165 IEAPositionPaperMSWfinal[1][1]

8/12/2019 165 IEAPositionPaperMSWfinal[1][1]

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E xCo 2003:02

A Position Paper Prepared by IEA Bioenergy

Municipal Solid Waste andits Role in Sustainability


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M unicipal S olid W aste (M S W ) is prim arily w aste w hich is produced by the

household,but also includes som e com m ercial and industrial w aste that is sim ilar in

nature to household w aste and has been deposited in m unicipal landfill sites.M S W

can be a liability if requiring disposal but also represents a considerable resource

that can be beneficially recovered,e.g.,by the recycling of m aterials such as

alum inium cans,m etals,glass,fibres,etc.,or through recovery operations such as

conversion to energy and com posting.H ow ever,significant quantities of M S W

continue to be disposed of in landfill largely due to its low cost and ready

availability.In the E uropean U nion the landfill directive (1999/31/E C ),as w ell as

m any national regulations,w ill reduce by 65% of the 1995 level,the am ount of

biodegradable m aterials going to landfill by 2016. C learly,new w aste m anagem ent

practices are needed.

In landfill the biodegradable com ponents of M S W (e.g.,paper and food w astes)

decom pose and em it m ethane a greenhouse gas 23 tim es m ore potent than carbon

dioxide (IP C C ,2001) and the cause of significant environm ental problem s.O ther

com ponents (e.g.,leachate) can also cause significant environm ental pollution in airand ground w ater,and give rise to odour.In general,valuable resources are w asted.

For these reasons m ost countries aim to reduce their dependence on the use of

landfills for M S W .The E U countries in particular have set am bitious targets for

reduction in the biodegradable com ponent of M S W consigned to landfill and a

consequent increase in M S W subjected to recycling and recovery operations.S om e

E uropean countries,e.g.,S w eden,G erm any and the N etherlands,have already

decided to ban the biodegradable fraction from landfills in the com ing years.In

state-of-the-art landfills the gas is extracted and used for energy purposes.

M any developed countries have adopted the principle of the w aste hierarchy in order

to guide their policies on M S W m anagem ent.The hierarchy (Figure 1) lays out the

preferred options for m anaging the w aste from the point w here it arises through to

final disposal.

Introduction

Cover Picture: M SW D istrict H eat P lant Spittelau,V ienna. Courtesy Fernw rm e W ien,V ienna, A ustria.

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Figure 1: The W aste H ierarchy

W here it is econom ically viable,and environm entally sound,recycling of m aterials

is preferable to treatm ent for energy recovery.In practice,how ever,even in

countries w ith highly developed recycling infrastructure,significant tonnages of

M S W rem ain after recycling to m ake energy recovery an environm entally justified

and econom ically viable option ahead of final disposal to landfill.R esearch,dem onstration and dissem ination are now focusing on the balance betw een w aste

m inim isation,m aterial recycling,energy recovery and landfill of the non-

biodegradable fractions.

W hilst the com position of M S W can be highly variable,particularly betw een

developed and developing nations,the rem oval of m aterials for recycling tends to

leave a residue that has a significant calorific (heat) value m aking it suited to

energy recovery operations.Typically,a tonne of M S W has about one-third of the

calorific value of coal (8-12 M J/kg as received for M S W and 25-30 M J/kg for

coal) and can give rise to about 600 kW h of electricity.Traditionally,m ixed w aste

is incinerated in m ass burning facilities;how ever,the trend w ith new installations is

to higher efficiencies in pow er and C om bined H eat and P ow er (C H P ) production.

S om e countries have a m inim um efficiency requirem ent.R ecent legislation in the

E U and A ustralia classifies only the renew able biom ass fraction of M S W -based

pow er production as renew able electricity.

M S W should thus be seen as a resource to be exploited rather than a w aste

requiring disposal.

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Environmental Benefits and Impacts

A s w ith all renew able energy technologies,the m ajor benefit associated w ith

energy recovery from M S W is a reduction of the gaseous pollutants that cause

both local and global effects.R ecently the IE A com pleted a com prehensive study

of the positive and negative im pacts of a range of renew able energy technologies.

