Environmental Protection
Agency
EPA 600/R-15/232 | November 2015 | www.epa.gov/ord
A Comparative Analysis of Life-Cycle
Assessment Tools for End-of-Life Materials
Management Systems
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EPA/600/R-15/232
November 2015
in
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EPA/600/R-15/232
November 2015
A Comparative Analysis of Life-
Cycle Assessment Tools
for End-of-Life Materials
Management Systems
Remediation and Redevelopment Branch
Land Remediation and Pollution Control Division
National Risk Management Research Laboratory
Office of Research and Development
Cincinnati, OH
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Ill
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Foreword
The US Environmental Protection Agency (US EPA) is charged by Congress with
protecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions leading
to a compatible balance between human activities and the ability of natural systems
to support and nurture life. To meet this mandate, US EPA's research program is
providing data and technical support for solving environmental problems today and
building a science knowledge base necessary to manage our ecological resources
wisely, understand how pollutants affect our health, and prevent or reduce
environmental risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the Agency's
center for investigation of technological and management approaches for
preventing and reducing risks from pollution that threaten human health and the
environment. The focus of the Laboratory's research program is on methods and
their cost-effectiveness for prevention and control of pollution to air, land, water,
and subsurface resources; protection of water quality in public water systems;
remediation of contaminated sites, sediments and ground water; prevention and
control of indoor air pollution; and restoration of ecosystems. NRMRL collaborates
with both public and private sector partners to foster technologies that reduce the
cost of compliance and to anticipate emerging problems. NRMRL's research
provides solutions to environmental problems by: developing and promoting
technologies that protect and improve the environment; advancing scientific and
engineering information to support regulatory and policy decisions; and providing
the technical support and information transfer to ensure implementation of
environmental regulations and strategies at the national, state, and community
levels.
This publication has been produced as part of the Laboratory's strategic long-term
research plan. It is published and made available by US EPA's Office of Research
and Development to assist the user community and to link researchers with their
clients.
Cynthia Sonich-Mullin, Director
National Risk Management Research Laboratory
IV
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Executive Summary
The approaches that communities use for providing solid waste collection and
management services have a significant impact on their economy, environment, and
the health and well-being of their residents. The US EPA recognizes a need for tools
that can be used by decision makers to characterize the interaction among social,
economic, and environmental impacts associated with the solid wastes typically
managed by communities, including municipal solid waste (MSW) and construction
and demolition debris (CDD) (US EPA, 2012a). This report evaluates multiple tools
that can be used to assess sustainability of the end-of-life (EOL) phase management
of these materials.
We identified and evaluated five life-cycle assessment tools that community
decision makers can use to assess the environmental and economic impacts of EOL
materials management options. The tools evaluated in this report are WARM,
MSW-DST, SWOLF, EASETECH, and WRATE. WARM, MSW-DST, and
SWOLF were developed for US-specific materials management strategies, while
WRATE and EASETECH were developed for European-specific conditions.
WARM and MSW-DST are available for free. There is an annual subscription fee
for WRATE. EASTECH is offered free to trained users; there is a 5,000 training
cost for commercial users. All of the tools (with the exception of WARM) allow
specification of a wide variety of parameters (e.g., materials composition and energy
mix) to a varying degree, thus allowing users to model specific EOL materials
management methods even outside the geographical domain they are originally
intended for. The flexibility to accept user-specified input for a large number of
parameters increases the level of complexity and the skill set needed for using these
tools.
The tools were evaluated and compared based on a series of criteria, including
general tool features, the scope of the analysis (e.g., materials and processes
included), and the impact categories analyzed (e.g., climate change, acidification).
A series of scenarios representing materials management problems currently
relevant to communities across the US was simulated to illustrate LCA applications
from a decision maker's perspective and to identify issues with tool use. An attempt
was made to apply the same parameters across the tools to provide the most
meaningful comparison of results; however, input values could not be specified the
same across all these tools because of variations such as materials classification and
nomenclature, management options included (e.g., single-stream MRF), and user-
specifiable parameters (e.g., decay rate constant, residual from MRFs) among tools.
For example, plastics in the simulated materials stream were categorized as "hard
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plastic," "soft plastic," or "drink bottles" in EASETECH while other of the tools
allowed simulation of plastics by resin types similar to how EOL plastics are tracked
for the MSW stream in the US.
While all of the tools evaluated can assess the environmental impact of common
materials management processes such as collection and transport, recovery and
recycling, composting (of biodegradable organics), combustion for energy recovery,
and disposal in a landfill, only WRATE can be used to assess the impacts of
emerging materials management technologies (e.g., pyrolysis). The life-cycle
inventories (LCIs) of several of these processes are based on data primarily available
at the time of tool development. While all of the tools include MSW materials, most
CDD materials are not included (with the exception of WARM). WARM is the only
tool among those evaluated in this report that assesses the impact of source
reduction. Only MSW-DST and SWOLF are designed to estimate materials
management system cost.
The tools differ in the nature of the environmental impacts assessed. For example,
WARM only assesses GHG impacts, while other tools include a variety of other
impact categories (e.g., acidification, eutrophication). Tools vary in the scope of
emissions included in LCA. For example, WARM'S and SWOLF's landfill GHG
emissions estimates include carbon storage, MSW-DST and EASETECH allow
users the flexibility to include or exclude landfill carbon storage, while WRATE
excludes carbon storage. Carbon storage, if included, reduces a landfill's net GHG
emissions estimate. None of the tools assess social impacts or characterize
interactions among environmental, economic, and social impacts.
Significant progress has been made in the last two decades in developing tools to
analyze environmental impacts from a life-cycle perspective. Additional research
effort is needed to update tool input data (e.g., LCIs) with more recent data than
those available at the time the tools were developed and to develop approaches and
methods to assess the social and economic impacts and characterize trade-offs
among the environmental, economic, and social impacts of EOL materials
management on community sustainability for decision making.
VI
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Notice
The US Environmental Protection Agency (US EPA) through the Office of Research
and Development funded and managed the research described here under contract
order number: EP-C-10-060 to Computer Science Corporation, Inc. The research has
been subject to the Agency's review and has been approved for publication as a US
EPA document. Use of the methods or data presented here does not constitute
endorsement or recommendation for use. Mention of trade names or commercial
products does not constitute endorsement or recommendation.
The appropriate citation for this report is:
Jain, P., Dyson, B., Tolaymat, T., Ingwersen, W., 2015. A Comparative
Analysis of Life-Cycle Assessment Tools for End-of-Life Materials
Management Systems. U.S. Environmental Protection Agency, Office of
Research and Development, Cincinnati, OH. EPA Report #
Vll
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Acknowledgements
We acknowledge the help of the following individuals for providing data and
information pertaining to tools evaluated in this report:
Dr. Morton Barlaz, North Carolina State University
Dr. James Levis, North Carolina State University
Mr. Keith Weitz, RTI International
Dr. Anders Damgaard, Technical University of Denmark
Dr. Wesley Ingwersen, Sustainable Technology Division, US Environmental
Protection Agency
We also appreciate the effort of two peer reviewers who took the time to carefully
read and greatly improve the report: Anthony Zimmer (EPA/ORD), and Donnie
Vineyard (EPA/ORD).
Vlll
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EPA/600/R-15/232
November 2015
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A Comparative Analysis LCA Tools Table of Contents
Table of Contents
Table of Contents x
List of Tables xii
List of Figures xiii
List of Abbreviations, Acronyms, and Initialisms xv
1 Introduction 1-1
1.1 Background 1-1
1.2 Report Objectives, Scope, and Approach 1-2
1.3 Report Organization 1-2
2 Use of LCA for EOL Materials Management 2-1
2.1 Using LCA in the Context of Sustainable Materials Management 2-1
2.2 EOL Materials Management LCA Tools Sieve Analysis 2-3
2.2.1 WARM 2-3
2.2.2 MSW-DST 2-4
2.2.3 SWOLF 2-4
2.2.4 EASETECH 2-5
2.2.5 WRATE 2-5
3 Detailed Evaluation of the Selected LCA Tools 3-1
3.1 Overview 3-1
3.2 Tool Scope 3-2
3.2.1 Overview 3-2
3.2.2 Material Properties 3-3
3.2.3 Material Generation Sectors 3-4
3.2.4 Electricity Energy Mix 3-5
3.2.5 Materials Collection 3-7
3.2.6 Material Transport 3-9
3.2.7 Materials Recovery 3-11
3.2.8 Material Recycling and Source Reduction 3-13
3.2.9 Landfilling 3-14
3.2.10 Incineration 3-21
3.2.11 Composting 3-23
3.2.12 Change in Land Use 3-25
3.2.13 Alternative Materials Management Methods 3-25
3.3 Economic Impacts 3-26
3.4 Tool Analysis/Output 3-28
4 Applications of the Tools from a Decision-Maker's Perspective 4-1
4.1 Relevant EOL Material Management Scenarios 4-1
4.2 Basis for Material Composition Assumptions 4-3
4.3 Additional Global Modeling Assumptions 4-6
4.4 Baseline Scenario 4-9
4.4.1 Scenario Description and Assumptions 4-9
4.4.2 Results and Discussion 4-9
4.5 LFG Treatment Options 4-13
4.5.1 Scenario Description and Assumptions 4-13
4.5.2 Results and Discussion 4-14
4.6 Impacts of Source-Separated Organics Processing 4-18
4.6.1 Scenario Description and Assumptions 4-18
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A Comparative Analysis LCA Tools Table of Contents
4.6.2 Results and Discussion 4-19
4.7 Impacts of Backyard Composting 4-21
4.7.1 Scenario Description and Assumptions 4-21
4.7.2 Results and Discussion 4-23
4.8 Impact of Materials Recovery 4-24
4.8.1 Scenario Description and Assumptions 4-24
4.8.2 Results and Discussion 4-26
4.9 Impacts of MRF Automation 4-28
4.10 Impacts of Recycling Plastics vs Recycling Glass 4-28
4.10.1 Scenario Description and Assumptions 4-28
4.10.2 Results and Discussion 4-29
4.11 Impacts of PAYT Program 4-31
4.11.1 Scenario Description and Assumptions 4-31
4.11.2 Results and Discussion 4-33
4.12 Impacts of CDD Recycling 4-33
4.12.1 Scenario Description and Assumptions 4-33
4.12.2 Results and Discussion 4-35
4.13 Impacts of E-Waste Collection and Recycling 4-35
4.13.1 Scenario Description and Assumptions 4-35
4.13.2 Results and Discussion 4-36
4.14 Impacts of Collection Vehicle Fuels Type 4-37
4.14.1 Scenario Description and Assumptions 4-37
4.14.2 Results and Discussion 4-38
4.15 Impacts of Collection Vehicle Types 4-39
4.16 Impacts of a Transfer Station 4-39
4.16.1 Scenario Description and Assumptions 4-39
4.16.2 Results and Discussion 4-40
4.17 Impacts of Several Thermal Treatment Options 4-42
4.17.1 Scenario Description and Assumptions 4-42
4.17.2 Results and Discussion 4-43
4.18 Impacts of Plastics Incineration vs Recycling 4-45
4.18.1 Scenario Description and Assumptions 4-45
4.18.2 Results and Discussion 4-46
4.19 Impacts of RDF Recovery Before and After Landfilling 4-48
4.20 Summary and Discussion 4-49
5 Summary 5-1
5.1 Summary of Tools Salient Features Comparison 5-1
5.2 Observations from the Tools Application for Evaluating Materials Management
Options 5-5
5.3 Data Gaps and Considerations for Future Research 5-6
6 References 6-1
Appendix A 1
XI
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A Comparative Analysis LCA Tools
Table of Contents
List of Tables
Table 1-1. Example Economic, Environmental, and Social Parameters of MSW Management Decision
Making 1-1
Table 3-1. Tool Versions Evaluated 3-1
Table 3 -2. Comparison of Tool Flexibility for Key LCA Parameters Categories 3-2
Table 3-3. Comparison of Tool Flexibility for Key Material-Specific Properties 3-4
Table 3 -4. Comparison of Materials Generation Sectors Considered by the Tools 3-4
Table 3 -5. Comparison of Tool Flexibility for Baseload and Marginal Energy Mix Data 3-6
Table 3-6. Comparison of Tools for Materials Collection Process Options and LCI Scopes 3-8
Table 3-7. Comparison of Tool Transportation Fuel Options 3-9
Table 3-8. Comparison of Tool Transportation Vehicle Options and LCI Scopes 3-10
Table 3-9. Comparison of Tool Transfer Station Options and LCI Scopes 3-11
Table 3-10. Comparison of Tool MRF Options and LCI Scopes 3-13
Table 3-11. Comparison of Tool Landfill Type Options 3-14
Table 3-12. Comparison of Tool LCI Scopes for Landfill Construction, Operation, Closure, and Post-
Closure Care Phases 3-17
Table 3-13. Comparison of Tool Flexibility and LCI Scope for Leachate and LFG 3-20
Table 3-14. Comparison of Tool Flexibility and LCI Scope for Materials Incineration Processes 3-22
Table 3-15. Comparison of Tool Flexibility and LCI Scope for Composting Processes 3-23
Table 3-16. Comparison of Tools for Alternative Materials Treatment Options and LCI Scopes 3-26
Table 3-17. Comparison of Tool Flexibility for Process-Specific Cost Data 3-27
Table 3-18. Comparison of Tool Analyses and Output Data Options 3-30
Table 3-19. Comparison of Analyzed Tool Impact Categories and Associated Units 3-31
Table 4-1. EOL Materials Management Scenarios Evaluated Using the LCA Tools 4-2
Table 4-2. Global Assumptions for Baseline Scenario 4-6
Table 4-3. General Global Assumptions 4-9
Table 4-4. Yard Waste and Food Scraps Diversion Rates Used for Backyard Composting Scenario ...4-22
Table 4-5. Material Capture Rate, Residual Rate, and Recycling Used for the MRFs Analyzed 4-25
Table 4-6. Materials Diversion Rates Assumed for the PAYT Scenario 4-32
Table 4-7. A List of the Scenarios that could be Evaluated Using the LCA Tools 4-50
Table 5 -1. Comparison of Salient Features of EOL Materials Management LCA Tools 5-3
Table A-l. Tool Descriptions and General Attributes 1
Table A-2. Tool Documentations Details 5
Table A-3. MSW Type Materials Included in Tool Scope 7
