what is gasification and why gasify waste?

1

Peter Brett Associates LLP

Gasification of Waste

Paul C Darley


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.


What is gasification

and why gasify waste?


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


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:

2


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 .


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


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).


Combustion

Combustionreactor

Residual MSW

Excess Air

Flue Gas

Ash

Energy = Heat Energy

Rankinesteam cycle

Electricity

Cleaned gases


Advantages of Combustion

• Enables energy to be recovered from waste.

• Reduces the volume of solid residue.

• Sanitises the solid residue.

• Well proven and reliable.


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.

3


• 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


Gasification

Gasificationreactor

Residual MSW

Air or O2

Syngas

Ash

Energy = Chemical Energy

Rankinesteam cycle

Electricity

Cleaned gases

Gas engine orGas turbine

Syngascleaning


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.


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.


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.


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.

4


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.


Why is the gasification

of waste so difficult?


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.


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]


-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

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


Peter Brett Associates LLP Peter Brett Associates LLP


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

5


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


Review of plants built

for the gasification of waste


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


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.


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

6


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.


• Already problems with boiler fouling.

• Modular configuration.

Avonmouth


Dargavel

Waste2Energy (Enerwaste / Planet)• Batch gasification process

for waste disposal.

• First plant built with power generation in Dargavel.


• 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)


150 ktpa Siemens Plant in Fürth, Germany

Operated 1997 to 1999 then dismantled due to safety concerns


225 ktpa Thermoselect Plant in Karlsruhe

Operated 1999 to 2004 then dismantled due to failure to perform


100 ktpa Plant in Chiba, Japan 2002

Source: Thermoselect

6 more plants operating successfully in Japan with this process


120 ktpa in Toyohashi, Japan 2002

Source: Mitsui

7 plants operating successfully in Japan with this process

7


125 ktpa in Kawaguchi, Japan 2002

Source: Ebara



135 ktpa in Ibaraki, Japan 1980

Source: Nippon Steel



MSW Gasification Plants in Japan

0

5

10

15

20

25

30

35

Nip

po

n S

tee

l

Mitsu

i

Eb

ara

JFE

(T'

sele

ct)

Taku

ma

KH

I

Hita

ch

i Zo

sen

Ka

wa

saki G

ike

n

JFE (

NKK

)

IHI

Ko

be

lco

Mitsu

bish

i H

I

KSTU

Gro

up

Ba

bc

oc

k H

ita

ch

i

NG

K

Hita

ch

i (in

cl.

2 p

lasm

a)

Su

mito

mo

Nu

mb

er o

f re

fere

nc

e f

ac

ilitie

s

Underconstruction

Operating

Commercial facilities processing > 30 ktpa

99 operating plants

5,351,370 tpa capacity 10 plants being built

745,800 tpa capacity


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!


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


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

8


The future of gasification


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.


A New Role for Gasification?

ResidualMSW

MBT SRF Gasification

Syngas

PowerPlant

Other co-fuelse.g. sewage sludge,

residues from producerresponsibility schemes


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?


Is energy from the gasification

of waste renewable?


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.

9


Environmental impacts

of waste gasification


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.


• 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


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.


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.


Any

questions?

what is gasification and why gasify waste?

Documents