of Municipal Solid Waste Advanced Thermal Treatment · management options and strategies available for dealing with Municipal Solid Waste to limit the residual amount left for disposal

www.defra.gov.uk

Advanced Thermal Treatment of Municipal Solid Waste

www.defra.gov.uk

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Page number

Preamble 1

Introduction 2

How it Works 3

Advanced Thermal Treatment 3Difference between Pyrolysis, Gasification and Incineration 3ATT Technology Overview 4Case Studies 7Summary 7

Markets for the Outputs 8

Recovery from ATT 8

Track Record 10

Contractual and Financing Issues 11

Grants and Funding 11Contractual Arrangements 11

Planning and Permitting Issues 13

Planning 13Plant Siting 13Traffic 13Air Emissions/Health Effects 13Dust/Odour 14Flies, Vermin and Birds 14Noise 14Litter 14Water Resources 14Visual Intrusion 14Size and Landtake 15Public Concern 15Environmental Impact Assessment 15Licensing/Permitting 15

Social and Perception Issues 16

Social Considerations 16Public Perception 16

Costs of Advanced Thermal Treatment 17

Contribution to National Targets 18

Recycling 18Recovery 18Landfill Allowance Trading Scheme (LATS) 18Renewable Energy 18

Further Reading and Sources of Information 19

Glossary 20

Contents Glossary

Mechanical Biological Treatment (MBT)

A generic term for mechanical sorting/separation technologies usedin conjunction with biological treatment processes, such ascomposting.

Municipal Solid Waste (MSW) Household waste and any other wastes collected by the WasteCollection Authority, or its agents, such as municipal parks andgardens waste, beach cleansing waste, commercial or industrialwaste, and waste resulting from the clearance of fly-tippedmaterials.

Pyrolysis During Pyrolysis organic waste is heated in the absence of air toproduce a mixture of gaseous and/or liquid fuels and a solid, inertresidue (mainly carbon).

Recyclate/Recyclable Materials Post-use materials that can be recycled for the original purpose, orfor different purposes.

Recycling Involves the processing of wastes, into either the same product or adifferent one. Many non-hazardous wastes such as paper, glass,cardboard, plastics and scrap metals can be recycled. Hazardouswastes such as solvents can also be recycled by specialist companies.

Refuse Derived Fuel (RDF) A fuel produced from combustible waste that can be stored andtransported, or used directly on site to produce heat and/or power.

Renewables Obligation Introduced in 2002 by the Department of Trade and Industry, thissystem creates a market in tradable renewable energy certificates,for which each supplier of electricity must demonstrate compliancewith increasing Government targets for renewable energygeneration.

Solid Recovered Fuel Refuse Derived Fuel meeting a standard specification, currentlyunder development by a CEN standards committee.

Source-segregated/Source-separated

Usually applies to household waste collection systems whererecyclable and/or organic fractions of the waste stream areseparated by the householder and are often collected separately.

Statutory Best Value Performance Indicators

Local Authorities submit performance data to Government in theform of annual performance indicators (PIs). The Recycling andComposting PIs have statutory targets attached to them thatAuthorities are required to meet.

Syngas 'Synthetic gas' produced by the thermal decomposition of organicbased materials through pyrolysis and gasification processes. Thegas is rich in methane, hydrogen and carbon monoxide and may beused as a fuel or directly combusted to generate electricity.

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This Waste Management Technology Brief is one of a series of documents prepared under the NewTechnologies work stream of the Defra Waste Implementation Programme. The Briefs areaddressing potentially important new technologies which may have an increasing role in divertingMunicipal Solid Waste (MSW) from landfill into a more sustainable and integrated wastemanagement alternative, extracting materials and energy from MSW for recovery and reducingquantities remaining for disposal. Other titles in this series include: An Introductory Guide to WasteManagement Options; Advanced Biological Treatment; Mechanical Biological Treatment &Mechanical Heat Treatment.

It should be noted that these documents are intended as guides to each generic technology areaand for more detailed or specific information on any particular technology, it is recommended thatthe Defra Waste Technology Data Centre is used as a resource. These Briefs deal primarily with thetreatment and processing of unsorted MSW and not source segregated wastes which are addressedby the activities of the Waste & Resources Action Programme (WRAP). Relevant references andsources of further information are cited throughout each document in this series.

The prime audience for these Briefs are local authorities, in particular waste management officers,members and other key decision makers for MSW management in England. For further informationon new technologies contact the New Technologies Supporter Helpline on 0870 2409894, email:[email protected]

Prepared by Enviros Consulting Limited on behalf of Defra as part of the New TechnologiesSupporter Programme.

We acknowledge support from the Department for Environment, Food & Rural Affairs, theEnvironment Agency, the Waste and Resources Action Programme, RPS and Be Environmental Ltd.

Disclaimer: Please read the note below before using this Document

This Document has been produced by Enviros Consulting Limited (Technical Advisors) on behalf ofDefra to provide assistance to Local Authorities and the waste management market generallythrough awareness raising of the key municipal waste management options for the diversion of BMWfrom landfill. The Document has been developed in good faith by the Advisors on behalf of Defra,and neither Defra nor its Advisers shall incur any liability for any action or omission arising out of anyreliance being placed on the Document by any Local Authority or organisation or other person. AnyLocal Authority or organisation or other person in receipt of this Document should take their ownlegal, financial and other relevant professional advice when considering what action (if any) to takein respect of any waste strategy, initiative, proposal, or other involvement with any wastemanagement option or technology, or before placing any reliance on anything contained therein.

Crown Copyright, 2005v.1.0

Glossary Preamble

Advanced Thermal Treatment (ATT)

Waste management processes involving medium and hightemperatures to recover energy from the waste. Primarily pyrolysisand gasification based processes, excludes incineration.

Aerobic In the presence of oxygen.

Biodegradable Capable of being degraded by plants and animals. Biodegradablemunicipal waste includes paper and card, food and garden waste,and a proportion of other wastes, such as textiles.

Biodegradable Municipal Waste (BMW)

The component of Municipal Solid Waste capable of beingdegraded by plants and animals. Biodegradable Municipal Wasteincludes paper and card, food and garden waste, and a proportionof other wastes, such as textiles.

Co-combustion Combustion of wastes as a fuel in an industrial or other (non wastemanagement) process.

Feedstock Raw material required for a process.

Floc A small loosely aggregated mass of flocculent material. In thisinstance referring to Refuse Derived Fuel or similar.

Gasification Gasification is the process whereby carbon based wastes are heatedin the presence of air or steam to produce a solid, low in carbonand a gas. The technology is based on the reforming process usedto produce town gas from coal.

Greenhouse Gas A term given to those gas compounds in the atmosphere thatreflect heat back toward earth rather than letting it escape freelyinto space. Several gases are involved, including carbon dioxide(CO2), methane (CH4), nitrous oxide (N2O), ozone, water vapourand some of the chlorofluorocarbons.

Green Waste Waste vegetation and plant matter from household gardens, localauthority parks and gardens and commercial landscaped gardens.

Global Warming The progressive gradual rise of the earth's surface temperaturethought to be caused by the greenhouse effect and responsible forchanges in global climate patterns. An increase in the near surfacetemperature of the Earth. Global warming has occurred in thedistant past as the result of natural influences, but the term is mostoften used to refer to the warming predicted to occur as a result ofincreased emissions of greenhouse gases form man-made sources.

Incineration The controlled thermal treatment of waste by burning, either toreduce its volume or toxicity. Energy recovery from incineration canbe made by utilising the calorific value of the waste to produceheat and/or power.

Materials RecyclingFacility/Materials Recovery Facility (MRF)

Dedicated facility for the sorting/separation of recyclable materials.

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Municipal Solid Waste (MSW) is waste collected by oron behalf of a local authority. It comprises mostlyhousehold waste and it may include somecommercial and industrial wastes. Nationally, thequantity of MSW is currently increasing year on year,presenting a growing problem for local authoritiesparticularly as new legislation, which limits (byimplication1) the amount of mixed MSW that can besent to landfill, comes into effect.

One of the guiding principles for European and UKwaste management has been the concept of ahierarchy of waste management options, where themost desirable option is not to produce the waste inthe first place (waste prevention) and the leastdesirable option is to dispose of the waste with norecovery of either materials and/or energy. Betweenthese two extremes there are a wide variety of wastetreatment options that may be used as part of awaste management strategy to recover materials (forexample furniture reuse, glass recycling or organicwaste composting) or generate energy from thewastes (for example through incineration, ordigesting biodegradable wastes to produce usablegases).

At present more than 75% of all MSW generated inEngland is disposed of in landfills. However,European and UK legislation has been put in placeto limit the amount of biodegradable municipalwaste (BMW) sent for disposal in landfill. Thediversion of this material is currently the mostsignificant challenge facing the management ofMunicipal Solid Waste in the UK.

There are a wide variety of alternative wastemanagement options and strategies available fordealing with Municipal Solid Waste to limit theresidual amount left for disposal to landfill. The aimof this guide is to provide impartial informationabout the range of technologies referred to asAdvanced Thermal Treatment (ATT). Thesetechnologies are designed to recover energy (in theform of heat, electricity or fuel) and can contributeto the diversion of BMW from landfill. They are partof a range of new alternatives currently beingassessed and investigated through the NewTechnologies work stream of Defra.

Further details about the new technologies featuredin this report are available from Defra's WasteTechnology Data Centre:

http://www.environment-agency.gov.uk/wtd

The technologies described in this Brief - AdvancedThermal Treatment - have a limited track record inthe UK (and indeed internationally) on MSW. Thereare many examples of ATT processes that areestablished as viable and bankable on various wastestreams (e.g. biomass, industrial wastes, tyres etc)but a lesser number proven on municipal wastes. Theaim of this document is to raise awareness of thetechnologies available and help remove barriers tothe development of appropriate ATT processes inEngland.

This guide is designed to be read in conjunction withthe other Waste Management Technology Briefs inthis series and with the case studies provided onDefra's Waste Technology Data Centre. Otherrelevant sources of information are identifiedthroughout the document.

Up-to-date information regarding RDF and ROCs canbe obtained from the DTI website or the NewTechnologies Supporter Helpline tel. 0870 2409894 [email protected]

The Waste Technology Data Centre www.environment-agency.gov.uk/wtd

New Technologies Supporter Helpline Tel. 0870 240 9894 E: [email protected]

Defra New Technologies website,http://www.defra.gov.uk/environment/waste/wip/newtech/index.htm

The Viability of Advanced Thermal Treatment of MSWin the UK, Fichtner Consulting Engineers Ltd, ESTET,2004.

Integrated Pollution Prevention and Control, DraftReference Document on Best Available Techniquesfor the Waste Treatments Industries, EuropeanCommission - Directorate General Joint ResearchCentre, January 2004.

Energy from Waste - A Good Practice Guide, Energyfrom Waste working group, CIWM, 2003.

Refuse Derived Fuel, Current Practice andPerspectives (B4-3040/2000/306517/Mar/E3), EuropeanCommission - Directorate General Environment, July 2003.

Review of Environmental & Health Effects of WasteManagement, Enviros Consulting Ltd, University ofBirmingham, Open University & Maggie Thurgood.Defra 2004.

AiIE Ltd, 2003, Review of residual waste treatmenttechnologies, Report prepared on behalf of Kingstonupon Hull City Council and East Riding of YorkshireCouncil.http/www.eastriding.gov.uk/environment/pdf/waste_treatment_technologies.pdf

The Additional Paper to the Strategy Unit, WasteNot Want Not study, 'Delivering the LandfillDirective: The Role of New & EmergingTechnologies', Dr Stuart McLanaghanhttp://www.number10.gov.uk/files/pdf/technologies-landfill.pdf

Planning for Waste Management Facilities - AResearch Study. Enviros Consulting Ltd. ODPM, 2004.http://www.odpm.gov.uk/stellent/groups/odpm_planning/documents/page/odpm_plan_030747.pdf

Procurement Toolkithttp://lasupport.defra.gov.uk/Default.aspx?Menu=Menu&Module=Article&ArticleID=102

For Works Contracts: the Institution of CivilEngineers 'New Engineering Contract'www.ice.org.uk

For large scale Waste Services Contracts through PFIAND following the Negotiated Procedures the 4ps'Waste Procurement Pack' www.4ps.gov.uk

Introduction Further Reading and Sources of Information

1Targets pertain to the biodegradable fraction

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Recycling

Recyclate derived from an ATT plant processinghousehold waste qualifies for BVPI 82a (Recycling)for any materials recovered prior to the thermaltreatment reactor. Any materials recovered after thethermal treatment (e.g. metals from the ash), do notcount towards BVPI 82a. Equally any char or ashrecycled does not count towards BVPI 82a.

The material must pass to the reprocessor (and notbe rejected for quality reasons) to count as recycling.It should be noted that if additional materials areextracted from the front end of the process forrecycling, they may experience market limitationsdue to being derived from a mixed MSW source.

