Overview of Waste Management Techniques for Fuels and ...important sources of fuel and energy zFocus of presentation: ... Thermal Processes (Gasification) zSub-stoichiometric air zVertical

CalRecoveryCalRecoveryCalRecovery

Overview of Waste Management Techniques for Fuels and Power in Europe and in the USA

L.F. Diaz, G.M. Savage, and L.L. Eggerth CalRecovery, Inc.Concord, California USA

[email protected]

California Biomass Collaborative 4th Annual Forum Sacramento, California (March 27-28, 2007)


OutlineIntroduction

General Types of Technologies

OverviewEU

USA

Conclusions


IntroductionManagement of MSW:

has undergone substantial changes in the past 50 years

now, fractions of solid waste and biomass are viewed as important sources of fuel and energy

Focus of presentation:deals with some techniques that have been demonstrated and some that are under development in the EU and in the US

broad, expansive topic; will only provide an overview


General Types of TechnologiesThermal

Physical-chemical

Biological

Sources: Diaz, L.F., G.M. Savage, and C.G. Golueke, Resource Recovery from Municipal Solid Wastes, Volume II, CRC Press, Inc., 1982Bilitewski, B., et al., Waste Management, Springer, Berlin, 1994


Thermal ProcessesCombustion

Gasification (sub-stoichiometric air)

Pyrolysis (absence of air, temp, pressure)

Plasma


Thermal Processes (Combustion)Concentration of oxygen:

stoichiometricexcess air

Degree of treatment:mass fired:

– types of grates:travelingreciprocatingrotating drum

fluidized bed (FBC)


Thermal Processes (Gasification)Sub-stoichiometric air

Vertical fixed bed

Horizontal fixed bed

Fluidized bed


Physical-Chemical ProcessesSeveral unit processes used to produce:

RDF/SRF

dRDF

liquid fuels

Hydrolysis (acid)


Biological ProcessesAnaerobic digestion:

in landfills

in reactors:– wet (5 to 10% dry solid matter)– dry (>30% dry solid matter)

Hydrolysis (enzymatic)

Hydrogen production


European UnionPrior to 2004, the EU consisted of 15 member states (EU-15)

Between 2002 and 2003, the EU-15 produced about 200 million tons of MSW

One of the most recent significant pieces of legislation regarding SWM – the Landfill Directive:

bans disposal of untreated organic materials into landfills


Targets for Biodegradable Waste Diversion (Landfill Directive) in the EU

35%2016 (2020)50%2009 (2013)75%2006 (2010)

% of Biodegradable Waste Allowed to Landfill (% of quantities in 1995)

Target Date *

* The directive allows for a 4-year derogation for Member States that were landfilling more than 80% of the biodegradable waste in 1995


EU Framework Directive on Waste (75/442/EEC)

Establishment of sustainable waste management

Requirements to protect human health and the environment

Defines waste types

Principles of waste hierarchy

REDUCEREUSE

RECOVERYRecycling

COMPOSTINGWaste-to-energy

DISPOSALLandfill

Incineration


Management of MSW in Some European Countries (2002)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Denmark

Netherlan

ds

Austria

Belgium

Sweden

France

Finlan

d

Spain

Italy

United King

dom

Portug

alGreec

e

Perc

ent o

f MSW Landfilling

Composting

Incineration

Recycling


Type of Treatment of MSW in Europe (2004)


WTE in the EU

50 million tons of MSW thermally treated in 420 plants produced:

- 20 million MWh of electricity

- 50 million MWh of heatIn 2005, 13 countries produced 12.7 million tons of RDF or SRF


filte

r

Recovery ofCl, Br, Hg,

gypsum

Inertizationdisposal(storage)

Utilization

Energyrecovery

(24 % power,

>50% CHP)low dioxin

Segregation ofpollutants

HClHBrHgSO2

Fly ash

Volume reductionand inertization

Controlledfeeding

Optimizedcombustion

control

Fundamentals of Modern Waste Incineration

Source: Vehlow, J. Germany


Waste-to-Energy Facilities Operating in Europe in 2004

1.14Other3.1829Sweden0.5421Norway3.430Denmark0.43Czech Republic

13.8861Germany1.47Austria

4.2252Italy3.1429Switzerland5.3612Netherlands2.318Belgium2.614UK1.063Portugal1.7811Spain12130France

