Comparing GHG Emissions: Waste Incineration vs. Energy Tech in UK, Essays (high school) of English Literature

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A Changing Climate for Energy from

Waste?

Final Report for Friends of the Earth

Author:

Dr Dominic Hogg

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A Changing Climate for Energy from Waste

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Executive Summary

This report lays down some challenges to conventional wisdom and some dearly held beliefs. It is a piece of work which, from the author’s perspective, has been many years in its gestation, and which has a number of important implications.

Fundamentally, it challenges what has become ‘conventional wisdom’: that energy from waste incineration is bound to ‘generate climate change benefits’. It does not, however, argue that such benefits may not be possible to derive. Rather, it highlights the fact that whether or not climate change benefits can be said to have been derived is dependent upon the assumptions used in the analysis and the performance of the relevant technologies, notably:

¾ the efficiency with which the incinerator generates energy (and in many UK-based studies, these have tended to be on the high side); ¾ the assumption concerning which energy source might be considered to be displaced by the incinerator (this will always be controversial); ¾ the efficiency with which these ‘displaced sources’ generate energy (these are tending to improve over time); ¾ whether or not one includes biogenic carbon in the analysis (most studies do not); ¾ the calorific value of the input waste; and ¾ what percentage of carbon (biogenic and non-biogenic, depending upon the view of the study) is in the waste combusted.

Notably, the study highlights the fact that typical UK incinerators, generating only electricity, are unlikely to be emitting a lower quantity of greenhouse gases, expressed in CO 2 equivalents, per kWh electricity generated than the average gas-fired power station in the UK. Rather, since gas- fired power stations emit a smaller quantity of GHGs per kWh, the presumption that energy from waste is always ‘good for climate change’ appears to imply a range of assumptions which are not always stated (or, perhaps, understood by those who presume this to be the case).

This need not necessarily imply that energy from waste incineration is bad for climate change. It could, after all, be true that incinerating waste and generating energy from it is the best way of dealing with waste. This is the more-or-less unanimous outcome of the vast majority of studies which have looked at the matter from the perspective of life cycle assessment (LCA). However, we argue that the use of conventional LCA-based approaches, and most notably, the largely unquestioned assumption that ‘biogenic carbon can be ignored’ (or that only what is not liberated as CO 2 after 100 years needs to be taken into consideration, which amounts to a similar assumption), is inappropriate for this type of analysis. Ignoring what happens to biogenic CO 2 during a 100 year period can only be an acceptable way to proceed if all technologies behave in a similar way over this time period, and if society is not especially interested in the time profile of emissions. Neither would appear to be true.

The work, therefore, poses a challenge to those engaged in LCA-based work, pushing them to recognise the significance – as many have already done – of time. It suggests they must go beyond merely recognising time as significant, and actually integrate the dimension of time into the analysis. This is important not least since the European Commission has placed considerable emphasis, in the development of its proposals for a Thematic Strategy on Waste Prevention and Recycling and a revised Waste Framework Directive, on the issue of climate change, and on the use of ‘life-cycle thinking’. In its current, conventional form, life-cycle assessment is not a reliable indicator of the contribution of waste treatments to climate change.