Further information about BVPIs can be obtainedfrom the Defra website and associated links12.

Recovery

ATT technologies will contribute towards recoverytargets on the tonnage of materials entering thethermal treatment process as all processes aredesigned to recovery energy. For more informationsee the Defra website and associated links14 and theguidance on BVPI 82c.

Landfill Allowance Trading Scheme (LATS)

The European Landfill Directive and the UK'senabling act, the Waste & Emissions Trading Act2003, require the diversion of BiodegradableMunicipal Waste (BMW) from landfill. ATT systemswill divert 100% of the BMW passing through thethermal process from landfill as the output (char orash) will not be classified as biodegradable even ifdisposed to landfill. Up to date information relatingto LATS can be obtained from the New TechnologiesSupporter Helpline and Defra's LATS informationwebpage13.

Renewable Energy

The Renewable Obligation (RO) was introduced in2002. Its function is to promote the development ofelectricity generated from renewable sources ofenergy. The obligation requires an increasingpercentage of the electricity supplied to be from

renewable sources for each year through to 2010.The target for 2010 is set at 10%. The ROconsultation for 2005 proposed that the targets forthe obligation are extended, with a target of 15%proposed for 2015. The obligation requires suppliersto surrender certificates (known as RenewableObligation Certificates - ROCs) to demonstrate thatthey have supplied the required amount ofrenewable electricity. If the supplier cannotsurrender the required amount of certificates it canbuy out the shortfall at a price of 3 p/kWhe. Thisbuy out means that ROCs have a value and thereforegenerators of renewable electricity (as defined in theobligation) can sell the electricity they generate andthe ROCs, which means they receive a premium forthe power they produce. The value of a ROC isdependent on availability. If the suppliers fail tomeet their target set in the RO then certificates willbe worth more than the buy out price of 3 p/kWhe.However, if the available quantity of renewableenergy exceeds the target then the value of ROCswould drop.

To encourage the development of Advanced ThermalTreatment technologies, the RO was amended in2004. The amendment stated:

"A generating station shall be an excludedgenerating station in any month during which itis fuelled with waste or partly by waste unless -(a) the only waste by which it is fuelled isbiomass; or (b) all of the waste by which it isfuelled in that month which is not biomass hasfirst been manufactured into a fuel which is ineither a gaseous or liquid form (or both) bymeans of a plant and equipment using advancedconversion technology only."

This means that renewable fraction of the electricitygenerated from the Advanced Thermal Treatment ofMSW is eligible for ROCs. [The renewable fraction isthe gross energy content of the waste that isconsidered to be renewable (biomass)] This wouldprovide an additional revenue stream for a proposedplant, as long as it meets the qualifyingrequirements. As the value of a ROC is not fixed, thelong term value would need to be assessed in detailto determine its overall financial value to theproject.

The renewable obligation is currently out toconsultation for a proposed revised system.

This section comprises an overview of the principlesof Advanced Thermal Treatment processes.

Advanced Thermal Treatment

Advanced thermal treatment technologies areprimarily those that employ pyrolysis and/orgasification to process municipal solid waste (MSW).It excludes incineration2 of wastes which is already amature and well established technology.

The gasification and pyrolysis of solid materials is nota new concept. They have been used extensively toproduce fuels such as charcoal, coke and town orproducer gas. Charcoal and coke are produced bypyrolysing wood and coal respectively and producergas is a combustible gas produced by the gasificationof coke in the presence of air and steam.

It is only in recent years that such pyrolysis andgasification have been commercially applied to thetreatment of MSW. The development of pyrolysisand gasification technologies is in its infancy in theUK but large scale plants have been built and are inoperation in Europe, North America and Japan.

Advanced thermal treatment plant

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Contribution to National Targets How it Works

Difference between Pyrolysis, Gasificationand Incineration

There are a variety of differences promoted todifferentiate advanced thermal treatment fromtraditional incineration technologies. Onedistinction is that smaller scale facilities are beingmarketed for treatment of MSW with some ATTprocesses than the scale typical of incineration. It isthe difference in scale and size that allows the localuse of both heat and electricity produced, and theprocess differences are described below. Pages 13to 16 discuss planning and public perceptionaspects of ATT .

Established Thermal Treatment - IncinerationIncineration usually involves the combustion ofunprepared (raw or residual) MSW. To allow thecombustion to take place a sufficient quantity ofoxygen is required to fully oxidise the fuel.Typically, incineration plant combustion (flame)temperatures are in excess of 850ºC and the wasteis converted into carbon dioxide and water. Anynon-combustible materials (e.g. metals, glass)remain as a solid, known as Bottom Ash, thatcontains a small amount of residual carbon.

Advanced Thermal Treatment - PyrolysisIn contrast to combustion, pyrolysis is the thermaldegradation of a substance in the absence ofoxygen. This process requires an external heatsource to maintain the temperature required.Typically, relatively low temperatures of between300ºC to 800ºC are used during pyrolysis ofmaterials such as MSW. The products producedfrom pyrolysing materials are a solid residue and asynthetic gas (syngas). The solid residue (sometimesdescribed as a char) is a combination of non-combustible materials and carbon. The syngas is amixture of gases (combustible constituents includecarbon monoxide, hydrogen, methane and a broadrange of other volatile organic compounds). Aproportion of these can be condensed to produceoils, waxes and tars. The syngas typically has a netcalorific value (NCV) of between 10 and 20 MJ/Nm3.If required, the condensable fraction can becollected by cooling the syngas, potentially for useas a liquid fuel.

2Incineration of MSW in the UK always involves some form of energyrecovery, either in the form of electricity generation and/or heat recovery.As such it is also commonly termed Energy from Waste. Mass burnincineration is another term used to refer primarily to large scale plantburning untreated waste. In this document we will refer to 'incineration' todistinguish from Advanced Thermal Treatment.

12 http://www.defra.gov.uk/environment/waste/localauth/index.htm13 http://www.defra.gov.uk/environment/waste/localauth/lats/index.htm14 http://www.defra.gov.uk/environment/waste/localauth/index.htm

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ATT Technology Overview

The actual plant design and configuration of ATTfacilities will differ considerably between technologyproviders. However, an ATT plant will typicallyconsist of the following key elements:

• Waste reception, handling and pre-treatment;

• Thermal treatment reactor;

• Gas and residue treatment plant (optional);

• Energy recovery plant (optional); and

• Emissions clean-up (see page 13).

Waste Reception, Handling and Pre-treatmentThe pyrolysis and gasification process is focused ontreating the organic based materials present in MSW(e.g. paper, plastics, card, putrescible waste, greenwaste). Therefore, non combustible materials andrecyclables, (typically metals and glass) may beremoved prior to the thermal treatment reactorstage. In addition and depending on the technologyemployed, the feed material might requireprocessing to remove excess moisture, and shreddingto reduce the size.

It is the preference (for most ATT processes) to treatonly pre-processed MSW that makes these systemsappropriate to be integrated into a wider municipalwaste management strategy. ATT processes may forexample be used in conjunction with sortingtechnologies such as those employed in MechanicalBiological Treatment plant (MBT - see separate Brief,in this series). Some MBT plant are designed to

produce a fuel stream(primarily composed ofpaper, card and plastics) asone of the outputs fromthe process. This iscommonly referred to asrefuse derived fuel or RDF(see Box 1). This may bemore amenable toprocessing in an ATT plantrather than raw MSW.

Refuse Derived Fuel

Thermal Treatment ReactorThe primary thermal treatment, whether pyrolysis orgasification, will produce syngas and solid residue.The composition of the syngas and solid residue willdepend on the process conditions employed, whichinclude operating temperature, oxygen level,heating rate and residence time in the reactor.

The main types of thermal treatment units available,their application and operating conditions aresummarised in Table 1. [There are also other factorsinfluencing the process such as direction of gas flow(e.g. horizontally or vertically)].

The cost of constructing, operating and maintainingATT facilities are addressed using a common costmodel on Defra's Waste Technology Data Centre.Both capital and operating costs are included forspecific technologies which may be used for thepurposes of indicative comparisons rather thanaccurate reflections of actual costs.

Typically around 40% of the capital costs foroperating a plant will be to cover capitaldepreciation. As a result these need to be viewed aslarge capital investments (which will requirereplacement components during its lifetime) with alifespan of not less than 10 or more usually 20 years.

Plants of this type have been applied to chemicaland process industries; these have all been largescale, capital intensive applications.

It is vital in any negotiation, that a true appreciationof the cost of essential repairs and refurbishment betaken into account.

For cost information on examples of differentprocesses see Defra's Waste Technology Data Centre.

www.environment-agency.gov.uk/wtd

How it Works Costs of Advanced Thermal Treatment

Box 1 Fuel from mixed waste processingoperations

The current prevalent term used for a fuel producedfrom combustible waste is refuse derived fuel (RDF).The types of technologies used to prepare/segregate a fuel fraction from MSW include manyof the MBT and Mechanical Heat Treatmentprocesses described within another Brief in thisseries. A CEN Technical Committee (TC 343) iscurrently progressing standardisation work on fuelsprepared from wastes, classifying a Solid RecoveredFuel (SRF). It is anticipated that once standards aredeveloped and become accepted by users, SRF willbecome the terminology used by the wastemanagement industry. Other terminology has alsobeen introduced to the industry as various fuelcompositions may be prepared from waste bydifferent processes. Examples include'Biodegradable Fuel Product' (BFP) and 'RefinedRenewable Biomass Fuel' (RRBF).

Within this Brief, refuse derived fuel is used as aterm to cover the various fuel products processedfrom MSW.

Advanced Thermal Treatment - GasificationGasification can be seen as between pyrolysis andcombustion in that it involves the partial oxidationof a substance. This means that oxygen is addedbut the amounts are not sufficient to allow the fuelto be completely oxidised and full combustion tooccur. The temperatures employed are typicallyabove 750ºC. The main product is a syngas, whichcontains carbon monoxide, hydrogen and methane.Typically, the gas generated from gasification willhave a net calorific value (NCV) of 4 - 10 MJ/Nm3.The other main product produced by gasification isa solid residue of non-combustible materials (ash)which contains a relatively low level of carbon.

[For reference, the calorific value of syngas frompyrolysis and gasification is far lower than naturalgas, which has a NCV of around 38 MJ/Nm3.]

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This section contains a discussion of the social andenvironmental considerations of ATT facilities.

Social Considerations

Any new facility is likely to impact on local residentsand may result in both positive and negativeimpacts. Potential impacts on local amenity (odour,noise, dust, landscape) are important considerationswhen siting any waste management facility. Theseissues are examined in more detail in the Planning &Permitting chapter of this Brief. Transport impactsassociated with the delivery of waste and onwardtransport of process outputs may lead to impacts onthe local road network. The Planning andPermitting chapter of this Brief provides an estimateof potential vehicle movements.

An ATT facility may also provide positive socialimpacts in the form of employment and educationalopportunities. Typical employment for a ATT plantof 50,000tpa capacity would be 2-6 workers per shift.The plant would operate on a shift system, to allowfor 24-hour operations. These facilities are also likelyto provide vocational training for staff. Newfacilities may be built with a visitor centre to enablelocal groups to view the facility and learn moreabout how it operates.

Public Perception

Public opinion on waste management issues is wideranging, and can often be at extreme ends of thescale. Typically, the most positively viewed wastemanagement options for MSW are recycling andcomposting. However, this is not necessarily reflectedin local attitudes towards the infrastructurecommonly required to process waste to compost, orsort mixed recyclables, or indeed to have an extrawheeled bin! It should be recognised that there isalways likely to be some resistance to any wastemanagement facility within a locality.

At present there is a relatively low level ofunderstanding of the concept of ATT by the public.There are no full scale commercial ATT operations inthe UK processing MSW. In public consultations thesetechnologies score inconsistently when explained indetail as a residual waste treatment technology.There is a general distrust of thermal systems in theUK, however some ATT providers accentuate thedifferences of their systems from incineration as akey part of the promotion of their technology.

Overseas development of advanced thermaltreatment again shows inconsistencies in publicopinion. In Australia developments of ATT plantreceived similar perceptions to that of incineration,partly due to campaigns from nationalenvironmental groups claiming parallels betweenthe technologies. The national environmentcampaign organisations in the UK are divided on thisissue. The UK public opinion has yet to be tested onATT proposals.

