size.
A large fraction of the clones detected at respiratory and transportable particle sizes (less than 3.3 μm in size) were phylogenetic neighbors to human pathogens that have been linked to several diseases such as pneumonia, meningitis, bacteremia or suspected to induce pathologic reactions such as endocarditis (i.e. Streptococcus pneumoniae, S. mitis, S. gordonii, Haemophilus parainfluenzae, Acinetobacter lwoffii, A. johnsonii, Propionibacterium acnes) [22]. This implies that the presence of numerous pathogens at small particle sizes has a potential for long-range transport and might have a negative impact on human as well as agricultural and ecosystem health. Further long-term studies on the
particle-size distribution of aerosolized microbes across the globe in conjunction with viability profiling of the migrating microorganisms are needed to provide a real perspective for the fields of environment and public health.
References [1]. Mandalakis, M. and Stephanou, E. G. (2002) J. Geophys. Res. 107: doi:10.1029/2001JD001566. [2]. Tolosa I., et al. (1997) Deep-Sea Res. II 44: 907-928. [3]. Dachs, J., et al. (2002) Environ. Sci. Technol. 36: 4229-4237. [4]. Douben, E. T. (2003) “PAHs: An Ecotoxicological perspective” in “Ecological & Environmental Toxicology Series”, Wiley. [5]. GESAMP (1990). State of the Marine Environment. GESAMP Reports and Studies – 39. [6]. Dachs, J. et al. (1996) Marine Chemistry 52: 75-86. [7]. Tsapakis, M. et al. (2003) Marine Chemistry 80: 283-298. [8]. Lipiatou, E. et al. (1997) Deep-Sea Research 44: 881-905. [9]. Moulin, C. and Chiapello, I. (2006) Geophys. Res. Let. 33:L18808 [10]. Prospero J. M. and Lamb P. J. (2003) Science 302:1024-1027. [11]. Moulin, C. et al. (1997) Nature 387:691–694. [12]. Griffin, D. W. (2007) Clin. Microbiol. Rev. 20: 459-477. [13]. Stetzenbach, L. D. et al. (2004) Curr. Opin. Biotech. 15: 170-174. [14]. Amann, R.I. et al. (1995) Microbiol. Rev. 59: 143–169. [15]. Mandalakis, M. and Stephanou, E. G. (2002) J. Geophys. Res. 107: 4716-4729. [16]. Mandalakis, M. et al. (2003) Environ. Sci. and Technol. 37: 542-547. [17]. Mandalakis, M. and Stephanou, E.G. (2004) Environ. Sci. and Technol. 38: 3011-3018. [18]. Tsapakis, M. and Stephanou, E.G. (2005) Environ. Sci. and Technol. 39: 6584-6590. [19]. Mandalakis, M. et al. (2005) Global Biogeochemical Cycles 19: art. no. GB3018, 1-16. [20]. Tsapakis, M. and Stephanou, E.G. (2007) Environ. Sci. and Technol. 41: 8011-8017. [21]. Tsapakis, M., et al. (2006) Environ. Sci. and Technol. 40: 4922-4927. [22]. Polymenakou, P. N., et al. (2008) Environmental Health Perspectives 116: 292-296. [23]. Anderson, P. and Hites, R. (1996), Environ. Sci. Technol. 30: 1756-1763 [24]. Schulz-Bull, D. E. et al. (1997) Croat. Chem. Acta 70: 309-321. [25]. Tselepides, A. and Polychronaki, T. (2000) “The CINCs project: Introduction”, Progress in Oceanography 46: 85-88. [26]. Kubilay, N. et al. (2000) Atmos. Environ. 34: 1293-1303.
[27]. Kellogg, C. A., et al. (2004) Aerobiologia 20: 99-110. [28]. Prospero, J. M. et al. (2005) Aerobiologia 21: 1-19. [29]. Brodie, E. L. et al. (2007) P. Nat. Acad. Sci. USA 104: 299-304.
Cloudiness uncertainty of climate science
Francisco Valero ([email protected])
Departamento de Astrofísica y Física de la Atmósfera
Facultad de Física
Universidad Complutense
28040-Madrid
First of all, we should indicate the necessity to put special emphasis in alerting on the
danger to relate all the apparently anomalous events that happen in the world to the
climate change. The climate change debate is characterized by deep uncertainty, which
results from factors such as lack of information, disagreement about what is known or
even knowable, linguistic imprecision, statistical variation, measurement error,
approximation, subjective judgment on the structure of the climate system, among
others. These problems are compounded by the global scale of climate change, which
produces varying impacts at local scales, long time lags between forcing and its
corresponding responses, very long-term climate variability that exceeds the length of
most instrumental records, and the impossibility of before-the-fact experimental
controls or empirical observations.
For that reason, it is advisable to insist on the need to discuss this problem from a
scientific viewpoint, avoiding to fall in exaggerations and analysis being interested in
any sense. It turns out essential to distinguish between myth and reality as regards the
climatic change. The main message that is usually transmitted is that we live in a
changing world, where the perception we frequently have on the certainty in the
physical, geological and climatological parameters of the Earth vanishes when long time
scales are handled.
The main conclusion is that one lives in a dynamic and changing world. Even in the
recent past, significant alterations in the climate and the temperature that are not
attributable to the man have taken place. Ever since the century XIII, a period of several
hundreds of years of duration begins in which a cooling of the planet with average
temperatures lower than to the present-day ones. This period is known as the Little Ice
Age. There is a consensus that the Little Ice Age ended in the mid-19th century,
probably as a consequence of the large-scale impact that they begin to have the human
activities.
“The present of the problem” gets fully into the present-day climate change and in the
greenhouse effect concluding that the analysis of data registered in the last 150 years
shows that there has been a significant increase in average temperatures. Also, the
concentration of CO2 in the atmosphere is rising continuously and rapidly year after
year, reaching nowadays the main values in the Quaternary as a result of emissions from
massive use of fossil fuels as our main source energy. However, it should be noted that
there are still many loose ends understanding and predicting changes on the planet: the
presence of natural CO2 sinks, the role of large ocean currents as giant energy conveyor
belts, etc…
The essential idea at the basis of climate change—that Earth can maintain a constant
temperature only if the rate at which energy reaches the planet equals the rate at which
energy returns to outerspace—is fundamental to the science of thermodynamics.
Measurements today confirm this idea of terrestrial energy balance to a high degree of
precision. By means of this balance one can know that not only greenhouse gases but
also water vapor and clouds in particular are determining elements of it.
The emission temperature Te may not be the actual surface or atmospheric temperature
of the planet. It is merely the blackbody emission temperature a planet requires to
balance the solar energy it absorbs
1/4
(1 )4
eS
T
where σ is the Stefan-Boltzmann constant (5.67x10-8 Wm-2
K-4
). Inserting the solar S
constant and the global albedo ρ values for the Earth of 1367 Wm-2
and A 0.30,
respectively, into the balanced equation, the Earth’s emission temperature turns out to
be about 255 K, which is much less than the observed global mean surface temperature
of 288 K. The difference between them is denoting the greenhouse effect intensity. With
this simple equation it may be studied the effect of changes in the global albedo and the
solar constant on the global emission temperature of the system. However, the surface
temperature cannot be directly related to either the solar constant or the global albedo
change because must be related to the transparency and opacity of the atmosphere with
respect to solar and thermal infrared radiation.