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A Comparative Analysis LCA Tools Table of Contents
List of Figures
Figure 2-1. Decision-Making Domain of Communities with Respect to EOL Phase Materials Flow 2-2
Figure 3-1. Example of Materials and Energy Inputs and Emissions Associated with Recovery of a Specific
MSW Constituent 3-12
Figure 3-2. Example of Materials and Energy Inputs and Emissions Associated with Materials Disposal in
Landfill 3-16
Figure 3-3. Example of Materials and Energy Inputs and Emissions Associated with Materials Incineration
for Energy Recovery 3-21
Figure 3-4. Example of Materials and Energy Inputs and Emissions Associated with Composting of Yard
Waste 3-24
Figure 4-1. Comparison of 2012 US EPA Fact and Figures and Tools' Default MSW Composition 4-3
Figure 4-2. Baseload Energy Mix Used for Simulations 4-7
Figure 4-3. Marginal Fuel Mix Used for Simulations 4-7
Figure 4-4. EOL Materials Flow with Composting of Yard Waste and Disposal of Remaining Materials
(Baseline Scenario) 4-9
Figure 4-5. Comparison of the LCA Tools' GHG Emissions Estimates for Baseline Scenario 4-11
Figure 4-6. Comparison of the LCA Tools' Acidification Impact Estimates for Baseline Scenario 4-12
Figure 4-7. Comparison of the LCA Tools' Total Annual Cost Estimates for Baseline Scenario 4-13
Figure 4-8. EOL Materials Flow with Materials Disposal in Landfill or Bioreactor Landfill with LFG
Collection and Treatment with or without Electricity Generation 4-14
Figure 4-9. Comparison of the LCA Tools' GHG Emissions Estimates for Different LFG Treatment
Options 4-15
Figure 4-10. EASETECH GHG Emissions Estimates with Offsets for LFG-to-Electricity Option 4-16
Figure 4-11. Comparison of the LCA Tools' Acidification Impact Estimates for Different LFG Treatment
Options 4-17
Figure 4-12. Comparison of the LCA Tools' Annual Landfill Cost Estimates for Different LFG Treatment
Options 4-18
Figure 4-13. EOL Materials Flow with Collection and (a) Composting, and (b) AD of Source-Separated
Organics 4-19
Figure 4-14. Comparison of LCA Tools' GHG Emission Estimates for Source-Separated Organics
Processing 4-20
Figure 4-15. Comparison of Total Annual Cost Estimates from SWOLF for the System with and without
Source-Separated Organics Processing 4-21
Figure 4-16. EOL Materials Flow with Backyard Composting of a Fraction of Source-Separated Organics
4-22
Figure 4-17. Comparison of LCA Tools' GHG Emission Estimates for Backyard Composting 4-23
Figure 4-18. Comparison of LCA Tools' Total Annual Cost Estimates for the System with Backyard
Composting 4-24
Figure 4-19. EOL Materials Flow with Materials Recovery via a Single/Dual-Stream Recycling Program
4-25
Figure 4-20. EOL Materials Flow with Materials Recovery via a Mixed-Materials Recycling Program ..4-
25
Figure 4-21. Comparison of LCA Tools' GHG Emission Estimates for Different Materials Recovery
Options 4-27
Figure 4-22. Comparison of LCA Tools' GHG Emission Estimates for Different Materials Recovery
Options 4-28
Figure 4-23. EOL Materials Flow for (a) Plastics and (b) Glass Recycling Scenario 4-29
Figure 4-24. Comparison of LCA Tools' GHG Emission Estimates for Plastics and Glass Recycling .4-30
Figure 4-25. Comparison of LCA Tools' Plastics and Glass Recycling Cost Estimates per MT Material
Collected 4-31
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A Comparative Analysis LCA Tools Table of Contents
Figure 4-26. EOL Materials Flow with a PAYT Program Implemented with a Single/Dual Stream Materials
Recovery Program 4-32
Figure 4-27. Comparison of LCA Tools' GHG Emission Estimates for the System with and without PAYT
Program 4-33
Figure 4-28. CDD Materials Composition assumed for CDD Recycling Scenario 4-34
Figure 4-29. EOL Materials Flows for CDD (a) Disposal, and (b) Recycling Scenarios 4-34
Figure 4-30. Comparison of WARM GHG Emission Estimates for the CDD Landfilling and Recycling
Options 4-35
Figure 4-31. EOL Materials Flow with E-waste (a) Disposal, and (b) Recycling Scenarios 4-36
Figure 4-32. Comparison of WARM GHG Emission Estimates for the E-Waste Landfilling and Recycling
Options 4-37
Figure 4-33. Comparison of LCA Tools' GHG Emission Estimates for Different Collection Vehicle Fuels
Options 4-38
Figure 4-34. Comparison of WRATE's Acidification Impact Estimates for Collection Vehicle Fuels
Options 4-39
Figure 4-35. EOL Materials Flow for Transfer Station Scenario 4-40
Figure 4-36. Comparison of LCA Tools' GHG Emission Estimates for the System with and without a
Transfer Station 4-41
Figure 4-37. Comparison of LCA Tools' Total Annual Cost Estimates for the System with and without
Transfer Station 4-41
Figure 4-38. EOL Materials Flow for Thermal Treatment Scenario 4-42
Figure 4-39. EOL Materials for Pyrolysis or Gasification Treatment Scenario 4-43
Figure 4-40. Comparison of LCA Tools' GHG Emission Estimates for the Baseline Scenario and Different
Thermal Treatment Options 4-44
Figure 4-41. Comparison of LCA Tools' Total Annual Cost Estimates for the Baseline Scenario and
Different Thermal Treatment Options 4-45
Figure 4-42. EOL Plastics Flow for (a) Recycling, and (b) WTE Scenarios 4-46
Figure 4-43. Comparison of LCA Tools' GHG Emission Estimates for Plastics Incineration and Recycling
4-47
Figure 4-44. Comparison of LCA Tools' Economic Benefits Estimates for Plastics Incineration and
Recycling 4-47
Figure 4-45. EOL Materials Flow with (a) RDF Production before Disposal, and (b) RDF Production after
Disposal followed by Landfill Mining 4-49
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A Comparative Analysis LCA Tools
Abbreviations, Acronyms, and Initials
List of Abbreviations, Acronyms, and Initials
AD
AE
APCD
BOD
BTU
CDD
CNG
CO
CO2
COD
CH4
DTU
EASETECH
EOL
GHG
HOPE
LCA
LCI
LCIA
LFG
MRF
MSW
MSW-DST
MT
NCSU
NH3
NOX
PAYT
PET
pdf
PM
PO4
POTW
RDF
SHC
SOX
SSO
SWOLF
TRACI
TSS
UK
US
US EPA
WARM
WEEE
WRATE
WTE
WWTP
Anaerobic Digestion
Accumulated Exceedance
Air Pollution Control Device
Biological Oxygen Demand
British Thermal Unit
Construction and Demolition Debris
Compressed Natural Gas
Carbon Monoxide
Carbon Dioxide
Chemical Oxygen Demand
Methane
Technical University of Denmark
Environmental Assessment System for Environmental Technologies
End of Life
Greenhouse Gas
High Density Polyethylene
Life-Cycle Assessment
Life-Cycle Inventory
Life Cycle Impact Assessment
Landfill Gas
Material Recovery Facility
Municipal Solid Waste
Municipal Solid Waste-Decision Support Tool
Metric ton
North Carolina State University
Ammonia
Nitric Oxides
Pay as You Throw
Polyethylene Terephthalate
portable document format
Particulate Matter
Phosphate
Publically-Owned Treatment Works
Refuse-Derived Fuel
Sustainable and Healthy Communities Research Program
Sulfur Oxides
Source-Separated Organics
Solid Waste Optimization Life-Cycle Framework
Tool for the Reduction and Assessment of Chemical and other Environmental
Impacts
Total Suspended Solids
United Kingdom
United States
United States Environmental Protection Agency
Waste Reduction Mode
Waste Electrical and Electronic Equipment
Waste and Resources Assessment for the Environment
Waste-to-Energy
Wastewater Treatment Plant
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A Comparative Analysis LCA Tools Section 1 - Introduction
1 Introduction
1.1 Background
The municipal solid waste (MSW) generation in the US has almost tripled in the last five decades from
approximately 80 million metric tons (MT) (at 2.68 pounds per person per day in 1960) to 225 million MT
(at 4.38 pounds per person per day in 2010) (US EPA 2014). MSW and construction and demolition debris
(CDD) are the primary end of life (EOL) materials that communities (through their local governments) are
responsible for managing. Historically, the spectrum of management options and services available to
communities has ranged from systems where EOL materials are collected and transported elsewhere for
further management to the development and operation of regional EOL materials management facilities
which accept and handle MSW from various surrounding communities. MSW management decision-
making is primarily driven by the cost of community-preferred options that meet the regulatory standards
(local, state, and federal) for protecting human health and the environment. Given the amount of MSW that
needs to be managed and its characteristics (e.g., biodegradability, potential for odor release), communities'
decisions on the materials and methods used for MSW management also have significant social and
environmental impacts that in turn have economic impacts (e.g., the impact on local ecosystem goods and
services from a site located adjacent to EOL materials management activities).
The US EPA Decision Maker's Guide to Solid EOL Materials Management II (1995) laid the groundwork
for decision making for integrated EOL materials management and discusses potential MSW management
approaches and the associated constraints. The guide briefly acknowledges life-cycle assessment (LCA)
as an approach to comparing several management strategies based on their environmental tradeoffs. The
US EPA's Sustainable and Healthy Communities Research Program (SHC) strives to provide tools for
community decision makers to more effectively and equitably evaluate and integrate parameters across all
three pillars of sustainability (i.e., economic, environmental, social) into their EOL materials-management-
related decisions to promote community sustainability (US EPA 2012a). Table 1-1 lists some examples of
the key economic, environmental, and social parameters that pertain to MSW management decision
making.
Table 1-1. Example Economic, Environmental, and Social Parameters of MSW Management
Decision Making
Sustainability
Pillar
Economic
Environmental
Social
Example Decision Parameters
Capital investment, revenue, financial risks, resource requirements, feedstock, end-uses,
scaling flexibility, land use, location, job creation, economic impact, impact on the value of
surrounding properties
Emissions (to water, land/soil, and air), odor, noise
Public safety /risks, transportation congestion, environmental justice,
aesthetics/visual quality
demographic impacts,
Several available tools can potentially be used for a LCA of materials-management options. Winkler and
Bilitewski (2007) and Gentil et al. (2010) evaluated several materials-management LCA tools. Winkler
and Bilitewski (2007) reported that large discrepancies among the results of six LCA tools used for the
study may lead to contrary conclusions based on the LCA for the integrated EOL materials-management
options (landfilling, incineration, or recycling and landfilling) simulated. Gentil et al. (2010) reviewed the
methodologies, input parameters, and technical assumptions used for various processes of nine LCA tools
including EASEWASTE (EASETECH precursor), WRATE, and MSW-DST, and concluded a need for
harmonizing and validating geographically independent assumptions for improving EOL materials LCA
M
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A Comparative Analysis LCA Tools Section 1 - Introduction
modeling capabilities. The evaluations identified issues to be considered in the development of new tools
or in improvements to existing tools. In addition, these evaluations focused on the environmental impact
aspect of LCA. Decision makers should also consider social and economic impacts in addition to the impact
on the environment (USGS 1998, US EPA 2009).
There is a need to identify and evaluate materials management LCA tools from the perspective of the
community (decision makers, facility operators, engineers, and regulators) that actively makes or influences
the decisions pertaining to EOL materials management systems. The use of LCA tools by this community
potentially would have significant impacts on decision making and the ensuing environmental, social, and
economic impacts on the community, and on adjacent communities. Considerations such as tool cost,
complexity, scope and capabilities, and relevance to the processes of interest are more important to these
users, who have limited LCA background, than factors such as tool methodologies, input parameters, and
data sources that were the focus of the evaluations conducted by previous studies.
1.2 Report Objectives, Scope, and Approach
The objective of this report is to identify and evaluate the tools that can be used by communities to conduct
a LCA of MSW management systems. The project scope included evaluation of up to five LCA tools.
Several LCA tools were identified and preliminarily evaluated to select five tools that are specifically
developed for the EOL phase management of MSW constituents. Community decision makers control the
MSW stream and processes only after the waste is discarded and placed in receptacles for collection. It
should be noted that the decision makers may influence consumer choices and subsequently the impacts of
upstream processes by implementing programs such as educational outreach to raise awareness among the
citizens about the impact of materials and their management alternatives.
The tool selection approach included identifying evaluation criteria, analyzing the tools using these criteria
based on a review of each tools' documentation, and then applying the selected tools to a series of scenarios
representing currently-relevant EOL materials-management issues. A set of criteria such as processes
included, source data (e.g., life-cycle inventory (LCI), characterization factors) used for LCA, impact
categories analyzed, user interface, and tool flexibility was identified to evaluate the selected tools primarily
from a user's perspective.
The assessment also considers the scope of processes (e.g., whether landfill gas (LFG) generation and
emission is included in the landfill process) included in each of the major EOL materials management
strategies. A detailed review of the sources and the data included in the life-cycle-inventories (LCIs) of
individual processes (e.g., a review of the data and the associated sources used for estimation of LFG
generation and emission in each unique tool), and an assessment of the uncertainty associated with the LCA
performed by the selected tools is beyond the scope of the evaluation presented in this report, though these
factors may have a significant impact on the tool results for a given scenario.
Documentation for each of the final tools selected was reviewed and several EOL management scenarios
were simulated to evaluate these tools based on the identified criteria and to illustrate the potential uses and
limitations of these tools for community decision making. The scenarios were selected based on the current
state of the practice of MSW management and the issues that community decision makers are facing across
the US. Data gaps and key research needs are identified.
1.3 Report Organization
The report is organized into six chapters. Chapter 1 presents the background, objectives, and scope of the
evaluation presented in this report. Chapter 2 briefly describes the relevance of LCA for EOL materials
management, discusses the tools selection process, and briefly describes the five LCA tools that are
evaluated. Chapter 3 introduces the tool evaluation criteria and presents a side-by-side evaluation of the
1-2
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A Comparative Analysis LCA Tools Section 1 - Introduction
five selected tools based on evaluation criteria. Chapter 4 presents a series of EOL materials management
scenarios that were analyzed using the tools; the results are compared between the tools. Chapter 5
summarizes the evaluation and presents the identified data gaps and potential areas for future research.