Overall, experience in developing wastemanagement strategies has highlighted theimportance of proactive communication with thepublic over waste management options. The use ofrealistic and appropriate models, virtual 'walk -throughs' / artists impressions should be used toaccurately inform the public. Good practice in termsof public consultation and engagement is animportant aspect in gaining acceptance for planningand developing waste management infrastructure.Defra are funding the development of small tomedium scale demonstration plant in England forlocal authorities to visit and for Defra to publishdata on performance. For more information contactthe New Technologies Supporter helpline on tel.0870 2409894 [email protected]

Table 1 : Thermal Treatment Reactors

Gas and Residue Treatment

Solids will inevitably be discharged from the process.These solids include metals together with carbon. Inthe case of gasification, the level of carbon is small;in pyrolysis it is significant. Larger particles of solidsin the thermal treatment reactor are usuallydischarged as bottom ash. Lighter ash is usuallycollected when the gas is separated with the use ofcyclones and ultimately filters. In addition, volatilemetals such as lead, tin, cadmium and mercury willbe carried in the gas until such point that the gas iscooled for them to be sufficiently condensed.

Energy Recovery/Utilisation of Syngas

One of the potential benefits of pyrolysis andgasification is that the syngas can be used in anumber of different ways.

In terms of producing energy, the most commonconfiguration is to burn the syngas in a boiler togenerate steam. The steam can then be used togenerate electricity by passing it through a steamturbine and, if there is a demand local to the plant,for heating. Using the heat in addition togenerating electricity improves the overall energyefficiency of the system significantly.

Social and Perception Issues How it Works

Reactor Typical Application Operating Conditions

Typically operate at low temperatures of around 400 - 600°C.The unit can accommodate large size feed material (200 mm).The kiln is heated externally and waste is fed in from one endof the kiln which slowly rotates creating a tumbling action.This mixes the waste and ensures contact with the heatingsurface and gases inside the kiln.

The tubes are heated externally and temperatures as high as800°C are used. The process can accommodate large size feedmaterial. The waste passes through the tube at a set speed toensure the pyrolysis process is complete.

Small size feed material required and therefore significant pre-treatment is necessary. The process operates at hightemperatures and the small size of the feed gives high heatingrates. The application of this technology is to maximise therate of pyrolysis.

Fluidised bed technology may be used for gasification orcombustion processes. The bed is a mass of particles (typicallyalumina) that has similar characteristics to a moving fluid. Thisis achieved by blowing hot gases through the bed of particles.This system provides good mixing and heat transfer to theincoming waste. Waste is pre-treated to remove large sizedmaterial. This technology is well suited to the gasification ofRefuse Derived Fuels.

There are a range of different reactor types that come underthis heading. A typical example is a grate system where thefeed passes along the grate and hot gases pass through thebed of waste heating it.

Rotating Kiln

Heated Tube

Surface Contact

Fluidised Bed

Fixed Bed

Pyrolysis

Pyrolysis

Pyrolysis

Gasification

Gasification

6 15

The syngas can also be used to fuel a dedicated gasengine. A syngas derived from a very well rungasifier, or which has been further processed forexample by reforming, may be suitable for use in agas turbine. Running these types of plant on syngasis still in its infancy and would require cleaning andcooling prior to use. However, using a gas engine orgas turbine could increase efficiencies for electricitygeneration. This is of particular relevance if aCombined Cycle Gas Turbine (CCGT) or CombinedHeat and Power (CHP) configuration is used (seeTable 2). Whilst high efficiencies can be achievedusing gas engines, the highest efficiencies can onlybe reached using a high calorific value gas.Efficiencies should be checked if using a lowercalorific value gas.

To minimise costs for energy generation, the ATTplant could be located adjacent to an existing powerplant and the syngas transferred to it. This wouldalso provide benefits if the existing plant has ahigher efficiency than a standalone unit. A key issuethat would need to be resolved to allow the transferof the syngas to an adjacent power plant is whetherit would need to comply with the Waste IncinerationDirective (WID). If the Directive covered the powerplant then this could require major improvementworks to the abatement system for controllingemissions and therefore make such an option lessattractive or entirely unviable. Early implementationof the WID and Large Plant Combustion Directivewould in almost all cases outweigh any potentialadvantages to the operator of the power plant.

In addition to using the syngas to produce energy, itcould also be used as a chemical feedstock. Thisoffers a further option for utilising the syngas butwould require the treatment plant to be local to theend user, in order to be a practicable solution. Thiswould require very high gas cleanliness; pollutants,notably sulphur and halogens, may need to beremoved prior to combustion of the gas. Thereduced gas volumes involved in cleaning thecombusted gas rather than the combustion gas givesa financial advantage to the process. Alkalis such aslime and sodium hydroxide are the favouredreagents for removal of the halogen streams.Sulphur can be removed by a variety of routes,largely dependant on the initial concentration(ranging from absorption to the Klaus reaction).

For reference, a summary of the potential netelectrical generating efficiencies for new buildthermal treatment plant employing various energyrecovery options is presented in Table 2. Forcomparison, the performance of a new mass burnincinerator is also provided. Table 4 also includesexamples of efficiencies from specific processes.

Table 2 : Potential net electrical generating efficiencies

• Existing large buildings and structures in the area;

• The potential of a stack associated with some airclean up systems for mixed waste processingoperations may impact on visual intrusion;

• Use of screening features (trees, hedges, banksetc); and

• The number of vehicles accessing the site andtheir frequency.

Many of these facilities are housed in 'warehouse'type clad steel buildings, however use of gooddesign techniques can help minimise visual intrusion.

Size and Landtake

Table 4 shows the land area required for thebuilding footprint and also for the entire site(including supporting site infrastructure) forexamples of Advanced Thermal Treatment facilities.

Table 4 : Landtake

Source:

* Planning for Waste Management Facilities - A Research Study, ODPM 2004

† Waste Technology Data Centre

For more information on Landtake for specific wastemanagement operations, see Defra's WasteTechnology Data Centre.

Public Concern

The Social and Perception Issues section relates topublic concern. In general public concerns aboutwaste facilities relate to amenity issues (odour, dust,noise, traffic, litter etc). With thermal based facilitieshealth concerns can also be a perceived issue.

Environmental Impact Assessment

It is likely that an Environmental Impact Assessment(EIA) will be required for an ATT facility as part ofthe planning process.

Whether a development requires a statutory EIA isdefined under the Environmental Impact Assessment(England and Wales) Regulations 1999. Furtherguidance is available in the DETR circular 02/99 onEnvironmental Impact Assessment.

For more information on Planning issues associatedwith waste management options see Planning forWaste Management Facilities - A Research Study.ODPM, 2004 see footnote 9.

Licensing/Permitting

Currently, the interpretation of all AdvancedThermal Treatment operations is that they require aPollution Prevention & Control (PPC) permit. It wouldbe prudent to assume that any facilities will becovered by the PPC Regulations.

For more information on licensing & permitting seethe Environment Agency web site11.

How it Works Planning and Permitting Issues

EnergySystems

Steam Boilerand Turbine

Efficiencies ofPyrolysis/Gasification

Treatment Plant

Efficienciesof

Incinerator

Gas Engine

CombinedCycle GasTurbine

Co-firing inexistingpower plant

10% - 20%

13% - 28%

30%

Up to 27%

19 - 24%

n/a

n/a

n/a

11 http://www.environment-agency.gov.uk/subjects/waste/?lang=_e

TTFacility

TotalLandtake

Ha

BuildingsAream2

Size,tonnes

perannum

IndicativeStack

Height

MassBurn*

90,000 5,850 1.7 65m

MassBurn*

250,000 6,600 4 70m

Pyrolysis† 60,000 - 0.98 -

Pyrolysis† 12,500 200 + access

Pyrolysis† 35,000 28,000 -32,000 4 -

'GeneralATT'*

50,000 3,600 1-2 30 - 70m

14 7

In addition to the conventional approach of flue gasclean-up, an alternative approach could be adoptedin which the syngas is cleaned prior to use as a fuelto a level where the resulting flue gases could bereleased to atmosphere without further cleaning.However, the cleaning of syngas to a standard wherethe requirements of the WID no longer apply hasnot yet been demonstrated.

The Defra study on Health & Environmental effectsof Waste Management processes (see FurtherReading) found no evidence of health effects linkedto ATT facilities, however due to the emergentnature of these technologies, the available data wasonly of a moderate quality. More detail on this issueis included in the Defra report10.

Dust/Odour

Any waste management operations can give rise todust and odours. These can be minimised by goodbuilding design, performing all operations undercontrolled conditions indoors, good workingpractices and effective management undertaken fordust suppression from vehicle movements. Many ATTprocesses are designed to operate under negativepressure within buildings to minimise dust andodour problems.

Flies, Vermin and Birds

ATT processing is unlikely to attract vermin and birdsdue to majority of waste throughput and operationsbeing completely enclosed in buildings. However,during hot weather it is possible that flies couldaccumulate, especially if they have been brought induring delivery of the waste. Effective housekeepingand on site management of tipping and storageareas is essential to minimise the risk from verminand other pests. In some operations waste heat fromthe process may be used to bring temperatures infresh input waste to levels above which flies can live.The use of RDF as a feedstock would reduce thisissue relative to raw waste.

Noise

Noise is an issue that will be controlled under thewaste licensing regulations. The main contributors tonoise associated with ATT are likely to be:

• vehicle movements/manoeuvring;

• traffic noise on the local road networks;

• mechanical processing such as waste preparation;

• air extraction fans and ventilation systems;

• steam turbine units; and

• air cooled condenser units.

Litter

Any waste which contains plastics and paper is morelikely to lead to litter problems. With ATT litterproblems can be minimised as long as good workingpractices are adhered to, vehicles use covers andreception and processing are undertaken indoors.

Water Resources

Water will be used but this will be specific to thetechnology and therefore it is not possible to providedetail on the nature of the effluent that might begenerated and how it should be managed. However,as part of the permitting requirements for a facility amanagement plan would be required for effluent.

The case studies on the Waste Technology DataCentre include an assessment of water usage.

Visual Intrusion

Virtual image of proposed ATT facility

Construction of any building will have an effect onthe visual landscape of an area. Visual intrusionissues should be dealt with on a site specific basisand the following items should be considered:

• Direct effect on landscape by removal of itemssuch as trees or undertaking major earthworks;

• Site setting; is the site close to listed buildings,conservation areas or sensitive viewpoints;

Case Studies

Some descriptive examples of ATT processes areincluded here to illustrate the different technologiesbeing promoted for MSW management. Thetechnical details of these and other examples,including mass and energy balances and SWOTanalysis of the strengths, weaknesses, opportunitiesand threats are included on the Waste TechnologyData Centre3.

Waste Gen (Tech Trade) Hamm GermanyThis is a pyrolysis plant. It processes a pre-preparedRDF to produce a syngas that is immediately burnt ina dedicated burner in an otherwise coal fired powerstation boiler. The resulting char after recovery ofmetals using magnets, and aggregate using aballistic separator, is fed into the station coalbunkers.Fuel is delivered to the plant in bales or bulk form,from a range of RDF producers. The fuel is conveyedto the two rotary kiln pyrolyser units (20m in lengthx 2.8m in diameter). Natural gas burners heat thepyrolysis drums.

The two pyrolysis drums replace 10% of the fuelinput to a coal fired 330MWe generating set. TheRDF is regarded as a fuel (at present in the UK it isclassified as waste) and the power station is notWaste Incineration Directive compliant.

KBI Waste & Energy Solutions GmbHThis is a Mechanical & Biological Treatment (MBT)plant followed by an oxygen blown 'down draught'gasifier. The purpose of the waste pre-treatment andthe gasifier is to produce a gas of a quality andconsistency such that the power plant can safely andreliably operate to a defined efficiency and emissionlimits.

Received waste is dried in a rotating compost drumand recyclates are removed. The waste then passesto a feed preparation area where additives such ascoke, (typically 17%) and limestone are introducedprior to gasification.

Oxygen is added at several points down the gasifierprogressively raising the temperature towards themaximum, normally 1500°C.

Additional feeds of steam and natural gas are usedso as to control the composition of the producedgas. The gas is burned in a conventional gas turbineset and the exhaust gas from the turbine is used toraise steam. Some of the steam/electricity is used bythe process with the excess available for export.

GEM, Graveson Energy Management, Romsey,Hampshire, UKThis process uses fast pyrolysis of a Refuse DerivedFuel (RDF see Box 1) to produce a gas suitable forburning or powering an engine. The essentialprinciple behind the process is to rapidly heat thefeed to around 820°C, in the absence of oxygen andhence induce rapid pyrolysis. To do this conventionalRDF floc has to be ground such that one majordimension of each RDF particle is less than 2mm.The ground floc then has to be dried to 5% moisturecontent prior to feeding into the pyrolyser. Thepyrolyser consists of a large vertical steel cylinderheated on its outside surface. A close fittingcylindrical drum is suspended and rotated within thiscylinder. The RDF is fed at the top of the cylinderand by falling through the gap between the cylinderand drum, is rapidly heated. Within a couple ofseconds the RDF has been pyrolysed. Char isseparated from the gas in a cyclone. The gas streamis cooled and scrubbed to remove acid gases. Thecleaned gas is then fed to a spark ignition enginegenerator set. Waste heat from the pyrolyser heater,the engine exhaust, engine cooling and theproduced gas cooler is collected and integrated withthe local heat requirements, hence giving acombined heat and power system.