The study adopted a life-cycle-based approach so that em issions related to the

m anufacture of system s,their construction,operation and disposal w ere taken into

account.The study found that,for conventional M S W energy recovery system s

(e.g.,m ass burn),the total em ission of CO 2 is 1100 kg per tonne of M S W and

1833 gram s of C O 2 per kW h.Various assessm ents have show n that about 20-40%

(depending strongly on the degree of separate collection of paper and organicw aste) of the carbon in M S W is derived from fossil sources,e.g.,plastics (see

Figure 9).The rem ainder is derived from biom ass and can be considered a

renew able resource.Thus the non-renew able elem ent of the em ission is about 367

gram s of C O 2 per kW h (i.e.,20% of the total em ission of 1833 gram s of C O 2 per

kW h).In F igure 2 typical C O 2 em issions from M S W are com pared w ith those

from fossil fuel sources.

Figure 2: Life C ycle C O 2 em issions gram s per kW h of electricity

The C O2 em ission show n for M S W in F igure 2 does not take into account

em issions that are avoided as a consequence of recovering energy from M S W .F or

exam ple,if the M S W w as consigned to landfill then about 70 kg of m ethane

(actual range 50-100 kg) could be released for each tonne of w aste.G iven the

higher global w arm ing potential of m ethane,this is equivalent to 1610 kg C O 2 pertonne of M S W .In m odern landfills about half of the m ethane can be extracted

and utilised for energy production,therefore reducing the overall em issions.

F urther,the generation of energy from M S W avoids the em issions related to

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generating that energy from fossil sources.The recovery of energy from M S W can

therefore lead to a net reduction in greenhouse gas em issions (see Figure 3).Thus,taking even the m ost pessim istic view ,i.e.,ignoring the benefits of avoiding landfill,

energy recovery from M S W leads to significant savings of greenhouse gas em issions

w hen com pared to conventional generation of energy from fossil fuels.

Figure 3: G reenhouse gas em issions from electricity production:M S Wincineration com pared to coal com bustion and landfilling of M S W .(kW he = kilow att hour of electricity)

Other recent results of studies on the im pact of solid w aste treatm ent system s on

greenhouse gas em issions are presented in F igure 4. In landfill,about half of the

C H4 is recovered (range of recovery rate 20 -80% ) and therefore som e em issions still

occur.If landfill gas is used in electricity generation,som e equivalent C O 2 em issions

can be avoided.W ith decreased landfilling of biodegradable m aterials the potential

for energy recovery w ill be reduced.W ith m ass incineration,no degradable organic

m aterial is deposited in landfill. S om e m aterials w ith high-em bedded energy,but

zero calorific value (e.g.,steel and glass) can be recovered before incineration and

hence som e CO 2 em issions can be avoided.It w as assum ed that the generated

electricity replaces coal-condensing pow er,as w ith landfill,and the energy-related

em issions are therefore negative even though quite significant am ounts of CO 2 are

em itted from incineration.In S olid R ecovered F uel (SR F ) recovery,the landfill

em issions are sm all due to the very sm all am ount of disposed organic w aste. D ue to

m ore efficient w aste separation and subsequently recycling,m ore CO 2 em issions fromsteel and glass m anufacturing can be avoided than w ith m ass incineration.The

largest effect on em issions is due to substitution of S R F for coal.W ith the SR F and

paper fibre recovery,the effect on energy-related em issions is sm aller than in the


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previous categories because a part of the com bustible m aterial (paper fibre) goes to

m aterial recycling. A lthough m ore paper m anufacturing em issions are saved,the

total effect is of the sam e m agnitude as the S R F production case.

Figure 4: G reenhouse gas em issions of different w aste m anagem ent system s in coalsubstitution.A n exam ple from a city w ith one m illion inhabitants.

The substitution of energy from M S W for energy from coal,leads to significant

savings in greenhouse gas em issions.

E ven w here the M S W is consigned to landfill there exists the possibility of utilising

the generated landfill gas (rich in m ethane) for energy recovery,but the potential

for substantial recovery w ill be reduced as the am ount of biodegradable m aterial is

reduced.In addition,the recycling of secondary m aterials saves energy w hich

otherw ise w ould have been consum ed for the m anufacture of products from prim ary

raw m aterials (e.g.,com post versus chem ical fertilisers).

