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Peter Brett Associates LLP
Gasification of Waste
Paul C Darley
Peter Brett Associates LLP
Scope of Presentation
• What is gasification and why gasify waste?
• Why is the gasification of waste so difficult?
• Review of waste gasification plants built.
• The future of waste gasification.
• Is energy from the gasification of waste renewable?
• Environmental impacts of waste gasification.
• Questions.
Peter Brett Associates LLP
What is gasification
and why gasify waste?
Peter Brett Associates LLP
CONCEPT PRODUCT
Thermal Treatment
Medium CVFuel Gas + Char
Low CVFuel Gas
Heat EnergyCombustionwith excess oxygen
Gasificationwith starved oxygen
Pyrolysiswith no oxygen
Mechanical Treatment Recyclable
Materials +RDF or SRF
Sorting & Separation
Mechanical Heat Treatment
Biological Treatment
Aerobic Digestion(with air) = composting
Soil Conditioner
Anaerobic Digestion(with no air) like landfilling
Biogas + Digestate
MSW
PROCESS
Waste Processing Options
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Where’s Energy Recovery in the Hierarchy?
An MP wrote to a current appeal Inspector:
• “The government’s headline commitment on energy from waste is particularly instructive: ‘We’re working to increase the use of anaerobic digestion, which is the process of creating biogas from organic waste.’ Incineration is perceived as a less clean, less sustainable policy option even than other forms of ‘energy from waste’.”
19 November 2013 (my emphasis) Peter Brett Associates LLP
Why Energy Recovery?
• Biological treatment is unsuitable…• So the alternative is landfill.
this is my compost heap:this is black bag waste:
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Where’s Energy Recovery in the Hierarchy?
There is a category error in this logic:
• By all means maximise the separation of garden waste that can be composted and food waste, farm slurries etc that can be anaerobically digested, but residual MSW cannot be treated biologically .
• By all means separate as much recyclate as possible from rMSW, but that will only be about 5–10% of the rMSW .
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FUEL PROCESS PRODUCT
Thermal Conversion Options
Combustion
Heat
Flue Gas & Ash
Excess Air
Gasification
Heat
Syngascontains energy, hence a fuel
Ash
StarvedAir
Pyrolysis Bio-oilliquid fuel
Charsolid fuel
No Air
MSW
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Combustion
• An exothermic reaction in which organic compounds are oxidised to CO2 and H2O. Chemical energy is converted to heat energy.• Also known as – burning, incineration, thermal
oxidation.
• Just like a coal incinerator or natural gas incinerator (more commonly known as a coal power station and a gas power station respectively).
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Combustion
Combustionreactor
Residual MSW
Excess Air
Flue Gas
Ash
Energy = Heat Energy
Rankinesteam cycle
Electricity
Cleaned gases
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Advantages of Combustion
• Enables energy to be recovered from waste.
• Reduces the volume of solid residue.
• Sanitises the solid residue.
• Well proven and reliable.
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Disadvantages of Combustion
• Bad PR image (and perception matters).
• Produces a large volume of flue gas.
• High cost of gas cleaning equipment.
• Low thermal efficiency.
• Large volume of residue (bottom ash).
• Produces a hazardous waste stream (fly ash and gas cleaning residue).
• Requires control of NOx and toxic organics.
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• A partial oxidation process in which organic compounds are converted to a synthesis gas (‘syngas’) comprising mainly CO and H2
• Also known as – starved air combustion, partial oxidation.
• In 1801 gasification produced charcoal; by 1850s ‘wood gas’ lit London; in 1860 it fuelled an engine invented by the Belgian engineer Lenoir; and coal and heavy oils have been gasified commercially for decades in the petrochemical industry.
Gasification
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Gasification
Gasificationreactor
Residual MSW
Air or O2
Syngas
Ash
Energy = Chemical Energy
Rankinesteam cycle
Electricity
Cleaned gases
Gas engine orGas turbine
Syngascleaning
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Gasification Options
• Gasification can be used to generate power by:• burning the syngas in a gas engine or gas turbine;
• raising steam to drive a steam turbine.
• The gas engine route gives rise to potential benefits of gasification, but has almost always failed at commercial scale.
• The steam route is robust but fails to realise the benefits of gasification over combustion.