Summary

This section explains that advanced thermaltreatment processes are primarily pyrolysis and/orgasification based. ATT plant, as highlighted by casestudies, are capital intensive facilities (also see page17) and have a design life of 15 - 25 years. Rigorousevaluation of the technology is essential to reduceany operational risks when processing theanticipated feedstock. Over this timescale thecomposition of waste is likely to alter and theprocess selected should be robust or flexible enoughto treat varying calorific values and compositions ofwaste feedstock.

Planning and Permitting Issues How it Works

10 http://www.defra.gov.uk/environment/waste/research/health/index.htm 3 www.environment-agency.gov.uk/wtd

8 13

ATT processes will all produce a gas (usually for energy recovery) and a solid residue (ash or char). Some systemsare also designed with mechanical preparation and sorting equipment to extract recyclables. Table 3 summarisesthe key outputs from ATT processes and the following sections address materials and energy recovery.

Table 3 : Examples of outputs from ATT processes

* care needs to be taken with the chemical composition of this and the hazards associated with it

This section contains information on the planningand regulatory issues associated with ATT facilitiesbased on case studies of existing facilities andinformation on planning from the Office of theDeputy Prime Minister research report9.

Planning

When considering the planning implications for anATT facility the following issues should beconsidered:

• Plant/Facility Siting;

• Traffic;

• Air Emissions/Health Effects;

• Dust/Odour;

• Flies, Vermin and Birds;

• Noise;

• Litter;

• Water Resources;

• Visual Intrusion; and

• Public Concern.

Some of these issues are discussed elsewhere in thisguide but a brief overview of each is provided here.

Plant Siting

ATT can take place in many different buildings at avariety of locations but the following considerationsshould be made:

• Preference should be given to sites for businessuse or traditional commercial/industrial urbanareas. Existing waste management facility sitesmay also be considered;

• The site chosen should be close to the primaryroad network or rail head connection, especially ifit is to be a large scale/centralised facility. The siteshould be appropriate for the movement of HGVtraffic without major restriction. Smaller ATTfacilities may not require such infrastructure tosupport them.

• Under current rules, premiums are only awardedfor electricity generated from renewable sources

in plants such as this. As fuel prices may rise overtime and if supply security is questioned,considerations must always be given to utilisingnot only the electricity from the plant but alsothe waste heat. As a result specific plant shouldlook to be sited close to where its electrical andthermal outputs can be used. In the UK this islikely to reduce the size of such plant.

Traffic

ATT facilities may be served by large numbers ofHGVs (depending on the scale of the facility) with apotential impact on local roads and the amenity oflocal residents. It is likely that the site layout/roadconfiguration will need to be suitable to accept arange of light and heavy vehicles. For a 50,000tpacapacity plant, up to 20 refuse collection vehicles perday would be anticipated.

Air Emissions/Health Effects

Flue GasesIn terms of complying with the Waste IncinerationDirective (WID) the major emission from a plant withenergy recovery is the release of flue gases from thecombustion of the syngas (and in some instances alsothe residual solid, if it has high carbon content). Theclean-up required for the flue gases is dependent onthe process from which they have been generated.One of the main benefits claimed by manufacturersfor pyrolysis and gasification plant is that emissionsof pollutants are lower than those fromconventional mass burn incineration and that plantare designed to comply with the emission limits setout in the Directive.

Entrained (fine) particles in the syngas can either beremoved before or after combustion depending onthe treatment process and combustion technologyemployed.

A further solid residue produced is from abatementplant used to clean-up the flue gases from thecombustion process. Both of these solid streams arehazardous in nature and must be disposed ofappropriately. Often they are combined as they areremoved during the same stage of the flue gasclean-up.

Markets for the Ouputs Planning and Permitting Issues

Ouputs

Slag

State

Solid, fused

Potential Markets

Aggregate

Ash Un-fused residue Aggregate replacement, metals can be separated

Flue GasTreatmentresidue

Solid, powder/sludge.Invariably a hazardouswaste; some potentialfor neutralising wasteacids

Specialist disposal or treatment potential use in chemicaltreatment works (e.g. neutralising acid waste)

Syngas Gaseous Heat or power generation/fuel/some chemical application

Condensate* Liquid Fuel/chemical application

Char Solid Hazardous waste but could be used as coal replacement incertain combustion applications or as a gasifier feedstock

The following section summarises some key issueswith regard to these outputs.

Recovery from ATT

Materials Recycling Recyclables derived from either the front endpreparation stage of an ATT plant or metalsextracted from the back end of the process (i.e. outof the ash) are typically of a lower quality than thosederived from a separate household recyclatecollection system, and generally have a lower value.The types of materials recovered from ATT processesalmost always include metals (ferrous and non-ferrous), usually from the front end of the process.Metal removal can help enhance overall recyclinglevels and enable recovery of certain constituentparts that would not otherwise be collected inhousehold systems (e.g. steel coat hangers, paperclips etc.).

Pyrolysis plant produce a bottom residue thatcontains significant amounts of carbon. This willneed to be disposed of to landfill, or treated furtherto reduce the carbon content for example bygasification or combustion. If treated further thefinal bottom residue could then be recycled as asecondary aggregate. Gasification tends to producea bottom residue which has a lower carbon contentand has usually been melted or fused, and this couldtherefore be recycled as aggregate. The recycling ofbottom ash would need to be undertaken inaccordance with relevant legislation but is likely tobe of equivalent or potentially better quality thanincinerator bottom ash, which is currently recycled inaggregate applications.

9 http://www.odpm.gov.uk/stellent/groups/odpm_planning/documents/page/ odpm_plan_030747.pdf

12 9

Before initiating any procurement or funding processfor a new waste management treatment facility, thefollowing issues should be considered: performancerequirements; waste inputs; project duration; projectcost; available budgets; availability of sites; planningstatus; interface with existing contracts; timescales;governance and decision making arrangements;market appetite and risk allocation.

Further guidance on these issues can be obtainedfrom:

Defra Procurement Toolkit5;

For Works Contracts: the Institution of CivilEngineers 'New Engineering Contract'6;

For large scale Waste Services Contracts throughPFI and following the Negotiated Procedures the4ps 'Waste Procurement Pack'7; and

Local Government PFI project support guide8.

Char from pyrolysis process

For more information on the contribution of ATT toBest Value Performance Indicators and recycling seeChapter 9 and for the latest developments, see theDefra website4 or contact the Supporter Helpline tel.0870 2409894 [email protected]

Energy RecoveryATT processes are designed to recover energy fromthe waste processed, either in the form of fuelproduction (liquid or gas), or combusting the syngasto generate electricity and/or heat for use on siteand export off site. Examples of energy recoveryfrom case studies are included on the WasteTechnology Data Centre. Energy recovery mayqualify for renewable energy incentives, in the formof Renewables Obligation Certificates (ROCs), seeContribution to National Targets section.

It should be noted that the processes using RDF willhave already incurred energy usage in thepreparation of the fuel and this prepared materialwill have a higher calorific value than raw MSW.

For more information on the contribution of ATT toBest Value Performance Indicators see page 18 andfor the latest developments, see the Defra website4

or contact the Supporter Helpline tel. 0870 [email protected]

Contractual and Financing Issues Markets for the Ouputs

4 http://www.defra.gov.uk/environment/waste/localauth/index.htm

5http://lasupport.defra.gov.uk/Default.aspx?Menu=Menu&Module=Article&ArticleID=102

6available at www.ice.org.uk

7available at www.4ps.gov.uk

8www.local.odpm.gov.uk/pfi/grantcond.pdf

10 11

Whilst ATT technologies are established technologiesfor the treatment of certain specific waste streams, itis only in recent years that such pyrolysis andgasification have been commercially applied to thetreatment of MSW. The prime drivers in the UK forthe development of these technologies areincreasing landfill costs and the implementation ofthe Landfill Directive.

Table 4 : ATT Plant

The development of pyrolysis and gasificationtechnologies for MSW is in its infancy in the UK butcommercial scale plant have been built and are inoperation in Europe, North America and Japan.

Examples of Advanced Thermal Treatment plant inthe UK and overseas are included in Table 4.

Grants & Funding

Development of ATT plant will involve capitalexpenditure of several million pounds. There are anumber of potential funding sources for LocalAuthorities (LA) planning to develop such facilities,including:

Capital Grants: general grants may be availablefrom national economic initiatives and EUstructural funds;

Prudential Borrowing: the Local GovernmentAct 2003 provides for a new 'prudential' systemof capital finance controls;

PFI Credits and Private Sector Financing:under the Private Finance Initiative a wasteauthority can obtain an annual subsidy fromcentral government through a Special Grant;

Other Private-Sector Financing: A contractormay be willing to enter into a contract to providea new facility and operate it. The contractor'scharges for this may be expressed as gate fees;and

Other Existing sources of Local Authorityfunding: for example National Non-DomesticRate payments (distributed by centralgovernment), credit (borrowing) approvals, localtax raising powers (council tax), income fromrents, fees, charges and asset sales (capitalreceipts). In practice there will be limitedopportunity to take advantage of these.

Contractual Arrangements

Medium and large scale municipal wastemanagement contracts are usually procured throughthe negotiated procedure of the Official Journal ofthe European Union (OJEU) process.

The contractual arrangement between the privatesector provider (PSP) and the waste disposalauthority (or partnership) may be one of thefollowing:

Separate Design; Build; Operate; andFinance: The waste authority contracts separatelyfor the works and services needed, and providesfunding by raising capital for each of the maincontracts. The contract to build the facility would

be based on the council's design and specificationand the council would own the facility onceconstructed;

Design & Build; Operate; Finance: A contract islet for the private sector to provide both thedesign and construction of a facility to specifiedperformance requirements. The Council owns thefacility that is constructed and makes separatearrangements to raise capital. Operation wouldbe arranged through a separate Operation andMaintenance contract;

Design, Build and Operate; Finance: TheDesign and Build and Operation and Maintenancecontracts are combined. The waste authorityowns the facility once constructed and makesseparate arrangements to raise capital;

Design, Build, Finance and Operate (DBFO):This contract is a Design, Build and OperateContract but the contractor also provides thefinancing of the project. The contractor designs,constructs and operates the plant to specifiedperformance requirements. Regular performancepayments are made over a fixed term to recovercapital and financing costs, operating andmaintenance expenses, plus a reasonable return.At the end of the contract, the facility is usuallytransferred back to the client in a specifiedcondition; and

DBFO with PFI: This is a Design, Build, Financeand Operate contract, but it is procured underthe Private Finance Initiative. In this case thewaste authority obtains funding for futurepayment obligations from Government as asupplement to finance from its own and privatesector sources.

The majority of large scale waste managementcontracts currently being procured in England areDesign, Build, Finance and Operate contracts. ManyWaste Disposal Authorities in two tier Englisharrangements (County Councils) seek to partner withtheir Waste Collection Authorities (usually District orBorough Councils). Sometimes partnerships are alsoformed with neighbouring Unitary Authorities tomaximise the efficiency of the waste managementservice and make the contract more attractive to thePrivate Sector Provider.

Track Record Contractual and Financing Issues

Manufacturer Primary Technology Country Operational Capacity, tpa Feed

Compact Power Tube Pyrolysis UK - Avonmouth 2001 8,000 Clinical Waste

Energos Grate Gasification Norway 1997 10,000 Industrial and Paper Wastes

Energos Grate Gasification Norway 2000 34,000 MSW

Energos Grate Gasification Norway 2001 36,000 MSW and Industrial Waste



Energos Grate Gasification Germany2002

Commissioning37,000 MSW and Industrial Waste


Commissioning80,000 MSW, Commercial, Industrial

Energos Grate Gasification Sweden 2005 80,000 Municipal and Industrial Waste

Enerkem/Novera Fluidised Bed Gasification Spain 2002 25,000 Plastics

FERCO Fluidised Bed Gasification USA 1997 165,000 Biomass

FERCO Fluidised Bed Gasification UK - Winkleigh Devon Planning 100,000 Biomass

Foster Wheeler Finland 1998 80,000 Mix waste

GEM Fast (ablative) Pyrolysis UK - BridgendNot yet

operational60,000 Pre-sorted MSW / RDF

Mitsui Babcock Rotary Kiln Pyrolysis Japan 2000 80,000 MSW






Thermoselect Tube Pyrolysis Germany 1999 225,000 Domestic and Industrial Wastes

Thermoselect Tube Pyrolysis Japan 1999 100,000 Domestic and Industrial Wastes

Thermoselect Tube Pyrolysis Japan 2003 50,000 Industrial Wastes

Techtrade/Wastegen Rotary Kiln Pyrolysis Germany 1984 35,000 RDF

Techtrade/Wastegen Rotary Kiln Pyrolysis Germany 2002 100,000 Domestic and Industrial Wastes

10 11

Whilst ATT technologies are established technologiesfor the treatment of certain specific waste streams, itis only in recent years that such pyrolysis andgasification have been commercially applied to thetreatment of MSW. The prime drivers in the UK forthe development of these technologies areincreasing landfill costs and the implementation ofthe Landfill Directive.

