Perennial energy crops:

Agronomy, Physiology,

Environmental and

Bioconversion

Prof. Salvatore L. Cosentino

Dipartimento di Agricoltura, Alimentazione e Ambiente, Di3A

(Department of Agriculture, Food and Environment)

University of Catania

Summer School

27 July 2015, Hotel

Hubei, Beijing, China

“Energy crops” may be defined as

crops specifically cultivated to

produce biomass which, for specific

traits to serve as an energy vector to

release energy either by direct

combustion or by conversion to other

vectors such as biogas or liquid

biofuels.

Energy crop

• High biomass yield close to the potential for each

environmental zone

• Able to use natural resources

• Able to be cultivated in low input soil tillage

• High ‘Water Use Efficiency’

• High ‘Nitrogen Use Efficiency’

• High “Radiation Use Efficiency”

• Resistant to biotic stress

• Resistant to abiotic stress

• Anti-erosion capacity

• Positive energy balance

• Low environmental impact

• With quality traits specific for each different end-use

Ideotype of an energy crop

– Brassica spp. - Bunias orientalis

– Eucalytus spp. - Reynoutria japonica

– Helianthus annuus - Reynoutria sachalinensis

– Salix spp. - Agrostemma githago

– Triticum aestivum - Spartium junceum

– Secale cereale - Solanum tuberosum

– Triticosecale - Spartina spp.

– Hordeum vulgare - Panicum virgatum

– Beta vulgaris - Acacia spp.

– Phalaris arundinaceae - Betula spp.

– Populus spp. - Onopordum nervosum

– Cannabis sativa - Nicotinia glauca

– Miscanthus spp. - Opuntia ficus-indica

– Hibiscus cannabinus - Sinapis alba

– Cynara cardunculus - Linum usitatissimum

– Sorghum bicolor - Crambe abissynica

– Alnus spp. - Zea mais

– Arundo donax - Phragmites australis

– Helianthus tuberosus - Robinia pseudoacacia

– Camelina sativa

Energy crops species in EU

• Ecology

• Area of origin

• Temperature requirements

• Water requirements

• Photoperiodic response

• Nutrients requirements

• Soil requirements

• Biology

• Phenology and growing season

• Growing habit (annual, perennial)

• Crop Physiology

• Radiation use efficiency

• Water use efficiency

• Nutrients use efficiency

• Agronomy

• Years of cultivation

• Breeding activity

• Role in crop rotation

• Propagation material

• Abiotic and biotic resistance

• Mechanisation (sowing, harvest, etc.)

Choice of the crops

Traditional food and feed crops

Rapeseed

Maize (biomass hybrids)

Sunflower (high oleic)

Hemp

Flax

Reed Canary grass

Switchgrass

Safflower

New crops (never or rarely cultivated with high possibility of improvement)

Miscanthus x giganteus Greef and Deu

Giant reed (Arundo donax L.)

Cardoon (Cynara cardunculus L.)

Brassica carinata A. Braun

Sweet and fiber sorghum

SRC (poplar, willow, eucalyptus)

New species

Castor bean (Ricinus communis L)

Saccharum spontaneum L.

Annual and perennials in temperate climate

Generally perennial grasses are attractive for biomass production due to their high yield potential, the high contents of lignin, cellulose and hemicellulose polysaccharides, and their positive social and environmental benefits

Environmental benefits Socio-Economic benefits

less water consumption; low fertilizers and pesticides

requirements; low GHG emissions; phytoremediation capacity; reduction of soil degradation and

erosion; adaptability to marginal lands; permanent soil cover; natural habits for wildlife.

development of new markets (e.g. biofuels and green products);

new sources of income and employment in rural areas;

development of regional economic structures;

biodiversity increase; potential inland renewable energy

sources (> energy security); improve the education, training, and

assistance services provided for farmers.

Zegada-Lizarazu et al., 2010, modified

Why perennial grasses?

The cultivation of energy crops in arable lands has raised a number of concerns in regards to land use change, either direct (DLUC) or indirect lands use change (ILUC).

• DLUC are more easily assessed locally (i.e., introduction of a new cropping system at a site where it has not taken place before);

• ILUC (i.e., use of agricultural land that displaces food production and causes natural land elsewhere in the world to be cultivated for food instead) need to be considered at a global scale (Van Stappen et al., 2011; Shortall, 2013).

Land Use Change

If energy crops are grown, Land Use Change (direct or

indirect, dLUC or iLUC) may be caused

European land cover (EEA, ETC-LUSI, 2010)

The relationship among potential, attainable, actual and marginal yield for a

lignocellulosic perennial bioenergy crop (modified from Rabbinge, 1993).