Clouds are potentially very important for the sensitivity of climate since they can affect
both solar and longwave radiative transfer in the atmosphere. Clouds of sufficient
thickness are typically almost perfect absorbers of terrestrial radiation and are excellent
reflectors of solar radiation at the same time. These two properties of clouds produce
opposite effects on the radiation balance. The reflection of solar radiation tends to cool
Earth, and because of the decrease in temperature with altitude in the atmosphere,
clouds reduce the outgoing terrestrial radiative flux at the top of the atmosphere, and so
tends to warm the system. Their effect on the global energy balance at the top of the
atmosphere may be illustrated with a simple model in terms of the difference in the net
radiation ΔN that results by adding a cloud layer with specified properties to a clear
atmosphere and Δρ the reflectance difference for clear and cloudy conditions, as given
by
4 ( )4
t
SN T E
Here, Tt is cloud top temperature and E() the outgoing longwave radiation (OLR)
under clear-sky conditions. Solving this equation for the cloud temperature when the
cloud produces no change in the net radiation leads to
1/4
( )4
t
SE
T
and assuming a lapse rate of Γ from a surface values of Ts, the cloud top temperature
can be related to its altitude zt because then
st tT T z
Inserting numeric values for a clear-sky longwave flux of 265 Wm-2
and a lapse rate of
6.5 Kkm-1
the results can be displayed in the following Figure
It is interesting to note that clouds with albedo changes and altitudes along the heavy
(zero) line would have no net effect on the system energy balance. However, those that
fall below this line will produce a reduction in net radiation, and therefore a cooling.
Clouds above the line will produce warming. In short, if the cloud top were to be rised,
the albedo contrast between cloudy and clear conditions will also increase in order to
balance the outgoing longwave radiation change. But it shoul be noticed that clouds
with high cold tops and low reflectance could cause a significant positive forcing net
radiation, while low bright clouds could cause a large negative forcing in net radiation
in the top of the atmosphere.
The IPCC has attempted to tackle the question about how much global warming has
been natural versus anthropogenically-induced, and by how much will humans and
natural changes in the Earth each contribute to future disturbance in its Special Report
on Emission Scenarios (SRES). These have been used to project the increases in CO2
concentrations (and other radiative constituents) out to 2100. Climate change
projections depend on detailed modeling. The most consistent way scientists codify our
knowledge is by constructing climate models made up of the many subcomponents of
the climate system that reflect our best understanding of each subsystem. The most
comprehensive models of atmospheric conditions are three-dimensional, time-
dependent simulators known as general circulation models (GCMs).
The IPCC 2007 climate forecast for this century rests on projections from climate
models. For the next decades, they project 0.2 ºC temperature rise per decade, and for
the end of this century IPCC provides 7 best estimates (for 7 assumptions of models)
ranging from 0.6-4.0 ºC. The warming is likely to lie in the range 2-4 ºC, with a most
likely value of about 3 ºC. But it is recognized that changes to clouds is the biggest
cause of uncertainty of predictions.
Global warming will change cloud characteristics and, hence, their warming or cooling
effect. This will exert a powerful feedback on climate change, but this feedback will
differ from model to model.
Some questions arises from this: can climate globally move along the baseline of the
first Figure or will do it outside? and, in this case, will it be above or below the
baseline?, and, if so, at what distance from this will do it? It is very likely that a
departure from the baseline would lead to a cloud forcing significantly higher than the
current CO2 forcing in the atmosphere.
References
Hartmann, D. L. (1994). Global Physical Climatology. International Geophysics Series, Volume
56. Academic Press.
LIOU, K.N.(2002). An Introduction to Atmospheric Radiation. International Geophysics Series,
Volume 84. Academic Press.
IPCC (2007). Climate Change 2007: The Physical Science Basis. Summary for Policymakers.
Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental
Panel on Climate Change.
THE ROLE OF CATALYSIS IN SUSTAINABLE DEVELOPMENT
Iacovos Vasalos, Angelos Lappas, Stella Bezergianni, Elli Herakleous Chemical Process Engineering Research Institute - CPERI, Centre for Research & Technology Hellas – CERTH, Thermi-Thessaloniki, Greece
Abstract
This work presents basic considerations of energy production technologies in association with sustainable development. Clean fossil fuels and biofuels, electricity produced by renewable energy sources, hydrogen are outlined. Furthermore the related research activities of the Chemical Process Engineering Research Institute (CPERI) in Greece are described. Some production technologies are compared and evaluated with tools like Life Cycle Analysis. Finally cost considerations regarding the different production technologies are discussed.
Keywords: energy, sustainability, biofuels, biomass, lca
1. Introduction
The terms of energy and sustainable development are recently drawing a lot of attention, as the effects of the green-house phenomenon are appearing on global scale. As the world energy consumption is continuously growing, it is important to develop energy production technologies, which do not threaten the ability of future generations to meet their needs, while maintaining healthy human environmental conditions and protecting the ecosystems. On that basis the European Energy Policy (EU Energy Committee, 2001) aims to the transition to a European economy of high energy efficiency, low CO2 emissions and reduction of Greenhouse gas (GHG) by 20% by 2030 from the emission levels of 1990. Transportation fuels are a key point of this policy, which require coordinated efforts for the acceleration of the introduction of high energy efficiency vehicles and encouraging the transition from the traditional vehicle to new transportation forms with ecological orientation.
The conventional primary energy sources such as oil, coal, and natural gas are decreased while biomass, nuclear power and other forms of energy sources are becoming more explored. Transportation fuels are heavily depending on crude oil based on a well established technology (Figure 1). The technological advancements leading to cleaner fuels and lower production costs were mainly associated with new catalyst developments. Nevertheless, as the oil reserves contain lower quality crude while the fuel specifications become stricter, the development of refinery processes becomes a highly intergrated process, including technological and catalyst advancements as well as the collaboration of government, universities and research institutes.
1
Figure 1. Typical refinery technology for the production of fuels
The primary environmental consideration for the production and usage of
transportation fuels is sulfur (Figure 2). Within the European Union the Euro IV standard in 2005 specified low sulfur diesel (maximum 50 ppm sulfur) for most highway vehicles [Errore. L'origine riferimento non è stata trovata.] while imposing the availability of ultra-low sulfur diesel (maximum of 10 ppm). Furthermore, according to European law, the final target which will become mandatory in 2009, is imposed via the Euro V fuel standard with a complete substitution of all low sulfur diesel with ultra low sulfur diesel. Furthermore the EU has recognized the reduction of GHG (i.e. mainly CO2 and particulates) and energy security as strong drivers for improving fuel economy.
Fuel Economy
Emission Control (NΟx ,PA , Soot ,CO,..)
Diesel
Zero S fuelSuitable for Fuel
Cells
Gasoline
Low S Diesel
Low S Gasoline
Fuel Economy
Emission Control (NΟx ,PA , Soot ,CO,..)
Diesel
Zero S fuelSuitable for Fuel
Cells
Gasoline
Low S Diesel
Low S Gasoline
Figure 2. Development of transportation fuels
2
As the internal combustion engines evolve, it is certain that fuels will evolve. New high fu
ission-reduction technologies will be discuss
2. Pollution reduction from diesel combustion
There is strong association between the diesel sulfur content and emission of ydroc
el economy engines such as ICE-CCS and FCEV will require new fuels. In order to produce new suitable and effective fuels, criteria such as reduced aromatics will play an important role. Furthermore, synthetic fuels such (ex low sulfur & aromatics GTL fuels) are expected to set future EURO standards. This situation might change, if industry engages in co-developing other alternative fuels.
In the sections that follow several emed including conventional refining technologies, biofuels and hydrogen.
h arbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) as indicated in Figure 3. For that reason a lot of effort has been given in research and development of catalysts and technologies that enable the diesel sulfur reduction.