Table 4 : ATT Plant

The development of pyrolysis and gasificationtechnologies for MSW is in its infancy in the UK butcommercial scale plant have been built and are inoperation in Europe, North America and Japan.

Examples of Advanced Thermal Treatment plant inthe UK and overseas are included in Table 4.

Grants & Funding

Development of ATT plant will involve capitalexpenditure of several million pounds. There are anumber of potential funding sources for LocalAuthorities (LA) planning to develop such facilities,including:

Capital Grants: general grants may be availablefrom national economic initiatives and EUstructural funds;

Prudential Borrowing: the Local GovernmentAct 2003 provides for a new 'prudential' systemof capital finance controls;

PFI Credits and Private Sector Financing:under the Private Finance Initiative a wasteauthority can obtain an annual subsidy fromcentral government through a Special Grant;

Other Private-Sector Financing: A contractormay be willing to enter into a contract to providea new facility and operate it. The contractor'scharges for this may be expressed as gate fees;and

Other Existing sources of Local Authorityfunding: for example National Non-DomesticRate payments (distributed by centralgovernment), credit (borrowing) approvals, localtax raising powers (council tax), income fromrents, fees, charges and asset sales (capitalreceipts). In practice there will be limitedopportunity to take advantage of these.

Contractual Arrangements

Medium and large scale municipal wastemanagement contracts are usually procured throughthe negotiated procedure of the Official Journal ofthe European Union (OJEU) process.

The contractual arrangement between the privatesector provider (PSP) and the waste disposalauthority (or partnership) may be one of thefollowing:

Separate Design; Build; Operate; andFinance: The waste authority contracts separatelyfor the works and services needed, and providesfunding by raising capital for each of the maincontracts. The contract to build the facility would

be based on the council's design and specificationand the council would own the facility onceconstructed;

Design & Build; Operate; Finance: A contract islet for the private sector to provide both thedesign and construction of a facility to specifiedperformance requirements. The Council owns thefacility that is constructed and makes separatearrangements to raise capital. Operation wouldbe arranged through a separate Operation andMaintenance contract;

Design, Build and Operate; Finance: TheDesign and Build and Operation and Maintenancecontracts are combined. The waste authorityowns the facility once constructed and makesseparate arrangements to raise capital;

Design, Build, Finance and Operate (DBFO):This contract is a Design, Build and OperateContract but the contractor also provides thefinancing of the project. The contractor designs,constructs and operates the plant to specifiedperformance requirements. Regular performancepayments are made over a fixed term to recovercapital and financing costs, operating andmaintenance expenses, plus a reasonable return.At the end of the contract, the facility is usuallytransferred back to the client in a specifiedcondition; and

DBFO with PFI: This is a Design, Build, Financeand Operate contract, but it is procured underthe Private Finance Initiative. In this case thewaste authority obtains funding for futurepayment obligations from Government as asupplement to finance from its own and privatesector sources.

The majority of large scale waste managementcontracts currently being procured in England areDesign, Build, Finance and Operate contracts. ManyWaste Disposal Authorities in two tier Englisharrangements (County Councils) seek to partner withtheir Waste Collection Authorities (usually District orBorough Councils). Sometimes partnerships are alsoformed with neighbouring Unitary Authorities tomaximise the efficiency of the waste managementservice and make the contract more attractive to thePrivate Sector Provider.

Track Record Contractual and Financing Issues

Manufacturer Primary Technology Country Operational Capacity, tpa Feed

Compact Power Tube Pyrolysis UK - Avonmouth 2001 8,000 Clinical Waste

Energos Grate Gasification Norway 1997 10,000 Industrial and Paper Wastes






Commissioning37,000 MSW and Industrial Waste


Commissioning80,000 MSW, Commercial, Industrial

Energos Grate Gasification Sweden 2005 80,000 Municipal and Industrial Waste

Enerkem/Novera Fluidised Bed Gasification Spain 2002 25,000 Plastics

FERCO Fluidised Bed Gasification USA 1997 165,000 Biomass

FERCO Fluidised Bed Gasification UK - Winkleigh Devon Planning 100,000 Biomass

Foster Wheeler Finland 1998 80,000 Mix waste

GEM Fast (ablative) Pyrolysis UK - BridgendNot yet

operational60,000 Pre-sorted MSW / RDF







Thermoselect Tube Pyrolysis Germany 1999 225,000 Domestic and Industrial Wastes

Thermoselect Tube Pyrolysis Japan 1999 100,000 Domestic and Industrial Wastes

Thermoselect Tube Pyrolysis Japan 2003 50,000 Industrial Wastes

Techtrade/Wastegen Rotary Kiln Pyrolysis Germany 1984 35,000 RDF

Techtrade/Wastegen Rotary Kiln Pyrolysis Germany 2002 100,000 Domestic and Industrial Wastes

12 9

Before initiating any procurement or funding processfor a new waste management treatment facility, thefollowing issues should be considered: performancerequirements; waste inputs; project duration; projectcost; available budgets; availability of sites; planningstatus; interface with existing contracts; timescales;governance and decision making arrangements;market appetite and risk allocation.

Further guidance on these issues can be obtainedfrom:

Defra Procurement Toolkit5;

For Works Contracts: the Institution of CivilEngineers 'New Engineering Contract'6;

For large scale Waste Services Contracts throughPFI and following the Negotiated Procedures the4ps 'Waste Procurement Pack'7; and

Local Government PFI project support guide8.

Char from pyrolysis process

For more information on the contribution of ATT toBest Value Performance Indicators and recycling seeChapter 9 and for the latest developments, see theDefra website4 or contact the Supporter Helpline tel.0870 2409894 [email protected]

Energy RecoveryATT processes are designed to recover energy fromthe waste processed, either in the form of fuelproduction (liquid or gas), or combusting the syngasto generate electricity and/or heat for use on siteand export off site. Examples of energy recoveryfrom case studies are included on the WasteTechnology Data Centre. Energy recovery mayqualify for renewable energy incentives, in the formof Renewables Obligation Certificates (ROCs), seeContribution to National Targets section.

It should be noted that the processes using RDF willhave already incurred energy usage in thepreparation of the fuel and this prepared materialwill have a higher calorific value than raw MSW.

For more information on the contribution of ATT toBest Value Performance Indicators see page 18 andfor the latest developments, see the Defra website4

or contact the Supporter Helpline tel. 0870 [email protected]

Contractual and Financing Issues Markets for the Ouputs

4 http://www.defra.gov.uk/environment/waste/localauth/index.htm

5http://lasupport.defra.gov.uk/Default.aspx?Menu=Menu&Module=Article&ArticleID=102

6available at www.ice.org.uk

7available at www.4ps.gov.uk

8www.local.odpm.gov.uk/pfi/grantcond.pdf

8 13

ATT processes will all produce a gas (usually for energy recovery) and a solid residue (ash or char). Some systemsare also designed with mechanical preparation and sorting equipment to extract recyclables. Table 3 summarisesthe key outputs from ATT processes and the following sections address materials and energy recovery.

Table 3 : Examples of outputs from ATT processes

* care needs to be taken with the chemical composition of this and the hazards associated with it

This section contains information on the planningand regulatory issues associated with ATT facilitiesbased on case studies of existing facilities andinformation on planning from the Office of theDeputy Prime Minister research report9.

Planning

When considering the planning implications for anATT facility the following issues should beconsidered:

• Plant/Facility Siting;

• Traffic;

• Air Emissions/Health Effects;

• Dust/Odour;

• Flies, Vermin and Birds;

• Noise;

• Litter;

• Water Resources;

• Visual Intrusion; and

• Public Concern.

Some of these issues are discussed elsewhere in thisguide but a brief overview of each is provided here.

Plant Siting

ATT can take place in many different buildings at avariety of locations but the following considerationsshould be made:

• Preference should be given to sites for businessuse or traditional commercial/industrial urbanareas. Existing waste management facility sitesmay also be considered;

• The site chosen should be close to the primaryroad network or rail head connection, especially ifit is to be a large scale/centralised facility. The siteshould be appropriate for the movement of HGVtraffic without major restriction. Smaller ATTfacilities may not require such infrastructure tosupport them.

• Under current rules, premiums are only awardedfor electricity generated from renewable sources

in plants such as this. As fuel prices may rise overtime and if supply security is questioned,considerations must always be given to utilisingnot only the electricity from the plant but alsothe waste heat. As a result specific plant shouldlook to be sited close to where its electrical andthermal outputs can be used. In the UK this islikely to reduce the size of such plant.

Traffic

ATT facilities may be served by large numbers ofHGVs (depending on the scale of the facility) with apotential impact on local roads and the amenity oflocal residents. It is likely that the site layout/roadconfiguration will need to be suitable to accept arange of light and heavy vehicles. For a 50,000tpacapacity plant, up to 20 refuse collection vehicles perday would be anticipated.

Air Emissions/Health Effects

Flue GasesIn terms of complying with the Waste IncinerationDirective (WID) the major emission from a plant withenergy recovery is the release of flue gases from thecombustion of the syngas (and in some instances alsothe residual solid, if it has high carbon content). Theclean-up required for the flue gases is dependent onthe process from which they have been generated.One of the main benefits claimed by manufacturersfor pyrolysis and gasification plant is that emissionsof pollutants are lower than those fromconventional mass burn incineration and that plantare designed to comply with the emission limits setout in the Directive.

Entrained (fine) particles in the syngas can either beremoved before or after combustion depending onthe treatment process and combustion technologyemployed.

A further solid residue produced is from abatementplant used to clean-up the flue gases from thecombustion process. Both of these solid streams arehazardous in nature and must be disposed ofappropriately. Often they are combined as they areremoved during the same stage of the flue gasclean-up.

Markets for the Ouputs Planning and Permitting Issues

Ouputs

Slag

State

Solid, fused

Potential Markets

Aggregate

Ash Un-fused residue Aggregate replacement, metals can be separated

Flue GasTreatmentresidue

Solid, powder/sludge.Invariably a hazardouswaste; some potentialfor neutralising wasteacids

Specialist disposal or treatment potential use in chemicaltreatment works (e.g. neutralising acid waste)

Syngas Gaseous Heat or power generation/fuel/some chemical application

Condensate* Liquid Fuel/chemical application

Char Solid Hazardous waste but could be used as coal replacement incertain combustion applications or as a gasifier feedstock

The following section summarises some key issueswith regard to these outputs.

Recovery from ATT

Materials Recycling Recyclables derived from either the front endpreparation stage of an ATT plant or metalsextracted from the back end of the process (i.e. outof the ash) are typically of a lower quality than thosederived from a separate household recyclatecollection system, and generally have a lower value.The types of materials recovered from ATT processesalmost always include metals (ferrous and non-ferrous), usually from the front end of the process.Metal removal can help enhance overall recyclinglevels and enable recovery of certain constituentparts that would not otherwise be collected inhousehold systems (e.g. steel coat hangers, paperclips etc.).

Pyrolysis plant produce a bottom residue thatcontains significant amounts of carbon. This willneed to be disposed of to landfill, or treated furtherto reduce the carbon content for example bygasification or combustion. If treated further thefinal bottom residue could then be recycled as asecondary aggregate. Gasification tends to producea bottom residue which has a lower carbon contentand has usually been melted or fused, and this couldtherefore be recycled as aggregate. The recycling ofbottom ash would need to be undertaken inaccordance with relevant legislation but is likely tobe of equivalent or potentially better quality thanincinerator bottom ash, which is currently recycled inaggregate applications.

9 http://www.odpm.gov.uk/stellent/groups/odpm_planning/documents/page/ odpm_plan_030747.pdf

14 7

In addition to the conventional approach of flue gasclean-up, an alternative approach could be adoptedin which the syngas is cleaned prior to use as a fuelto a level where the resulting flue gases could bereleased to atmosphere without further cleaning.However, the cleaning of syngas to a standard wherethe requirements of the WID no longer apply hasnot yet been demonstrated.

The Defra study on Health & Environmental effectsof Waste Management processes (see FurtherReading) found no evidence of health effects linkedto ATT facilities, however due to the emergentnature of these technologies, the available data wasonly of a moderate quality. More detail on this issueis included in the Defra report10.

Dust/Odour

Any waste management operations can give rise todust and odours. These can be minimised by goodbuilding design, performing all operations undercontrolled conditions indoors, good workingpractices and effective management undertaken fordust suppression from vehicle movements. Many ATTprocesses are designed to operate under negativepressure within buildings to minimise dust andodour problems.