Agronomic marginal land

Marginality Variables Phisically Slope, Rock fragment, Bedrock depth, Flooding, Ponding,

Other restrictions

Biologically Temperature, Moisture, Soil erosion, Soil depth, Sand content, Production, Cation exchange capacity, Salinization, Sodicity, Acidity, Alkalinity, Drainage, Water table, Soil layer restriction, Other restrictions

Environmentally-Ecologically

Slope, Erosion, Wetland, Nutrient loss, Biodiversity, Resilience, Resistance, Buffer zones or corridors, Other restrictions

Economically Breakeven price or yield, Trade-off, Proximity to market,

Transportation network, Other restrictions

Politically Existing legislative framework restricting its agricultural use, Other restrictions

Social Zone programs, Reserve, Tourism attraction

Land abandonment

Unused/Abandoned lands

Marginal land

Agronomic constrains

Economic constrains

Political constrains

Social constrains

Other constrains

Marginal land

Biology of rhizomatous perennial grasses

• Rhizome: subterranean stems, dense, knotty, tangled, branched, robust.

• Stem: empty, with nodes and internodes.

• Leaf: several, departing from nodes

• Inflorescence: apical panicle

• Seed: caryopsis

Perennial rhizomatous grasses

Rhizome

Roots

Roots

Rhizome

Arundo

Miscanthus

Belowground (rhyzome and root system)

1. Main buds (develop stems in spring)

2. Seconday buds (develop stems in summer)

3. Extension buds (develop rhizomes; extend during summer; diverge trend, with apical main buds and extension buds)

3

1

2 2

3 3

Belowground (Giant reed rhizome)

0 – Rhizome of the year 1 – Rhizome of the prevoius season 2 – Rhizome of two previous years

Belowground (M. sinensis rhizome)

• Stem: height up to 6 m; basal stem diameter 20-40mm; smooth, empty, several nodes (12-30), ofter filled with a white wax, colour green/yellow/white.

• Leaf: usually from 15 to 30, 30-70 cm lenght and 2.0-7.5 cm wide, green glaucous colour, recline, sharp, parallelenerve, ligule cut off.

Aboveground (Giant reed stem and leaf)

Si dipartono da un denso ciuffo di

foglie piuttosto alte.

Stem: height up to 4 m;

basal diamater 5-15 mm,

smooth, empty, several

nodes (12-20). Number on a square meter about 90 - 140

Leaf: lenght between 30 and 135 cm, different size and coulour depending on the species.

Aboveground (Miscanthus stem and leaf)

Summer stem Spring stem Two-year stem Three-year stem

Giant reed stem age in a natural stand

One-year Two-year stem

Miscanthus stem age

• Vegetative growth: February-March (new visible stems from the soil). Nutrients are mobilized from belowground to aboveground.

• Development: February to October (spring stem

elongation, and new stems develop in summer time).

• Flowering: August to November. Inflorescence come out from the flag leaf, at the extremity of the stem. Drought stress postpones flowering.

• Stasis: November to February (stems start to loose moisture, leaves start to be senescent and the panicle flakes). Nutrients move down from above to belowground.

Biology of PRG in warm-temperate

Febru

ary

Mar

chApr

ilM

ay

June Ju

ly

Aug

ust

Sep

tem

ber

Octob

er

Nov

embe

r

Dec

embe

r

Janu

ary

Febru

ary

Mar

chApr

il

Bio

ma

ss y

ield

(t D

M h

a-1

)

0

10

20

30

40

50

Arundo

Miscanthus

Aboveground dry biomass accumulation

Febru

ary

Mar

chApr

ilM

ay

June Ju

ly

Augus

t

Septe

mbe

r

Octob

er

Nov

embe

r

Dec

embe

r

Janu

ary

Febru

ary

Mar

ch

LA

I

0

2

4

6

8

10

12

Arundo

Miscanthus

Thermal threshold

• Arundo 6.9-7.5 °C (Copani et al. 2009; Spencer and Ksonder, 2006)

• Miscanthus 10.0 °C (Jensen et al., 2012)

Flowering

• Miscanthus: photoperiod between 14.2 and 12.1 h (Jensen et al., 2012)

• Arundo: delayed and progressive

RUE

• Arundo 1.09

• Miscanthus 1.25

Leaf losses and

nutrient

translocation

Moisture content at

harvest

• Miscanthus: 15-20%

• Arundo: 35-50%

Transpiration

activity

LAI in Mediterranean area

Leaf area Index Miscanthus x giganteus (Cosentino et al., 2007)

Leaf Area Index Arundo donax (Cosentino et al., 2014)

Agronomy of rhizomatous perennial grasses

PRG grow on a variety of soil types including coarse sands, gravelly soil, heavy clays, and river sediments and tolerate extremely saline soils.

