Environmental assessment of waste to energy processes specifically incineration and anaerobic ...

424 Pages·2014·6.71 MB·English

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University of Southampton

Faculty of Engineering and the Environment

Environmental Assessment of
Waste to Energy Processes
Specifically Incineration and Anaerobic Digestion
Using Life Cycle Assessment

By
Anuda Tawatsin

Thesis submitted for the degree of Master of Philosophy

March 2014

UNIVERSITY OF SOUTHAMPTON

ABSTRACT
FACULTY OF ENGINEERING AND THE ENVIRONMENT

Thesis for the degree of Master of Philosophy

ENVIRONMENTAL ASSESSMENT OF WASTE TO ENERGY PROCESSES SPECIFICALLY
INCINERATION AND ANAEROBIC DIGESTION USING LIFE CYCLE ASSESSMENT

Anuda Tawatsin

Municipal solid waste is an issue every community in the world has to be concerned with.
Without any management, municipal solid waste poses environmental and health risks to the
community such as from water and air pollution. In selecting methods to deal with the waste,
environmental impacts considerations are important to reduce these risks. Environmentally
sustainable waste management processes should also decrease greenhouse gases contributing
to global warming and climate change. Waste to energy (WtE) processes lessens and replaces
the use of fossil fuels reducing greenhouse gases.

The research aims to assess the environmental impacts and energy recovery of WtE
processes, specifically incineration or energy recovery facilities (ERF) and anaerobic
digestion (AD) to select suitable options or any combinations thereof as part of an integrated
waste management system for different locations and conditions by using life cycle
assessment (LCA) methods.

WRATE (Waste and Resources Assessment Tool for the Environment) an LCA model is
used to assess scenarios designed systematically with different combinations of
incineration/ERF and AD. The study also varies other factors such as different recycling
schemes and recycling rate, household waste composition and population density to
determine the suitable combinations for different local conditions.

Results for both UK and Thailand confirm the need to reduce disposal of waste into landfills.
The scenario with Incineration/ERF for heat recovery and a post collection recycling scheme
and the combination scenario with Incineration/ERF for heat recovery and Anaerobic
Digestion for vehicle fuel a post collection recycling scheme lead the ranking for most energy
recovery and less environmental impacts.

The parameter exerting the greatest influence on LCIA of these set of scenarios is WtE
technology. Second is recycling scheme with recycling rate as a subset. Third is energy
recovery type. Population density also affects the outcome slightly by the magnitude of the
values.

Keywords: Anaerobic Digestion, Incineration, Life Cycle Assessment, Municipal Solid
Waste, Recycling, Waste to Energy, WRATE.

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Table of Contents

CHAPTER 1 RESEARCH OVERVIEW....................................................................................................1
1.1 INTRODUCTION.......................................................................................................................................1
1.1.1 Sustainable Development............................................................................................................1 
1.1.2 Global warming and energy.........................................................................................................1 
1.1.3 Municipal solid waste..................................................................................................................2 
1.1.4 Policy............................................................................................................................................4 
1.1.5 Resource recovery........................................................................................................................5 
1.1.6 Energy from waste.......................................................................................................................6 
1.1.7 Evaluation and assessment tools.................................................................................................8 
1.2 RESEARCH AIM AND OBJECTIVES...........................................................................................................9
1.2.1 Aim...............................................................................................................................................9 
1.2.2 Objectives...................................................................................................................................10 
1.2.3 Scope..........................................................................................................................................11 