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• 1.0 INTRODUCTION................................................................................................................. Contents
  • 1.1 This Report...........................................................................................................................
• GREENHOUSE GAS EMISSIONS? 2.0 DOESN’T INCINERATION WITH ENERGY GENERATION HELP TO REDUCE
  • 2.1 The Issue
  • 2.2 Analysis................................................................................................................................
    • 2.2.1 Sensitivity Analysis........................................................................................................
    • 2.2.2 A Look to the Future......................................................................................................
  • 2.3 Summary
• WASTE TREATMENT?.............................................................................................................. 3.0 ISN’T INCINERATION THE MOST CLIMATE-FRIENDLY FORM OF RESIDUAL
  • 3.1 Methodological Issues
  • 3.2 Analysis..............................................................................................................................
  • 3.3 Results................................................................................................................................
• 4.0 CLIMATE CHANGE AND WASTE MANAGEMENT – OTHER KEY ISSUES
  • Public Perspective? 4.1 What are the Prospects for Energy from Waste Being Considered Acceptable from the
  • 4.2 Proposals for a Thematic Strategy and for a Revised Waste Framework Directive..........
    • 4.2.1 Recovery Targets in the Waste Strategy......................................................................
  • Climate Change Performance of Incineration?............................................................................ 4.3 Will Including Incineration with CHP Under the Renewables Obligation Improve the
• 5.0 CONCLUSIONS AND RECOMMENDATIONS
  • 5.1 Energy from Waste Incineration Compared with Fossil Fuel Generation.........................
  • 5.2 Energy from Waste as a Treatment for Residual Waste
  • 5.3 A Revised Landfill Tax?....................................................................................................
  • 5.4 Anaerobic Digestion of Source Separated Organic Materials
  • 5.5 Recovery / Disposal / CHP
  • 5.6 Climate-friendly Options for Residual Waste Management?............................................
  • 5.7 Is Climate Change the Only Issue That Matters?
• A.1.0 GHG EMISSIONS PER UNIT OF ENERGY GENERATION..................................
  • A.1.1 Approach Taken
  • A.1.2 UK Coal-fired Power Station;
  • A.1.3 UK Oil-fired Power Station;...........................................................................................
  • A.1.4 UK Gas-fired Power Station;..........................................................................................
  • A.1.5 Combined Heat and Power
  • A.1.6 Waste-to-energy Incineration (electricity only);
  • A.1.7 Waste to Energy, CHP....................................................................................................
  • A.1.8 Waste to Energy, Heat Only
• A.2.0 METHODOLOGICAL ISSUES.....................................................................................
  • A.2.1 Should We Include Biogenic Emissions of CO 2?
  • A.2.2 How Should One Account for Biogenic CO 2?
• A.3.0 WASTE MANAGEMENT OPTIONS...........................................................................
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  • A.3.1 Incineration iv
  • A.3.2 Landfill
  • A.3.3 Aerobic MBT..................................................................................................................
  • A.3.4 AD-based MBT
• A.4.0 BRIEF REVIEW OF PREVIOUS LITERATURE
  • A.4.1 ERM Study
  • A.4.2 CIWM
  • A.4.3 CIWM Position Statement..............................................................................................
  • A.4.4 Oakdene Hollins

None of this is to imply that ‘energy from waste’ has no role to play in managing waste within the UK.^5 What matters, perhaps, is that some of the assumptions underpinning the debates are made absolutely clear so that policy – whatever it ultimately is – can be informed by the full range of arguments. ‘Sound science’ does not always mean seeking an unequivocal and uncontested view of the world. As often as not, it means understanding different arguments, and the significance of different assumptions, and making judgements on the basis of all the available information rather than partial presentations of it.

The issue of waste management and climate change – precisely because it is accorded increasing significance in policy debates – is one where interest groups are apt to deploy those assumptions which best suit their own line of argument. For this reason, one needs to tread carefully where this issue is concerned.

Another feature of this debate is the fact that it is not just ‘assumptions’ which influence outcomes, but more fundamentally, methodologies. The European Commission has recently expressed enthusiasm for ‘life-cycle thinking’ and lifecycle analysis. The Thematic Strategy on the Prevention and Recycling of Waste states

the proposal is to modernise the existing legal framework – i.e. to introduce lifecycle analysis in policymaking and to clarify, simplify and streamline EU waste law. This will contribute to resolving current implementation problems and move the EU decisively onto the path of becoming an economically and environmentally efficient recycling society.

Those who have taken the time and effort to critically review lifecycle analyses will know that assumptions influence results, so it is unlikely that a single answer would result from such analyses – making the supposed objective of clarifying and simplifying waste law through the use of lifecycle analysis a somewhat naïve one.

Since, as we will show, lifecycle analyses gives very different results to cost-benefit analyses, the choice of one methodology over another on the part of the Commission begs the question, ‘why the preference for one rather than the other?’ It seems ironic, after all, that in the context in which the Thematic Strategy emerged – that of concerns for competitiveness, and the elaboration of the Lisbon Agenda – the relative costs and benefits of alternative actions would be considered irrelevant.