Main practices: • Plowing 30-40 cm • Disk harrow 20 cm • Cultivator 20 cm

Soil tillage

Most of them do not produce viable seeds (e.g. giant reed, M. x giganteus) so propagation only by:

• Rhizome

• Stem cuttings

• Micro-propagation

Target Plant density

(10,000-20,000 ha-1)

PRG propagation

Thermal threshold

• Arundo 6.9-7.5 °C (Copani et al. 2009; Spencer and Ksonder, 2006)

• Miscanthus 10.0 °C (Jensen et al., 2012)

Thermal threshold for stem sprouting

Copani et al. 2009

CI CB CM CA . Media anni

0

10

20

30

4007/08

08/09

09/10

R3 R1 T10 T5 . Media anni

0

10

20

30

40

07/08

08/09

09/10

Stem cuttings yield tend to equal rhizomes yield over years

Copani et al., 2013

Stem cutting vs rhizomes

Stem cutting of Miscanthus x giganteus

By PRIMUS Ltd.

• Important during the first year

(mechanical or chemical

weeding).

• No necessary in the following

years due to strong competition

for water and solar radiation by

PRG to weeds

Giant reed establishment

M. x giganteus long-term

Weed control

• Fertilization needed during the establishment, become

less important over years due to nutrient recycling from

below to aboveground (spring) and viceversa (autumn).

• No nitrogen in the year of establihment due to leaching

Depending on soil chemical-physical properties: 60-120 kg

N, 0-100 kg P2O5 and 0-100 kg K2O5 ha-1

Fertilization

Irrigation very important during the establishment and to sustain long

term productivity.

Water volume: 300-1200 mm (depending on rainfall abundance,

distribution and cultivation area)

Irrigation

Species IWUE (g l-1)

EWUE (kJ l-1)

NUE (g g-1)

ENUE (MJ g-1)

Arundo donax 10.7 68.6 355.9 5.8

Miscanthus spp. 6.1 42.1 307.2 7.5

Nitrogen and Irrigation Use Efficiencies

Cosentino et al. 2014

Crop Water Use and Biomass yield In

Arundo donax L.

Giant reed. Cosentino et al. 2014

Miscanthus. Cosentino et al. 2007

CWU and WUE

Harvest time

Miscanthus x giganteus

Arundo donax

Giant reed

Winter cut

Miscanthus

Autumn cut Giant reed

Autumn cut

Miscanthus

Winter cut

Giant reed and M. x giganteus long-term (Winter vs

Autumn harvest, N fertilization vs no-fertilization)

Biomass yield (Winter vs Autumn harvest, N

fertilization vs no-fertilization)

Long-term yield of Arundo and Miscanthus

in semi-arid area

To remove PRG at the end of crop cycle there are mainly two methods: mechanical, chemical or both.

• An excavator or a deep plowing can be useful to dig out the

rhizomes on the surface and subsequently remove them for the plot.

• Alternatively a late-season application of 3% glyphosate onto the foliar mass is efficient and effective with least hazardous to biota. Glyphosate is only effective in fall when plants are actively transporting nutrients to the root zone, and multiple treatments are usually needed.

• Other herbicides registered for aquatic use can be very effective in controlling PRG at other times of the year.

Remove PRG after cycle

Physiology of rhizomatous perennial grasses

Saccharum Arundo Miscanthus

A (

um

ol C

O2

m-2

s-1

)

0

5

10

15

20

25

30

Saccharum Arundo Miscanthus

Gs (

mol m

-2 s

-1)

0,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

0,16

Saccharum Arundo Miscanthus

E (

mm

ol H

2O

m-2

s-1

)

0

1

2

3

4

5

6

Saccharum Arundo Miscanthus

Lea

f W

UE

(um

ol C

O2/m

mo

l H

2O

)

0

1

2

3

4

5

6

7

Photosynthesis, Stomatal conductance, transpiration

rate and leaf WUE in C3 and C4 crops

Gas exchange and leaf WUE of Arundo in relation to available soil water content

E (mg H20 cm-2

s-1

)

0 5 10 15 20 25

A (

mo

ls C

O2

m-2

s-1

)