R ecovering energy from M S W also avoids all other potential im pacts associated

w ith the deposition of waste,e.g.,leachates/groundw ater contam ination and longer-

term pollutant liabilities.The deploym ent of any technology w ill have local

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environm ental im pacts and it is these rather than national or global environm ental

concerns w hich influence public acceptability and siting decisions.For M S W energy

recovery,local im pacts are associated w ith traffic m ovem ents,noise,visual intrusion,

loss of am enity and local effects of pollutants.A s w ith other technologies these

im pacts can be m inim ised if best practices in the design,siting and operation of plant

are adopted.

The benefits of energy recovery from w aste fuels are such that any state-of-the-art

w aste m anagem ent policy should include energy recovery irrespective of the

individual local strategic preferences (e.g.,com posting versus anaerobic digestion).

Drivers and Barriers

The utilisation of the biodegradable fraction of M S W as a bioenergy resource is

intim ately linked w ith the w aste m anagem ent policies that a country practises and

w ith public perception.E nergy recovery system s for M S W thus have to be integrated

w ith other m ethods of treatm ent,recovery and disposal to avoid conflicting claim s on

the w aste/fuel stream .P olicies prom oting the diversion of w aste from landfill provide

an opportunity for M SW energy recovery.

P ublic perception and hostility are currently critical barriers hindering the deploym ent

of energy recovery system s for M S W in several countries.S elective reporting on

em issions has contributed to negative perceptions.For exam ple,reporting em issions

from 30-year-old facilities but not from new ones that m eet the m ost stringent m odern

em ission standards.

IE A B ioenergy can play a significant role in rem oving m isconceptions concerning

M S W energy recovery by prom oting inform ation exchange and presentation of reliable

data on em issions from state-of-the-art waste energy recovery facilities.

M S W conversion-to-energy,like any other fuel-to-energy process,w ill generate

em ission of pollutants.H ow ever,all state-of-the-art M SW conversion-to-energy

technologies are certified to m eet the m ost stringent em ission standards,includingthose for dioxins,furans and other toxic pollutants.


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The Role of Technology

The num erous conversion routes for M S W to energy are illustrated in F igure 5.

B asically,these involve therm ochem ical processes (such as incineration,gasification

and pyrolysis) and biological processes (such as anaerobic digestion).W ith the

exception of m ass burning or incineration system s,all other process routes utilise

an upgraded fuel.This can be accom plished either by separation at source follow ed

by sim ple m echanical treatm ent such as size reduction,or by extensive m echanical

treatm ent of M S W to produce Solid R ecovered Fuel (S R F ).

Figure 5: P athw ays for M S W treatm ent for recovery and recycling processes

S R F is a solid fuel that in m ost cases has w ell-defined characteristics,properties

and com position and can be traded as a fuel for energy generation.S R F presents

significant opportunities as the m ain pollution sources have been rem oved during

the m echanical pre-treatm ent process.It has a relatively high heating value and can

be standardised as a com m ercial fuel.S R F can be co-utilised w ith several other

solid fuels such as coal and/or biom ass in co-com bustion or co-firing processes.

The E uropean C om m ission has issued a m andate to C E N /TC 343 for the adoption

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of European standards for SR F so that such fuels could be traded in the energy

m arket.Typical technical solutions are show n in Figure 6 below .These are in addition

to com m ercial co-firing alternatives of w ood fuels and coal.

Figure 6: Typical co-utilisation applications of SR F

There are several state-of-the-art technologies for converting M S W to energy.

M oreover Solid R ecovered F uel offers significant environm ental and m arket

opportunities,is relatively clean and can be traded in the m arket for num erous energy

applications replacing fossil fuels.


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Figure 9: C arbon content of M S W (W t% )

U p to 80% of the carbon content of M S W is biom ass derived and therefore

is renew able.