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Relative Efficiencies
Prime ‘mover’ Power recovery efficiency
Trends
Steam Turbine 18–27%Proven technology. Higher efficiencies require more exacting boiler operating conditions which is less proven. Gasification + close-coupled combustion perceived as surrogate incineration.
Gas Engine 37–41%Proven in Japan on multiple plants. Stand-alone gas engines would achieve 37% efficiency if integrated with an Organic Rankine Cycle – but this is currently unproven.
Gas Turbine (IGCC)
42–50%
Gas turbines and IGCC are proven at large scale on coal gasification plants (‘clean coal’). Some firm s have announced an intention to incorporate a gas turbine in their processes. Higher GT efficiency i s balanced by the energy debit to compress syngas.
Fuel Cell 40–80% The ultimate goal – but still 5–10 years away. Lots of R&D effort and government funding in this area.
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Plasma Gasification
Plasma technology can be used in conjunction with gasification in three different ways:
• to gasify the waste;
• to refine the syngas produced; and/or
• to vitrify the residue to convert if from a hazardous waste to a valuable product.
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Advantages of Gasification
• Enables energy to be recovered from waste.
• Reduces the volume of solid residue.
• Sanitises the solid residue…
as does combustion, but in addition it may be:
• More efficient.
• Lower environmental impact.
• Lower visual impact. And maybe in future will
• Produce a transportable fuel, e.g. gas to grid or liquid biofuel for transport use.
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Disadvantages of Gasification
• Most facilities for the gasification of waste to date have been unsuccessful.
This is not just a problem for the developer:
• It leaves waste without its intended disposal route.
• It wastes the time of planners and others.
• It dents the confidence of funders which makes other projects harder to realise.
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Why is the gasification
of waste so difficult?
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Issues faced by Waste Gasification
• The technology is embryonic compared with combustion technologies for coal or waste –• the first waste incinerator was built in Nottingham in
1874.
• The chemistry is extremely complex compared with that for combustion –• there are a huge number of variables in the physical
configuration and the thermodynamic parameters;
• the following slides will illustrate this point.
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Chemical Equilibrium Thermodynamics
Solid-Gas Reactions
• C + O2 → CO2 (combustion) [exothermic]
• C + ½O2 → CO (partial combustion) [exothermic]
• C + 2H2 → CH4 (hydrogasification) [exothermic]
• C + H2O → CO + H2 (water-gas) [endothermic]
• C + CO2 → 2CO (Boudouard) [endothermic]
Gas-Gas Reactions
• CO + H2O → CO2 + H2 (shift) [exothermic]
• CO + 3H2 → CH4 + H2O [exothermic]
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0
1
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600 700 800 900 1000 1100 1200 1300 1400 1500
log1
0Keq
T (K)C+2H2O=CO2+2H2 C+H2O=CO+H2 C+2H2=CH4C+CO2=2CO CO+3H2=CH4+H2O
Chemical Equilibrium Thermodynamics
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Chemical Equilibrium Thermodynamics
Reactions Equilibrium conditions
Effect of increase in T Effect of increase in PRate of reaction
(kinetics)
Solid-Gas Reactions
C + ½O2 → CO To Right To Left Fast
C + O2 → CO2 --- --- Very Fast
C + 2H2 → CH4 To Left To Right Slow
C + H2O → CO + H2 To Right To Left Moderate
C + CO2 → 2CO To Right To Left Slow
Gas-Gas Reactions
CO + H2O → CO2 + H2 To Left --- Moderate
CO + 3H2 → CH4 + H2O To Left To Right Slow
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Limitless Options
Slagging gasification
Close-coupledgasification to
steam and power
High temperaturegasification to
syngas
Plasma-basedsystems to syngas
Plasmagasification
Plasma-assistedgasification