0.150.160.170.180.190.2
0.210.220.230.24
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
HC
(g/
ml)
22.12.22.32.42.52.62.72.8
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
CO
(g/
ml)
2.9
0.4
0.45
0.5
0.55
0.6
0.65
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
NO x
(g/m
l)
0.150.160.170.180.190.2
0.210.22
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
HC
(g/
ml)
0.230.24
0.150.160.170.180.190.2
0.210.22
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
HC
(g/
ml)
0.230.24 2.9
22.12.22.32.42.52.62.72.8
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
CO
(g/
ml)
2.9
22.12.22.32.42.52.62.72.8
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
CO
(g/
ml)
0.4
0.45
0.5
0.55
0.6
0.65
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
NO x
(g/m
l)
0.4
0.45
0.5
0.55
0.6
0.65
0 50 100 150 200 250 300 350 400 450 500Sulfur Level (ppm)
NO x
(g/m
l)
In the Chemical Process Engineering Research Institute (CPERI) technologies uch a
Figure 3. Emissions vs. sulfur level
s s catalytic hydrodesulfurization (HDS) are assessed. CPERI is equipped with hydroprocessing pilot plant units such as the AU-55 described in Figure 4. These units enable the assessment and comparison of several HDS catalysts based on defined experimental protocols (i.e. operating temperature, pressure, liquid and Η2 flow-rates). An example of the experimental results from assessing two different HDS catalysts under several experimental conditions is given in Figure 4. Based on experiments such as this one, refiners can assess different available commercial catalysts on their effectiveness of sulfur removal. This process is very critical for the petrochemical industry considering that sulfur levels in diesel will affect many other quality parameters.
3
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
H2
ChargePump
ReactorFeedTank
L.P.Separator
N2
Processed Oil
Off Gasto Scrubber
RuskaPump
Process Flow Diagram for
AU-55
Drawn P.I.05/01
Number of Reactors 4Reactor Volume 350 mlReactor Diameter 22.23 mm Reactor Length 902 mm Operating Pressure 0-2000 psigOperating Temp 65-1400 oFLiquid Feed Rate 1-190 ml/hGas Rate 0-2 ft3/h
CPERICPERI
Figure 4. Process flow diagram of CPERI hydroprocessing unit
67,4
10,5 5,0 3,032,8 24,2
4,6 21,3
82,4
18,5 9,9 6,2
604,6
205,2
112,0
25,2
107,5126,5
0
100
200
300
400
500
600
700
1 2 3 4 5 6 7 8 9
Condition
Prod
uct S
ulfu
r(pp
mw
t)
CoMo Catalyst NiMo Catalyst
High Pressure Low Pressure
CPERI Test Results
67,4
10,5 5,0 3,032,8 24,2
4,6 21,3
82,4
18,5 9,9 6,2
604,6
205,2
112,0
25,2
107,5126,5
0
100
200
300
400
500
600
700
1 2 3 4 5 6 7 8 9
Condition
Prod
uct S
ulfu
r(pp
mw
t)
CoMo Catalyst NiMo Catalyst
High Pressure Low Pressure
Figure 5. Catalyst assessment for different experimental conditions
4
3. Biofuels
Biofuels have started drawing a lot of attention by incorporating the EU directive 30/2003. According to the EU directive, by 2010 5.75% of the energy content of transportation fuels (gasoline and diesel) should be gradually replaced by biofuels. Beyond the EU directive, the use of biofuels is imperative in order to lower the dependency on oil and oil producing countries, as well as enable the use of more environmentally friendly transportation fuels, since it has been proven that the use of biofuels decreases significantly air, water and soil pollution.
The most significant axis towards the production and sustainability of biofuels is the agricultural sector responsible for the production of biomass, the raw material used for biofuels production. The designation of areas employed for biomass production is a factor of the biofuel produced per area as well as the fuel demand. In Figure 6 the outcome of a European research project is given, indicating three different cases of biofuels (ethanolo/biodiesel, biodiesel only and BTL-fuel) and the fuel demand vs. area demand, indicating opportunities for biomass and biofuels production. In order to be able to perform such analysis, it is necessary to estimate the production cost of different types of biomass (rapeseed, cotton, sunflower, sweet sorghum, sugar-beet, etc) at different areas, based on farm badgets.
0
5
10
15
20
25
Fuel-Demand Area-Demand
Fuel
-Dem
and
(Mio
t)
0
5
10
15
20
25
Are
a-D
eman
d(M
ioha
)
Scenario 1: 50/50% EtOH/BiodieselScenario 2: 100% BiodieselScenario 3: 100% BTL-Fuel
Scenario 1: 50/50% EtOH/BiodieselScenario 2: 100% BiodieselScenario 3: 100% BTL-Fuel
EtOH
EtOH
BTL
BTL
Bio-dieselBio-
diesel
Bio-dieselBio-
diesel
Bio-dieselBio-
diesel
Bio-dieselBio-
diesel
BTL
Figure 6. Demand for biofuels and agricultural area (2012)[Errore. L'origine riferimento non è stata trovata.]
Biofuels production and usage was initiated from the first generation biofuels,
which are mainly biodiesel produced from the transesterification of vegetable oils and bioethanol produced form sugar containing plants. These technologies are well known and tested and offer excellent product quality which is also compatible with current fossil-based fuels. Nevertheless, first generation biofuels are associated to high production costs mostly due to their limits on types of biomass employed. Furthermore, the lands designated for such cultivations are competing with others which could be used for food-crops. Finally, first generation biofuels are currently under consideration of whether they contribute to sustainability.
The future of biofuels lies on the second generation biofuels, which are divided into two categories: i) enzymatic technologies (production of ethanol from lingo-cellulosic material, i.e. farm and forest residues) and ii) thermo-chemical technologies (synthetic fuels, bio-oil, hydroprocessing vegetable oil etc). Both these technologies offer flexibility on the biomass employed and are not competing with the food industry, but are associated with high investment costs, which require further investigation. In CPERI we are involved in the thermo-chemical technologies for second generation biofuels production as indicated in the following paragraphs.
5
3.1. Co-hydroprocessing petroleum fractions with vegetable oil
Hydroprocessing is a well-established technology in CPERI, employed for catalyst evaluation as described in section-2. The same technology is explored for the production of hybrid-fuels using mixtures of conventional petroleum fractions such Vacuum Gas Oil (VGO) with vegetable oil. In pilot plant units such as the one described in Figure 4Errore. L'origine riferimento non è stata trovata., various feedstock mixtures of VGO and vegetable oil are tested at different operating conditions (reactor temperatures, system pressures, liquid and H2 feed-rates etc) in order to identify optimal feedstocks and operating conditions for such technology.
A sample of the feedstock components (VGO and vegetable oil) as well as of the final hybrid fuel is shown in Figure 7 in series. Depending on the VGO-vegetable oil mixing analogies and the operating conditions, the quality of the hybrid fuel produced changes. Studies among different catalysts provide additional information regarding the most effective catalysts that can be used for such technology (Figure 8).
Figure 7. VGO, vegetable oil and hybrid fuel (end product)
01020304050607080
%
Catalyst A Catalyst B
Conversion (%)
Figure 8. Hydroprocessing conversion for two different catalysts
6
3.2. Biomass-to-Liquids process (BTL)
The Biomass to Liquids or BTL technology appears as one of the most prominent pathways of synthetic biofuels production. As it is depicted in the schematic diagram of Figure 9 the biomass is pyrolised in a excess of air and then gasified. The produced synthesis gas (mainly CO + H2) after a cleaning and desulfurization step becomes the feedstock to a Fischer-Tropsch (FT) reactor where CO and H2 molecules are synthesized into paraffins. The intermediate paraffinic stream, known as FT-wax is upgraded in a following step via hydrocracking, producing a C5
+ product which contains mostly diesel molecules. The produced diesel shows excellent quality parameters according to CPERI’s results.
BTL - fuel
AirAir
NTV
SlagCoke
NTV-Gas
Cleaning
Desulfurization(Adsorption)
Synthesis GasFischer-Tropsch-Reactor
Fischer-Tropsch-Reactor
Hydrocracker
C1 - C4 (5%)
BiomassBiomass
StabilisorStabilisor
Gasi-fier
Pyrolysis
Figure 9. Simplified diagram of Biomass-To-Liquids (BTL) process
The yields and qualities of the FT-fuels produced depend heavily on the catalyst employed for the hydrocracking process, as it is shown in Figure 10. In this indicative comparative study, two different catalysts exhibited different yields for the BTL fuels (naphtha, kerosene and diesel) for different temperatures. In particular, catalyst A appears a less effective catalyst for diesel production as compared to catalyst B, since for three different temperatures its selectivity changed dramatically.