References used throughout the report are provided in Chapter 6. The terms "LCA", "tool," and "model"
are used to describe the appropriate aspect of the comparison, but are not necessarily interchangeable. LCA
is the assessment process, while the programs compared in this study are referred to as tools that model the
LCA of the EOL-phase materials-management options.
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2 Use of LCA for EOL Materials Management
2.1 Using LCA in the Context of Sustainable Materials Management
Recycling rate is a benchmark commonly used by communities to quantitatively assess the environmental
impact of a MSW management system. Recycling rate, which presents the mass fraction of materials
recycled out of the total amount generated, does not account for the materials' properties (e.g., LFG
generation or leaching potential) that may significantly influence the environmental impact. In addition,
the definition of recycling varies from state to state. For example, some communities consider the use of
yard waste as landfill daily cover as recycling whereas others do not.
LCA, on the other hand, is a standardized approach for analyzing the impacts across the life cycle or a
specific stage of a product or process based on the unique characteristics of individual materials. LCA can
be used to analyze the system-wide impact of an integrated EOL materials-management system or that of
a specific process (e.g., transporting MSW from curbside to the management facility).
The International Organization of Standardizations (ISO 14040) defines LCA as a "compilation and
evaluation of the inputs, outputs and potential environmental impacts of a product system throughout its
life cycle." Over its life cycle, a product goes through four distinct stages: raw material acquisition,
manufacturing, use/maintenance, and recycling/ disposal. The LCA process generally consists of four
distinct steps: goal definition and scoping, inventory analysis, impact assessment, and interpretation (ISO
1997). The goal definition and scoping step primarily entails defining goals (e.g., determine the EOL
materials management option with the least impact on the environment) and scope (e.g., should the analysis
be conducted for the entire life cycle of the product/system of interest or should it be limited to a particular
stage [e.g., manufacturing, use, or end-of-use management]).
The second step in an LCA is inventory analysis. In this step the inputs (e.g., energy, materials) and outputs
(e.g., products; byproducts; emissions to air, water, and land) associated with the product(s) or process(es)
within the scope of the LCA are quantified. The output of this step is referred to as life cycle inventories
(LCIs) and consists of a quantitative compilation of all the inputs (natural [e.g., soil mined for use as daily
cover for landfill, water] and technosphere resources [e.g., truck transport, electricity]) as well as all the
outputs (e.g., emissions to water and air from 1 kg of MSW placed in landfill). One approach to the analysis
of manufacturing processes is to consider the region of origin for both virgin and recycled manufacturing
given that emissions regulations and the CO2 intensity of the energy grid vary by country. This level of
information is difficult and likely changes with time. An alternative approach is to use global averages for
both virgin and recycled manufacturing processes. Similarly, the EOL management practices of the
discarded materials destination regions and the associated emissions should be taken into consideration for
LCIs if the materials are exported outside the US.
In the third LCA step (referred to as life-cycle impact assessment [LCIA]), the LCIs are multiplied with
corresponding factors known as characterization factors to assess end point (or midpoint) damage
categories (e.g., climate change, eutrophication). The final step in LCA is interpretation. The LCA results
are interpreted in relation to the goal-definition phase of the LCA study, involving review of the scope of
the LCA as well as the nature and quality of the data collected.
Figure 2-1 presents the flow of MSW materials after they are taken out of service. These post-consumer
materials may be source segregated and sent directly to a recycled materials vendor or the remanufacturer
by large consumers (e.g., regional-scale chain stores) or may be placed in collection containers or recycling
bins for collection by community MSW management divisions or their franchised haulers. These materials
may be processed further in a material recovery facility, composted, combusted for energy recovery, or
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Section 2- Use of LCA for EOL Materials Management
landfilled. The materials recovered from material recovery facilities (MRFs) are sent to facilities for
remanufacturing, either in the US or abroad.
Several sub-processes (e.g., LFG generation from biodegradation of organics fraction deposited in landfill)
and emissions are associated with each of the major processes depicted in Figure 2-1. Each of these sub-
processes may have several options with unique environmental, economic, and social impacts that
community decision makers would have to evaluate in selecting the most appropriate one. Two examples
of decisions that communities may have to make pertaining to these processes are as follows:
1. Should diesel or natural gas trucks fleet be used for waste collection in case a community owns and
operates it waste collection fleet?
2. Should we control LFG even if we are not required to by regulations?
The MSW management system for community decision makers generally begins from the point that the
EOL materials are discarded and placed on the curbside for collection by the community's MSW
management division. Community decision makers usually have no authority over decisions related to
upstream processes (e.g., production, packaging, and/or the use of consumer products, backyard
composting of food scraps). Therefore, most of the tools evaluated in this study do not include processes
outside the direct control of the community decision makers. It should be noted that these decision makers
can indirectly impact these upstream processes by influencing consumer products choices with
environmental awareness and outreach programs.
Source Segregated
Recyclables
(eg. Corrugated
containers from
commercial
establishments)
Exporting to
another
Community
Post-consumer Materials
- Mixed MSW
-Yardwaste
-Separated
Recyclables
-Separated Organics
-CDD
Potentially
Recyclable
Material
MRF
-Single Stream
- Dual Stream
-Mixed Waste
-CDD
RecyclablesL_Metab
Material
Reprocessing
- Reuse
- Recycling
Collection
- Curbside
- Dropoff center
- Dumpster
Combustible
Material
Residuals
-Organic Waste-
Biological Treatment
-Composting
-Anaerobic
V. J
Decision-making domain of community solid waste divisions
Thermal Treatment
- Incineration
- Gasification
- Pyrolysis
I
Ash
i
Landfilling
- MSW Landfill
- Bioreactor
Landfill
- CDD Landfill
-Ash Landfill
Backyard Composting
(eg. Grass- cycling, Food
Waste and Yard Waste
Composting)
Compost Use
(eg. Soil amendments
& mulch)
Figure 2-1. Decision-Making Domain of Communities with Respect to EOL Phase Materials Flow
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2.2 EOL Materials Management LCA Tools Sieve Analysis
We identified 29 LCA software tools through an extensive literature search. The scope of the EOL materials
manager's decision-making domain was used as the primary screening criteria to select tools for subsequent
evaluation. As discussed in the previous section, the decision-making domain of the US EOL materials
management community, including municipalities and engineers, is limited to the EOL stage of materials.
The upstream stages (e.g., raw material acquisition, product manufacturing, and use) are beyond the EOL
materials-management community's control; the emissions from upstream stages have already occurred by
the time a community EOL materials-management department receives the discarded products. Many of
the tools identified for this evaluation (e.g., Simapro, Gabi) can be used to conduct the LCA of the entire
life cycle of a material (encompassing all four stages of its life cycle) and are much broader in scope than
needed for making EOL management decisions at the community level. Some tools, on the other hand,
were specifically developed to conduct an LCA for the EOL phase (e.g., WRATE, MSW-DST). Only the
tools that assess impacts of the EOL phase were selected for further evaluation.
Various databases (e.g., Ecoinvent, NREL US LCI database) can be used to assess LCIs for different
processes. It should be noted that LCIs are an intermediate and not an end goal of LCA. However, some
of the identified tools provided LCIs as the final tool output. These tools (e.g., EPIC-CSR, MIMES,
WASTED) were not considered for further evaluation. Some of the tools identified (e.g., Impact 2002+)
were determined to be merely the characterization factors databases; these tools can only be used for a life
cycle impact assessment (LCIA) for given LCIs and cannot be used for an MSW management system LCA.
These tools were excluded from further evaluation. Some tools were also excluded from further analysis
due to the scarcity of the information available (e.g., SSWMSS, MSWI), while some (e.g., ORWARE) were
excluded based on the developer's recommendation to use other tools due to the specific tool's limitations
(e.g., lack of updates since development). The following tools were selected for a second level of
evaluation: WRATE, MSW-DST, EASETECH, HOLIWAST, WARM, WAMPS, and SWOLF. The seven
tools listed were further evaluated to select up to five tools for the more detailed technical evaluation
presented in this report. The tools were evaluated based on release year, documentation/technical support
available, and applicability or ability to analyze systems for the geographical region of the interest (i.e. US).
Although many of the location-specific characteristics (e.g., EOL materials composition) can be changed
in most of these tools, not all the tools are designed to include the US-specific EOL materials-management
processes. Therefore, the tools developed specifically for the US (WARM, MSW-DST, SWOLF) were
selected. Of the remaining four tools, EASETECH and WRATE were identified as having the most flexible
processes included (e.g., collection, material recovery); therefore, EASETECH and WRATE were also
selected for further evaluation. The following subsections provide a brief overview of these five tools;
more detailed information on the tool assumptions and emissions factors is provided in Chapter 3, with
additional details presented in a series of tables in Appendix A.
2.2.1 WARM
WARM was developed in 1998 and has been updated through thirteen versions. WARM was developed
for US EOL materials managers to track the energy use and greenhouse gas (GHG) emissions of alternative
EOL materials-management practices. WARM is available in both a spreadsheet and web-based interface
that allows the user to compare the net energy use and total GHG emissions of a baseline EOL materials
management approach (for example landfilling 1,000 tons of food scraps) with those of an alternative
strategy, such as composting 1,000 tons of food scraps. WARM currently recognizes 54 material types
(e.g., food scraps, concrete, mixed MSW, yard trimmings, drywall, etc.). The accessibility and ease of use
of the tool has allowed for a much wider user base than any other model evaluated in this study.
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WARM contains a database of emission factors for the different EOL materials management strategies (i.e.,
source reduction, recycling, combustion, composting, and landfilling); the tool estimates GHG emissions
and energy use based on these emissions factors and the data input by the user. WARM requires at a
minimum that the user input the baseline scenario's EOL materials quantities and methods of management,
then input the corresponding quantities of the materials that are managed in the comparison scenario (the
mass balance between the baseline and alternative scenarios must be consistent or an error message will
prevent the tool from generating the output results). The user can adjust default values to describe the
management scenarios (e.g., energy grid mix, the type of landfill control system, or transportation distance
to management facilities). The results of the assessment provide the user with GHG emissions totals (in
CO2 equivalents and carbon equivalents) and energy use (British Thermal Units (BTUs)) for the baseline
and alternative scenario and the difference between the two scenarios.
Three general sets of documentation are available for WARM: management practices (e.g., landfilling,
composting), materials (e.g., asphalt concrete, clay bricks), and model background documents (which
include links to various additional documents) that are available on the EPA website. The latest version of
the tool was updated in June 2014 and is available free of charge through EPA's website.
2.2.2 MSW-DST
MSW-DST development began in 1994 and was designed to help US EOL materials planners evaluate the
economic and environmental aspects of integrated MSW management operations, including collection,
transfer, materials recovery, composting, waste-to-energy (WTE), and landfill disposal. The tool includes
39 materials (including materials classified as "other"). Most of the key input parameters can be specified
by the user. The user begins tool use by entering different EOL materials-management processes to be
included in the analysis. Specific values and parameters may be selected within MSW-DST by modifying
process inputs.
The tool can estimate the construction and operating costs of EOL materials-management facilities. It also
calculates energy consumption, GHG emissions, and other emissions, including criteria air pollutants and
releases to water, and assesses the impacts using TRACI (Tool for the Reduction and Assessment of
Chemical and other Environmental Impacts) characterization factors. The tool can optimize estimates for
the single user-specified economic or environmental parameter of choice. The results are generated in excel
spreadsheet format. Results for more than one scenario cannot be produced at the same time; therefore,
comparing two scenarios requires the user to set up two tool runs and then manually compare the output
spreadsheet results.
Both the tool and its documentation are available for download on the RTI website free of charge. A
majority of the documentation is dated between 1997 and 2003, with a few materials from 2006 and one
document as recent as 2011. The most recent "version number" is version 1.0, which suggest no new
"version" has been released; only updates to the original version have been released. Access to the tool
requires submitting a login request at RTFs website to obtain permission to use the tool.
2.2.3 SWOLF
This tool is designed for EOL materials planner for LCA of management systems, including transportation,
composting, anaerobic digestion, materials recovery, and landfilling, and WTE processes. At the time of
this study, the SWOLF tool was under development by researchers in the Department of Civil, Construction
and Environmental Engineering at North Carolina State University (NCSU) under grants from the National
Science Foundation and the Environmental Research and Education Foundation. Due to SWOLF's current
state of development, information on final documentation, license cost, and interface is not final. A
developmental version that operates on spreadsheets was evaluated in this study, but the final version is
expected to consist of a desktop application.
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SWOLF will be made publically available when tool development is complete. There will be no cost to use
the full model for non-commercial applications. There may be a royalty-based fee for commercial use, but
this has not yet been finalized. Tool documentation has not been published, but the modeling of each process
in SWOLF is based on the developer's research, much of which has been published. These separate papers
detail the assumptions and data used to construct each process model. Once the tool is published there is
expected to be documentation for each process, as well as the overall model. The developers also plan video
tutorials and demo guides.
2.2.4 EASETECH
This tool is designed for EOL materials planners for conducting an LCA of integrated EOL materials
management operations; these include transportation, composting, resource recovery, WTE and landfilling.
EASE-WASTE, the precursor to EASETECH, development began in 2000 at the Technical University of
Denmark (DTU). EASETECH development began in 2010 and has been updated through two versions
(2.0.0 Internal Institute Version). The latest version of the tool and documentation were released in August
2014 and are available for use only after the user completes training offered by DTU. The approximate cost
for training and the software for a commercial license is 5,000 (approximately $5,550 at 2015 exchange
rates). Tool technical resources include support from developers, the EASETECH documentation manual,
and training exercises.
EASETECH uses an interface that allows the user to create a sequential flow of EOL materials through
various processes and to estimate emissions associated with EOL materials management strategies (such as
landfilling, recycling, and combusting MSW). It estimates emissions in a format that allows the user to
view the net or selected individual process emissions. EASETECH requires the user to enter EOL materials
tonnage and then to specify the EOL materials management scenario by directing material flows through
the processes of interest. Default values and processes are available for use if, for example, the user does
not have site-specific information or more detailed data available (e.g., EOL materials composition data).
EASETECH can estimate a variety of environmental impacts; the user has the option of selecting from six
impact assessment methods to estimate the impacts of the raw emissions. The default tool inputs such as
EOL materials streams compositions and processes are mostly representative of Denmark and Western
Europe.