Electrode TorchGasificationand melting
Fluidised bedgasification andplasma melting
Updraftgasification andplasma melting
Downdraftgasification andplasma melting
Close-coupledgasification
manyprocesses
Low temperaturegasification
manyprocesses
manyprocesses
manyprocesses
Gasification
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Review of plants built
for the gasification of waste
Peter Brett Associates LLP
Waste Gasification Plants in the UK
Operator Location Technology Start-up Fuel Capacity(t/a)
Gross Power
Heat O/P
New Earth SolutionsGroup Ltd (formerlyCompact Power Ltd)
Avonmouth,Bristol
Compact Powerpyrolysis & gasificationwith steam cycle
2001 Clinicalwaste
8,000 0.3 MW none
Environmental PowerInternational Ltd (EPi)
Mitcham,Surrey
EPi pyrolysis with gasengine
2002 SRF 8,000 1.0 MW none
Enviropower Ltd(trading as Rabbit)
Lancing,West Sussex
BPL gasification withsteam cycle
2008 C&D wastewood
60,000 5.1 MW none
Scarborough PowerLtd (Yorwaste Ltd &Graveson EnergyManagement Ltd)
Seamer Carr,North Yorks
GEM gasification withgas engines
2009 RDF fromMSW
18,000 2.2 MW 0.4 MW
BioGen Power Ltd(Ener-G Energos)
Newport, Isleof Wight
Energos gasificationwith steam cycle
2009 rMSW 30,000 2.3 MW none
Scotgen Ltd (AscotEnvironmental Ltd)
Dargavel,Dumfries
Enerwaste gasificationwith steam cycle
2009 MSW &hazwaste
60,000 6.0 MW none
Operating Shut down Peter Brett Associates LLP
More Waste Gasification Plants in the UK
Operator Location Technology Start-up Fuel Capacity(t/a)
Gross Power
Heat O/P
New Earth SolutionsGroup Ltd
Canford,Dorset
NEAT pyrolysis/gasiwith gas engine
2011 SRF 8,000 1.0 MW none
New Earth SolutionsGroup Ltd
Avonmouth,Bristol
NEAT pyrolysis/gasiwith steam cycle
2013 SRF fromMSW
100,000 13 MW none
East LondonSustainable EnergyFacility (Biossence)
Rainham,Essex
Metso gasificationwith steam cycle
2014 MSW MBTresidue
130,000 25 MW none
InnovativeEnvironmentalSolutions UK Ltd(Chinook & EMR)
Oldbury,WestMidlands
Chinook gasificationwith steam cycle
2014 ASR 137,500 40 MW none
IES UK Ltd(Chinook & EMR)
Bootle,Merseyside
Chinook gasificationwith steam cycle
2014 ASR 160,000 40 MW none
Tees Valley RE(Air Products)
Tees Valley AlterNRG plasmagasification
2014 rMSW &C&IW
340,000 50 MW ?
Operating Shut down In build
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Biomass Power Ltd• Formerly Talbott’s Heating Ltd.
• 4,000 waste wood fuelled industrial heaters.
• Biomass power plants built in Stirling, Scotland; Lancing, West Sussex; and Bagnolo, Italy.
• Uses a steam system for power generation.
• Problems with boiler fouling.
• Lancing plant designed for mixed MRF residue.
• Lancing plant has gained ROCs since 2009.
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Energos
• Developed and commercialised in Norway.
• 6 plants in Norway and 1 in Germany.
• Focus on small to medium scale (30 ktpa to 80 ktpa) and heat-supply applications.
• Use a steam system for power generation.
• Objective was low emissions from efficient gasification rather than abatement.
• Contracts became unprofitable and the company went bankrupt.
• IP bought by the UK company Ener-G in 2004.
• Revamped plant at the Isle of Wight to process RDF – accredited for ROCs.
Forus
Averøy
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New Earth Technologies• Integrated waste treatment and
power generation facility.
• Technology developed from Compact Power process.
• 6.4 MWe plant operating (Phase 1).
• Additional 6.4 MW (Phase 2) currently being commissioned.
• Uses a steam system for power generation.
• Already problems with boiler fouling.
• Modular configuration.
Avonmouth
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Dargavel
Waste2Energy (Enerwaste / Planet)• Batch gasification process
for waste disposal.
• First plant built with power generation in Dargavel.
• Uses a steam system for power generation.
• Boiler fouling problems.
• 60,000 t/a of rMSW and hazardous waste to generate 6 MWe.
• Plant start-up 2009.
• SEPA revoked Scotgen’sEnvironmental Permit in August 2013 and Scotgen went into administration.