1.1 This Report

This report explores a number of issues at the interface of energy, waste and climate change. It asks, and seeks to answer (from different perspectives) the following questions:

1. How does energy from waste incineration compare, in terms of emissions of greenhouse gases per unit of energy generated, with other technologies for generating energy in the UK? and

(^5) The term ‘energy from waste’ could, of course, mean just about anything - landfills generate ‘energy from

waste’. So do anaerobic digesters, which can be used to treat source separated materials, or residual waste. So do incinerators. So do power plants and industrial facilities where they combust waste derived fuels. And so could pyrolysis and gasification facilities. ‘Energy from waste’ ought not to imply, necessarily, ‘incineration’.

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2. How does energy from waste incineration compare with other residual waste treatment technologies in terms of their impact upon climate change?

In addition, it asks the following questions:

1. What are the prospects for energy from waste being considered acceptable from the public perspective?
2. Is there a rational argument in the proposals for a Thematic Strategy and for a Revised Waste Framework Directive for a distinction between recovery and disposal, as applied to incineration?
3. Will including incineration with CHP under the Renewables Obligation improve the climate change performance of incineration?

The final Section contains Conclusions and Recommendations related to the preceding analysis.

The analysis is supplemented by additional technical information within the Annexes.

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The Institute for Civil Engineers also produced a report which sought to make a case for more energy from residual waste. A critical review of key assumptions used in the report is given in Annex 4.

These documents tend to support the view that energy from waste incineration is ‘good’ for climate change, generally without much by way of clear qualification.

The European Commission in its Thematic Strategy on the Prevention and Recycling of Waste, is more equivocal, arguing that energy efficiency is a key determinant of the relative performance of energy from waste:^7

A definition of recovery that takes into account that energy produced by a municipal incinerator substitutes the use of resources in other power plants will better reflect the environmental benefits of incineration. However, the energy efficiency of municipal incinerators can vary dramatically. At low energy efficiencies incineration might not be more favourable than landfill. At high energy efficiency incineration could be as favourable as mechanical recycling or composting of certain waste flows.

This seems reasonable under the assumptions that are usually employed in life cycle analyses. Essentially, if one assumes that energy generated ‘displaces’ emissions which would otherwise be generated in other power stations, the greater the efficiency, then the larger is the quantity of polluting emissions displaced.

The question is, though, in the UK, how valuable is energy from waste incineration in the battle to combat climate change?

2.2 Analysis

Energy from waste plants generate either:

• Electricity only;
• Electricity and heat; or
• Heat only.

The assumption is that energy from waste generates energy in such a way that a lower quantity of greenhouse gases are emitted per unit of energy output than is the case with conventional fossil fuel energy generation. So how well does energy from waste really perform in this regard?

Figure 1 below shows how energy from waste incineration fares against fossil fuel sources in the current context. The details for the calculations can be found at Annex 1. In this illustration, the value of each kilowatt hour (kWh) of heat is deemed to be equivalent to 0.4kWh of electricity. The rationale for this is that the average rate of conversion from heat to electricity is of the order 40% in the UK.^8 This shows that if energy from waste

(^7) European Commission (2005) Taking Sustainable Use of Resources Forward: A Thematic Strategy On

The Prevention and Recycling of Waste , Communication From The Commission To The Council, The European Parliament, The European Economic And Social Committee And The Committee Of The Regions, Brussels, 21.12.2005. (^8) As we shall see, the European Commission, in proposing an efficiency criteria to distinguish between

‘disposal’ and ‘recovery’, attributes a weighting of 1.1 to heat and 2.6 to electricity, a ratio of 0.42.

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generates electricity only, then when one excludes emissions of CO 2 from biogenic sources of carbon in waste, the emissions from incinerators are actually greater than those from conventional gas-fired power stations.

The position improves considerably if the incinerator operates in CHP mode, or where it generates heat only at high efficiencies, but in both cases, the performance relative to gas is still only marginally better. It should be noted that in both cases, it is assumed that the majority of heat generated is put to good use, and this has not always proved possible at incinerators outside areas where the demand for heat is much higher (than here), such as in Scandinavia.

Evidently, performance relative to coal and oil is very good under these assumptions.