2.2.5 WRATE
WRATE was first released in 2007 and has undergone two major updates, the first in 2010 and the most
recent in March of 2014. The tool was originally developed for the Environmental Agency (United
Kingdom) but is now owned and supported by Golder Associates (UK) Ltd. A demo version of the tool
with limited functionality is available online for free (http://www.wrate.co.uk/Page/Download).
Documentation is available for the tool with the software, and process-specific information is provided for
each of the processes in the tool. An annual license for the standard version of the software costs £ 1,500
(approximately $2,400 at 2015 exchange rates).
WRATE uses a graphical interface that allows the user to create the EOL materials flow through a desired
sequence of processes (such as collection, landfilling, recycling and combusting MSW) for a
selected/specified EOL materials stream.
The tool was designed to be primarily representative of UK EOL materials management systems;
international data were used if UK data were not available. The tool estimates emissions based on the
Ecoinvent database and other sources of emissions factors in a format that allows the user to view the net
and individual process emissions. The tool provides outputs in a variety of formats (e.g., tabular, graphical)
that can be exported and saved. WRATE requires EOL materials tonnage to be provided by the user. The
user must then select the individual EOL materials management processes that the EOL materials mass will
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A Comparative Analysis LCA Tools Section 2 - Use of LCA for EOL Materials Management
be passed through until it reaches its final destination for disposal or reuse. Default values and process are
available for use if site-specific information or more detailed data are not available (e.g., EOL materials
composition data).
The user has some flexibility in specifying the various management processes, for example, choosing the
type of landfill containment design (e.g., type of cap or liner), transportation distances, and treatment
technologies. The user can compare multiple EOL materials management scenarios as long as the waste
tonnage managed is the same for each scenario. The emissions impacts estimated by WRATE (using CML
2001 method) include global warming potential (GHGs), acidification potential, eutrophication potential,
freshwater aquatic ecotoxicity, human toxicity, and resource depletion.
It should be noted that of all the tools, WRATE is the only one with several versions available for use,
including a free demo and two versions available for purchase (the Standard and Expert versions). The
Expert version has expanded functionally over the Standard version and can create user-defined processes,
allowing access to the background Ecoinvent LCI database and providing the ability to change impact
assessment methods. The Expert version's annual license costs nearly four times more than the Standard
version. Therefore, the Standard version of the tool is evaluated in this report as it was assumed that the
Standard version of the tool would be the more frequently used. This report is based on the use of WRATE
(Software Version 3.0.1.5) which was issued in 2014, and Database Version 3.0.1.8 which became available
in February 2015.
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A Comparative Analysis LCA Tools Section 3 - Detailed Evaluation of the Selected LCA Tools
3 Detailed Evaluation of the Selected LCA Tools
3.1 Overview
The tools were evaluated and compared based on general attributes, scope, and analysis and outputs. The
results of the tool evaluations are organized in a series of tables for ease of comparison. These tables can
also be used as a guide for selecting the most appropriate tool for the LCA of an EOL material's
management system. The information presented in this chapter is primarily derived from tool
documentation pages. Tables A-l and A-2 in Appendix A presents basic details such as tool cost, method
of availability, developer, prevalence of use/distribution, and available user support. Please note that the
tools have been updated since their original release. Table 3-1 presents the versions of the tools that were
evaluated in this report. These tools have only become available in the past two decades. WARM was
initially developed in 1998 and has undergone 14 revisions since then. SWOLF has not officially been
released and is expected to be available for use in the near future.
Table 3-1. Tool Versions Evaluated
Tool
WARM
MSW-DST
SWOLF
EASETECH
WRATE
Version Evaluated
Version 13, prior to March 2015 update
Version 1.0 published in 2002, last update from June 2014
Pre-release version. Last software update provided
Internal Institute Version 2.0.0 (software), August
30 March 2015.
20 14 (database)
Version 3.0.1.5 (software) (7 March 2014)
WARM, MSW-DST, and SWOLF have been developed for the EOL materials and management practices
specific to the US. With some exceptions, EASETECH is generally representative of conditions in Denmark
and Western Europe. WRATE was developed to be representative of the UK EOL material management
systems. Based on data provided by the developers, 190 (including 29 copies of trial version) and 161
copies/licenses of MSW-DST and EASETECH, respectively, were distributed as of June 2015.
Approximately 230 licenses were sold for WRATE from 2008 through 2013. The US EPA does not track
number of WARM downloads. However, there are 300 unique users on WARM's updated mailing list.
The preceding usage is only noted as a reference to compare against the overwhelming need; 39,000 local
governments (counties, municipalities, and townships) in the US in 2012 (Hogue, 2013) that routinely
make decision pertaining to EOL management of materials discarded by the communities.
Table 3-2 compares tool flexibility with respect to key LCA inputs such as the EOL materials stream
composition and the energy mixes which the user may specify for modeling purposes. All of the tools
provide default values for a range of modeling parameters; however, not all of the tools allow users to
replace default values with their own data. Tool flexibility is particularly important for users attempting to
adjust input parameters to reflect an alternative geographic area than the one used to develop model default
conditions. Although WRATE and EASETECH are designed to represent conditions in Europe, these tools
have the flexibility to allow modification of input parameters (e.g. materials composition) to simulate US
conditions. Similarly, SWOLF and MSW-DST have flexibility to represent European conditions.
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Section 3 - Detailed Evaluation of the Selected LCA Tools
Flexibility can also be evaluated with respect to the individual tool processes (i.e., collection, transportation,
specific EOL materials management technologies, etc.). Overall tool processes are evaluated and compared
in subsequent sections. While tool adjustability and the user's ability to modify the underlying assumptions
and data are desired features, a large number of user-specifiable inputs increases tool complexity. WARM
offers the fewest parameters that can be modified by the user among the tools evaluated in this study.
EASETECH allows users to create processes not included in the tool. For example, Jain et al. (2014)
created a process to simulate landfill mining, which is not included in the tool, to assess the impact of
mining of old landfills with and without resource recovery. It should be noted that, as discussed in Chapter
2, the standard version of WRATE was used for this report. The expert version of the tool offers more
flexibility than the standard version.
Table 3-2. Comparison of Tool Flexibility for Key LCA Parameters Categories
Flexibility with tool
parameters
Allows user to adjust material
composition and generation
rate (e.g., 1,000 tons/day)
Allows modification of
material properties
Allows more than one material
stream to be managed at once.
Allows input of additional
material types (in addition to
those provided by tool)
Allows specification of the
energy mix of the area of
interest
Allows addition/modification
of processes (aside from
adjusting default values)
WARM
^
-
^
-
e
-
MSW-DST
y'a
^
^b
_d
^
-
SWOLF
^
^
Sc
_d
s
s
EASETECH
S
S
S
S
Sf
S
WRATE
S
-
S
-
v'f
p
_ 6
a. Population and per capita generation (Ib/person-day) are used to calculate overall material generation rate for a
year - the user does not directly input the total amount of material managed in a year.
b. However, must include at least one residential material stream.
c. SWOLF requires one initial material composition be defined, but different compositions for different sectors
can be added in later processes.
d. The tool includes a limited number of blank materials for which custom properties can be entered.
e. The user can only select a default energy mix for the US national average or for the US state of interest; the user
cannot specify a unique energy mix.
f. The tool comes pre-loaded with a variety of different grid mix and specific fuel energy-production processes.
The user can create a unique grid mix.
g. Only the Expert version allows the user to create unique processes.
3.2 Tool Scope
3.2.1 Overview
The materials, material characteristics, material generation sectors (e.g., residential, multi-family,
commercial), energy mix, and the specific management processes (e.g., collection, transportation, and
treatment) are some of the key input parameters for an LCA. This section explores and discusses the extent
of the adjustability of tool-specific modeling parameters for different materials-management options and
includes a comparative discussion of material properties, generation sectors, marginal electricity mix (i.e.,
the standard grid mix assumed by the model for offsetting purposes) and material handling processes
3-2
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A Comparative Analysis LCA Tools Section 3 - Detailed Evaluation of the Selected LCA Tools
considered by these tools. The information provided in this section was developed from tool documentation
and from using these tools for the scenarios modeled (and discussed in Chapter 4).
3.2.2 Material Properties
Each tool allows the evaluation of the EOL management of a variety of materials. The different types of
specific materials (organized by general material category [e.g., paper, plastic]) included in each tool are
presented in Table A-3 (see Appendix). Of the tools evaluated, EASETECH is the only one that allows the
user to input additional custom-defined materials beyond those included by default. While DST has "other"
categories for paper, plastic, and aluminum, it does not allow the user to create more categories than those
that already exist. The "other" categories in DST are only editable in limited ways. A notable difference
between the two European-developed tools (WRATE and EASETECH) and the US-based tools (WARM,
MSW-DST, and SWOLF) is that the plastic material categories listed in the US tools specify individual
plastic types (i.e., polyethylene terephthalate (PET), high density polyethylene (HDPE)) while the European
tools only provide general plastic descriptors (e.g., hard plastic, dense plastic, soft plastic). It should be
noted that the US EPA data, which decision makers typically reply upon, tracks plastics discarded in MSW
by their resin type. Inconsistencies in material name terminology used by several tools and the names
typically used in the US presented a challenge in using these tools, especially WRATE and EASETECH.
However, this challenge was addressed by developing a common EOL materials stream composition in all
the tools which as closely as possible simulated the same fractionation of materials; this allowed the
comparison of tool results for the different material management scenarios evaluated in Chapter 4. More
details on how this composition was selected are presented in Chapter 4.
Table A-3 also presents the CDD materials available for modeling in each tool. These materials are
classified into the following categories: wood, brick, concrete, wall board, asphalt shingles, asphalt
pavement, fines, soil, carpet, and other. As shown in Table A-3, WARM is the only tool which includes a
majority of CDD materials generated in the US (e.g., wallboard, wood, carpet, asphalt shingles, or asphalt
pavement material). WARM does not, however, assess soil or fines, which is material typically generated
from CDD processing activities. Both European tools assess soil and WRATE assesses fines (<10mm and
unspecified fines). The tools also evaluate several materials that do not fit under the definition of MSW or
CDD materials. These additional materials are compared in Table A-3 and include the following categories:
non-hazardous industrial waste/processed materials, biosolids, and other non-MSW materials (e.g., fly ash).
When a potential tool user has material-specific (e.g., moisture content) or material-management-process-
specific (e.g., electricity consumption per mass of ferrous metal recovered) data, LCA tools that allow
modifying material and process properties and underlying assumptions provide an opportunity for a better
simulation of the user's materials stream than a tool that does not offer such capabilities. Table 3-3
compares the tools' abilities to accommodate user-defined physical, biological, and chemical material
properties. As shown in the table, it is evident that users have the most flexibility in modifying material
properties in SWOLF, EASETECH, and MSW-DST.
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Section 3 - Detailed Evaluation of the Selected LCA Tools
Table 3-3. Comparison of Tool Flexibility for Key Material-Specific Properties
Material Properties
Physical
Biological
Chemical
Moisture content
Energy content
Ash content
Material density
Combustion efficiency
Decay rate constant (k)
Methane generation potential
Elemental constitution
WARM
-
-
-
-
-
,/d
-
-
MSW-DST
v'a
,/b
/
/
/
,/e
-
-
SWOLF
/
/*
^
^
^
/
/
/
EASETECH
/
^
^
-
,/c
/
_f
/
WRATE
-
-
-
-
-
-
-
-
a. Water content fraction
b. BTU/lb
c. Can be adjusted through modification of a material's volatile solids content
d. Five k rate defaults to select from
e. There is an option to select a "user defined k," but there currently is no place to set this k value.
f. This parameter is not used in the tool per se, however, the fraction of anaerobically degradable carbon can be
modified to mimic variation in methane generation potential
3.2.3 Material Generation Sectors
Material generation sectors are the classifications of the sources of materials that require EOL management.
These classifications generally include single-family residential (e.g., individual homes with curbside
collection), multi-family residential (e.g., apartment buildings), industrial (e.g. factories), and commercial
(e.g., retailers, schools, hospitals, prisons). Material generation sectors are an important consideration for
performing an LCA of EOL materials management from a decision maker's perspective as local
governments have varying control over the flow of materials from these sectors. For example, a local
government may have greater control over the collection and management of materials from single-family
homes than those from multi-family residences and commercial sectors. In addition, material generation
sectors have an important impact on EOL materials composition and on viable options (and corresponding
environmental, economic, and social impacts) for material collection and transport. For example, single-
family homes typically produce small amounts of EOL materials over a larger area, whereas multi-family
homes generate larger amounts within a smaller footprint. Therefore, it is reasonable to conclude that the
total fuel consumption and vehicle wear per mass of material collected from these two sectors will likely
be different. The different generation sectors that can be selected in each of the tools is presented in Table
3-4.
Table 3-4. Comparison of Materials Generation Sectors Considered by the Tools
Generation Sectors
Residential (single-
family)
Multi-family
Commercial
Industrial
WARM
_a
-
_c
-
MSW-DST
/
^
^
-
SWOLF
/
/
/
-
EASETECH
/
^
-
^
WRATE
,/b
-
,/a
_e
a. Mixed paper is the only material specifically identified as originating from primarily residential sources.
b. Household waste is a defined EOL materials stream.
c. Office paper and mixed paper material categories described as primarily originating from offices.
d. Commercial - office waste is a defined EOL materials stream.
e. Co-collected trade waste is a defined EOL materials stream.
WARM is the only tool that does not allow the selection of sector-specific material streams that include a
default EOL materials stream composition. However, WARM does allow the selection of multiple materials
and allows user-specified quantities of each material for analysis; so a custom-designed aggregated material
stream is possible. Of the other four tools, only WRATE and EASETECH allow the selection of EOL
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material streams originating from specific generation sectors where sector-specific stream compositions
can be readily modified by the user. SWOLF does not currently allow a simultaneous analysis of multiple
generation sector materials streams (each with a unique composition); however, the developer indicated
that a future version of the tool will have this capability. It should be noted that, unlike the other tools,
MSW-DST does not allow the inclusion of additional material categories beyond those included in the
default sector-specific material stream composition.