CHAPTER 2 LITERATURE REVIEW....................................................................................................13
2.1 MUNICIPAL SOLID WASTE.....................................................................................................................13
2.1.1 Composition...............................................................................................................................13 
2.1.2 Proximate analysis.....................................................................................................................17 
2.1.3 Ultimate analysis.......................................................................................................................19 
2.1.4 Heating values...........................................................................................................................21 
2.2 WASTE TO ENERGY CONVERSIONS........................................................................................................22
2.2.1 Biological conversions................................................................................................................22 
2.2.2 Thermal conversions..................................................................................................................26 
2.3 ENERGY ASSESSMENT...........................................................................................................................31
2.4 LIFE CYCLE ASSESSMENT (LCA)............................................................................................................32
2.4.1 LCA software models..................................................................................................................33 
2.4.2 WRATE.......................................................................................................................................33 
2.4.3 Studies using WRATE..................................................................................................................37 
2.4.4 Comparisons of LCA studies.......................................................................................................38 
2.4.5 Comparisons with AD.................................................................................................................39 
2.4.6 Comparisons with Landfill gas...................................................................................................40 
2.4.7 Comparisons with Incineration..................................................................................................41 
2.4.8 Comparisons with Gasification and Pyrolysis.............................................................................42 
2.5 REVIEW CONCLUSIONS..........................................................................................................................42

CHAPTER 3 RESEARCH METHODOLOGY........................................................................................43
3.1 ASSEMBLE DATA AND INFORMATION ON INCINERATION AND ANAEROBIC DIGESTION
AND OTHER RELATED WASTE MANAGEMENT PROCESS...........................................................................43
3.2 PLAN AND DEVELOP POSSIBLE COMBINATIONS OF INCINERATION AND ANAEROBIC
DIGESTION WASTE MANAGEMENT SCHEMES..........................................................................................44
3.3 MAP EACH OF THE SCENARIOS OF INCINERATION AND ANAEROBIC DIGESTION AND
THEIR COMBINATIONS IN WRATE.........................................................................................................45
3.4 CONDUCT LIFE CYCLE ASSESSMENT USING WRATE AND INTERPRET THE RESULTS............................45
3.4.1 Life Cycle Inventory ...................................................................................................................45 
3.4.2 Life Cycle Impact assessment.....................................................................................................46 
3.4.3 Interpretation.............................................................................................................................47 
3.5 COMPARING THE SCENARIOS WITH EXAMPLES ENCOUNTERED IN PRACTICE.........................................48
3.6 MODIFY THE SCENARIOS TO BETTER REPRESENT EXISTING WASTE MANAGEMENT IN PRACTICE...........48
3.7 CONDUCT LIFE CYCLE ASSESSMENTS OF THE SCENARIOS WITH THE DIFFERENT PARAMETERS
AND ANALYSE THE RESULTS...................................................................................................................48
3.8 ESTABLISH A METHOD TO DETERMINE THE COMPARISON OF ENERGY PERFORMANCE AND
LIFE CYCLE IMPACT ASSESSMENT IN ORDER TO RANK THE SCENARIOS..................................................49
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3.9 COMPILING THE SCENARIOS ACCORDING TO THE ENERGY PERFORMANCE AND LIFE CYCLE IMPACT
ASSESSMENT RANKING OF THE SCENARIOS……………………………………………………….…..49
3.10 CONSTRUCT THE DECISION MAKING MATRIX OF SUITABLE SCENARIOS…………………………. ......49
3.11 IDENTIFY CASE STUDIES AND THE RELEVANT NATIONAL AND LOCAL POLICIES………………………49
3.12 APPLYING THE RAPID SCREENING METHOD FOR DECISION MAKING OF WASTE TO ENERGY SCHEMES
FOR THE CASE STUDY…………………………………………………………………………………..49
3.13 UTILISE THE RESULTS TO IMPROVE THE POLICIES RELATED TO THE CASE STUDY …………………….50

CHAPTER 4 PHASE ONE SCENARIO DESIGN...................................................................................51
4.1 SCENARIO NAMES.................................................................................................................................51
4.2 RECYCLING SCHEMES …...………………………………………………………………………….51
4.3 SCOPE AND BOUNDARY …...………………………………………………………………………….54
4.4 ELECTRICITY MIX ……………………………………………………………………………………..54
4.5 WASTE COMPOSITION………………………………………………………………………………….55
4.6 PROCESSES SELECTED FOR USE IN THE STUDY………………………………………………………….57
4.7 SCENARIO MAPS………………………………………………………………………………………..59