Figure 1: Excludes CO 2 from Biogenic Carbon, Heat=0.4 x Electricity

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Gas-fired Coal fired stations Oil-fired stations Incinerator, electricity only

Incinerator, CHP Gas-fired CHP Incinerator, heat only

g CO2(equ) per kWh electricity equivalent

2.2.1 Sensitivity Analysis

Heat Counted On the Same Basis as Electricity

In the above case, reflecting an (approximate) average electricity generation efficiency in the UK of 40%, each unit of heat energy generated is assumed to count for 0.4 units of electricity equivalent. If heat is counted on the same basis as electricity, then the figures appear as in Figure 2 below. The incinerators generating heat improve, in relative terms, considerably. However, there is no effect (for obvious reasons) on the incinerator generating electricity only.

Biogenic Carbon Included

It has become ‘normal’ to assume that the emissions of CO 2 from biogenic sources of carbon should be ignored. In some comparisons, this may be valid. In others, it almost certainly is not (see Annex 2). In particular, where, as with some processes, biogenic emissions occur over many years, and where comparisons are being made between

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plastics are not captured so well as other materials. Their ‘concentration’ is apt, therefore, to increase in residual waste.

Figure 3: Includes CO 2 from Biogenic Carbon, Heat=0.4 x Electricity

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Gas-fired Coal fired stations Oil-fired stations Incinerator, electricity only Incinerator, CHP Gas-fired CHP Incinerator, heat only

g CO2(equ) per kWh electricity equivalent

Of course, the efficiency of incinerators might increase. But equally, so might the efficiency of other generation technologies, including those using fossil fuels. In what follows, the same figures as were estimated for the current period are estimated for the future. Again, the underlying assumptions are to be found in Annex 1.

Figure 4 shows that under the scenarios considered, the performance of incinerators may worsen relative to the fossil fuel generating technologies. In this case, where only electricity is being generated, the performance is more or less on a par with oil-fired and coal-fired generation, with gas-fired generation performing far better. Gas-fired generation actually performs better than the case where the incinerator operates in CHP and heat-only mode also.

The reasons for this are:

• The efficiency improvements anticipated in the fossil fuel generation technologies are no less important – possibly more so - than those anticipated for incinerators;
• Whilst the net calorific value of the waste increases, so does the non-biogenic carbon content. The latter rises more quickly than the former. This is principally due to the fact that the assumption concerning the capture rates of materials in the waste stream are such that these are lower for plastics than for other targeted recyclables. The proportion of plastics in residual waste therefore rises. Some might suggest this is speculation, yet rather, it reflects experience in advanced situations in Europe (where, for example, 50% recycling rates are already being

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met) and in UK schemes.^10 An important corollary of this is that, contrary to the oft-stated mantra that one should burn plastics to generate energy from them, from a climate change perspective, this would possibly be the least desirable thing to do on the basis that fossil carbon is being burned in facilities with a relatively low level of efficiency of energy generation.

Figure 4: Excludes Biogenic Carbon, Heat=0.4 x Electricity, Future Scenario

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Combined cycle gas turbine stations

Coal fired stations Oil-fired stations Incinerator, electricity only

Incinerator, CHP Gas, CHP Incinerator, heat only

g CO2(equ) per kWh electricity equivalent

It should be noted that some of the fossil fuel technologies – most likely, coal - would improve their performance – at least by this measure – if they were to co-fire with biomass / gasified biomass. In the same way as the incinerators’ performance worsens as a result of the higher non-biogenic carbon content of waste, so the performance of the conventional fossil fuel technologies would be improved by reducing the non-biogenic carbon content of the input fuel (though the net calorific value would decline to some extent).

Heat Counted On the Same Basis as Electricity

If heat is counted on the same basis as electricity, then the figures appear as shown in Figure 5. As before, the performance of the incinerators operating in CHP and heat generation modes are improved in relative terms.

Biogenic Carbon Included

The inclusion of biogenic CO 2 has the effect of worsening the position of all the incinerator scenarios (see Figure 6). Fossil fuel generation appears improves significantly in relative terms. The significance of including biogenic carbon will be taken up further below.

(^10) One of the reasons why the targets for plastics recycling under the revised Packaging Directive were set

so low relative to other materials was related to the low level of capture actually being achieved.