3.2.4 Electricity Energy Mix
The particular fuel feedstock mix used for electricity generation can vary significantly from region to
region. LCA tools often use an area's (e.g., national, statewide) typical electricity generation practices as a
point of reference for estimating offsets associated with electricity generation from materials-management
processes (e.g., anaerobic digestion (AD), materials combustion for electricity generation). Therefore, the
ability to select an electricity energy mix used in the user-specific region is important to accurately estimate
the environmental burdens avoided as a result of a potential materials-management strategy. This ability is
especially critical when considering the use of a non-US tool (e.g., WRATE, EASETECH) to evaluate the
environmental impacts resulting from materials management in the US; default European energy mixes
may be very different from the energy mix in the US. The baseload fuel mix is the mix of different fuels
used to produce the electricity used in the model processes, while the marginal fuel mix includes the fuel
use displaced by electricity production in alternative electricity generating processes (e.g., EOL material
incineration, LFG-to-electricity). Table 3-5 summarizes the flexibility and some of the background data
used to develop the electricity energy mixes for each of the tools.
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Table 3-5. Comparison of Tool Flexibility for Baseload and Marginal Energy Mix Data
Energy Mix
Data and
Parameters
Geographical
source of
energy mix
data
Year of data
Energy
sources
included in
energy mix
Baseload fuel
mix
parameter
Energy
generating
efficiencies
Marginal fuel
mix
Transmission
type
Transmission
losses
WARM
US-specific, the
user has the
option of
selecting a
national energy
mix or one
specific to each
state based on the
regional location
of the state.
2010
Not adjustable
Not adjustable
Not adjustable
Not adjustable
Not adjustable
Not adjustable
MSW-DST
Default values
are US
specific, and
based on US
national
averages.
Default/User
can specify
which energy
data are used.
Adjustable;
includes coal,
natural gas,
residual oil,
distillate oil,
nuclear, hydro,
wood, other
Adjustable
Adjustable
Adjustable d
NA
NA
SWOLF
Default
values are
based on
US
national
averages.
2010
(defaults)
Adjustable;
has a large
variety of
options
(see note)b
Adjustable
Adjustable
NA
Adjustable
Adjustable
EASETECH
Default mixes
include Europe
(EU-27),
Sweden and
Denmark. The
user may create
a custom mix.
2001-2002
Adjustable;
energy
conversion
processes
include coal,
natural gas,
LPG, wind,
waste and fuel
oil
Adjustable
Adjustable0
Adjustable
NA
Adjustablef
WRATE
Defaults are provided
for European
countries. A user
could enter data
specific to another
country outside of
Europe.
Depends on the
country selected3
Adjustable; includes
coal, oil, gas CCGT,
nuclear, waste,
thermal other,
renewables thermal,
solar PV, wind, tidal,
wave, hydro,
geothermal, renewable
other
Adjustable
Adjustable
Adjustable
Adjustable6
Adjustable8
a. Energy mixes have been extrapolated out for some countries. For example, England has default energy mix
estimates available from 2002 to 2035.
b. Includes Diesel Oil Combined-Cycle, Diesel Oil Combustion Turbine, Geothermal, Hydroelectric,
Conventional, Hydroelectric, Reversible, MSW Steam, Natural Gas Combined-Cycle, Natural Gas Combustion
Turbine, Natural Gas Steam, Oil Steam (Resid Fuel Oil LS), Pre-Existing Nuclear LWRs, Residual Coal Steam,
Solar Photovoltaic, Solar Thermal, Wind, Wood/Biomass Steam, Biomass Integrated Gasification Combined-
Cycle, Geothermal - Binary Cycle and Flashed Steam, Integrated Coal Gasification Combined Cycle, Integrated
Coal Gasification Combined Cycle ~ CO2 Capt, Natural Gas - Advanced Combined-Cycle (Turbine), Natural
Gas - Advanced Combustion Turbine, Natural Gas - Combined-Cycle (Turbine), Natural Gas - Combustion
Turbine, Natural Gas Combined Cycle - CO2 Capture, Nuclear LWRs in 2015, Oxyfuel Coal Steam - CO2
Capture, Pulverized Coal Steam - 2010, Solar PV Centralized Generation, Solar Thermal Centralized
Generation, Wind Generation Class 4, Wind Generation Class 5, Wind Generation Class 6
c. not included as a specific parameter, but can be accounted for in process equations
d. Marginal fuel mix is not available, but fuels can be included or excluded from fuel displacement.
e. high voltage, medium voltage, low voltage
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A Comparative Analysis LCA Tools Section 3 - Detailed Evaluation of the Selected LCA Tools
f. not included as a specific parameter, but can be accounted for in process equations
g. corresponds to the transmission type
3.2.5 Materials Collection
There are a variety of ways in which materials may be sorted and stored by the generator for collection.
The two broadest classifications of MSW (i.e., mixed waste) material produced in the US include
recyclables and non-recyclables. Recyclable materials may be separated from non-recyclable materials as
a single category (i.e. single-stream recyclables), which typically includes a combination of containers (e.g.,
metal, glass, plastic) and fibers (i.e. paper materials); only one recycling bin is placed curbside. However,
recyclables may also be further separated into containers and fibers so that there are two recycling bins
placed curbside in what is known as a dual-stream recycling program. Some communities have recycling
drop-off centers located in more rural areas as a means of minimizing the number of collection points. Other
communities sometimes require the segregation of additional EOL materials streams, such as food scraps
and yard waste, from other mixed EOL materials.
Several factors, including the collection frequency, dictate the type of collection container selected, which
in turn would affect the and the quality of the materials (e.g. rain-soaked recyclable paper from a non-lidded
bin, dry paper from an enclosed bin) and the quantity of resources and energy consumed to make the
containers. Different EOL materials collection and curbside recycling practices have different impacts on
the quality of the recovered recyclable materials (e.g., broken glass mixed with fibers in single-stream
collection bins), the overall participation in recycling, the number of trucks which must be sent out to collect
the materials, and the type of processing that may be necessary to further segregate and classify the collected
materials. All these factors will have an influence on the environmental burdens associated with a specific
material collection strategy. Table 3-6 summarizes the types of EOL materials collection configurations
available in the tools and the types of LCI data that are incorporated into their analyses.
As shown in Table 3-6, although WARM can evaluate the management of mixed waste, yard waste, and
different categories of recyclable materials, WARM appears to only incorporate a general material
collection LCI in its analysis; collection strategies specific to single-stream or dual-stream recycling cannot
be evaluated. The collection and transport LCIs are linked together in MSW-DST. A user can select from
21 collection scenarios. The collection strategies are organized by material generating sector, whether
recyclables are separated and placed curbside or taken to a drop off center, and by the collection vehicle
configuration (e.g., multiple single-compartment vehicles, one multi-compartment vehicle provides
collection for refuse and recyclables).
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Table 3-6. Comparison of Tools for Materials Collection Process Options and LCI Scopes
Collections
Single-stream recyclables
Dual-stream recyclables
Multi -stream
Mixed waste
Drop-off
Source separated organics
(SSO)
Yard waste
CDD
LCI -number of bins
adjustable
LCIs -Collections containers
manufacturing and
maintenance over its service
life
LCI - EOL management of
collection container
Separately accounts for
emissions during collection
from those resulting from full
and empty vehicle transport
WARM
No
No
No
No
No
No
No
No
No
No
No
No
MSW-DST
Yes
No
Yes
Yesa
Yesb
No
Yes
No
Yes
Nod
No
Yes
SWOLF
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Nod
No
Yes
EASETECH
Yesa
No
No
Yes
No
No
No
Yesc
No
No
No
Yes
WRATE
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
a. components of single stream
b. provided for all sectors
c. includes "bulky waste" which primarily consists of wood, other metal, cardboard, stones/concrete and other
non-combustible materials
d. lifespan only considered for cost estimation
WRATE has additional flexibility with respect to the number of collection options from which the user may
select, such as a variety of bags, bins, skips (i.e., a larger dumpster-like bin), intermodal containers (i.e.,
containers that may undergo multiple modes of transport such as rail, ship, and truck), and drop-off options
to select from. Within each collection method category there is a drop-down menu of more specific types
of collection containers that the user can select from. For example, in the bins category the user can select
a bin based on size or based on whether the bin does or does not have wheels. WRATE does not have
specific collection processes per se for the pickup of single-stream, dual-stream, or other specifically-named
streams, but the tool allows the user to direct the material(s) to the container option(s) of choice and then
to select a collection vehicle of choice. Therefore, the collection containers can be adapted to fit the
containers that would be needed for types of EOL materials collection methods that are common in the US
(i.e., single-, dual-, mixed-EOL materials streams). The user must also specify the total number of
containers used to manage the EOL materials. The collection emissions in WRATE vary depending on the
type of container (e.g., a bin instead of a bag). Raw material consumption (accounted for with every
container type), container maintenance (i.e., washing), and container lifespan are included in the collection
emission estimate.
EASETECH has several types of collection processes the user can select from (e.g., residual waste, bulky
waste, and paper), and includes the ability to create a custom-defined collection process. The collection
scenario is described in each process, with the type of collection (e.g., curbside or drop-off), type of truck,
truck load size, where collection occurs (e.g., urban setting), what type of collection container is used, and
how often pick up occurs. EASETECH does not have predefined processes for single- and dual-stream
recycling collections; the residual waste collection process is for mixed EOL materials streams. However,
the user could create processes to simulate dual- or single-stream collection. For the collection process of
the tool, fuel consumed between the first and last collection stop is analyzed in the collections aspect of the
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assessment. Fuel consumed while driving the collection vehicle between the last collection point and the
drop-off point and to and from the garage is not included in the collection emission estimate. It is included
in the transport process.
3.2.6 Material Transport
MSW-DST and SWOLF include collection vehicle movement prior to and following the completion of
collection routes as part of collection transport activities whereas EASETECH and WRATE model this
vehicle movement separately from collection. WARM considers only the transport process and also
includes emissions associated with collection. The tools generally estimate fuel consumption and the
associated emissions resulting from material collection and subsequent transport in one of two ways.
WARM, EASETECH, and WRATE estimate the emissions based on the distance over which materials are
transported and the total quantity of materials transported. MSW-DST and SWOLF, on the other hand,
estimate emissions based on a large number of parameters such as distance of the first collection point from
the garage, number of stops, rest breaks, average distance between stops, and distance from the last point
of collection to the next management point, and distance to the garage.
LCA tools that can be flexible and incorporate a range of transport vehicle and fuel options can be used to
assess the impacts of potential operational changes, such as switching fleet vehicle fuels from diesel to
compressed natural gas (CNG). As presented in Table 3-7, WRATE provides a high level of flexibility as
it lets the user assess the use of four additional fuels in addition to diesel; however, it should be noted that
not all vehicles in WRATE are compatible with all fuel types. For example, electric vehicles can only be
specified for collection using a manually-pushed collection cart. Also, the vehicles types included in
WRATE are not necessarily the same as those that may be employed in the US for collection, which would
make the assessment of a switch to an alternative fuel less relevant for performing a US-based LCA.
Transportation fuel types in MSW-DST and WARM cannot be adjusted.
Table 3-7. Comparison of Tool Transportation Fuel Options
Transport Fuel Options
Diesel
CNG
Biodiesel
Gasoline
Electric
WARM
Yesa
No
No
No
No
MSW-DST
Yesa
No
No
Yesa
No
SWOLF
Yes
Nob
No
No
No
EASETECH
Yes
No
No
No
Yesc
WRATE
Yes
Yes
Yes
Yes
Yesd
a. but user cannot adjust the fuel that is used
b. developer plans to include this feature in a future version
c. for the freight train option only
d. only available for a pedestrian operated cart
Aspects of transport that impact an LCA in addition to the type of fuel consumed include whether the
collection vehicle can be automatically loaded or must be manually loaded by the operator, the size of the
collection vehicle (e.g, fewer larger vehicles will be needed for a route), emissions associated with vehicle
manufacturing and maintenance, and the road types. The ability to analyze the use of other modes of
material transport (e.g., rail, ship) is another tool functionality that can help community leaders select a
collection management strategy with a lower environmental impact. Table 3-8 summarizes the general
transportation options available, transportation parameters that can be adjusted, and transportation LCIs
that are incorporated in each of the tools.
As Table 3-8 shows, the WARM tool cannot be adjusted for different types of transport, whereas MSW-
DST and SWOLF have additional flexibility with the option of selecting single- and multiple-compartment
vehicles, vehicle material drop-off, and rail transport. Only SWOLF, EASETECH, and WRATE include
materials transportation via ship. SWOLF allows the user to specify the size of the collection vehicles
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while WRATE provides several default vehicles with varying sizes that can be selected from. User can
adjust parameters such as number of workers and vehicle time per house in MSW-DST and SWOLF to
simulate various collection vehicle types. LCIs incorporating transportation vehicle manufacture and
operational lifespan do not appear to be available in the US tools or in EASETECH; however, in addition
to operations, WRATE considers environmental impacts associated with vehicle manufacture and
maintenance. None of the tools consider how vehicles that reach the end of their useful life are managed
(e.g., recycled, landfilled).
Table 3-8. Comparison of Tool Transportation Vehicle Options and LCI Scopes
Transport Mode Options
Multi -compartment vehicle
Automatically -loaded vehicle
Manually -loaded vehicle
Ship
Rail
Individual drop off
Ability to specify vehicle capacity
Ability to adjust number of transport
vehicle
Adjustable transport distance
Ability to specify type of roadway vehicles
travel
LCIs - Vehicle lifespan
LCIs - Vehicle manufacture
LCIs - Vehicle operation and maintenance
LCIs - Vehicle EOL management
WARM
No
No
No
No
No
No
No
No
No
No
No
No
No
No
MSW-DST
Yes
No
No
No
Yes
Yes
Yes
No
Yes
No
Nob
Nob
Yes
No
SWOLF
No
No
No
Yes
Yes
Yesa
Yes
Yes
Yes
Yes
Nob
Nob
Yes
No
EASETECH
No
No
No
Yes
Yes
No
No
No
Yes
Yes
No
No
No
No
WRATE
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
No
a. for some streams, not all
b. only considered for cost estimation
Transfer stations, where EOL materials and/or recyclable materials are moved from short- to long-haul
vehicles before they are sent for additional processing or treatment, are typically used for materials
collection and transport operations in the US. Transfer stations have a covered area for loading, unloading,
and storing materials; equipment to move and load materials; loading bays; scale house; and usually include
office space. Emissions from transfer stations include those associated with natural resource extraction and
manufacturing of materials used for facility construction and maintenance; electricity, fuel and water used
for facility operation; and EOL management of materials generated from facility maintenance and
decommissioning. Table 3-9 summarizes the options available in each tool with respect to transfer stations
and the included LCIs.