0.00%
20.00%
40.00%
60.00%
80.00%
100.00%
Temperature
Yie
ld o
f fra
ctio
ns
DieselKeroseneNaphtha
BaseBase-10oC Base+10oC Base+16.5oC Base+25oC Base+32.5oC
Catalyst A Catalyst B
BTL-naphtha: 80-150°CBTL-kerosene: 150-200°CBTL-diesel: 200-320°C
0.00%
20.00%
40.00%
60.00%
80.00%
100.00%
Temperature
Yie
ld o
f fra
ctio
ns
DieselKeroseneNaphtha
BaseBase-10oC Base+10oC Base+16.5oC Base+25oC Base+32.5oC
Catalyst A Catalyst B
BTL-naphtha: 80-150°CBTL-kerosene: 150-200°CBTL-diesel: 200-320°C
Figure 10. Comparison of two hydrocracking catalysts for upgrading FT-wax to fuels
7
3.3. Biomass fast pyrolysis process
In Figure 11 a detailed schematic view of the CPERI biomass catalytic pyrolysis pilot plant unit is presented. The experimental system is fully automated and consists of a biomass and a solid feed section, a reactor and a product recovery line. The biomass feed section includes a 4-liter cylindrical hopper and a screw feeder, which control the biomass flow into the reactor. The solids feed system includes a 30-liter fluid bed regenerator vessel. The reactor system consists of a reactor and regenerator which allows continuous regeneration of the spent catalyst. The regenerator is connected to the reactor through a heated transfer line with a slide valve controlling the catalyst flow to the reactor during the experiment. The reactor consists of an injector and a riser section. The injector is designed to promote the direct mixing of the hot catalyst with the biomass particles. Gases and solids leaving the riser enter tangentially into the cyclonic head of the stripper that allows solids removal. The liquid product recovery system includes a three-meter long air-cooled heat exchanger and a liquid product stabilizer.
TO PRODUCTRECOVERY
FLUIDIZINGGAS
SCREWFEEDER
SPENTCATALYST
BIOMASSFEEDTANK
SLIDEVALVE
SLIDEVALVE
SPENTMATERIAL
TANK
INJECTOR
LIFT GAS
HEAT CARRIERVESSEL
RISER
STRIPPER/DISENGAGER
STRIPPINGGAS
CYCLONEFILTER
TO PRODUCTRECOVERY
FLUIDIZINGGAS
SCREWFEEDER
SPENTCATALYST
BIOMASSFEEDTANK
SLIDEVALVE
SLIDEVALVE
SPENTMATERIAL
TANK
INJECTOR
LIFT GAS
HEAT CARRIERVESSEL
RISER
STRIPPER/DISENGAGER
STRIPPINGGAS
CYCLONEFILTER
Figure 11. Schematic diagram of the biomass fast pyrolysis process.
The flexibility of the biomass pyrolysis unit allows experimentation with various
feedstocks and catalyst types. In Figure 12 the product results using three different reactor types are compared with the ones from a fixed bed reactor.
02468
101214161820
Acids
Carbon
yls
Alcoho
lsHCs
Phenols
Light P
henols
Heavy
Product
Yiel
d (w
t %)
Fixed bed reactorInert inorganic heat carrier in CFB reactorZSM-5 additive in CFB reactorFCC catalyst in CFB reactor
Yie
ld (w
t% o
n bi
omas
s)
02468
101214161820
Acids
Carbon
yls
Alcoho
lsHCs
Phenols
Light P
henols
Heavy
Product
Yiel
d (w
t %)
Fixed bed reactorInert inorganic heat carrier in CFB reactorZSM-5 additive in CFB reactorFCC catalyst in CFB reactor
Yie
ld (w
t% o
n bi
omas
s)
Figure 12. Components of biooil produced from biomass fast pyrolysis
8
4. Towards Sustainable Development
The development of biofuels will only guarantee reduction of CO2 emissions if proper sustainability tools are employed to evaluate various production processes. One such tool is the Life Cycle Analysis or LCA tool. This tool enables a thorough examination of any process’s inputs and outputs in terms of materials and energy used. Of particular interest are the associated environmental impacts which are directly attributed to the production process and use of its product(s), as it is schematically depicted in Figure 13.
Energy
Materials
Waste:
Solid
Liquid
Gaseous
Energy
Materials
Waste:
Solid
Liquid
Gaseous
Energy
Materials
Waste:
Solid
Liquid
Gaseous
Figure 13. Basis of Life Cycle Analysis (LCA) evaluation tool
LCA calculations performed in CPERI show that the use of bio-oil for heat production has a great impact on the reduction of greenhouse gas emissions (Figure 14). This is due to the renewable nature of biomass feedstock and also to the closed carbon cycle resulting to zero CO2 emissions during the bio-oil combustion, which is the main greenhouse gas as far as the heating oil is concerned. However, the combustion of biooil (extracted from cultivated willow) shows different results compared to the combustion of biodiesel produced via the transesterification process. In general, the use of biomass feedstock coming from cultivations almost doubles the greenhouse gas emissions compared to the use of wood waste.
Feedstock provision & Production process Production process
Figure 14. Biodiesel vs. Bio-oil for heating applications
-60%
Biooil Biodiesel
GH
G e
mis
sions,
g C
O2 e
q/kW
h
Biooil Biodiesel
GH
G e
mis
sions,
g C
O2 e
q/kW
h
-35%
9
5. Hydrogen: The future fuel Hydrogen is considered by many the most prominent energy source. There are
many pathways for hydrogen production Figure 15. Hydrogen is currently produced in traditional refineries via reforming units, and is consumed within the refinery circuit. The promising Fuel Cell or FC technology enables conversion of hydrogen into energy via various fossil and renewable sources.
H2 Production
Conventional Fuels
H2 Production Unit
CO2 Deposition
H2 Production
Conventional Fuels
H2 Production Unit
CO2 Deposition
Renewable Sources
Biomass, PV Wind Energy, Solar
Energy
Renewable Sources
Biomass, PV Wind Energy, Solar
Energy
HYDROGEN
Transport
Electric Power Generation
Houses
Hydrogen
Use of H2
Thermoelectric Engines
Fuel Cells
HYDROGENHYDROGEN
Transport
Electric Power Generation
Houses
Hydrogen
Use of H2
Thermoelectric Engines
Fuel Cells
Thermoelectric Engines
Fuel Cells
Figure 15. Towards hydrogen (H2) economy
The present and the future reformers efficiency determines the choice of fuels and the related infrastructure for fuel cells applications (particularly in transport). In Table 1 five different reforming technologies are summarized. As it is indicated some technologies appear to be more efficient than others. However all the above technologies depend upon non-renewable sources such as natural gas, gasoline and ammonia.
Table 1. Present and future H2 production technologies and their efficiencies
Technology Temperature Efficiency Natural gas 700°C 80% Methanol 280°C 80% Ethanol 900°C 60% Gasoline 900°C 60 - 70% Ammonia 600-700°C 80 - 90%
In CPERI there is a lot of work in exploring alternative technologies of hydrogen
production, which depend on renewable sources, such as biomass. In Figure 16 the hydrogen production via steam reforming of the aqueous phase of bio-oil produced by biomass pyrolysis is depicted. The choice of catalyst employed for biomass pyrolysis affects the overall hydrogen yield, as shown in Figure 17. Current work focuses on identifying optimal catalysts and operating conditions which maximize hydrogen production yields.