CHAPTER 5 PHASE ONE RESULTS......................................................................................................71
5.1 HEADLINE VALUES................................................................................................................................71
5.1.1 Biodegradable waste to landfill.................................................................................................72 
5.1.2 Energy Recovered.......................................................................................................................73 
5.1.3 Land take....................................................................................................................................73 
5.1.4 Waste Composted......................................................................................................................74 
5.1.5 Waste Landfilled........................................................................................................................74 
5.1.6 Waste Recovered.......................................................................................................................74 
5.1.7 Waste Recycled..........................................................................................................................75 
5.2 LIFE CYCLE IMPACT ASSESSMENTS......................................................................................................75
5.2.1 Climate change, GWP (Global Warming Potential)...................................................................76 
5.2.2 Acidification potential................................................................................................................76 
5.2.3 Eutrophication potential............................................................................................................77 
5.2.4 Fresh water aquatic ecotoxicity.................................................................................................77 
5.2.5 Human toxicity...........................................................................................................................78 
5.2.6 Resources depletion of abiotic resources...................................................................................78 
5.2.7 Multiple impact assessments.....................................................................................................79 
5.3 COMPARISON OF SELECTED GROUP OF SCENARIOS................................................................................81
5.3.1 Comparison of key scenarios with source segregation of waste...............................................81 
5.3.2 Comparison of incineration/ERF and AD....................................................................................84 
5.3.3 Comparison of energy recovery type: electricity, heat and combined heat and electricity.......90 
5.3 IMPROVEMENTS FOR PHASE TWO........................................................................................................102

CHAPTER 6 PHASE TWO SCENARIO DESIGN................................................................................103
6.1 SCENARIO NAMES AND CODES............................................................................................................103
6.2 RECYCLING MATERIAL CAPTURE RATES............................................................................................109
6.3 BACKGROUND INFORMATION.............................................................................................................110
6.4 ELECTRICITY MIX................................................................................................................................110
6.5 WASTE COMPOSITION.........................................................................................................................112
6.6 OTHER WASTE PROPERTIES ……………………… …………………………………………………114
6.7 PROCESSES SELECTED FOR USE IN STUDY …………………………………………………………….115
6.8 SCENARIO MAPS ……………………………………………………………………………………117

CHAPTER 7 PHASE TWO RESULTS AND RANKING…………………………………………… ..129
7.1 RESULTS………………………………………………………………………………………………129
   7.1.1 Life Cycle Impact Assessment (LCIA) results   ……………………………………………………………………  ...129 
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7.1.2 Climate change/GWP LCIA results ……………………………………………………………………………………....137 
7.1.3 Energy recovery results……………………………………………………………………………………………………....144 
7.2 RANKING……………………………………………………………………………………………..151
7.2.1 Ranking method…………………………………………………………………………………..151
7.2.2 Combined LCIA ranking ……………………………………………………………………………… ..152
7.2.3 Combined LCIA and energy recovered ranking …………………………………………………… ..154
7.24 Climate change LCIA and energy recovered ranking ……… ………………………………………..155
7.3 PHASE TWO CONCLUSIONS …………………………………………………………………………..157
7.3.1 LCIA conclusions ………………………………………………………………………………..157
7.3.2 Ranking conclusions …………………………………………………………………………………..159