Flies, Vermin and Birds

ATT processing is unlikely to attract vermin and birdsdue to majority of waste throughput and operationsbeing completely enclosed in buildings. However,during hot weather it is possible that flies couldaccumulate, especially if they have been brought induring delivery of the waste. Effective housekeepingand on site management of tipping and storageareas is essential to minimise the risk from verminand other pests. In some operations waste heat fromthe process may be used to bring temperatures infresh input waste to levels above which flies can live.The use of RDF as a feedstock would reduce thisissue relative to raw waste.

Noise

Noise is an issue that will be controlled under thewaste licensing regulations. The main contributors tonoise associated with ATT are likely to be:

• vehicle movements/manoeuvring;

• traffic noise on the local road networks;

• mechanical processing such as waste preparation;

• air extraction fans and ventilation systems;

• steam turbine units; and

• air cooled condenser units.

Litter

Any waste which contains plastics and paper is morelikely to lead to litter problems. With ATT litterproblems can be minimised as long as good workingpractices are adhered to, vehicles use covers andreception and processing are undertaken indoors.

Water Resources

Water will be used but this will be specific to thetechnology and therefore it is not possible to providedetail on the nature of the effluent that might begenerated and how it should be managed. However,as part of the permitting requirements for a facility amanagement plan would be required for effluent.

The case studies on the Waste Technology DataCentre include an assessment of water usage.

Visual Intrusion

Virtual image of proposed ATT facility

Construction of any building will have an effect onthe visual landscape of an area. Visual intrusionissues should be dealt with on a site specific basisand the following items should be considered:

• Direct effect on landscape by removal of itemssuch as trees or undertaking major earthworks;

• Site setting; is the site close to listed buildings,conservation areas or sensitive viewpoints;

Case Studies

Some descriptive examples of ATT processes areincluded here to illustrate the different technologiesbeing promoted for MSW management. Thetechnical details of these and other examples,including mass and energy balances and SWOTanalysis of the strengths, weaknesses, opportunitiesand threats are included on the Waste TechnologyData Centre3.

Waste Gen (Tech Trade) Hamm GermanyThis is a pyrolysis plant. It processes a pre-preparedRDF to produce a syngas that is immediately burnt ina dedicated burner in an otherwise coal fired powerstation boiler. The resulting char after recovery ofmetals using magnets, and aggregate using aballistic separator, is fed into the station coalbunkers.Fuel is delivered to the plant in bales or bulk form,from a range of RDF producers. The fuel is conveyedto the two rotary kiln pyrolyser units (20m in lengthx 2.8m in diameter). Natural gas burners heat thepyrolysis drums.

The two pyrolysis drums replace 10% of the fuelinput to a coal fired 330MWe generating set. TheRDF is regarded as a fuel (at present in the UK it isclassified as waste) and the power station is notWaste Incineration Directive compliant.

KBI Waste & Energy Solutions GmbHThis is a Mechanical & Biological Treatment (MBT)plant followed by an oxygen blown 'down draught'gasifier. The purpose of the waste pre-treatment andthe gasifier is to produce a gas of a quality andconsistency such that the power plant can safely andreliably operate to a defined efficiency and emissionlimits.

Received waste is dried in a rotating compost drumand recyclates are removed. The waste then passesto a feed preparation area where additives such ascoke, (typically 17%) and limestone are introducedprior to gasification.

Oxygen is added at several points down the gasifierprogressively raising the temperature towards themaximum, normally 1500°C.

Additional feeds of steam and natural gas are usedso as to control the composition of the producedgas. The gas is burned in a conventional gas turbineset and the exhaust gas from the turbine is used toraise steam. Some of the steam/electricity is used bythe process with the excess available for export.

GEM, Graveson Energy Management, Romsey,Hampshire, UKThis process uses fast pyrolysis of a Refuse DerivedFuel (RDF see Box 1) to produce a gas suitable forburning or powering an engine. The essentialprinciple behind the process is to rapidly heat thefeed to around 820°C, in the absence of oxygen andhence induce rapid pyrolysis. To do this conventionalRDF floc has to be ground such that one majordimension of each RDF particle is less than 2mm.The ground floc then has to be dried to 5% moisturecontent prior to feeding into the pyrolyser. Thepyrolyser consists of a large vertical steel cylinderheated on its outside surface. A close fittingcylindrical drum is suspended and rotated within thiscylinder. The RDF is fed at the top of the cylinderand by falling through the gap between the cylinderand drum, is rapidly heated. Within a couple ofseconds the RDF has been pyrolysed. Char isseparated from the gas in a cyclone. The gas streamis cooled and scrubbed to remove acid gases. Thecleaned gas is then fed to a spark ignition enginegenerator set. Waste heat from the pyrolyser heater,the engine exhaust, engine cooling and theproduced gas cooler is collected and integrated withthe local heat requirements, hence giving acombined heat and power system.

Summary

This section explains that advanced thermaltreatment processes are primarily pyrolysis and/orgasification based. ATT plant, as highlighted by casestudies, are capital intensive facilities (also see page17) and have a design life of 15 - 25 years. Rigorousevaluation of the technology is essential to reduceany operational risks when processing theanticipated feedstock. Over this timescale thecomposition of waste is likely to alter and theprocess selected should be robust or flexible enoughto treat varying calorific values and compositions ofwaste feedstock.

Planning and Permitting Issues How it Works

10 http://www.defra.gov.uk/environment/waste/research/health/index.htm 3 www.environment-agency.gov.uk/wtd

6 15

The syngas can also be used to fuel a dedicated gasengine. A syngas derived from a very well rungasifier, or which has been further processed forexample by reforming, may be suitable for use in agas turbine. Running these types of plant on syngasis still in its infancy and would require cleaning andcooling prior to use. However, using a gas engine orgas turbine could increase efficiencies for electricitygeneration. This is of particular relevance if aCombined Cycle Gas Turbine (CCGT) or CombinedHeat and Power (CHP) configuration is used (seeTable 2). Whilst high efficiencies can be achievedusing gas engines, the highest efficiencies can onlybe reached using a high calorific value gas.Efficiencies should be checked if using a lowercalorific value gas.

To minimise costs for energy generation, the ATTplant could be located adjacent to an existing powerplant and the syngas transferred to it. This wouldalso provide benefits if the existing plant has ahigher efficiency than a standalone unit. A key issuethat would need to be resolved to allow the transferof the syngas to an adjacent power plant is whetherit would need to comply with the Waste IncinerationDirective (WID). If the Directive covered the powerplant then this could require major improvementworks to the abatement system for controllingemissions and therefore make such an option lessattractive or entirely unviable. Early implementationof the WID and Large Plant Combustion Directivewould in almost all cases outweigh any potentialadvantages to the operator of the power plant.

In addition to using the syngas to produce energy, itcould also be used as a chemical feedstock. Thisoffers a further option for utilising the syngas butwould require the treatment plant to be local to theend user, in order to be a practicable solution. Thiswould require very high gas cleanliness; pollutants,notably sulphur and halogens, may need to beremoved prior to combustion of the gas. Thereduced gas volumes involved in cleaning thecombusted gas rather than the combustion gas givesa financial advantage to the process. Alkalis such aslime and sodium hydroxide are the favouredreagents for removal of the halogen streams.Sulphur can be removed by a variety of routes,largely dependant on the initial concentration(ranging from absorption to the Klaus reaction).

For reference, a summary of the potential netelectrical generating efficiencies for new buildthermal treatment plant employing various energyrecovery options is presented in Table 2. Forcomparison, the performance of a new mass burnincinerator is also provided. Table 4 also includesexamples of efficiencies from specific processes.

Table 2 : Potential net electrical generating efficiencies

• Existing large buildings and structures in the area;

• The potential of a stack associated with some airclean up systems for mixed waste processingoperations may impact on visual intrusion;

• Use of screening features (trees, hedges, banksetc); and

• The number of vehicles accessing the site andtheir frequency.

Many of these facilities are housed in 'warehouse'type clad steel buildings, however use of gooddesign techniques can help minimise visual intrusion.

Size and Landtake

Table 4 shows the land area required for thebuilding footprint and also for the entire site(including supporting site infrastructure) forexamples of Advanced Thermal Treatment facilities.

Table 4 : Landtake

Source:

* Planning for Waste Management Facilities - A Research Study, ODPM 2004

† Waste Technology Data Centre

For more information on Landtake for specific wastemanagement operations, see Defra's WasteTechnology Data Centre.

Public Concern

The Social and Perception Issues section relates topublic concern. In general public concerns aboutwaste facilities relate to amenity issues (odour, dust,noise, traffic, litter etc). With thermal based facilitieshealth concerns can also be a perceived issue.

Environmental Impact Assessment

It is likely that an Environmental Impact Assessment(EIA) will be required for an ATT facility as part ofthe planning process.

Whether a development requires a statutory EIA isdefined under the Environmental Impact Assessment(England and Wales) Regulations 1999. Furtherguidance is available in the DETR circular 02/99 onEnvironmental Impact Assessment.

For more information on Planning issues associatedwith waste management options see Planning forWaste Management Facilities - A Research Study.ODPM, 2004 see footnote 9.

Licensing/Permitting

Currently, the interpretation of all AdvancedThermal Treatment operations is that they require aPollution Prevention & Control (PPC) permit. It wouldbe prudent to assume that any facilities will becovered by the PPC Regulations.

For more information on licensing & permitting seethe Environment Agency web site11.

How it Works Planning and Permitting Issues

EnergySystems

Steam Boilerand Turbine

Efficiencies ofPyrolysis/Gasification

Treatment Plant

Efficienciesof

Incinerator

Gas Engine

CombinedCycle GasTurbine

Co-firing inexistingpower plant

10% - 20%

13% - 28%

30%

Up to 27%

19 - 24%

n/a

n/a

n/a

11 http://www.environment-agency.gov.uk/subjects/waste/?lang=_e

TTFacility

TotalLandtake

Ha

BuildingsAream2

Size,tonnes

perannum

IndicativeStack

Height

MassBurn*

90,000 5,850 1.7 65m

MassBurn*

250,000 6,600 4 70m

Pyrolysis† 60,000 - 0.98 -

Pyrolysis† 12,500 200 + access

Pyrolysis† 35,000 28,000 -32,000 4 -

'GeneralATT'*

50,000 3,600 1-2 30 - 70m

16 5

This section contains a discussion of the social andenvironmental considerations of ATT facilities.

Social Considerations

Any new facility is likely to impact on local residentsand may result in both positive and negativeimpacts. Potential impacts on local amenity (odour,noise, dust, landscape) are important considerationswhen siting any waste management facility. Theseissues are examined in more detail in the Planning &Permitting chapter of this Brief. Transport impactsassociated with the delivery of waste and onwardtransport of process outputs may lead to impacts onthe local road network. The Planning andPermitting chapter of this Brief provides an estimateof potential vehicle movements.

An ATT facility may also provide positive socialimpacts in the form of employment and educationalopportunities. Typical employment for a ATT plantof 50,000tpa capacity would be 2-6 workers per shift.The plant would operate on a shift system, to allowfor 24-hour operations. These facilities are also likelyto provide vocational training for staff. Newfacilities may be built with a visitor centre to enablelocal groups to view the facility and learn moreabout how it operates.

Public Perception

Public opinion on waste management issues is wideranging, and can often be at extreme ends of thescale. Typically, the most positively viewed wastemanagement options for MSW are recycling andcomposting. However, this is not necessarily reflectedin local attitudes towards the infrastructurecommonly required to process waste to compost, orsort mixed recyclables, or indeed to have an extrawheeled bin! It should be recognised that there isalways likely to be some resistance to any wastemanagement facility within a locality.

At present there is a relatively low level ofunderstanding of the concept of ATT by the public.There are no full scale commercial ATT operations inthe UK processing MSW. In public consultations thesetechnologies score inconsistently when explained indetail as a residual waste treatment technology.There is a general distrust of thermal systems in theUK, however some ATT providers accentuate thedifferences of their systems from incineration as akey part of the promotion of their technology.

Overseas development of advanced thermaltreatment again shows inconsistencies in publicopinion. In Australia developments of ATT plantreceived similar perceptions to that of incineration,partly due to campaigns from nationalenvironmental groups claiming parallels betweenthe technologies. The national environmentcampaign organisations in the UK are divided on thisissue. The UK public opinion has yet to be tested onATT proposals.