10
Aqueous Phase 55%
(Carbohydrates)
GasesBio-oil
Char
Biomass Pyrolysis
Water Addition
Ratio 2/1Organic Phase
Non-soluble(Lignin)
20% Organics
80% Water
Steam reforming Hydrogen catalyst
Aqueous Phase 55%
(Carbohydrates)
GasesBio-oil
Char
Biomass Pyrolysis
Water Addition
Ratio 2/1Organic Phase
Non-soluble(Lignin)
20% Organics
80% Water
Steam reforming Hydrogen catalyst
Figure 16. Biomass pyrolysis for H2 production
Figure 17. Hydrogen yield compared with thermodynamic equilibrium
6. Cost Considerations The feasibility of these new alternative fuel production technologies depends
upon the economics, and the question that arises is “Can alternative fuels be produced in competitive prices?” The cost of diesel (from crude oil valued at 70b$/bbl) and of natural gas is 14 and 8 €/GJ excluding taxes. In Table 2 the current production cost prices of biofuels and hydrogen from various production technologies are compared. Currently hydrogen from natural gas exhibits the lowest cost. Biofuels do not seem as an alternative solution. However the second generation biofuels are envisioned as an attractive perspective as their production cost is continuously improving.
11
Table 2. Production costs of renewable fuels
13 €/GJTropical Ethanol
18 €/GJDomestic biofuelBiofuels
21 €/GJSecond generation biofuel
11 - 14 €/GJ
9 €/GJ
From wind or biomass
From natural gas (CO2storage)
Hydrogen
13 €/GJTropical Ethanol
18 €/GJDomestic biofuelBiofuels
21 €/GJSecond generation biofuel
11 - 14 €/GJ
9 €/GJ
From wind or biomass
From natural gas (CO2storage)
Hydrogen
The future of renewable energy sources appears quite attractive as it is summarized in Table 3. Current costs of electricity produced via renewable energy sources are quite high with the exception of wind and biomass. However the future targets set indicate that in the future all renewable energy sources will be equally competitive, composing a mosaic of energy sources and fuels.
Table 3. Current and target prices of electricity produced by different renewable sources
420Solar energy
412Geothermic energy
3 - 54 –8Biomass
2,5 - 54 - 9Wind turbine
6 – 2625 - 50PV
TargetEuro cent / kWh
TodayEuro cent / kWh
420Solar energy
412Geothermic energy
3 - 54 –8Biomass
2,5 - 54 - 9Wind turbine
6 – 2625 - 50PV
TargetEuro cent / kWh
TodayEuro cent / kWh
7. Conclusions Energy conservation is a key parameter for sustainable development as well as
new energy technologies. Catalytic process for producing clean and sustainable energy from fossil and renewable sources appear promising technologies while the choice of suitable catalysts may offer significant yields and reduce production costs.
There are several energy production technologies which are based on renewable sources. The evaluation of new energy technologies with tools such as Life Cycle Analysis is necessary in order to ensure the sustainable development of the energy sector. As renewable energy sources are abundant in the Mediterranean countries, this region should lead the development and application of renewable energy sources.
12
Strategic Basic Actions in the Mediterranean Area Luís Vázquez
Departamento de Matemática Aplicada Facultad de Informática
Universidad Complutense de Madrid 28040-Madrid
[email protected] www.fdi.ucm.es/profesor/lvazquez
The problems connected to the energy crisis, climate changes and water shortage require new ideas and instruments to be solved. The basic research is one of the main generators of breaking through ideas and it is the appropriate scenario to create the conditions that can allow approaching the solution of the above problems in different contexts. The complexity of the problems imposes the combination and commitment of history and innovation in a framework of a true partnership among the government, the academia and the industry. A set of conclusions emerged during the Conference is the following:
• The vectors of the future are the students. For this reason, it is necessary a formation plan of students at the different levels of graduate, Ph.D. and postdoctoral studies on climate changes, energy and water issues. It should be very fruitful to organize a program similar to the old Erasmus Program and focalized in the Mediterranean area. This program would be associated to a suitable Ph.D. programme.
• A promising initiative should be the creation of a “Mediterranean
Meteorological and Climatic Data Base”. With the new Grid Technology, such data could be shared and shaped by every country. This instrument would allow preparing and testing accurate climatic models for the Mediterranean Area.
• Creation of a network of stations to monitor the pollution level of the
Mediterranean.
• Creation of a “Virtual Supercomputing Centre” which integrate the computer resources and facilities of the different involved institutions on the basis of the new Grid Technology. This Centre would create a computing environment that could be used in other areas.
• Actions generated from the National Academies to get funding from the
European Community in order to support the flow of students and professors among the different Mediterranean countries.
• Basically, the universities support the Education and the Research. In
cooperation with the industry, the appropriate scenarios for the Innovation should be created and supported.
Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
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Barbara Tomassetti1, Marco Verdecchia1,2, Guido Visconti1,2 and Valentina Colaiuda1
(1) Centro di Eccellenza CETEMPS, Università dell’Aquila, L’Aquila, Italy (2) Dipartimento di Fisica, Università dell’Aquila, L’Aquila, Italy
Abstract
Climate changes at regional scale are connected to many factors one of the most important being the
changes in the land vegetation cover. A quantitative evaluation of such effects are also difficult to
obtain due to the complex land-atmosphere interactions. In this study we analyse the possible
hydrometeorological effects linked to the drainage of Fucino’s Lake in the nineteenth century and the
changes for few meteorological case studies linked to the vegetation cover modification over Abruzzo
region in the central Italy in the last twenty years. To this purpose MM5 limited area model has been
used. As a first preliminary step, several different meteorological case studies have been simulated with
MM5 model forced with the two different land used scenarios. Results show significant changes in the
rainfall spatial distribution, while the differences for the circulation appear to be negligible and changes
in the surface temperature are spatially limited; nevertheless, as also suggested by other authors, such
local temperature changes are as large as those that result from the anthropogenic increase of
greenhouse gases.
Keywords. meteorological models, Climate change, land use change. 1. Introduction
It is well recognized that the land use changes induced both by anthropogenic and natural factors can
affect the climate at regional scale and many efforts have been done by many authors to estimate such
effects. Feddema et al., (2005) carried out different climatic simulation for different scenarios proposed
by the Intergovernmental Panel on Climate change (IPCC) but including the future land cover changes.
They find that average annual temperature difference for all the scenarios are less than 0.1 oC because
of offsetting regional climate signals. Nevertheless significant changes are predicted at regional scale,
as an example the effect of converting tropical broadleaf forest to agriculture in the Amazon produces a
significant warming for the next century well above 2 oC. RAMS Regional Atmospheric Model has
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
been used by Marshall et al. (2004) to study whether the conversion of natural wetlands to
accommodate the expanding agricultural production in south Florida could have an impact on incidence
of freeze events in those areas. They find that for all the simulated case studies, temperatures were
generally colder respect to the control run curried out with pre-1900 land use cover.
Tomassetti et al. (2003) studied the hydrometeorological effects induced by the drainage of the Fucino
Lake in the Central Italy. They find that the lake affects the temperature of the surrounding basin in all
seasons and precipitation mainly in the cold season, when cyclonic perturbations move across the
region. Some effects of the lake also extend over areas quite far from the Fucino basin.
Pielke (2005) stressed as, although the globally averaged surface temperature change over time may be
close to zero in response to land use and land cover change and variability, the regional changes in
surface temperature and precipitation can be as large as those that result from the anthropogenic
increase of greenhouse gases. Because of this, it appears of noticeable importance to assess the effects
at regional scale induced by the observed changes of land cover in the last decades.
In this paper we investigate the local meteorological effects induced by the changes in the land cover
observed in the last 20 years over the Abruzzo Region (Central Italy), respect with other studies also
cited above, here we consider different and heterogeneous changes in the land cover including the
increase of urban areas and the expansion of forests as the decreases of areas used for the agriculture
activities in the past and mainly characterized by rade forest and grassland at present time. According
to other authors, the analysis of different case studies lead to the conclusion that, although the
heterogeneity of the land cover changes induce different effects on the ground-atmosphere interaction,
the simulated impact at local scale on ground temperatures and precipitation fields are comparable to
those that are supposed to be the results of global changes.