CHAPTER 8 Decision making matrix……………………………………………………………………161
8.1 DESIGN OF DECISION MAKING MATRIX BASED ON LCIA……………………………………………....161
8.1.1 Options for selection criteria……………………………………………………………………………….161
8.1.2 Values of Energy Recovered and Life Cycle Impact Assessment……………………………………...163
8.1.3 Scenario code and name and combined ranking……………………………………………………… 163
8.2 CASE STUDY: PHUKET, THAILAND…………………………………………………………………….164
8.2.1 Background Information…………………………………………………………………………………. .164
8.2.2 Phuket waste management plans…………………………………………………………………………..165
8.2.3 Application of Decision making matrix based on LCIA………………………………………………..166

Chapter 9 Conclusions…………………………………………………………………………………… .171
  9.1 USING LCA TO ASSESS WTE TECHNOLOGY……………………………………………………….171
9.2 DECISION MAKING MATRIX………………………………………………………………… …...174
9.3 FURTHER WORK …………………………………………………………………………… …...175

References………………………………… …………………………………………………………… … .177

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List of Figures

Figure 1.1 Open dumping at a landfill site in Thailand 2
Figure 1.2 MSW generation per person per day 3
Figure 1.3 Percentage of MSW utilised in incineration with energy recovery 6
Figure 1.4 Waste Management Practices with WtE conversions 9
Figure 2.1 Single phase AD plant with pasteurizer 24
Figure 2.2 Classification of process alternatives for anaerobic digestion 25
Figure 2.3 The Marchwood Energy Recovery Facility near Southampton, UK 29
Figure 2.4 Model of Chineham Energy Recovery Facility near Basingstoke, UK 30
Figure 2.5 Life Cycle Assessment Framework 32
Figure 4.1 Scenario 1 map 60
Figure 4.2 Scenario 4 map 61
Figure 4.3 Scenario 7 map 62
Figure 4.4 Scenario 10 map 63
Figure 4.5 Scenario 13 map 64
Figure 4.6 Scenario 21 map 64
Figure 4.7 Scenario 25 map 66
Figure 4.8 Scenario 29 map 67
Figure 4.9 Scenario 33 map 69
Figure 5.1 Amount of Biodegradable Waste in Landfill 72
Figure 5.2 Amount of Energy Recovered 73
Figure 5.3 Amount of Land Take 73
Figure 5.4 Amount of Waste Composted 74
Figure 5.5 Amount of Waste Landfilled 74
Figure 5.6 Amount of Waste Recovered 75
Figure 5.7 Amount of Waste Recycled 75
Figure 5.8 Climate change, GWP (Global Warming Potential) 76
Figure 5.9 Acidification potential 76
Figure 5.10 Eutrophication potential 77
Figure 5.11 Fresh water aquatic ecotoxicity 77
Figure 5.12 Human toxicity 78
Figure 5.13 Resources depletion of abiotic resources 78
Figure 5.14 Multiple impact assessments 80
Figure 5.15 Comparison of 3 source segregation scenarios 82
Figure 5.16 Resources depletion of 3 source segregation scenarios 82
Figure 5.17 Resources depletion of 3 source segregation scenarios, web chart 83
Figure 5.18 Eutrophication potential of 3 source segregation scenarios 83
Figure 5.19 Incineration and AD with no recycling 85
Figure 5.20 Climate change for Incineration and AD with no recycling 85
Figure 5.21 Resources depletion for Incineration and AD with no recycling 86
Figure 5.22 Incineration and AD with post collection recycling 87
Figure 5.23 Climate change for Incineration and AD with post collection recycling 87
Figure 5.24 Resources depletion for Incineration and AD with post collection recycling 88
Figure 5.25 Incineration and AD with source segregation 89
Figure 5.26 Climate change for Incineration and AD with source segregation 89
Figure 5.27 Resources depletion for Incineration and AD with source segregation 90
Figure 5.28 Energy recovery type with no recycling 91
Figure 5.29 Acidification potential by process stage 92
Figure 5.30 Energy recovery type with post process recycling 93
Figure 5.31 Acidification potential by process stage 94
Figure 5.32 Energy recovery type with post collection recycling 95
Figure 5.33 Acidification potential by process stage 96
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