WARM does not allow users to include transfer stations in transporting materials. MSW-DST has five types
of vehicle transfer stations that are based on the materials processed. The transfer stations vary in whether
a tipping floor is used or if materials are directly tipped into a container, the bay loading type (either one or
two levels), whether or not compaction occurs, and what type of loading equipment is used. MSW-DST
also has three rail transfer station options. Information on the construction and operation and maintenance
of the transfer station can be input/selected by the user.
WRATE has four types of transfer stations a user can select based on material transport mode: intermodal
containers at seaport, intermodal inland water or rail, rail large/compaction and transfer, and road vehicle
transportation. The user has the option to specify the facility's capacity. Emissions estimated from the use
of a transfer station in WRATE include the construction, operation, and maintenance of the facility; the
user does not have the option to adjust other parameters in the transfer station processes. EASETECH does
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not have any processes specific to transfer stations; however, the user could adjust the material recovery
facility (MRF) process to mimic the emissions of a transfer station.
SWOLF includes four types of transfer stations, each of which receive waste from a different collection
process: mixed waste, dual stream, single stream, and separated organics. Each type of transfer station has
unique LCIs, and a unique set of operational parameters that can be adjusted. The distance to each transfer
station from collection, and the distance from the transfer station to the next process can be defined within
the model for each type of transfer station, and each possible destination. Transfer stations also allow
collected waste to be transitioned to another transportation method in SWOLF, such as rail or ship transport.
Table 3-9. Comparison of Tool Transfer Station Options and LCI Scopes
Transfer Station3
Type - Road
Type - Rail
Type - Port
Type - Inland water
Type - Ship
Facility capacity /throughput adjustable?
LCIs - Construction of transfer station
LCIs - Operation and maintenance of the
transfer station
LCIs - Demolition and EOL management
of the transfer station
WARM
No
No
No
No
No
NA
NA
NA
NA
MSW-DST
Yes
Yes
No
No
No
Yes
Noc
Yes
No
SWOLF
Yes
Yes
No
No
Yes
Yes
Noc-d
Yes
No
EASETECH
Nob
No
No
No
No
NA
NA
NA
NA
WRATE
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
a. based on location and transport mechanism
b. allows the switch between different forms of transport, but no default transfer station process is included in the
model
c. considered only for cost estimate
d. developer plans to include this feature in a future version
3.2.7 Materials Recovery
MRFs are used to recover and process recyclable EOL materials or recyclable material streams and
generally serve as an intermediate point between material collection and material re-use. MRFs can be
designed around a variety of configurations, which in the US are typically based on the type of materials
received at the facility (e.g., single-stream recyclables, dual-stream recyclables, mixed EOL materials).
MRFs typically include a covered area for tipping and loading materials, sorting equipment, equipment to
move and load materials, storage space for material stockpiles, and offices. Emissions attributable to MRFs
include those associated with manufacturing (including natural resources extraction) of construction
materials and energy used for facility construction; production of energy (electricity and fuels) resources
(including water) used for facility operation; emissions (e.g., leachate, dust) from materials processing
operations; and EOL management of materials generated from facility maintenance and decommissioning.
Factors that impact emissions from a MRF include the facility's level of mechanization (manual sorting
would require less fuel than mechanized sorting), process efficiency, the distance from the MRF to a
disposal facility (for residuals), the distance from the recovered materials end user(s), and the end-use
application of the recovered recyclables (e.g., producing refuse derived fuel (RDF) from recyclables to
replace combustion fuel may offset different emissions than using the recyclables as a raw feedstock
replacement for virgin materials).
Figure 3-1 presents an example of the material and energy inputs and emissions associated with the recovery
of a specific recyclable (e.g., corrugated containers) at an MRF that should be accounted for in an LCA.
Table 3-10 presents a side-by-side comparison of the MRF types available, the degree of MRF
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customization, and the inclusion/exclusion of several types of LCI data specific to MRFs for each of the
tools.
PM
Other Air
Emissions
Other
Solid
Liquid
Emissions
ility Construction &
3ment Manufacturing
ation & Maintenance
Consumables
EOL Corrugated
Products
Transport ^
1
1
Corrugated Products Recovery, at Materials Recovery Facility
t
Nan- Recyclable
C-orrigatsd
products
1
EOL
H^ Disc Screen -corugated- -*
Products
r-»
1
1
Baler
Baled, recovered
Corrugated products
Air
I I
Water Electricity
Other
Fuels
I
I
Legend
Elementary Flow
Technosphere Ftow
Process Boundary
Figure 3-1. Example of Materials and Energy Inputs and Emissions Associated with Recovery of a
Specific MSW Constituent
WARM does not account for the environmental impacts associated with MRF construction, operation, or
maintenance. WARM uses material-specific recovery rates (i.e. the total amount of a material recycled
minus contamination) to estimate the emissions associated with recycling; users cannot adjust these. MSW-
DST includes eight MRF designs that can be selected depending on how materials are collected: mixed
EOL materials MRF, presorted recyclables MRF, commingled recyclables MRF, co-collection MRF
(recyclables and mixed EOL materials collected in a single-compartment truck), co-collection MRF
(processes commingled recyclables and mixed EOL materials collected in a three-compartment truck),
front-end MRF to a composting facility, front-end MRF to an AD facility, and a front-end MRF to an RDF
facility; DST does not include AD process. The degree of mechanical sorting that occurs at MRFs can be
selected in MSW-DST. With the mixed EOL materials and commingled recyclable MRFs, users can choose
whether there is manual or mechanical opening of bags and aluminum sorting. Also, the user can specify
energy consumption for various types of equipment and the recovery rate of each material.
The options for WRATE's MRF facilities include one that processes mixed EOL materials into RDF, one
that produces RDF for a cement kiln/gasifier/pyrolysis, an MRF that has a vibrating screen, and an MRF
that sorts with an infrared plastics separation. Although WRATE does not have single- and dual-stream
material compositions built into the tool, the user can create and route the EOL materials composition that
mimics these stream types. The recovery rates for each specific type of MRF in MSW-DST and WRATE
are built into the tool and cannot be changed. This could be a problem if a user wanted to compare MRFs
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with the same equipment configuration but with different recovery percentages. These recovery percentages
are specific to UK facilities. WRATE also has a process called a civic amenity, which is a facility that
accepts and sorts EOL material dropped off by civilians that is typically too large to fit in a garbage
container. The process includes LCIs for facility construction, operation, and maintenance.
In EASETECH there is one predefined MRF in the tool, which is a paper-sorting facility. Although this is
the only predefined option, it is possible to simulate other types of MRFs that can accept a variety of
materials since users can create their own customized processes and can control the mass flows and energy
and fuel demands of the facility. However, this type of customized MRF process development will likely
be beyond the ability of the average tool user.
SWOLF has unique process models for mixed waste, single stream, and dual stream MRFs each with MRF-
specific assumptions on recovery rates and LCIs. Recovery of each individual material in SWOLF can be
assigned to sorting streams and/or equipment within the MRF process. This allows allocation the impact
associated with each piece of equipment in the MRF to the material fraction it recovers. SWOLF allows
simultaneous use of the single-stream and dual-stream recyclables collection and recovery processes for a
curbside collection program.
Table 3-10. Comparison of Tool MRF Options and LCI Scopes
MRF
Single stream
Dual stream
Mixed EOL materials stream
CDD
RDF producing facility
Materials reuse option
available
Facility capacity /throughput
adjustable?
Manual sorting option
Automated (mechanical)
sorting option
Semi-mechanical sorting
option
Recovery rate adjustable
LCIs - Construction of MRF
LCIs - Operation and
maintenance of MRF
LCIs - Demolition and EOL
management of MRF
WARM
No
No
No
No
No
No
No
No
No
No
No
No
No
No
MSW-DST
Yesa
Noa
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Nod
Yesd
No
SWOLF
Yes
Yes
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
No46
Yes
No
EASETECH
Yesb
No
No
No
No
No
Yes
No
No
No
Yes
No
Yes
No
WRATE
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yesc
No
Yes
Yes
No
a. it is unclear if the comingled recyclables MRF and presorted recyclables MRF represent a single-stream or a dual-
steam MRF, respectively.
b. only includes a paper sorting facility
c. all available MRF options are semi-mechanical
d. included only for the cost estimate
e. developer plans to include this feature in a future version
3.2.8 Material Recycling and Source Reduction
EOL materials recovered from MRFs can be recycled either in a closed-loop (i.e., an EOL material is
processed and converted back into the original saleable product) or an open-loop process (i.e., the EOL
material is converted into an alternate, generally lower-quality product). An example of an MSW
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Section 3 - Detailed Evaluation of the Selected LCA Tools
constituent recycled in an open-loop process is paper. For example, some of the tools' paper recycling
processes take higher-quality paper (e.g., office paper) and convert it to lower-quality paper product. CDD
materials, as included in WRATE and WARM, are also typically recycled in open-loop processes. For
example, asphalt shingles in WARM are used to offset some of the asphalt necessary for the production of
asphalt pavement, and concrete is recycled and modeled as a replacement for aggregate.
The tools may assume a closed-loop or open-loop recycling process or offer the user a choice to select the
recycling type depending on material being analyzed. For example, EASETECH provides choices of
several paper types (of both the same quality and of lower quality) that can be manufactured from recycled
mixed paper. The tools typically model the recycling credit by accounting for the emissions resulting from
MRF operation, emissions associated with the avoided virgin material production, and emissions resulting
from the additional processing required to convert the recovered material to a virgin-equivalent precursor
material at a recycling facility (e.g., converting aluminum cans to aluminum sheets).
A unique feature of WARM is the ability to analyze the GHG impacts associated with the source reduction
of an EOL material, where source reduction avoids the emissions associated with product raw material
acquisition, manufacturing, transport, and EOL management. Source reduction essentially precludes the
existence of a given product or material. For example, a re-usable water bottle can be expected to source
reduce a number of PET bottles depending on the re-usable water bottle's expected life span. Except for
WARM, it appears that none of the tools allow the exclusive analysis of material source reduction.
3.2.9 Landfilling
Landfilling is the predominant EOL management method of materials in the US, primarily attributed to
lower costs compared to other EOL management options in most regions of the country. Different types of
landfills (e.g., MSW, ash, CDD) have varying impacts depending on the construction materials used for the
facility, the size and operation of the landfill, the types of wastes received, and emissions (e.g., LFG and
leachate) as materials in the landfill decompose over time. A material's disposal LCA may include LCIs
of material, energy inputs, and emissions associated with landfill construction; EOL materials placement
and compaction; biochemical degradation (e.g., emissions associated with LFG and leachate management);
and closure and post-closure-care activities. Figure 3-2 presents an LCI flow diagram depicting the energy,
materials, and emissions flows that occur over the lifetime of a landfill. Table 3-11 presents the types of
landfills a user can select from within each of the tools.
Table 3-11. Comparison of Tool Landfill Type Options
Landfill Options
MSW
CDD
Ash
Inertd
Bioreactor
WARM
Yes
Yesc
No
No
Yesg
MSW-DST
Yes
No
Yes
No
Yes
SWOLF
Yes
No
Yes
No
Yesf
EASETECH
Yesa
No
Yese
No
Yesg
WRATE
Yesb
No
Yesb
Yesb
No
a. household waste
b. landfill process can accept MSW, ash and inert materials - there are no landfill processes specific to these
materials
c. CDD material in WARM is assumed to go to a CDD landfill which is modeled as an MSW landfill with no gas
collection system
d. inert is not a term typically used in the US, but refers to landfills which contain only material assumed to pose
low risk of gas generation or contaminant leaching.
e. bottom ash landfill
f. user can modify the parameters to simulate bioreactor LFG production
g. no discrete option, can set k value to reflect bioreactor operation
3-14
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A Comparative Analysis LCA Tools Section 3 - Detailed Evaluation of the Selected LCA Tools
A user cannot specify the type of landfill modelled in WARM; however, the user can adjust the landfill's
conditions (i.e., moisture level and decay rate) used to simulate different landfill types (e.g., the user can
select a decay rate consistent with that of a bioreactor). The domain of landfill disposal-related inputs and
outputs considered varies significantly among the different LCA tools. For example, outside of LFG
management, WARM only considers GHG emission from materials placement and compaction activities,
whereas WRATE includes materials and inputs and emissions associated with landfill construction,
operation, and closure. Table 3-12 includes a detailed description of the individual LCIs accounted for in
each tool associated with landfill construction, operation, and closure/post-closure care.
Carbon storage represents the carbon fraction that does not biodegrade under the typical anaerobic
conditions of a landfill environment (Barlaz 1998). WARM, MSW-DST, SWOLF, and EASETECH
include carbon storage for their landfill process whereas WRATE does not. MSW-DST and EASETECH
offer flexibility to exclude carbon storage from landfill emissions whereas WARM does not offer such
flexibility. Although not included as a default, MSW-DST allows user to estimate carbon storage in an
additional calculation step. In SWOLF, carbon storage can be excluded by adjusting the carbon storage
factors to zero.
3-15
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
t t t t
' . Fuel Combustion Stormwater Fugit^e U
t t
Fugit^e Leachate leachate LFG, captured for
t t
Fugitive COz Fugitive ChU
: _ _ Transport, truck short-haul >
Transport, truck, long-haul >>
Geomembrane, HDPE, at plant ^
-Pipe, HDPE, at plant ->
Pepe. PVC. at plant- >
_ _ Hot Mix Asphalt (HMA), at production facility.
, Steel billets, at plant- -H^
: , change in Sand use ' ^
1 1
Landfilling of EOL Materials
' FueSCombustton
Products
. ^ Landfill Construction
+ T '
1 ! FuelCombustson
Diesel PM
Products
' 1
landfill Operation f
" '*" Fuei Combustson
jj^ ~if~-
1 ' ' Landfill Closure &
^ Post-Closure
f + 4.