Húsavík, Iceland 2006 (no heat recovery)
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150 ktpa Siemens Plant in Fürth, Germany
Operated 1997 to 1999 then dismantled due to safety concerns
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225 ktpa Thermoselect Plant in Karlsruhe
Operated 1999 to 2004 then dismantled due to failure to perform
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100 ktpa Plant in Chiba, Japan 2002
Source: Thermoselect
6 more plants operating successfully in Japan with this process
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120 ktpa in Toyohashi, Japan 2002
Source: Mitsui
7 plants operating successfully in Japan with this process
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125 ktpa in Kawaguchi, Japan 2002
Source: Ebara
6 plants operating successfully in Japan with this process
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135 ktpa in Ibaraki, Japan 1980
Source: Nippon Steel
36 plants operating successfully in Japan with this process
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MSW Gasification Plants in Japan
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Underconstruction
Operating
Commercial facilities processing > 30 ktpa
99 operating plants
5,351,370 tpa capacity 10 plants being built
745,800 tpa capacity
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Why Gasification works in Japan
• Waste disposal costs are exceptionally high.
• Power prices are exceptionally high.
• A long term view is taken of infrastructure investments.
• There is a desire to develop world-leading technologies.
• Not all the ‘MSW’ plants process MSW.
• Maybe plant failures are not admitted!
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Operating MSW Gasification Plants by Country
2%
83%
1% 4%
2%1%
5%
1%
UK Japan USA Australia Germany France Norway Sweden
111 plants in 8 countries
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Number of MSW Gasification Plants with Syngas to Added-value Products
'Over-the-fence', 1
Gas engines, 4Gas turbines, 0
Chemicals, 1
Steam cycle, 105
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The future of gasification
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Challenges
• Technical – cleaning the syngas sufficiently for its use in a reciprocating engine.
• Legislative – defining gasification so plants that deserve benefits get them & others don’t.
• Financial – determining which projects carry an unacceptable risk and which do not.
• Planning – knowing which projects will be beneficial to the public and which will not.
• Environmental – need not be a concern.
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A New Role for Gasification?
ResidualMSW
MBT SRF Gasification
Syngas
PowerPlant
Other co-fuelse.g. sewage sludge,
residues from producerresponsibility schemes
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A New Role for Gasification?
• Lowers technology risk by providing a more homogenous feed to a gasifier.
• Addresses issue of finding a market for the MBT output.
• Offers potential of integrating other residues.
• Keeps conversion of SRF separate from power station operation.
• Offers upside potential from ROCs, CfDs etc.
• Minimises disposal costs?
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Is energy from the gasification
of waste renewable?
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Gasification and Renewable Energy
• Why is waste gasification included in renewables legislation?
• Requirements of the Renewables Obligation.
• Requirements of Ofgem (the RO Regulator).
• Requirements to gain accreditation.
• Requirements to actually get ROCs etc.
• The role of fuel preparation.
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Environmental impacts
of waste gasification
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Gasification and its Environmental Impact
• Emissions to atmosphere have to meet the same standard as for combustion plants• claims by some gasification technology suppliers
that the gasifier produces less toxins are irrelevant: it’s what is emitted that matters.
• Standards for solid residue and liquid effluent are the same as for combustion plants.
• Standards for noise and traffic impacts are the same as for combustion plants.
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• Risks to human safety e.g. from an explosion• on the gasification plant site
• in the locality and beyond
• Risks to human health• gaseous emissions from stack
• hazardous solid residues
• Risks to human quality of life• noise from the gasification plant
• road traffic to and from the site
same as combustion
potentially < combustion
same as combustion
minimal but > combustion
minimal but > combustion
Gasification and its Environmental Impact
same as combustion
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Dioxins in Context
� German Environment Ministry study Waste Incineration – A Potential Danger? 2005: ‘in 1990 one third of all dioxin emissions in Germany came from EfW Plants; by 2000 it was less than 1% (<0.5g); today it is even lower’.
� In 2005 Jürgen Trittin, German Minister for the Environment from the Green Party, said: ‘Dioxin emissions from Energy-from-Waste are not an issue.
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Dioxins in Context
� In 2007 a study carried out by Lisbon University’s Institute of Preventive Medicine concluded that waste incineration ‘does not impact on dioxin blood levels of nearby residents’.
� Nevertheless we should minimise dioxin formation – and we can do so by appropriate equipment design.
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Any
questions?