Overall, experience in developing wastemanagement strategies has highlighted theimportance of proactive communication with thepublic over waste management options. The use ofrealistic and appropriate models, virtual 'walk -throughs' / artists impressions should be used toaccurately inform the public. Good practice in termsof public consultation and engagement is animportant aspect in gaining acceptance for planningand developing waste management infrastructure.Defra are funding the development of small tomedium scale demonstration plant in England forlocal authorities to visit and for Defra to publishdata on performance. For more information contactthe New Technologies Supporter helpline on tel.0870 2409894 [email protected]

Table 1 : Thermal Treatment Reactors

Gas and Residue Treatment

Solids will inevitably be discharged from the process.These solids include metals together with carbon. Inthe case of gasification, the level of carbon is small;in pyrolysis it is significant. Larger particles of solidsin the thermal treatment reactor are usuallydischarged as bottom ash. Lighter ash is usuallycollected when the gas is separated with the use ofcyclones and ultimately filters. In addition, volatilemetals such as lead, tin, cadmium and mercury willbe carried in the gas until such point that the gas iscooled for them to be sufficiently condensed.

Energy Recovery/Utilisation of Syngas

One of the potential benefits of pyrolysis andgasification is that the syngas can be used in anumber of different ways.

In terms of producing energy, the most commonconfiguration is to burn the syngas in a boiler togenerate steam. The steam can then be used togenerate electricity by passing it through a steamturbine and, if there is a demand local to the plant,for heating. Using the heat in addition togenerating electricity improves the overall energyefficiency of the system significantly.

Social and Perception Issues How it Works

Reactor Typical Application Operating Conditions

Typically operate at low temperatures of around 400 - 600°C.The unit can accommodate large size feed material (200 mm).The kiln is heated externally and waste is fed in from one endof the kiln which slowly rotates creating a tumbling action.This mixes the waste and ensures contact with the heatingsurface and gases inside the kiln.

The tubes are heated externally and temperatures as high as800°C are used. The process can accommodate large size feedmaterial. The waste passes through the tube at a set speed toensure the pyrolysis process is complete.

Small size feed material required and therefore significant pre-treatment is necessary. The process operates at hightemperatures and the small size of the feed gives high heatingrates. The application of this technology is to maximise therate of pyrolysis.

Fluidised bed technology may be used for gasification orcombustion processes. The bed is a mass of particles (typicallyalumina) that has similar characteristics to a moving fluid. Thisis achieved by blowing hot gases through the bed of particles.This system provides good mixing and heat transfer to theincoming waste. Waste is pre-treated to remove large sizedmaterial. This technology is well suited to the gasification ofRefuse Derived Fuels.

There are a range of different reactor types that come underthis heading. A typical example is a grate system where thefeed passes along the grate and hot gases pass through thebed of waste heating it.

Rotating Kiln

Heated Tube

Surface Contact

Fluidised Bed

Fixed Bed

Pyrolysis

Pyrolysis

Pyrolysis

Gasification

Gasification

4 17

ATT Technology Overview

The actual plant design and configuration of ATTfacilities will differ considerably between technologyproviders. However, an ATT plant will typicallyconsist of the following key elements:

• Waste reception, handling and pre-treatment;

• Thermal treatment reactor;

• Gas and residue treatment plant (optional);

• Energy recovery plant (optional); and

• Emissions clean-up (see page 13).

Waste Reception, Handling and Pre-treatmentThe pyrolysis and gasification process is focused ontreating the organic based materials present in MSW(e.g. paper, plastics, card, putrescible waste, greenwaste). Therefore, non combustible materials andrecyclables, (typically metals and glass) may beremoved prior to the thermal treatment reactorstage. In addition and depending on the technologyemployed, the feed material might requireprocessing to remove excess moisture, and shreddingto reduce the size.

It is the preference (for most ATT processes) to treatonly pre-processed MSW that makes these systemsappropriate to be integrated into a wider municipalwaste management strategy. ATT processes may forexample be used in conjunction with sortingtechnologies such as those employed in MechanicalBiological Treatment plant (MBT - see separate Brief,in this series). Some MBT plant are designed to

produce a fuel stream(primarily composed ofpaper, card and plastics) asone of the outputs fromthe process. This iscommonly referred to asrefuse derived fuel or RDF(see Box 1). This may bemore amenable toprocessing in an ATT plantrather than raw MSW.

Refuse Derived Fuel

Thermal Treatment ReactorThe primary thermal treatment, whether pyrolysis orgasification, will produce syngas and solid residue.The composition of the syngas and solid residue willdepend on the process conditions employed, whichinclude operating temperature, oxygen level,heating rate and residence time in the reactor.

The main types of thermal treatment units available,their application and operating conditions aresummarised in Table 1. [There are also other factorsinfluencing the process such as direction of gas flow(e.g. horizontally or vertically)].

The cost of constructing, operating and maintainingATT facilities are addressed using a common costmodel on Defra's Waste Technology Data Centre.Both capital and operating costs are included forspecific technologies which may be used for thepurposes of indicative comparisons rather thanaccurate reflections of actual costs.

Typically around 40% of the capital costs foroperating a plant will be to cover capitaldepreciation. As a result these need to be viewed aslarge capital investments (which will requirereplacement components during its lifetime) with alifespan of not less than 10 or more usually 20 years.

Plants of this type have been applied to chemicaland process industries; these have all been largescale, capital intensive applications.

It is vital in any negotiation, that a true appreciationof the cost of essential repairs and refurbishment betaken into account.

For cost information on examples of differentprocesses see Defra's Waste Technology Data Centre.

www.environment-agency.gov.uk/wtd

How it Works Costs of Advanced Thermal Treatment

Box 1 Fuel from mixed waste processingoperations

The current prevalent term used for a fuel producedfrom combustible waste is refuse derived fuel (RDF).The types of technologies used to prepare/segregate a fuel fraction from MSW include manyof the MBT and Mechanical Heat Treatmentprocesses described within another Brief in thisseries. A CEN Technical Committee (TC 343) iscurrently progressing standardisation work on fuelsprepared from wastes, classifying a Solid RecoveredFuel (SRF). It is anticipated that once standards aredeveloped and become accepted by users, SRF willbecome the terminology used by the wastemanagement industry. Other terminology has alsobeen introduced to the industry as various fuelcompositions may be prepared from waste bydifferent processes. Examples include'Biodegradable Fuel Product' (BFP) and 'RefinedRenewable Biomass Fuel' (RRBF).

Within this Brief, refuse derived fuel is used as aterm to cover the various fuel products processedfrom MSW.

Advanced Thermal Treatment - GasificationGasification can be seen as between pyrolysis andcombustion in that it involves the partial oxidationof a substance. This means that oxygen is addedbut the amounts are not sufficient to allow the fuelto be completely oxidised and full combustion tooccur. The temperatures employed are typicallyabove 750ºC. The main product is a syngas, whichcontains carbon monoxide, hydrogen and methane.Typically, the gas generated from gasification willhave a net calorific value (NCV) of 4 - 10 MJ/Nm3.The other main product produced by gasification isa solid residue of non-combustible materials (ash)which contains a relatively low level of carbon.

[For reference, the calorific value of syngas frompyrolysis and gasification is far lower than naturalgas, which has a NCV of around 38 MJ/Nm3.]

18 3

Recycling

Recyclate derived from an ATT plant processinghousehold waste qualifies for BVPI 82a (Recycling)for any materials recovered prior to the thermaltreatment reactor. Any materials recovered after thethermal treatment (e.g. metals from the ash), do notcount towards BVPI 82a. Equally any char or ashrecycled does not count towards BVPI 82a.

The material must pass to the reprocessor (and notbe rejected for quality reasons) to count as recycling.It should be noted that if additional materials areextracted from the front end of the process forrecycling, they may experience market limitationsdue to being derived from a mixed MSW source.

Further information about BVPIs can be obtainedfrom the Defra website and associated links12.

Recovery

ATT technologies will contribute towards recoverytargets on the tonnage of materials entering thethermal treatment process as all processes aredesigned to recovery energy. For more informationsee the Defra website and associated links14 and theguidance on BVPI 82c.

Landfill Allowance Trading Scheme (LATS)

The European Landfill Directive and the UK'senabling act, the Waste & Emissions Trading Act2003, require the diversion of BiodegradableMunicipal Waste (BMW) from landfill. ATT systemswill divert 100% of the BMW passing through thethermal process from landfill as the output (char orash) will not be classified as biodegradable even ifdisposed to landfill. Up to date information relatingto LATS can be obtained from the New TechnologiesSupporter Helpline and Defra's LATS informationwebpage13.

Renewable Energy

The Renewable Obligation (RO) was introduced in2002. Its function is to promote the development ofelectricity generated from renewable sources ofenergy. The obligation requires an increasingpercentage of the electricity supplied to be from

renewable sources for each year through to 2010.The target for 2010 is set at 10%. The ROconsultation for 2005 proposed that the targets forthe obligation are extended, with a target of 15%proposed for 2015. The obligation requires suppliersto surrender certificates (known as RenewableObligation Certificates - ROCs) to demonstrate thatthey have supplied the required amount ofrenewable electricity. If the supplier cannotsurrender the required amount of certificates it canbuy out the shortfall at a price of 3 p/kWhe. Thisbuy out means that ROCs have a value and thereforegenerators of renewable electricity (as defined in theobligation) can sell the electricity they generate andthe ROCs, which means they receive a premium forthe power they produce. The value of a ROC isdependent on availability. If the suppliers fail tomeet their target set in the RO then certificates willbe worth more than the buy out price of 3 p/kWhe.However, if the available quantity of renewableenergy exceeds the target then the value of ROCswould drop.

To encourage the development of Advanced ThermalTreatment technologies, the RO was amended in2004. The amendment stated:

"A generating station shall be an excludedgenerating station in any month during which itis fuelled with waste or partly by waste unless -(a) the only waste by which it is fuelled isbiomass; or (b) all of the waste by which it isfuelled in that month which is not biomass hasfirst been manufactured into a fuel which is ineither a gaseous or liquid form (or both) bymeans of a plant and equipment using advancedconversion technology only."

This means that renewable fraction of the electricitygenerated from the Advanced Thermal Treatment ofMSW is eligible for ROCs. [The renewable fraction isthe gross energy content of the waste that isconsidered to be renewable (biomass)] This wouldprovide an additional revenue stream for a proposedplant, as long as it meets the qualifyingrequirements. As the value of a ROC is not fixed, thelong term value would need to be assessed in detailto determine its overall financial value to theproject.

The renewable obligation is currently out toconsultation for a proposed revised system.

This section comprises an overview of the principlesof Advanced Thermal Treatment processes.

Advanced Thermal Treatment

Advanced thermal treatment technologies areprimarily those that employ pyrolysis and/orgasification to process municipal solid waste (MSW).It excludes incineration2 of wastes which is already amature and well established technology.

The gasification and pyrolysis of solid materials is nota new concept. They have been used extensively toproduce fuels such as charcoal, coke and town orproducer gas. Charcoal and coke are produced bypyrolysing wood and coal respectively and producergas is a combustible gas produced by the gasificationof coke in the presence of air and steam.

It is only in recent years that such pyrolysis andgasification have been commercially applied to thetreatment of MSW. The development of pyrolysisand gasification technologies is in its infancy in theUK but large scale plants have been built and are inoperation in Europe, North America and Japan.

Advanced thermal treatment plant

i

Contribution to National Targets How it Works

Difference between Pyrolysis, Gasificationand Incineration

There are a variety of differences promoted todifferentiate advanced thermal treatment fromtraditional incineration technologies. Onedistinction is that smaller scale facilities are beingmarketed for treatment of MSW with some ATTprocesses than the scale typical of incineration. It isthe difference in scale and size that allows the localuse of both heat and electricity produced, and theprocess differences are described below. Pages 13to 16 discuss planning and public perceptionaspects of ATT .

Established Thermal Treatment - IncinerationIncineration usually involves the combustion ofunprepared (raw or residual) MSW. To allow thecombustion to take place a sufficient quantity ofoxygen is required to fully oxidise the fuel.Typically, incineration plant combustion (flame)temperatures are in excess of 850ºC and the wasteis converted into carbon dioxide and water. Anynon-combustible materials (e.g. metals, glass)remain as a solid, known as Bottom Ash, thatcontains a small amount of residual carbon.

Advanced Thermal Treatment - PyrolysisIn contrast to combustion, pyrolysis is the thermaldegradation of a substance in the absence ofoxygen. This process requires an external heatsource to maintain the temperature required.Typically, relatively low temperatures of between300ºC to 800ºC are used during pyrolysis ofmaterials such as MSW. The products producedfrom pyrolysing materials are a solid residue and asynthetic gas (syngas). The solid residue (sometimesdescribed as a char) is a combination of non-combustible materials and carbon. The syngas is amixture of gases (combustible constituents includecarbon monoxide, hydrogen, methane and a broadrange of other volatile organic compounds). Aproportion of these can be condensed to produceoils, waxes and tars. The syngas typically has a netcalorific value (NCV) of between 10 and 20 MJ/Nm3.If required, the condensable fraction can becollected by cooling the syngas, potentially for useas a liquid fuel.