Efectrjcfty Gasoline Diesel
1 1 1
t t t t
1 1 1 1
Electricity Gaso ine Diesel Water
1 1 1
1 1 1
Legend
Elementary Flow
Technosphere Flow
Pro-cess Boundary
Figure 3-2. Example of Materials and Energy Inputs and Emissions Associated with Materials Disposal in Landfill
3-16
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
Table 3-12. Comparison of Tool LCI Scopes for Landfill Construction, Operation, Closure, and Post-
Closure Care Phases
Landfill Parameters
Construction
materials
included in
analysis
Construction
energy
included in
analysis
Landfill
operations
included in
analysis
Liner Type
Cap Type
Soil
Geomembrane
HOPE pipes
Operational equipment
manufacturing
Operations equipment EOL
management
Electricity
Diesel, gasoline
EOL materials placement
and compaction (fuel usage
and equipment emissions)
Cover material
Geosynthetic clay liner
Clay
Other
Clay
HOPE
Landfill carbon storage included in
estimate?
Closure fuel consumption included in
estimate?
Post-closure care included in estimate?
WARM
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
Yes
No
No
MSW-DST
Yes
Yes
Yes
No
No
No
No
Yes
Yes
No
Yese
Yes (Single-
composite
and double
composite
liner)
No
No
Nof
Yes
Yes
SWOLF
Yes
Yes
Yes
No1
No
No
No
Yes
Yes
No
Yese
Yes
(Single-
composite
and
double
composite
liner)
Yes
Yes
Yes
Yes
Yes
EASETECH
Noa
Noc
Noc
No
No
Yes
Yesd
Yesd
Only soil
transport
No
No
Geomembrane
and clay (1-
meter thick)
composite
liner
No
No
Yes«
No
No
WRATE
Nob
Yes
Yes
No
No
No
Yes
Yes
Yes
Yes, clay
composite
Yes
Yes
(Dense
asphaltic
concrete
(DAC)
and
HOPE)
Yes
Yes
No
Yesh
No
a. only transport of soil
b. soil is included in the operation and closure of the landfill but not in construction
c. it is not clear if HDPE granulate consumption is used to estimate emissions from construction of HDPE piping,
geomembrane or both
d. unable to differentiate between construction and operation fuel and electricity usage
e. account for clay used in composite liners - a single clay liner cannot be modelled
f carbon storage not included by default, but tool can calculate
g. can be excluded from estimate
h. includes material resources used to cap the landfill
i. only considered for cost estimation
In WARM, landfilled CDD materials are predetermined to go to a CDD facility that is assumed to have no
LFG recovery; all other materials are assumed to be taken to an MSW landfill. While WARM does not
allow the user to specify the time-horizon over which EOL materials are placed in an MSW landfill, an
average time horizon is accounted for in the tool's calculations. WARM accounts for material-specific LFG
collection efficiencies based on user-specified decay rate constants reflecting different landfill moisture
conditions. These LFG collection efficiencies are based on user-specified LFG collection operational
scenarios (i.e., the schedule of LFG collection system installation and coverage areas), and a 100-year time
3-17
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A Comparative Analysis LCA Tools Section 3 - Detailed Evaluation of the Selected LCA Tools
horizon. WARM does not account for GHG emissions released as a result of leachate generation and
management.
MSW-DST estimates LFG emissions and offsets for traditional and bioreactor landfills based on LFG
generation rate, collection efficiency, and methane oxidation through landfill cover, electricity generation,
and carbon storage. The LFG emission methodology used by the model is very similar to that used by
WARM. MSW-DST, however, offers more flexibility for user inputs. For example, unlike WARM, the tool
allows users to specify the LFG collection efficiency for each year LFG is collected. The model uses a
material-specific methane generation potential to estimate LFG generation for a user-specified MSW
composition and a first-order decay model for a 100-year time frame. LFG is assumed to be comprised of
50% methane and 50% carbon dioxide (CCh) by volume. Potential LFG management methods include
venting, flaring, and combustion for energy recovery. The model accounts for a variety of trace LFG
constituents that are modeled independently of MSW composition.
MSW-DST's leachate generation rate is estimated based on a time-varying precipitation fraction that enters
the landfill. The tool assumes a leachate collection and treatment timeframe of 100 years with 99.8%
leachate collection efficiency and assumes insignificant leachate generation in the post-closure period (after
100 years) based on the placement of a low-permeability cap at the end of the operating period. The
uncollected leachate is assumed to be released to the environment. The tool specifically accounts for
biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia (NHs), phosphate (PO.4),
total suspended solids (TSS), arsenic, cadmium, chromium, lead, mercury, selenium, and silver emissions
in leachate. The tool documentation also lists several hydrocarbons, but these do not appear to be included
in the model. The generic MSW contaminant yields are allocated to different materials. The BOD, COD,
and TSS yields are allocated based on the LFG attributed to the biodegradation of specific material
components. NHs and PO4 are allocated to material fractions based on the initial concentration of these
contaminants for different materials. The generic MSW metal yields are allocated to individual material
components based on the total metal content of specific materials. Emissions from leachate transport to a
wastewater treatment plant (WWTP) are based on travel distance, leachate load, and the pre-combustion
and combustion emissions of fuel used for transport. The tool also includes emissions associated with
electricity use for leachate treatment and biogenic carbon dioxide emissions associated with BOD removal.
SWOLF bases its calculation for LFG generation on a user-specified material-specific methane generation
potential and decay rate constant. The tool's default value for the methane content of the LFG is 50%. All
trace gases included in the tool are independent of the material composition. Methane and trace gases have
individual destruction efficiency values that can be input for each LFG management option (e.g., flare, vent,
combustion engine).
Leachate generation and concentration in SWOLF is calculated independent of material composition.
Leachate generation is based on annual precipitation, assuming a certain fraction of precipitation becomes
leachate. The fraction of precipitation that becomes leachate can be varied every year of landfill operation
to account for the effects of covering the working face and capping the cell. The default leachate capture,
defined as the fraction of the leachate collected by the collection system, is 99.8%. Leachate not collected
by the collection system is released to groundwater untreated. The amount of leachate that is recirculated
and the fraction that is sent to a WWTP can be customized. Leachate not recirculated is assumed to be
transported by truck to an off-site treatment facility. SWOLF accounts for the electricity used for treating
leachate sent to a WWTP and energy used for transportation and disposal of the generated sludge. The BOD
removed from the material also creates additional GHG impacts. The WWTP treatment efficiency for
BOD, COD, NH3-N, PO4, TSS, metals, and trace organics can be user specified. Compounds not removed
by the WWTP are assumed to be released to the environment.
3-18
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A Comparative Analysis LCA Tools Section 3 - Detailed Evaluation of the Selected LCA Tools
For modeling landfill management options in EASETECH, the user has the choice of selecting from pre-
constructed landfilling processes (comprised of a number of sub-processes that have already been
agglomerated) or selecting individual landfill sub-processes (e.g., LFG generation, oxidation through soil
cover, leachate treatment). EASETECH includes a process that can simulate MSW landfills with different
LFG recovery options (i.e., flaring, LFG-to-electricity) and another process that simulates ash landfilling.
It should be noted that EASETECH models the instantaneous landfill deposition of the entire mass of
materials specified by the user - the tool cannot model a progressive increase in LFG generation associated
with the annual placement of landfilled material over a user-specified time horizon. This has a significant
impact on how the tool estimates LFG production and collection. Because peak LFG production in
EASETECH occurs immediately, when compared to other tools such as MSW-DST (which accounts for
annual materials placement and an associated annual increase in LFG production over the operation life of
the landfill), the EASETECH LFG emission estimate will be greater unless LFG collection is specified to
occur at landfill startup. Trace LFG constituents are independent of landfilled material composition, and
the conversion and speciation of methane and trace LFG constituents by different LFG destruction devices
(and cover soil oxidation) can be specified for individual LFG constituents.
Leachate generation volume in EASETECH is based on an assumed infiltration rate, landfilled material
thickness and density, and a leachate collection system efficiency. The model includes leachate
management sub-processes, including leachate generation, simulation of a leachate collection system,
storage of carbon in leachate and soil, leachate treatment, and treated effluent emissions to surface water
and the ocean. Concentrations of specific contaminants in leachate are not related to landfilled material
composition. However, different concentrations for individual contaminants can be modified over different
user-selected time horizons. The user also can add or delete from the list of contaminants included in the
model. The default leachate collection efficiency of the landfill liner is assumed to decrease over time,
where lower collection efficiencies are assumed after 80 years. The user also has the option of including
storage of carbon in the leachate and soil. Energy use for the treatment of leachate is included in the WWTP
process available in the tool. The WWTP also accounts for some electricity produced onsite as a result of
the use of biogas from the AD of the sewage sludge. The WWTP process includes air emissions from the
AD of treatment sludge. Management of the remaining sludge includes dewatering, drying, burning, and
assuming that the burned sludge is applied to industrial soil. The emissions to water from treatment effluent
are also included in the estimate.
WRATE's documentation states that the leachate-simulating tool LandSim (Version 2.5), developed by the
UK Environmental Agency, was used to assess leachate impacts. The tool assumes a 20,000-year period,
by which time it was assumed that the liner and cap of the landfill would have degraded. WRATE is the
only tool that assumes such a long time horizon; the other tools assume a 100-year time period. WRATE
leachate emissions are estimated using a linear regression incorporating the three landfill size options
available in the tool (i.e., 2.5, 5, and 10 million MT total capacity) and material types that contribute to each
contaminant. The leachate emissions for each contaminate are therefore related to the capacity of the site
in which it is produced. The total amount of leachate emissions is the sum of leakage plus discharge to
sewer, including the removal factors after treatment at a WWTP.
WRATE LFG emissions were estimated using GasSim (vl.5). The tool estimates LFG generation and
partitions the LFG between collection, LFG migration, surface emissions, and biological methane
oxidation. It can analyze the impact of having a combustion plant for collected LFG destruction and also
accounts for LFG energy recovery, including an assessment of gas atmospheric dispersion. The landfill fill
rates in GasSim were assumed such that each landfill size would be filled after 20 years and assuming that
progressive capping would occur over time to maximize LFG capture. Methane oxidation in the cap was
assumed to be 10%. GasSim modeling was run to simulate a 150-year period since LFG production was
assumed to be negligible following this extended time horizon.
3-19
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
Two landfill process options are available in WRATE. One allows the user to select a LFG collection
efficiency and choose whether collected LFG is simply vented, used for energy recovery, or combusted in
a flare. The other process does not allow the user to specify collection efficiency and estimates emissions
by assuming maximum energy recovery. Table 3-13 summarizes landfill leachate and gas-related
parameters considered by tools. WARM does not consider leachate generation and the associated
emissions. It includes the emissions associated with LFG.
Table 3-13. Comparison of Tool Flexibility and LCI Scope for Leachate and LFG
Consideration
WARM
MSW-
DST
SWOLF
EASETECH
WRATE
Leachate
Leachate collection included in emissions
estimate
Are emissions based on material
composition?
Leakage from liner included in emissions
estimate
Leachate transport to treatment plant included
in emissions estimate
Leachate treatment plant -construction and
maintenance LCIs included in emissions
estimate
Leachate treatment-energy use included in
emissions estimate
Management of leachate treatment residuals
included in emissions estimate
Leachate treatment plant removal factors
included in emissions estimate
Assumed leachate generation time horizon
No
NA
NA
NA
NA
NA
NA
NA
NA
Yes
Yes
Yes
No
No
No
Yes
Yes
100 years
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
100 years
Yes
No
Yes
Noa
No
Yes
No (POTW)
Yes (WWTP)
Yes
100 years
Yes
Yes
Yes
No
No
No
Unknown
Yes
20,000
years
Landfill Gas
Gas collection system construction
Are emissions based on material
composition?
Is generation rate adjustable?
Gas collection efficiency adjustable?
Methane oxidation adjustable?
LFG destruction option (flare)?
Assumed LFG generation time horizon
Beneficial Direct use (e.g., use in a
use of boiler)
collected gas Electricity generation
District heating
Equipment manufacturing
Equipment EOL management
No
Yes
Yesc
Yese
Nof
Yes
100 years'1
No
Yes
No
No
No
Yes
Yes
No
Yes
Yes
Yes
100 years1
No
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
100 years
Yes
Yes
No
No
No
Yesb
Yes
Yesd
Yes
Yes
Yes
100 years
Yes
Yes
Yes
No
No
Yes
Yes
Noc
Yes
No«
Yes
150yearsh
No
Yes
No
No
No
a. but the user can add a transport process leading to the treatment process
b. through flare treatment only
c. by decay rate from available defaults
d. by manually adjusting decay rate LFG generation can be adjusted
e. can select from four default options, each material has its own collection efficiency based on the moisture and
recovery scenario
f. fixed at 20% for landfills with LFG collection before final cover.
g. fixed at 10% as modeled in GasSim
h. user cannot adjust
3-20
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
i. tool documentation states that user can select from 20 years, 100 years, or 500 years; however, this was not seen
in the tool
3.2.10 Incineration
In addition to those emissions directly resulting from material combustion (also referred to as incineration
or waste-to-energy \WTE\), the environmental burdens associated with material incineration include
preprocessing that may occur prior to the combustion of the EOL materials (depending on the incineration
technology used); and the construction, operation and decommissioning of the incineration facility
including air pollution control devices; and solid (e.g., ash), liquids (e.g., leachate from ash disposal in
landfill), and gaseous emissions (e.g., 62, SOX). A general life cycle flow diagram that identifies material,
energy and emissions flows through a general WTE process is depicted in Figure 3-3. Incineration facility
types, energy recovery options, and some of the key LCI data necessary for an LCA associated with the
management of materials by incineration are included in Table 3-14.
* A
Bottom & Fly
Other Solid Liquid
Waste i Emissions
1 1
-Transport >
.
Activated Carbon
EOL
Materials
Materials Incineration, at Waste-to-Energy Facility
t t t t t t tals
CO; CO CH- SO: HCI NO« PM .
1 1 1
" Pollution Control
1
Air
Emissions
1
1
EOL Materials
Incineration
] L
t
letals
-Electricity- -
Air
Water
Legend
Elementary Flow
Technosphere Flow
Process Boundary
^
Figure 3-3. Example of Materials and Energy Inputs and Emissions Associated with Materials
Incineration for Energy Recovery
3-21
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
Table 3-14. Comparison of Tool Flexibility and LCI Scope for Materials Incineration Processes
Combustion facilities
WTE facility, mass burn
WTE facility, RDF
Incinerator (without energy
recovery)
Autoclave
Energy
recovery
options that
can be
selected
Electricity
generation?
District
heating?
Cogeneration
of electricity
and steam?
Distance to combustion facility
adjustable?
Transport of ash residual to ash
landfill adjustable?
Steel recycling offsets
included in analysis?
Air emissions?