The paper is organized as follow: in the following section a quick description of the results of Fucino
lake simulation is reported. In section 3 changes in land use for the considered region are discussed and
a short description of technique adopted to digitalize vegetation cover is also given. In section 4 a quick
description of MM5 meteorological model is reported and a short discussion of the physical
parameterization adopted for the current study is also given. In the last section the different simulated
case studies are introduced and the results obtained for the two different land use scenarios are also
discussed.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
2. The hydrometeorological effects of Fucino lake drainage in the Abruzzo Region
The Fucino Lake, with an area of about 150 square kilometers, was the largest reservoir of fresh water
in the Abruzzi region of central Italy until it was drained towards the end of the nineteenth century
(1873). A first attempt to drain the lake was made by the Roman Emperor Claudius around 50 B.C.
About 30.000 workers excavated a channel that provided the lake with an artificial emissary. However,
after some time the channel was clogged with detritus and the lake returned to its original level. One of
the reasons for draining the Fucino Lake was that, because of its shallowness, the lake level would
change rapidly in response to changes in climatic forcings. These changes in lake levels produced
considerable damage to the people living on the lake’s shores and to the agricultural activities that
flourished in the surrounding basin. The main hydrological input for the lake was autumn and winter
rainfall. Precipitation transported erosion debris from the hills surrounding the lake, resulting in muddy
lake waters and in the generation of extensive marsh areas. The drainage of the lake would, therefore,
allow for a substantial increase in the availability of areas usable for agricultural purposes. The location
of the lake within the Central Italy is shown in Fig.1
Figure 1. The location of Fucino lake drained towards the end of the nineteenth century.
The hydrometeorological effects of Fucino Lake were been carried out using MM5 meteorological
model (see section 4) for different meteorological scenarios with two different aims: on one hand we
was interested if a limited area land cover modification can significantly affect the precipitation,
circulation, relative humidity and temperature fields in the surrounding basin, on the other hand we was
testing the ability of the mesoscale model to realistically reproduce these effects at regional scale. An
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
example of the results discussed in Tomassetti et al. (2003) is reported in Figure 2 that shows the
precipitation differences between the lake and no-lake experiments for the case study of 24 July, 1999.
Figure 2. Difference in 2-day accumulated precipitation between the lake experiment and the corresponding control experiment for the case study of 24 July, 1999. Units are cm.
This summer strong forcing case (SUMSF) begins on 23 July 1999, at 12:00GMT and shows a
cyclonic circulation entering the Mediterranean area and developing into a strong cyclogenesis over the
southern Tyrrenian Sea. Strong easterly winds advecting warm and humid air toward the eastern Italian
coasts produced heavy precipitation during this event. For this and other strong forcing cases,
simulations show a strong influences of the lake on the precipitation fields in wide area, for the specific
case shown in Figure 2 an increase of rainfall is observed in the most internal areas, with a significant
decrease of precipitation (close to the 50%) in the areas close to the cost where the major peaks of
rainfall fields were observed also causing many damages in few localities of the Adriatic coasts. As a
more general conclusion the different simulations show that for the low forcing cases the influence of
the lake results to be very low and in most cases limited to the areas close to the lake, while the effects
are always most significant and affecting wide areas for strong forcing case studies.
For what concerns the water vapor, in all the simulated cases the lake produces a general increase in
water vapor loading over the area. In both the winter and summer weak forcing cases, when the
background winds are relatively weak, the increase in water vapor is mostly concentrated over the
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
Fucino basin, where a relatively large increase in water vapor is found. In the strong forcing cases the
lake-moisture signal is more widespread and less evident.
The primary dynamical effect of lakes of the size of the Fucino is to sustain mesoscale sea-breeze
results discussed in Tomassetti et al. (2003) indicate that the presence of the lake can
circulations due to the land-water gradient in atmospheric heating (e.g. Atkinson, 1981). A temperature
difference of 1–2K between the lake and the surrounding land areas is observed which triggers onshore
low level diverging winds of up to 4 m/s with corresponding horizontal wind difference for an east-
west cross section cutting across the lake. Two adjacent sea-breeze-like overturning cells can be
observed to extend to about 700 mb. These are produced by the land-water thermal contrast and are
then advected by the weak background winds. Similar sets of organized mesoscale circulations induced
by patches of surface thermal inhomogeneities have been simulated in a number of different studies,
and have been shown to possibly affect precipitation under convectively unstable conditions (e.g.
Pielke, 1974; Yan and Anthes, 1988; Pielke and Avissar. 1990; Seth and Giorgi, 1996; Giorgi and
Avissar, 1997).
In summary, the
affect both the atmospheric humidity and precipitation not only over the Fucino basin but also over
broader areas of the Abruzzi region, especially when wintertime storms move across the area. Overall,
the sensitivity experiments also show that the triple-nested regional model configuration (see section 4
for a general discussion of the model, and figure 6 and related discussion for the model running
configuration) developed for the Abruzzi region is capable of simulating realistic lake-breeze
circulations due to the presence of the lake and we therefore expect to can realistically simulate, with a
similar approach, the most general effects linked to the changes of land use over the whole region.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
3. Land use change in Abruzzo Region in the last two decades
The Abruzzo region, with an area of more than 1200 Km2, is located in the Central-East Part of Italy
and it is characterized by a complex orography with few mountains peaks over 2000 m. The vegetation
cover changes over the region have been analyzed using two different set of aerial ortophotography for
the early ‘80s and 2002 respectively. An example of this changes are shown in Figure 3 where two
aerophotography of 1954 and 2002 are compared.
For a systematic study of land cover changes, the area of Abruzzo region has been divided in cells of 1
Km2 and, for each grid point, the land use is established considering a random point and following a
sampling technique known as Unaligned Systematic Sampling (USS) (Fattorini, 2003, Fattorini et al.,
2003). Land use has then been classified for each grid cell using 6 different types listed in the Table 1:
Table 1. Land use types used to classify the Abruzzo Region from aerial ortophotography. For each land type the corresponding integer code used by MM5 meteorological model is also reported.
Land Use Description MM5 Vegetation Integer Identification
Urban Areas 1
Dryland Crop 2
Crop/Wood Mosaic 6
Mixed Forest 15
Irrigated Crop and Pasture 3
Other From USGS database
In the same table the land use Vegetation Integer Identification used by MM5 meteorological model
(see next section) are also reports. Land use data are available at this step for a regular grid in vectorial
form (it means a list of latitudes, longitudes and the corresponding land use code), these data are then
upscaled at MM5 innermost domain grid (see Figure 6 and related discussion) with an horizontal
resolution of 3 Km. According to Dickinson et al. (1986) we assume that land surface interaction can
be adequately described, for each grid point, by the soil and vegetation characteristics of the region that
occupies the majority of the area in the considered cell. For the subdomain not covered by aerial
ortophotography or the areas outside the Abruzzo Region where such analysis has not been carried out,
land use type is deduced from USGS global data base.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
Figure 3. Aerial ortophotography of a portion of Abruzzo region for 1954 and 2002 respectively.
A first overview of observed changes at a discrete resolution are reported in Figure 4 where the maps of
1980 and 2002 land use are compared using a grid of 3 Km of horizontal resolution. The panels of
figure 4 reports the whole high resolution domain simulated with MM5 meteorological model, but it
has to be noticed that the land cover changes have been considered and analyzed for the Abruzzo
Region only, administrative boundaries of this region are also shown in the panels of the same picture.