Contribution to Sustainable Energy

Life-cycle-based assessm ents of the m ajor environm ental im pacts (or sustainability

indicators) of M S W have show n the positive benefits to be gained from M S W energy

recovery.These gains are in the form of:

R educed greenhouse gas em issions

R educed acid gas em issions

R educed depletion of natural resources (fossil fuels and m aterials)

R educed im pact on w ater (leaching)

R educed land contam ination

In the long term the potential for M S W energy supply is lim ited by the availability of raw

m aterial there is a finite resource in each area.N onetheless,review s of the short- to

m edium -term potential for the range of renew able sources indicate that M S W energy

recovery could be an im portant contributor to pow er generation.F or exam ple,the A TLA S

study indicates that at present about 7% of energy produced from renew able sources in

the E U is derived from M S W m aking it the third largest contributor after large-scale

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hydro and use of biom ass for heat.A TLA S also indicates the im portance of the

contribution from M S W into the future,w ith a sim ilar ranking of m arket share in

2010.E nergy recovery from M S W is therefore one of the m ajor players in the

early introduction of renew able energy.

M S W energy recovery has the potential to m ake a significant contribution to

sustainable developm ent

Conclusion

E nergy recovery from M S W is already contributing to reducing global and local

environm ental im pacts.The potential contribution and cost of deploym ent are such

that it is likely to continue to m ake a contribution on a par with other renew able

technologies currently entering the m arket place.D eploym ent of M SW energy

recovery should be encouraged w herever it presents a viable and attractive w ay of

integrating w ith recycling and re-use activities and m inim ising the im pact of w aste

disposal.

E nergy recovery from w aste can reduce em issions of greenhouse gas and other

gaseous,liquid and solid pollutants,has a great potential for assisting in m eeting

the K yoto obligations,and can significantly contribute to sustainable developm ent.

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Abbreviations

C H P C om bined H eat and P ow er

C H4 M ethane.A greenhouse gas 23 tim es m ore potent than C O 2C O2 C arbon dioxide

E C E uropean C om m unity

E U E uropean U nion

g gram s

IE A International E nergy Agency

IP C C Intergovernm ental P anel on C lim ate Change

kg kilogram s

kW h kilow att hourK yoto K yoto P rotocol - an international agreem ent aim ed at reducing

greenhouse gas em issions

M J M egajoules (10 6 Joules)

M SW M unicipal Solid W aste

SR F Solid Recovered Fuel

Acknowledgements

D r K yriakos M aniatis,the M em ber for the E uropean C om m ission

coordinated an editorial group w hich included P rofessor K ai S ipil and D r

G erard S m akm an to prepare and review drafts of the text.D r N iranjan

P atel,the L eader of Task 36 and the participants in the Task,especially

M r D avid B axter,M r Gerry Atkins and D r D avid G ranatstein,providedinvaluable input at key stages.The assistance of D r G erfried Jungm eier

and m em bers of industry in the various Contracting P arties to IEA

B ioenergy is also gratefully acknow ledged.M em bers of the E xecutive

C om m ittee discussed and com m ented on a num ber of drafts to im prove

the text.The A ssistant Task Leader,G race G ordon,M rs Judy G riffith and

M r Justin F ord-R obertson provided valuable assistance in preparing the

text for publication.The S ecretary facilitated the editorial process and

arranged final design and production.


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IEA Bioenergy Contacts

Secretariat M r John TustinP O B ox 6256W hakarew arew aR otoruaN E W ZE A LA N DP hone: +64-7-348-2563Fax: + 64-7-348-7503E m ail: jrtustin@ xtra.co.nz

Website

w w w.ieabioenergy.com

Task 36: Energy from Integrated SolidWaste Management Systems

L eader:D r N iranjan PatelA E A Technology E nvironm entF 6 Culham ,A bingdonOX14 3D BU N IT E D K IN G D O MP hone: +44-1235-464-158Fax: + 44-1235-463-001E m ail: niranjan.patel@ aeat.co.uk

This position paper was produced by theE xecutive Com m ittee of IE A B ioenergy.TheIm plem enting A greem ent on B ioenergy form spart of a program m e of international energytechnology collaboration undertaken under theauspices of the International Energy A gency.

165 IEAPositionPaperMSWfinal[1][1]

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