Treated Waste (million tonnes)No. of PlantsNation

Source: CEWEP


Management of Boiler and Filter Ash in Europe

Extraction/sintering

Fusion/vitrification

Stabilization

Filler in asphalt (NL)

‘Utilization‘ in salt mine (D)

Storage for future use

Source: Vehlow, J., 2006


200 kg

FilterBoiler

Scru

bber

DEN

OX

Scru

bber

Polis

hing

MSW(1000 kg)

Bottom Ash

160kg

Utilizationin construction

20 kg metals

20 kg to disposal

15 kgfly ash

12 kgsalts

Solid Residues of MSW Incineration

Source: Vehlow, J. Germany


United StatesUndergone major changes in the last 50 years

Several important laws:Resource Conservation and Recovery Act

Clean Air Act

Clean Water Act

Occupational Safety and Health Act

Superfund and Toxic Substances Control Act


United States (cont.)In 2003, generated about 240 million tons per year of MSW

Spend about US$40 billion per year to manage the wastes


MSW Management in the United States (2003)

Land disposal, 55.4%Recovery, 30.6%

Combustion, 14.0%

Source: US EPA


Waste-to-Energy Facilities Operating in the US (2005)

84,20830,73889Total

1,9487059Modular

17,4836,38016RDF

64,77723,65364Mass combustion

Capacity (tons/day)

Capacity(tons/yr x 1000)

No. of Facilities

Type of Unit

Source: 2005-2006 Municipal Waste Combustion in the United States, 8th Edition, E.B. Berenyi


Number of Waste-to-Energy Facilities in the United States (1982 to 2004)

59

103111

129

112

10092

89

75

136

0

20

40

60

80

100

120

140

160

1982 1984 1986 1988 1990 1993 1996 1998 2001 2004

Year

Num

ber o

f Fac

ilitie

s

Source: 2005-2006 Municipal Waste Combustion in the United States, 8th Edition, E.B. Berenyi


Options for Optimizing Thermal Processes

Increase energy efficiencyReduce flow of flue gasMinimize development of polluting and toxic substances such as dioxins, CO and NOx

Reduce or avoid corrosionImprove ash management


Current Developments in Optimization

Water-cooled grates

Recirculation of flue gas

Enrichment of primary air with oxygen

Cladding of boiler tubes


Gasification

Discovered at outset of 19th century

Conversion of the organic fraction of waste or biomass into a mixture of combustible gases through partial oxidation at high temperatures (400 to 1500 °C)


GasificationCarbon in waste or biomass reacts with steam and oxygen (from air) at sub-stoichiometric conditionsPrimary reactions:

C + O2 -> CO2 (exothermic)C + H2O -> CO + H2 (endothermic, water gas)C + CO2 -> 2 CO (endothermic)CO + H2O -> CO2 + H2 (exothermic, generator gas)

Resulting synthesis gas (syngas) can be used for:energy production in IC engines or turbinessynthesis of chemicalshydrogen production


IC Engine Firing Pyrolysis Gas

Engine and DynamometerGasifier (rt) and Gas Conditioner (lt)


Engine Cylinder and Valves After Test Run


IC Engine Firing Pyrolysis Gas


Thermoselect


Gasification as Front-end Plant

Source: Bilitewski, B., 2006


PyrolysisEndothermic reaction of organic fraction of waste, biomass, or liquid waste in the absence of oxygen at high temperature and pressure

Organic matter is transformed to a gas, liquid, and a solid (char)

Temperature and pressure levels affect the relative ratios of gas, liquid, and solid


Thermal Gasification – System Schematic

PyrolysisReactor

Organic Feed

Char (e.g., carbon black)

Pyrolysis (syn) gas

Pyrolytic Oil

Heat


PyrolysisSeveral pilot plants have been operated

Reliability and maturity of the technology has not been demonstrated at full-scale

Major issues deal with solid residues produced, gas clean-up, quality of liquid fuel, and air emissions


Pyrolysis (or Gasification) and Melting System in Japan

Gasification

Melting

Slag

Source:Matsuto, T


Slag and Metal in Japan

About 150 melting systems in operation in 2002 in Japan

Source: Matsuto, T.