The more evidences in such changes are the increase of urbanized areas especially in the central-east
zone, closest to the Adriatic sea and the increases of areas covered by mixed forest, while a significant
portion of areas covered by irrigated crop in the ‘80s are mainly covered by forests at present time. The
overall most evident change deal with the transformation of Wood/Crop mosaic to areas covered by
mixed forest at present time. Different types of land use modification affect 471 points corresponding
to more than 4200 Km2, therefore about the 40% of the Abruzzo Region was affected by changes in
land cover in spite of almost the 30% of its territory is considered protected areas and are subject to
many restrictions for what concerns the anthropic activities.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
Figure 4. Land use map for Central Italy in the 1980 (left panel) and 2002 (right panel) at MM5 model horizontal resolution. The increase of mixed forest area and the decrease of crops area are evident as the enhancement of the urbanized areas close to the Adriatic Sea. The “white” areas correspond to other type of land cover not reported in
the label bar. Administrative boundaries are also shown.
A more quantitative analysis is reported in the table 2 where the different observed changes are
quantified in terms of number of grid cells. The most evident modification consists in the increasing of
areas covered by different type of forest: the total area interested by this type of changes is about 3200
Km2; more than half of this area (about 1800 Km2) was covered by a mosaic of crop and woods in the
early 80’s, while about 900 Km2 covered by forest, were characterized by Dryland Crop about two
decades ago. Also a large area of irrigated crops are now lost and they are transformed in urban area
and forest respectively, for about 40% and 60%.
These most relevant changes of land use are also summarized in Figure 5 where the different colours
corresponds to the different major changes listed in the table 2.
Table 2. Number of grid cells affected by different land cover changes from 1980 to 2002. The cells correspond to the MM5 meteorological model innermost domain grid (see figure 3 and related discussion), the horizontal resolution is
3 Km2 and therefore each cell approximately corresponds to 9 Km2.
Modification Number of affected cells
From Urban to Irrigated Crop 1
From Irrigated Crop to Urban 44
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
From Irrigated Crop to Forest 62
From Irrigated Crop to Dryland Crop 6
From Forest to Urban 3
From Forest to Irrigated Crop 2
From Forest to Dryland Crop 2
From Crop/Wood mosaic to Forest 201
From Dryland crop to Urban 2
From Dryland Crop to Forest 100
From Dryland Crop to Crop/Wood mosaic 47
From Other to Forest 1
Figure 5. The most evident land use changes over Abruzzo Region in the last two decades. Vegetation integer identification reported in the label bar are the same described in table 1, therefore, as an example “from 6 to 15” means “from crop/wood mosaic to forest”.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
4. MM5 meteorological simulation
The meteorological model used in this work is the non-hydrostatic version of the NCAR/Pennsylvania
State University Mesoscale Model MM5 (Dudhia 1993; Grell et al., 1994). MM5 is a primitive
equation, and σ vertical coordinate model used by a broad research community for a variety of
applications. It also includes a number of different options of physical parameterizations. MM5 has
been operational for the Central Italy since 1998; for the simulations discussed in this paper the Kain-
Fritsch cumulus cloud scheme (Kain and Fritsch, 1990), along with an explicit cloud water/ice scheme
(Grell et al., 1994) is used. Radiative transfer is represented by the simplified scheme described in Grell
et al. (1994) and boundary layer physics is described by the MRF scheme (Troen and Mahrt, 1986). For
land surface processes the standard MM5 scheme is used, in which the surface temperature is
calculated via a force-restore method and evaporation is computed using a fixed moisture availability
parameter (the ratio of actual to potential evaporation) dependent on the surface vegetation type. For
the simulation discussed in the present paper 24 unevenly spaced σ levels while the adopted
parameterizations are discussed in Bianco et al. (2997).
One of the most important feature of MM5 model is the possibility to carry out simulation with
different nested geographical domains, running at different horizontal resolution.
Figure 6. Schematic view of three nested domains used for operational meteorological forecast in Abruzzo region with MM5 mesoscale model. The outer domain covers Italy and the surrounding regions at a grid interval of 27 km; the intermediate domain covers central Italy at a 9-km grid interval, while the innermost domain encompasses the Abruzzo region at 3-km horizontal resolution.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
Fig. 6 shows the model triple nested domain used for this work as for the operational activities for the
meteorological forecast. The outer domain covers Italy and the surrounding regions at a grid interval of
27 km; the intermediate domain covers central Italy at a 9-km grid interval, while the innermost domain
encompasses the Abruzzo region at a 3-km grid interval. The different domains are nested in a two-way
mode, as described, for example, by Zhang et al. (1986). The MM5 performance in reproducing
synoptic and mesoscale circulation over the region of interest here is discussed in Paolucci et al., 1999;
while the ability of this model in reproducing thermally driven circulation in a region of complex
topography with different Planetary Boundary Layer (PBL) parameterizations has been investigated by
Bianco et al. (2006), Tomassetti et al. (2003) also demonstrated the ability of the model to efficiently
simulate the effects of land use change on the hydro-meteorological cycle.
Impacts following Land Cover Change are caused by modifications to the vegetation cover and soil
characteristics. As an example modifications from trees to grass reduces leaf area index increasing
albedo, decreases roughness length, and also alters root distribution and depth (Sellers 1992; Jackson et
al. 1996). Also these changes affect the partitioning of available water between runoff and evaporation,
thereby affecting soil moisture and possibly rainfall. Further, these changes affect the partitioning of
available energy between sensible and latent heat, affecting local air temperature and boundary layer
structure (Betts et al. 1996; Lyons 2002). Changes in roughness length may also affect wind patterns
(Sud and Smith 1985). It also been recognized that these changes may cause remote changes in air
temperature, rainfall, and wind (Zhang et al. 1996; Chase et al. 2000; Zhao and Pitman 2002).
INCREASE TEMPERATURE
DECREASE TEMPERATURE
INCREASE SH FLUX INCREASE LH FLUX
INCREASE EVAPOTRANSPIRATION
INCREASE NET RADIATION
INCREASE LAI INCREASE ROUGHNESS LENGTH
INCREASE SOIL MOISTURE
DECREASE ALBEDO
Figure 7. Schematic view of different physical processes affecting the soil-atmosphere exchange of humidity and energy.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
The overall effects of these changes are resumed in the block diagram reported in Figure 7. A decrease
of albedo can produce an increase in the net radiation and then an increase of temperature while an
increase of LAI and then an increase of roughness length or soil moisture can concur in a decreasing of
temperature. It is not clear which effect would dominate in a global land cover change scenario.
A first preliminary analysis has been carried out to understand the actual changes of the physical
parameters affecting the land-atmosphere interactions, to this aim the variation of four parameters (the
albedo, the percentage available moisture, the roughness length and the emissivity) have been
calculated. MM5 model assign the value of these variables as a function of season and land use type,
the seasonal average values for different soil cover characterizing the simulated geographical domain
are listed in table 3.
Table 3. Seasonal average values of Physical parameters affecting land-atmosphere interaction for different vegetation categories characterizing the Abruzzo Region.
MM5 Vegetation
Integer identification
Vegetation
description
Albedo
(%)
Moisture
Available (%)
Roughness
Length (cm)
Emissivity
(% at 9 μm)
1 Urban 15 10 50 88
2 Dryland Crop and Past. 20 45 10 92
3 Irrigated Crop and Past. 20.5 50 10 92
6 Crop and Wood Mosaic 18 42.5 20 90
15 Mixed Forest 13.5 45 50 94
From the comparison of the more frequent changes reported in table 2 and the values of physical
parameters listed in table 3, it is straightforward to note as, despite of different and heterogeneous
vegetation cover changes, the resulting net effect is a noticeable increase of roughness length and a
decrease in the soil moisture availability and albedo, for example both the changes from land use type
from 2 to 3 and from 6 to 15 produce a decrease of albedo and an increase of roughness length. The
same effect is produced in the areas covered by dryland crop and pasture in the ‘80s and characterized
by mixed forest at present time. The maps of changes for different parameters are reported in figure 8,
it is evident as only few grid points are affected by the increase of albedo or a decrease of roughness
length, while the changes of Emissivity is almost negligible over all the domain.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
Figure 8. Changes in albedo (left upper panel), percentage of available soil moisture (upper right panel), roughness length (lower left panel) and Emissivity (lower right panel) as consequence of observed land cover changes in the last two decades.