0

10

20

30

40

50

Arundo donax

Miscanthus x giganteus

Relation between net photosynthesys and transpiration rate

0,0 0,5 1,0 1,5 2,0

0

2

4

6

8

10

12

14

16

18

20

Arundo donax

Miscanthus x giganteus

E (

mg

H20

cm

-2 s

-1)

Gs (mol m-2 s-1)

Stomatal conductance against Transpiration rate in Arundo and Miscanthus x giganteus

Available soil water deficit(%)

0 20 40 60 80 100

Pre

da

wn

le

af

wa

ter

pote

ntia

l (b

ars

)

-8

-6

-4

-2

0

f=y0+a*(1-exp(-b*x))

Available soil water deficit (%)

0 10 20 30 40 50 60 70 80 90 100

Pre

daw

n l

eaf

wate

r p

ote

nti

al

(bars

)

-3,0

-2,5

-2,0

-1,5

-1,0

-0,5

0,0

y = -0.5379 -0.007303 e(x/16.3488)

Arundo donax Miscanthus x giganteus

Available soil water deficit (%) and Predawn leaf

water pontential (bars) in 0-100 cm soil depth

Intercepted radiation (MJ m-2

)

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Bio

mass y

ield

(g D

M m

-2)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Arundo (b=1.09)

Miscanthus (b=1.25)

Radiation Use Efficiency (g MJ-1 )

Radiation Use Efficiency (g MJ-1 ) of Arundo

(Irrigation and N fertilization)

Radiation Use Efficiency of Miscanthus (g MJ-1 )

(Irrigation and N fertilization)

Environmental issue of rhizomatous perennial grasses

PRG and cardoon in small CHP: OPTIMA results (IFEU, 2015)

-50 -40 -30 -20 -10 0 10 20 30

Climate change

Non-renewable

energy use

Acidification

Marine eutrophication

Freshwater

eutrophication

Ozone depletion

Particulate matter

Miscanthus

Giant reed

Switchgrass

Cardoon

Advantages Disadvantages

Inhabitant equivalents per 10 ha per yearIFEU 2015

Overall net results of the scenario “Biomass → Small CHP” compared to the fossil

equivalent with different feedstock types per agricultural area. Error bars indicate

variation of results due to yield levels.

Miscanthus under different conversion: OPTIMA results (IFEU, 2015)

Overall net results for Miscanthus used for different conversion options compared to the

fossil equivalent. Error bars indicate variation of results due to conversion efficiency (see

section

-50 -40 -30 -20 -10 0 10 20 30

Climate change

Non-renewable

energy use

Acidification

Marine eutrophication

Freshwater

eutrophication

Ozone depletion

Particulate matter

Inhabitant equivalents per 10 ha per year

Domestic heat

Small CHP

Large CHP

Pyrolysis oil

Biochar

2G Ethanol

1,3-Propanediol

Advantages Disadvantages

IFEU 2015

Yield variation impact of Miscanthus on the overall scenario: OPTIMA results (IFEU, 2015)

Impact of yield variation on the overall net results of the scenario “Miscanthus → Small

CHP”. “Low yield” corresponds to the yield level set for the main scenario “marginal land

-50 -40 -30 -20 -10 0 10

Climate change

Non-renewable energy use

Acidification

Marine eutrophication

Freshwater eutrophication

Ozone depletion

Particulate matter

Inhabitant equivalents per 10 ha per year

Miscanthus: very low yield

Miscanthus: low yield

Miscanthus: standard yield

IFEU 2015

Advantages Disadv.

Impact of varying energy carriers for drying, drying efficiency and moisture content prior to drying on the results for the impact category climate change of the scenario “Giant reed → Small CHP (OPTIMA results, IFEU, 2015)

Climate change

-25 -20 -15 -10 -5 0 5 10 15

Standard: natural gas

Light fuel oil

Biomass

Standard drying efficiency

High drying efficiency

Low drying efficiency

Standard drying

Open air-drying

Standard: natural gas

Light fuel oil

Biomass

Standard drying efficiency

High drying efficiency

Low drying efficiency

Standard drying

Open air-drying

IE / (10 ha × year)

Agriculture Transports Drying Pelleting Conversion Use phase Credits: power provision Credits: fuel provision for heat Credits: fuel combustion heat Net result

Credits Emissions

IFEU 2015

Advantages Disadvantages

Impact of irrigation and consideration of water-induced indirect land use changes on the results for selected impact categories of the scenario “Miscanthus → Small CHP (OPTIMA results, IFEU, 2015)

-40 -35 -30 -25 -20 -15 -10 -5 0 5 10

Climate change

Non-renewable

energy use

Acidification

Marine eutrophication

Particulate matter

Inhabitant equivalents per 10 ha per year

Default (irrigation)

No irrigation

Water iLUC

IFEU 2015

Advantages Disadv.