Fischer-Tropsch (FT) Process

Proven technology, originally invented in Germany in 1920s

Catalyzed chemical reaction where hydrogen and carbon monoxide are converted to liquid hydrocarbons

Typical catalysts based on Fe and Co

Main objective is to produce a synthetic substitute to petroleum


Plasma

It is an ionized gas

Considered by some as the “fourth state of matter”

For example – water molecules:below 0°C ---------------------- Solid (i.e., ice)above 0°C ---------------------- Liquid (water)above 100°C -------------------- Gas (steam)above 5,000 to 10,000°C ----- Plasma (ionized

gas)


PlasmaEnergy that is added causes neutral atoms of gas to split

As atoms split a plasma of positively and negatively charged atoms and electrons is formed

Need high voltage to generate electric arc, two electrodes (cathode and anode) and gas (helium, air)


Plasma – Commercial ApplicationsWelding and cutting

Steel melting furnaces

Some hazardous and radioactive wastes treated


Plasma – Application to SWSmall unit operating in a cruise ship for about 3 years

Some propose to “gasify” the waste and use gas to generate electricity

Several “start-up” companies during the last few years, most operate pilot plants

Concerns about gas cleaning and solid residue produced

Unproven on commercial scale in United States


Biogasification – System Schematic

Bioreactor(high/low moisture)

Organic Feed

Organic Residue

Biogas(medium- to high-Btu)

Heat


Process Rate Limiting FactorsTwo-stage, biological process

The final stage (methane formation) is the slowest, and thus the rate-limiting one

Successful acceleration of processing rate will decrease cost


Organic Waste Management in Europe

Potential organic waste in EU15:15 million tons/year

Treatment (2004):11 million tons biowaste and 7 million tons of greenwaste

3.5 million tons A/D

All plants process:about 42% (+2% to 2002)

8.5 million tons of compost

Source: European Composting Network (ECN)


Status of Anaerobic Digestion of Organics in Europe (2005)

About 87 industrial plants with a capacity of about 3.0 million tons/year:

• smaller space requirements compared to windrow composting• easier emission/odor management• about 46% are dry, 54% are wet digestion systems• better removal of impurities (plastics, metals)• recovery of energy (subsidies 0.1 €/KWh) and fuel-> 5000 on-farm co-digestion plants (Germany, Austria)


Mechanical-Biological Treatment MBT (2005)

=> Pre-treatment of rest waste after separate collection (or of mixed MSW) by mechanical processes followed by composting or digestion to stabilize the material before landfilling

Italy 94 plants - 7.5 million tons/yearGermany 60 plants - 5.0 million tons/yearAustria 15 plants - around 0.5 million tons/yearSpain 15 plants - 1.1 million tons/yearFrance 77 old MSW plants – 1.9 million tons/year

First plants in the Netherlands, UK, and Belgium

Goal: production of residue with very low organic matter content that is suitable for landfilling

Source: European Composting Network (ECN)


A/D Plants in Europe as of 2004

2,910,20087Totals

943,50029Others

786,70011VALORGA

517,00012LINDE/BRV

234,50010OWS/DRANCO

215,50016KOGAS

213,0009MAT/BAT

Capacity (Mg/a)No. of PlantsSystem


Pilot Food Waste Digester in Richmond, California (1984)


New Tunnel Anaerobic Digester Digester (Dry Fermentation)

Bunkers for Feedstock Digesters in Enclosure (insulation being installed)


Discontinuous Dry Fermentation with Percolation

substrate

fermenter

garage door

wheel loader

waste gas

biogas

perkolation tank

Source: Weiland, P. FAL, Germany


Continuous Dry Fermentation withPlug-Flow Feeding

biogas

digestate

substrate fermenter

mixer

solidsseparation

solids

processwater

M

M


Biogas Plants for Co-Digestion of Cattle Manure and Other Biomass (UTS)


Growth of Biogas Plants in Germany


Number of plants has increased substantially:100 in 1990

1050 in 2000

2800 in 2005


Relevant Financial IncentivesAward “Green Certificates” (GC):