If we consider only the area where the land use change has been investigated, i. e. only the
geographical domain inside the administrative boundaries of Abruzzo region shown in the panels of
figure 8, the average albedo changes in the last 20 years form 18.2% to 16.5%, the average available
moisture decrease from 46.4% to 38.4% and the average roughness length increase from 22.3 to 33.6
cm, while the emissivity do not significantly changed. We conclude that, despite the changes in
vegetation cover over the considered region are different and heterogeneous, such changes produce a
decrease of albedo and an increase of soil moisture in most of the area, therefore we expect a
significant climatic and meteorological effect over the region. The aim of the first preliminary
experiments whose results are discussed in the next two sections, will be to estimate such effects
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
5. Meteorological effects simulated for different case studies
The work of Tomassetti et al. (2003), summarized in section 2, show that the triple nested regional
model configuration developed for the Abruzzo region is capable to realistically simulate the
hydrometeorological changes induced by modification of land use. More specifically it has been
demonstrated that the model appears capable of describing the changes in the circulation, precipitation
and surface temperature fields induced by the draining of the Fucino Lake and significant
hydrometeorological effects over the surrounding basin and possibly over more extend area of the
region are found. The same authors also showed that the presence of the lake could strongly influences
the distribution of the precipitation for a severe events occurring during July 1999 (see also section 2).
Because of these sensitivity studies it is straightforward to use a similar approach to investigate the
changes induced by the modification of land cover and land use over all the regions. To this aim
different meteorological case studies for different seasons have been selected. These case studies are
also characterized by different meteorological condition and are quickly listed in the following table 4.
Tabella 4. Selected case studies to investigate the meteorological effects of land use change over the Abruzzo region.
Case Study Date Main characteristics
CS1 23-25 January 2003 Very intense precipitations causing flood events
CS2 8-10 May 2002 Very intense precipitations
CS3 2-4 June 2004 Weak Precipitations
CS4 23-25 July 2003 High Pressure – No precipitation
CS5 25 September 2004 Weak Precipitations
For each case study two different run have been carried out, the first using early 80’s land use condition
and the second one forced with the present day land use map (see Figures 3-4); we will refer hereafter
to these runs as RUN80 and RUN00 respectively. All the simulation have been initialized using
European Center for Medium range Wheatear Forecast (ECMWF) analysis and all the case studies
have been simulated using the three nested domain described in the previous section.
A first important case study (CS1 hereafter) corresponds to the severe meteorological event of January
23-25, 2003 which caused loss of human life, many damages to buildings and infrastructures and few
flood events in the small river basins of Abruzzo Region (see Tomassetti et al., 2005) , during the first
phase (Fig. 9 left panel) a cyclogenesis was observed in the gulf of Genoa. At upper level an intrusion
of cold air from north east associated to a though extending from Scandinavia to South Mediterranean
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
region was present. The following 24 hours were characterized by the deepening of the surface pressure
minimum (Fig. 9 right panel), and an intense convective activity was still under course in the Abruzzo
Region causing intense precipitation events with rain rate ranging from 20 to 45 mm/hours (Verdecchia
et al., 2008). The most intense rainfall were observed in the south-eastern part of the innermost domain
shown in Figure 1, with maximum of accumulated precipitation of about 50 cm within two simulated
days.
Figure 9. Contour line of mean sea level pressure (hPa) for January 24, 2003 h: 12 (left panel) and for January 25, 2003 h: 12 (right panel).
The ability of MM5 model to capture the complex spatial and temporal variability of the precipitation
field for this specific case study has been discussed by Verdecchia et al. (2008).
A quick selection of the preliminary results obtained with the above described model are reported in the
figures 10-16.
The daily average temperature is observed to increase as a consequence of last 20 years land use
change, the map of such differences are reported in Figure 10 for different case studies. The increasing
of temperature is more pronounced in the internal areas and within the area subjected to a strong
antropic activities close to the coast of Adriatic Sea. The warming can be probably explained with the
decrease of albedo and soil moisture availability (see also figure 8 and related discussion). Nevertheless
the magnitude of the such warming is most evident for the case study characterized by an high pressure
in summer and it is reduced in the case of strong forcing (case study CS2) due to the dispersion by the
more intense background winds.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
The same comparison of ground temperature are also reported for daytime and nighttime in figure 11
and 12 respectively. Daytime average ground temperature increases up to 3 degree for the case study
CS4, while it is almost negligible during nighttime.
Figure 10. Daily average Ground Temperature differences between RUN00 and RUN80 for the case study CS4 (left upper panel), CS3 (upper right panel), CS5 (lower left panel) and CS2 (lower right panel).
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
Figure 11. Daytime Average Temperature differences for the CS4 (left upper panel), CS3 (upper right panel), CS5 (lower left panel) and CS2 (lower right panel).
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
Figure 12. Nighttime Average Temperature differences for the CS4 (left upper panel), CS3 (upper right panel), CS5 (lower left panel) and CS2 (lower right panel).
Changes in the precipitation fields (Figure 13) appear to be very different for the selected case studies,
ranging from few millimeters for the case study of may 2002 up to few centimeters for the case studies
of September 2004.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
Figure 13. Differences of 48 hours of Accumulated rain for the CS1 (left upper panel), CS2 (upper right panel), CS3 (lower left panel) and CS5 (lower right panel).
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
A further interesting analysis is reported in Figure 14 where for different case studies (columns) we
compare the daily temperature cycle, but considering only the portion of surface affected by a specific
change, more specifically: the first row of plots reports the change in daily temperature cycle for the
grid points where land use changed from cultivation to forest, the second row the daily cycle for grid
points where a change from grass to forest has been simulated, and in third row of plots the comparison
is carried out for the portion of surface where a change from grass to rade forest is observed. The first
evidence is that the observed land use modification mainly affects the daily maximum with a
decreasing of temperature up to 3 oC, while the nighttimes temperatures are slowly modified. The
increasing of maximum temperature are also more evident for the terrain where the grasses have been
replaced by the forests.
Figure 14. Differences in the daily temperature cycle for different case studies (columns) and different kind of land use change. The first rows report these changes for areas where forests replaced the cultivated areas. Second rows reports the different obtained selecting only the grid points where grasses have been replaced by forest. In the last
rows the same analysis is carried out for pixel changing from grasses to rade forsts.
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Tomassetti et al., Regional model simulation of meteorological effects induced by land use changes in the Abruzzo Region in the last twenty years
6. Conclusions
Different simulations have been carried out with MM5 mesoscale model to investigate the
meteorological effects of observed land use change over Abruzzo Region in the last 20 years. A first
preliminary simulation was carried out to investigate the ability of MM5 meteorological model to
realistically simulate the hydrometeorological effects of Fucino Lake drainage. Different case studies
have then been simulated to study the effects at regional scale linked to the modification of land use
over the Abruzzo region in the last twenty years. According to other authors, the results of simulations
show that the regional changes in surface temperature and precipitation can be as large as those that
result from the anthropogenic increase of greenhouse gases. Comparison of different simulations also
show that the warming caused by the changes in the land cover is more pronounced during daytime
respect to the nighttime.
Acknowledgements. Authors are indebted to Prof. Giuseppe Scarascia Mugnozza and Prof. Giorgio
Matteucci of Dipartimento di Scienze dell’Ambiente Forestale, Università della Tuscia, Viterbo, Italy
and Enrico Pompei of Corpo Forestale dello Stato (Italy) for providing data about the land use change
over Abruzzo Region.
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