Since irrigation scenarios for Miscanthus, giant reed and switchgrass are

based on the same amount of applied water, the impact of water-induced iLUC

is equal for these crops.

Biomass Bioenergy Oil combustible

Yield (t ha-1) Emission t CO2

equ. ha-1 (a)

Emission t CO2 equ.

ha-1 (b)

Emission t CO2

equ. ha-1 saved

(b-a)

Biofuel

Arundo 35.7 6.8 44.4 37.7

Miscanthus 17.3 4.2 21.6 17.5

Cardoon 18.2 4.0 22.7 19.1

Fiber sorghum 24.6 5.7 30.7 25.1

ETBE

Sweet sorghum 21.4 15.8 19.9 3.9

Biodiesel

Rapeseed 2.6 1.9 3.1 1.2

CO2 equ. emission saved

Bioconversion of rhizomatous perennial grasses

No-food lignocellulosic cell wall

Winter harvest: higher biomass yield, lower moisture content, lower leaf to stem ratio, higher hemicellulose, cellulose, lignin and slightly lower ash content.

Species Harvest Hemicellulose Cellulose Lignin Ash

Miscanthus (stems) Winter 23.87±3.4 45.91±4.6 22.40±2.0 3.55±1.9

Autumn 24.82±0.4 29.63±1.3 18.01±0.6 3.40±1.6

Miscanthus (leaves) Winter 31.98±0.5 38.95±0.4 15.11±1.1 5.11±1.2

Autumn 28.87±1.4 27.68±1.1 16.49±0.2 6.40±1.4

Arundo (stems) Winter 26.36±1.1 34.95±2.2 20.64±1.7 5.43±0.8

Autumn 18.92±5.6 32.43±2.9 19.57±4.2 6.81±2.1

Arundo (leaves) Winter 24.47±2.2 26.39±1.8 17.43±0.6 8.14±0.7

Autumn 18.22±5.1 24.32±7.1 18.32±1.4 7.43±2.3

Biomass quality (Winter vs Autumn harvest)

Lignocellulosic biomass

Thermochemical Biochemical

Main conversion pathways

Lignocellulosic biomass

Thermochemical conversion

Combustion

Heat and/or Electricity

Pyrolysis

Biooil, Char, Gas

Gassification

Gas

Thermochemical conversion

Main parameter for thermochemical conversion • Moisture content;

• Bulk density,

• Ash content,

• Mineral content

• CHN-composition,

• Lower heating value (LHV),

• Micro Carbon Residue Testing (MCRT)

• Ash melting behaviour (initial deformation temperature – IDT, softening temperature – ST, hemispherical temperature – HT and fluid temperature – FT)

Operational conditions for main thermochemical conversions

Lignocellulosic biomass

Size reduction

Pretreatment

Steam, Chemicals

Filtration

Liquid

Detoxification hydrolisate

Inhibitory composunds,

Chemicals

Solid

Washing solid

Solid

Saccharification

Cellulase enzymes

C5-C6 sugars

Fermentation

Bioethanol

Lignin residue

SSF/SSCF

Yeasts

Distillation

Size reduction

By-products

Biochemical conversion (e.g. II generation bioethanol

Main parameter for Biochemical conversion • Glucan content;

• Xylan content;

• Arabinan content;

• Galactan content;

• Mannan content;

• Rhamnan content;

• Acid insoluble lignin;

• Acid soluble lignin;

• Acetyl groups;

• Extractives;

• Ash.

C5 fermentation to ethanol

Miscanthus (Scordia et al. 2013)

Arundo (Scordia et al. 2012)

C6 fermentation (SSF) to ethanol

Arundo (Scordia et al. 2013)

Miscanthus (Scordia et al. 2013)

Find out the most suitable native plant for a targeted environment

Breeding program to improve yield, propagation, increase stress tolerance, optimize raw material composition for specific end-use

Optimize agronomic practices, as propagation, growth management and harvest (mainly for marginal lands)

New machinery development for agamic propagation establishment, harvest, transportation and storage

Technologies to enhance bioconversion efficiencies

Environmental and economic assessment

Develop Decision Support System (agronomic, economic, environmental models) also in relation to climate change

Social acceptance

Future Research Perspectives

Thank you for your

attention

Salvatore L. Cosentino

(cosentin@unict.it)