European Directive 2001/77/CE

promotes production of energy from renewable sources

provides financial incentive to producer (time period and amount vary from country to country)

one GC = 50 MWh of energy

in Italy, financial incentive is 0.115 €/kWhe per year (~.138 US$/kWhe year)

in Italy, incentive is valid for 8 years from startup of plant – can be extended 4 more years (financial incentive reduced to 60%)

in Germany, incentives last over 20 years


Renewable Sources of Energy Act(2006) -- Germany

Technology bonus: € 0.02/kWhe (e.g. dry fermentation)

KW-Bonus: € 0.02/kWhe for external heat utilization

4,08,64501 - 5.000

6,09,60151 - 500

6,011,16150

Energy crops bonus

[€ 0.01/kWhe]

Compensation

[€ 0.01/kWhe]

Electricalcapacity

[kW]



HydrogenHydrogen is considered a clean energy source

Hydrogen has a high energy yield (122 kJ/g) --about 2.75 higher than fossil fuels

Current methods for the production of hydrogen mainly use fossil fuels as energy source, are energy-intensive and not always environment friendly


Hydrogen in NatureAll processes that produce hydrogen biologically depend upon the presence of a hydrogen-producing enzyme

Hydrogen-producing enzymes catalyze the “simple”chemical reaction

2 H+ + 2 e- H2

Currently three enzymes are known: Nitrogenase

Fe-Hydrogenase

NiFe-Hydrogenase


Biological Hydrogen ProductionBiological hydrogen production processes can be classified as follows:

biophotolysis of water using algae and cyanobacteria

photodecomposition of organic compounds by photosynthetic bacteria

fermentative hydrogen production from organic compounds (“dark” fermentation)

hybrid systems using photosynthetic and fermentative bacteria


Enzymatic HydrolysisMicrobial conversion of cellulose into glucose

Most common microorganisms are Trichodermaviridae

Demonstrated at pilot scale


Enzymatic Hydrolysis (cont.)Processing involves several steps:

feed preparation (addition of nutrients and sterilization to microorganisms)

treatment of organic residues (cellulose)

hydrolysis of cellulose

glucose separation


General -- Operations and Maintenance

O&M associated with commercial-scale processing of waste mixtures is oftentimes substantially underestimated

Lack of independent, reliable estimates of O&M costs for commercial-scale processing alternatives


General -- Unscheduled O&M Problems

Valve clogged with contamination; even

very low concentrations of

undesirable materials can bring a system to a halt


General -- Operations and Maintenance (cont.)

Reliability, availability, and maintainability of equipment can result in very low overall system processing efficiency:

pre-processing/feedstock preparation

conversion subsystem

residue handling subsystem

pollution control subsystem


Conclusions Inefficiency of collection and transportation of organic wastes is a serious impediment to these wastes, contributing substantially to energy generationR&D needed to improve efficiency of waste-to-energy conversion processes, thereby reducing cost of energy generation


Conclusions (cont.)Legislative mandates and financial incentives are encouraging the growth of biotreatment in Europe

Many plants now operating in Europe of varying sizes; most are small, relative to needs of US

Financial incentives promoting A/D mostly as an investment

Return on investment may be 5 years or less


Conclusions (cont.)Limited or conflicting information to make sound management decisions

Need reliable, scientifically based information

Optimization of bioreactor designs and quick removal and purification of gases offer good possibilities for bio-hydrogen systems

Biological hydrogen production processes are mostly operated at ambient temperatures and pressure; thus, less energy-intensive than the current production processes


20th Anniversary of Sardinia SymposiumTo be held at the Forte Village Complex at S. Margheritadi Pula (Cagliari, Sardinia), Italy – October 1-5, 2007One of the most important conferences in the world, dealing with many issues in waste managementTopics include:

policy and educationrecycling, minimizationtreatment of different fractionslifecycle assessment

Additional information at www.sardiniasymposium.it

Documents

Overview of Waste Management Techniques for Fuels and ...important sources of fuel and energy zFocus of presentation: ... Thermal Processes (Gasification) zSub-stoichiometric air zVertical