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Table 1: GHG Emissions (g CO 2 equ per kWh)

Excludes Biogenic Carbon, Heat=0.4 x Electricity Current Future

Gas-fired 382 325 Coal fired stations 835 605 Oil-fired stations 770 587 Incinerator, electricity only 510 580 Incinerator, CHP 341 377 Gas-fired CHP 395 372 Incinerator, heat only 305 368

Excludes Biogenic Carbon, Heat=1x Electricity Gas-fired 382 325 Coal fired stations 835 605 Oil-fired stations 770 587 Incinerator, electricity only 510 580 Incinerator, CHP 177 203 Gas-fired CHP 241 229 Incinerator, heat only 133 156

Includes Biogenic Carbon, Heat=0.4 x Electricity Gas-fired 382 325 Coal fired stations 835 605 Oil-fired stations 770 587 Incinerator, electricity only 1645 1405 Incinerator, CHP 1086 906 Gas-fired CHP 395 372 Incinerator, heat only 967 884

The assumption that energy from waste incineration ‘helps to combat climate change’ is not so obvious from the above analysis. In particular, where incinerators generate electricity only, as is the case with the majority in the UK:

1. The emissions of GHGs, when biogenic CO 2 is excluded, are likely to be greater for each kWh of electricity generated than those from currently operating average gas-fired power stations (we estimate them to be around 25% higher) though they are likely to be lower than those from currently operating oil-fired and coal-fired generation;
2. In future, the emissions of GHGs per kWh, excluding biogenic CO 2 , may, in relative terms, worsen as: a. efficiencies of fossil-fuel powered generation increase; and b. the proportion of non-biogenic carbon in residual waste increases. This is what is estimated to occur – at least in this analysis - as recycling rates increase over time (though clearly, this is based upon an unrealistic assumption of constant waste composition over the next 14 years).

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As regards the future scenarios, much clearly depends upon how the composition of waste changes over time (it may be that plastics production shifts to bio-derived materials, etc.). No one knows how waste composition will change over the next fifteen years, but we do know that it will.

The picture is somewhat different where incinerators operate in either CHP, or heat only, mode and where they are operating at high efficiencies of generation with a clear use for the energy generated. In this case:

1. When biogenic CO 2 is omitted, both emit a lower quantity of GHGs per kWh electricity equivalent than any of the fossil fuel technologies. However, even with what are effectively high operating efficiencies (and much higher than the average efficiency of a CHP facility in the UK), the performance gives only a 25% saving relative to average gas-fired generation, raising questions as to the conditions under which this could really be sustained in the UK context;
2. Whether or not this remains the case in the future seems unclear. Much depends upon the relative improvements in efficiency of the fossil-fuel technologies relative to the incinerators. Since the ‘heat only’ case has been based – for the future - upon an assumption of 100% efficiency relative to the lower heating value of the feedstock, this seems unlikely to be improved greatly (not least since the gross calorific value of waste is typically only 10% or so higher than the net calorific value, and there is likely to be greater convergence as more of the higher moisture content materials are removed for recycling). Consequently, there is a possibility that the benefit that these technologies would appear to deliver in the current context might be eroded in the future.

All of the above assumes that heat is converted to an electricity equivalent through multiplying by a factor of 0.4. The rationale for this is related to the higher quality of energy provided by electricity and the fact that heat is being converted to energy at roughly 40% efficiency. If the factor used is 1, then though the picture for incinerators generating electricity only is unchanged, whilst the picture for those generating CHP or heat only is improved considerably.

It might be argued that the value of heat, relative to electricity, increases as the efficiency of generation of electricity increases. If this view was taken, this would further improve the performance of the processes generating heat where one awards heat a weighting equal to average electricity generation efficiencies.

Crucially, of course, most UK incinerators are currently generating electricity only. Such incinerators cannot unequivocally be said to be contributing to solving the problem of climate change. This depends upon various assumptions, notably – as is clear from the analysis above - the source of energy which one assumes is being ‘displaced’ by the generation of energy from waste by incinerators.

We have commented elsewhere that this argument is not likely to be easily resolved, precisely because lobby groups – including the incinerator industry and environmental

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