2Incineration of MSW in the UK always involves some form of energyrecovery, either in the form of electricity generation and/or heat recovery.As such it is also commonly termed Energy from Waste. Mass burnincineration is another term used to refer primarily to large scale plantburning untreated waste. In this document we will refer to 'incineration' todistinguish from Advanced Thermal Treatment.

12 http://www.defra.gov.uk/environment/waste/localauth/index.htm13 http://www.defra.gov.uk/environment/waste/localauth/lats/index.htm14 http://www.defra.gov.uk/environment/waste/localauth/index.htm

2 19

Municipal Solid Waste (MSW) is waste collected by oron behalf of a local authority. It comprises mostlyhousehold waste and it may include somecommercial and industrial wastes. Nationally, thequantity of MSW is currently increasing year on year,presenting a growing problem for local authoritiesparticularly as new legislation, which limits (byimplication1) the amount of mixed MSW that can besent to landfill, comes into effect.

One of the guiding principles for European and UKwaste management has been the concept of ahierarchy of waste management options, where themost desirable option is not to produce the waste inthe first place (waste prevention) and the leastdesirable option is to dispose of the waste with norecovery of either materials and/or energy. Betweenthese two extremes there are a wide variety of wastetreatment options that may be used as part of awaste management strategy to recover materials (forexample furniture reuse, glass recycling or organicwaste composting) or generate energy from thewastes (for example through incineration, ordigesting biodegradable wastes to produce usablegases).

At present more than 75% of all MSW generated inEngland is disposed of in landfills. However,European and UK legislation has been put in placeto limit the amount of biodegradable municipalwaste (BMW) sent for disposal in landfill. Thediversion of this material is currently the mostsignificant challenge facing the management ofMunicipal Solid Waste in the UK.

There are a wide variety of alternative wastemanagement options and strategies available fordealing with Municipal Solid Waste to limit theresidual amount left for disposal to landfill. The aimof this guide is to provide impartial informationabout the range of technologies referred to asAdvanced Thermal Treatment (ATT). Thesetechnologies are designed to recover energy (in theform of heat, electricity or fuel) and can contributeto the diversion of BMW from landfill. They are partof a range of new alternatives currently beingassessed and investigated through the NewTechnologies work stream of Defra.

Further details about the new technologies featuredin this report are available from Defra's WasteTechnology Data Centre:

http://www.environment-agency.gov.uk/wtd

The technologies described in this Brief - AdvancedThermal Treatment - have a limited track record inthe UK (and indeed internationally) on MSW. Thereare many examples of ATT processes that areestablished as viable and bankable on various wastestreams (e.g. biomass, industrial wastes, tyres etc)but a lesser number proven on municipal wastes. Theaim of this document is to raise awareness of thetechnologies available and help remove barriers tothe development of appropriate ATT processes inEngland.

This guide is designed to be read in conjunction withthe other Waste Management Technology Briefs inthis series and with the case studies provided onDefra's Waste Technology Data Centre. Otherrelevant sources of information are identifiedthroughout the document.

Up-to-date information regarding RDF and ROCs canbe obtained from the DTI website or the NewTechnologies Supporter Helpline tel. 0870 2409894 [email protected]

The Waste Technology Data Centre www.environment-agency.gov.uk/wtd

New Technologies Supporter Helpline Tel. 0870 240 9894 E: [email protected]

Defra New Technologies website,http://www.defra.gov.uk/environment/waste/wip/newtech/index.htm

The Viability of Advanced Thermal Treatment of MSWin the UK, Fichtner Consulting Engineers Ltd, ESTET,2004.

Integrated Pollution Prevention and Control, DraftReference Document on Best Available Techniquesfor the Waste Treatments Industries, EuropeanCommission - Directorate General Joint ResearchCentre, January 2004.

Energy from Waste - A Good Practice Guide, Energyfrom Waste working group, CIWM, 2003.

Refuse Derived Fuel, Current Practice andPerspectives (B4-3040/2000/306517/Mar/E3), EuropeanCommission - Directorate General Environment, July 2003.

Review of Environmental & Health Effects of WasteManagement, Enviros Consulting Ltd, University ofBirmingham, Open University & Maggie Thurgood.Defra 2004.

AiIE Ltd, 2003, Review of residual waste treatmenttechnologies, Report prepared on behalf of Kingstonupon Hull City Council and East Riding of YorkshireCouncil.http/www.eastriding.gov.uk/environment/pdf/waste_treatment_technologies.pdf

The Additional Paper to the Strategy Unit, WasteNot Want Not study, 'Delivering the LandfillDirective: The Role of New & EmergingTechnologies', Dr Stuart McLanaghanhttp://www.number10.gov.uk/files/pdf/technologies-landfill.pdf

Planning for Waste Management Facilities - AResearch Study. Enviros Consulting Ltd. ODPM, 2004.http://www.odpm.gov.uk/stellent/groups/odpm_planning/documents/page/odpm_plan_030747.pdf

Procurement Toolkithttp://lasupport.defra.gov.uk/Default.aspx?Menu=Menu&Module=Article&ArticleID=102

For Works Contracts: the Institution of CivilEngineers 'New Engineering Contract'www.ice.org.uk

For large scale Waste Services Contracts through PFIAND following the Negotiated Procedures the 4ps'Waste Procurement Pack' www.4ps.gov.uk

Introduction Further Reading and Sources of Information

1Targets pertain to the biodegradable fraction

20 1

This Waste Management Technology Brief is one of a series of documents prepared under the NewTechnologies work stream of the Defra Waste Implementation Programme. The Briefs areaddressing potentially important new technologies which may have an increasing role in divertingMunicipal Solid Waste (MSW) from landfill into a more sustainable and integrated wastemanagement alternative, extracting materials and energy from MSW for recovery and reducingquantities remaining for disposal. Other titles in this series include: An Introductory Guide to WasteManagement Options; Advanced Biological Treatment; Mechanical Biological Treatment &Mechanical Heat Treatment.

It should be noted that these documents are intended as guides to each generic technology areaand for more detailed or specific information on any particular technology, it is recommended thatthe Defra Waste Technology Data Centre is used as a resource. These Briefs deal primarily with thetreatment and processing of unsorted MSW and not source segregated wastes which are addressedby the activities of the Waste & Resources Action Programme (WRAP). Relevant references andsources of further information are cited throughout each document in this series.

The prime audience for these Briefs are local authorities, in particular waste management officers,members and other key decision makers for MSW management in England. For further informationon new technologies contact the New Technologies Supporter Helpline on 0870 2409894, email:[email protected]

Prepared by Enviros Consulting Limited on behalf of Defra as part of the New TechnologiesSupporter Programme.

We acknowledge support from the Department for Environment, Food & Rural Affairs, theEnvironment Agency, the Waste and Resources Action Programme, RPS and Be Environmental Ltd.

Disclaimer: Please read the note below before using this Document

This Document has been produced by Enviros Consulting Limited (Technical Advisors) on behalf ofDefra to provide assistance to Local Authorities and the waste management market generallythrough awareness raising of the key municipal waste management options for the diversion of BMWfrom landfill. The Document has been developed in good faith by the Advisors on behalf of Defra,and neither Defra nor its Advisers shall incur any liability for any action or omission arising out of anyreliance being placed on the Document by any Local Authority or organisation or other person. AnyLocal Authority or organisation or other person in receipt of this Document should take their ownlegal, financial and other relevant professional advice when considering what action (if any) to takein respect of any waste strategy, initiative, proposal, or other involvement with any wastemanagement option or technology, or before placing any reliance on anything contained therein.

Crown Copyright, 2005v.1.0

Glossary Preamble

Advanced Thermal Treatment (ATT)

Waste management processes involving medium and hightemperatures to recover energy from the waste. Primarily pyrolysisand gasification based processes, excludes incineration.

Aerobic In the presence of oxygen.

Biodegradable Capable of being degraded by plants and animals. Biodegradablemunicipal waste includes paper and card, food and garden waste,and a proportion of other wastes, such as textiles.

Biodegradable Municipal Waste (BMW)

The component of Municipal Solid Waste capable of beingdegraded by plants and animals. Biodegradable Municipal Wasteincludes paper and card, food and garden waste, and a proportionof other wastes, such as textiles.

Co-combustion Combustion of wastes as a fuel in an industrial or other (non wastemanagement) process.

Feedstock Raw material required for a process.

Floc A small loosely aggregated mass of flocculent material. In thisinstance referring to Refuse Derived Fuel or similar.

Gasification Gasification is the process whereby carbon based wastes are heatedin the presence of air or steam to produce a solid, low in carbonand a gas. The technology is based on the reforming process usedto produce town gas from coal.

Greenhouse Gas A term given to those gas compounds in the atmosphere thatreflect heat back toward earth rather than letting it escape freelyinto space. Several gases are involved, including carbon dioxide(CO2), methane (CH4), nitrous oxide (N2O), ozone, water vapourand some of the chlorofluorocarbons.

Green Waste Waste vegetation and plant matter from household gardens, localauthority parks and gardens and commercial landscaped gardens.

Global Warming The progressive gradual rise of the earth's surface temperaturethought to be caused by the greenhouse effect and responsible forchanges in global climate patterns. An increase in the near surfacetemperature of the Earth. Global warming has occurred in thedistant past as the result of natural influences, but the term is mostoften used to refer to the warming predicted to occur as a result ofincreased emissions of greenhouse gases form man-made sources.

Incineration The controlled thermal treatment of waste by burning, either toreduce its volume or toxicity. Energy recovery from incineration canbe made by utilising the calorific value of the waste to produceheat and/or power.

Materials RecyclingFacility/Materials Recovery Facility (MRF)

Dedicated facility for the sorting/separation of recyclable materials.

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Page number

Preamble 1

Introduction 2

How it Works 3

Advanced Thermal Treatment 3Difference between Pyrolysis, Gasification and Incineration 3ATT Technology Overview 4Case Studies 7Summary 7

Markets for the Outputs 8

Recovery from ATT 8

Track Record 10

Contractual and Financing Issues 11

Grants and Funding 11Contractual Arrangements 11

Planning and Permitting Issues 13

Planning 13Plant Siting 13Traffic 13Air Emissions/Health Effects 13Dust/Odour 14Flies, Vermin and Birds 14Noise 14Litter 14Water Resources 14Visual Intrusion 14Size and Landtake 15Public Concern 15Environmental Impact Assessment 15Licensing/Permitting 15

Social and Perception Issues 16

Social Considerations 16Public Perception 16

Costs of Advanced Thermal Treatment 17

Contribution to National Targets 18

Recycling 18Recovery 18Landfill Allowance Trading Scheme (LATS) 18Renewable Energy 18

Further Reading and Sources of Information 19

Glossary 20

Contents Glossary

Mechanical Biological Treatment (MBT)

A generic term for mechanical sorting/separation technologies usedin conjunction with biological treatment processes, such ascomposting.

Municipal Solid Waste (MSW) Household waste and any other wastes collected by the WasteCollection Authority, or its agents, such as municipal parks andgardens waste, beach cleansing waste, commercial or industrialwaste, and waste resulting from the clearance of fly-tippedmaterials.

Pyrolysis During Pyrolysis organic waste is heated in the absence of air toproduce a mixture of gaseous and/or liquid fuels and a solid, inertresidue (mainly carbon).

Recyclate/Recyclable Materials Post-use materials that can be recycled for the original purpose, orfor different purposes.

Recycling Involves the processing of wastes, into either the same product or adifferent one. Many non-hazardous wastes such as paper, glass,cardboard, plastics and scrap metals can be recycled. Hazardouswastes such as solvents can also be recycled by specialist companies.

Refuse Derived Fuel (RDF) A fuel produced from combustible waste that can be stored andtransported, or used directly on site to produce heat and/or power.

Renewables Obligation Introduced in 2002 by the Department of Trade and Industry, thissystem creates a market in tradable renewable energy certificates,for which each supplier of electricity must demonstrate compliancewith increasing Government targets for renewable energygeneration.

Solid Recovered Fuel Refuse Derived Fuel meeting a standard specification, currentlyunder development by a CEN standards committee.

Source-segregated/Source-separated

Usually applies to household waste collection systems whererecyclable and/or organic fractions of the waste stream areseparated by the householder and are often collected separately.

Statutory Best Value Performance Indicators

Local Authorities submit performance data to Government in theform of annual performance indicators (PIs). The Recycling andComposting PIs have statutory targets attached to them thatAuthorities are required to meet.

Syngas 'Synthetic gas' produced by the thermal decomposition of organicbased materials through pyrolysis and gasification processes. Thegas is rich in methane, hydrogen and carbon monoxide and may beused as a fuel or directly combusted to generate electricity.

www.defra.gov.uk

Advanced Thermal Treatment of Municipal Solid Waste

www.defra.gov.uk

Documents

of Municipal Solid Waste Advanced Thermal Treatment · management options and strategies available for dealing with Municipal Solid Waste to limit the residual amount left for disposal