Combustion products disposal
and leachate emissions from
landfill?
Gross electrical efficiency
adjustable?
Heat efficiency
adjustable?
Adjustable mix of electricity
and district heating available?
Metals recovery rate fixed?
LCIs - Construction of
combustion facility
LCIs - Operation of
combustion facility
LCIs - Demolition and EOL
management of combustion
facility
LCIs - Ash landfill
construction and operations
WARM
Yes
No
No
No
Yes
No
No
Yes
No
Yes
Yes
No
No
No
No
Yes
No
No
No
No
MSW-DST
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Nod
No
No
Yes
Yes
No
Yes
SWOLF
Yes
Yes
Yesb
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Noe
Noe'f
Yes
No
Yes
EASETECH
Yes
Noa
Yesb
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
No
Yes
WRATE
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yesc
Yes
Yes
Yes
No
Yes
Yes
No
Yesc
a. there is not a designated RDF WTE process to select; however, this type of facility can be simulated by using
generic processes
b. energy recovery can be disabled
c. does not specifically have an ash landfill process, however the tool user could specify any of the landfill processes
to accept only ash and therefore the emissions associated with that process would be included in the assessment
d. cannot model heat recovery
e. developer plans to include this feature in a future version
f. only considered for cost estimation
None of the models account for the environmental burdens resulting from the decommissioning of the
incineration facility once it has reached its EOL. All of the tools provide the ability to account for the benefit
associated with ferrous metal recovery from incinerator ash. It is also interesting to note that while all tools
can account for incineration energy recovery for electricity production (commonly practiced), the tools
(with the exception of WARM) also allow for specifying energy recovery for district heating (a less
common practice in the US).
3-22
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
3.2.11 Composting
Composting is becoming an increasingly popular method of managing organic materials. The overall
environmental impact resulting from a specific composting operation would depend on its size (e.g., small-
scale home composting versus industrial-sized yard waste composting), the type of materials being
composted, the methods of managing the compost at the facility, and emissions released (e.g., biogas and
leachate) as the compost is processed and matures over time. An LCA for a composting process should
include materials and energy inputs and emissions associated with constructing, operating, maintaining,
and decommissioning the infrastructure and mobile equipment used at composting facility. Figure 3-4
presents, as an example, materials and energy inputs and emissions that could be considered for an LCI of
composting yard waste which represents a commonly composted MSW material. Table 3-15 lists the types
of default composting options a user can select from for each LCA tool.
Table 3-15. Comparison of Tool Flexibility and LCI Scope for Composting Processes
Composting facilities
Facility type
options that
can be
selected for
Backyard
composting
In-vessel
composting
Windrow
composting
Moisture control adjustable?
Aeration energy adjustable?
Distance to composting
facility adjustable?
LCIs - Construction of
composting facility
LCI - Operation of
composting facility
LCI - Decommissioning of
composting facility
WARM
No
No
Yes
No
NA
Yes
No
Yes
No
MSW-DST
No
Yes
Yes
No
No
Yes
No
Yes
No
SWOLF
No
Yes
Yes
Yes
Yes
Yes
Noc'd
Yes
No
EASETECH
No
Yes
Yes
Yes
Noa
Yes
No
Yes
No
WRATE
Yes
Yes
Yes
No
No
Yes
Yes
Yesb
No
a. can adjust amount of overall processing energy
b. maintenance also included
c. developer plans to include this feature in a future version
d. only considered for cost estimation
WARM assumes windrow composting for all compostable materials. Also, except for WARM, all the tools
can simulate composting using in-vessel technology. WRATE is the only tool that can simulate backyard,
in-vessel, and windrow composting. Finally, similar to the other management processes discussed
previously (e.g., MRF, incinerators), none of the tools accounts for the emissions resulting from the EOL
management of the composting facility and its associated equipment.
3-23
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
- Transport, truck ^
Facility Construction &
Equipment Manufacturing
Operation & Maintenance
Consumables
Change in Land
Use
Legend
Elementary Ftow
Technosphere Flow
Process Boundary
| 1 1 1 1 1 | Water Vapor & Fuel '
PM ca CH4 NHs NMVOC NsO CO Contact Water Combustion
,. . . Waste
Emissions Products
1 I
Windrow Composting of Yard Waste
tttt t t UJL A *t f i * A f f
PMca c* NH, NMVOC MO co ,,,,,«, wm | Combustion T c Fue, T Fuel
|.«| Em- PM pr(>duct5 PM K CombusttonMethanol r»M combustion
Carbon Produds Products
fr Yard Wa<*pStorknilP ---- Loader Conveyance to
* Windrows
i i i
Diesel Diesel Diesel
1 1 1
1 1 1
Screen Rejects
f f fl« ttttttt±± f 1
pM 1 Combustion PM CCS CH* NHi | MZQ CC Vapw Wste PM Combustion
PM pmducts I i NMVOC & Emteio« P»**
Loader ^ " ~~ ^
romme ^_ _ Conveyanceto «_ _ Yard Waste Decomposition Windrow Turning .*-
Screening _
~ Screening ~ _^ ^ ^
j < ^ L___________^_____^^ 4
lit i
Electricity Diesel ,,, ' Diesel
1 Water
1 1 1
1 I
Water Diesel Elect icity
1
1
1
Compost, from
Yard Waste *
Figure 3-4. Example of Materials and Energy Inputs and Emissions Associated with Composting of Yard Waste
3-24
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A Comparative Analysis LCA Tools Section 3 - Detailed Evaluation of the Selected LCA Tools
3.2.12 Change in Land Use
Prior to the construction of facilities and infrastructure necessary for material processing and management,
it is usually necessary to develop greenfield areas for anticipated use. Undeveloped land may provide
environmental services that could be accounted for in an LCA. For example, wetland areas may serve as
points of groundwater infiltration and aquifer recharge, woodland areas serve as sinks for carbon dioxide,
and vegetated strips of land between residences and highways may provide sound buffers to mitigate traffic
noise pollution. None of the tools consider the removal of the existing environmental services of
undeveloped land.
3.2.13 Alternative Materials Management Methods
Community decision makers are exploring alternative materials management technologies to reduce
economic and environmental impacts associated with materials management. This section discusses the
inclusion of several these treatment alternatives in the five tools evaluated. Specifically, these technologies
include AD, pyrolysis, and gasification. The following paragraphs present a brief description of each of
the technologies and some of the environmental considerations associated with each.
AD involves the biodegradation of organic matter by microbes in the absence of oxygen to produce biogas
with high concentrations of methane as well as a semi-stabilized solid residual. While AD is commonly
used for treating sludge and manure, the method can also be used to treat the organic fraction of MSW (e.g.,
food scraps and yard waste). The captured methane from organic degradation can be used directly in a
thermal application (e.g., space heating, boiler fuel) or it can serve as an energy source for electricity
generation. Digester solid residues may be beneficially applied as a soil amendment following additional
stabilization.
Pyrolysis is thermal decomposition of materials in the absence of oxygen to a combustible gaseous stream
(commonly referred to as syngas), a liquid fuel, and a solid residue (i.e. slag or char) (Tchobanoglous et al.,
1993). Size reduction, removal of inorganics, and material drying are the primary pre-processes that are
used for MSW pyrolysis and are commonly recommended or required by current technology providers
(Tchobanoglous and Kreith, 2002). Pre-processed MSW is placed in a pyrolysis reactor and maintained at
elevated temperatures ranging from approximately 400 to 800 °C utilizing an external heat source for its
thermal decomposition.
Gasification involves the thermochemical conversion of carbon-based materials at high temperatures
(usually in excess of 600 °C) into a synthetic fuel gas (i.e., syngas) mainly comprised of carbon monoxide
(CO) and hydrogen. While gasification reactions differ from strict pyrolysis by the addition of a limited
amount of an oxidant, gasification requires a pyrolysis step where carbonaceous material is volatilized and
reduced to lower weight compounds (char). Syngas from gasification (and pyrolysis) may be directly
combusted for steam-cycle power generation or, after varying degrees of cleaning and refining, may be
fired in internal combustion engines and gas turbines. It can also potentially be converted into other
chemicals, liquid fuels, or fertilizer products. The char is then subsequently gasified through partial
oxidation.
As shown in Table 3-16 below, SWOLF is the only US tool to include any of these technologies in its
software and although both AD and gasification are listed as processes the tool has available, the
gasification process is currently not available for use. WRATE offers a variety of options for alternative
material treatment technology processes simulations. However, as described in tool documentation, some
of the data for the alternative treatment processes come from limited experience and were developed from
a single operating or hypothetical facility. EASETECH includes AD processes reflective of hypothetical
facilities and a single Swedish facility, where the hypothetical facility uses recovered biogas for a combined
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
heat and power production process, while the Swedish facility uses the biogas for heat recovery and vehicle
fuel production.
Table 3-16. Comparison of Tools for Alternative Materials Treatment Options and LCI Scopes
Alternative treatment
facilities and parameters
Anaerobic digester-food
Anaerobic digester-MSW
Anaerobic digester-yard
waste
Pyrolysis
Gasification
Mechanical biological
treatment0
Distance to treatment facility
adjustable?
LCI - Construction of
alternative treatment facility
LCI - Operation of
alternative treatment facility
LCI - Demolition and EOL
management of alternative
treatment facility
WARM
No
No
No
No
No
No
NA
NA
NA
NA
MSW-DST
No
No
No
No
No
No
NA
NA
NA
NA
SWOLF
Yes
Yes
Yes
No
Nob
Nob
Yes
Nob'e
Yes
No
EASETECH
Yes
Yes
Yes
No
No
No
Yes
No
Yes
No
WRATE
Yes
Yesa
Yes
Yes
Yes
Yes
Yes
Yes
Yesd
No
a. with restrictions
b. developer plans to include this feature in a future version
c. mechanical biological treatment combines mixed material stream sorting and material recovery with a form of
biological treatment (composting or AD)
d. maintenance also included
e. only considered for cost estimation
3.3 Economic Impacts
The economic impacts resulting from the selection of a particular EOL materials management strategy are
often some of the most critical factors considered by community decision makers when evaluating different
materials management options. Among all the tools evaluated in this report, only MSW-DST and SWOLF
provide process-specific annualized cost estimates as an output. Table 3-18 presents a listing of the user-
adjustable parameters used for process-cost estimation. Cost estimates provided by these tools include
labor and equipment capital costs for varying degrees of process complexity, and quantify costs associated
with energy and process-related material consumption. Many of the default cost values (e.g., market price
of recyclables) are representative of the market conditions at the time of tool development and may need to
be adjusted for a reliable cost estimate.
Some of the cost models included in the tools account for economies of scale where a larger facility is more
cost-effective. The cost models, in general, are linear and do not account for economies of scale. SWOLF
offers flexibility to define and specific cost inputs for several facility sizes to account for economies of
scale. Although annualized process-specific cost estimates such as those presented by MSW-DST and
SWOLF are some of the key considerations used in decision making, EOL management options have other
economic impacts such as affecting area property values and through job creation. None of the tools
evaluated can assess these broader economic impacts.
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
Table 3-17. Comparison of Tool Flexibility for Process-Specific Cost Data
Consideration
WARM
MSW-
DST
SWOLF
EASETECH
WRATE
Energy Price
Diesel Fuel Price
Purchased Electricity Price
Waste as Fuel
Electricity Buy -Back Rate
-
-
-
-
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
-
-
-
-
-
-
-
-
Collection
Fringe Benefit Rate
Other Expense Rate
Administrative Rate
Hourly Wage of a Collector
Hourly Wage of Driver
Workers per Vehicle
Unit Price of a Bin
Capital and Maintenance Cost for Vehicles
Number of Containers at each Commercial
Location
-
-
-
-
-
-
-
-
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Transfer Station
Life of structure
Building Construction, Energy Use,
Maintenance Rate
Engineering, Permitting Contingency Rate
Land Acquisition Rate
Paving and Site Work
Equipment Installation, Operating &
Maintenance
Labor Rate and Productivity Data
Vehicle Throughput
Fuel Requirement
-
-
-
-
-
-
-
-
-
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
MRF
Equipment Cost
Equipment Fuel/Electricity Consumption
Equipment Maintenance Cost
Market Prices of Recyclable Materials
Building Costs
Baling Wire
Labor Cost and Productivity Data
-
-
-
-
-
-
-
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
Table 3-17 (cont). Comparison of Tool Flexibility for Process-Specific Cost Data
Consideration
WARM
MSW-
DST
SWOLF
EASETECH
WRATE
Composting
Site Preparation
Paving
Fencing
Building Construction (Office, Compost
Pad and Equipment)
Land Acquisition
Engineering
Operating and Maintenance
Compost Amendment Costs
Equipment Repair
Revenue from Sold Compost
-
-
-
-
-
-
-
-
-
-
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Waste-to-Energy/Refuse-Derived Fuel/Process Refuse Fuel Production Facility
Lifespan
Capacity Factor
Heat Rate
Construction Cost
Operating and Maintenance
-
-
-
-
-
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
-
-
-
-
-
-
-
-
-
-
Landfill
Landfill Characteristics (e.g., dimensions,
slope, height, depth below grade)
Number of Cells/Facility Life
Landfill Engineering and Construction
Operation and Maintenance Cost (including
labor, leachate treatment and disposal,
groundwater monitoring, Overhead)
-
-
-
Yes
Yes
Yesa
Yes
Yes
Yes
Yesb
Yes
-
-
-
-
-
Beneficial Use of Collected Gas
Capital Cost of Turbine
Capital Cost of Internal Combustion Engine
Electric Buy -Back Revenue
Revenue from Thermal Energy
Equipment EOL management
-
-
-
-
-
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
No
-
-
-
-
-
-
-
-
-
a. Over 40 user-specifiable parameters
b. Over 180 user-specifiable parameters
3.4 Tool Analysis/Output
Only MSW-DST and SWOLF analyzes and provide cost data as an output. The output of an LCA can
generally be separated into three levels: raw emissions, emissions characterized into impact categories, and
normalized characterized impacts. With the exception of WARM, all tools provide a breakdown of the
emissions by each major process used in the management system studied. This gives the user an indication
of the major emission contributors and therefore an idea of some of the more environmentally critical
components of the system. Although WARM documentation can be used to assess the contributions of
individual processes, the tool outputs only aggregated emissions.
Raw emissions (e.g., amount of methane released to air, amount of mercury released to air) can be
characterized into environmental impact categories (e.g., global warming, human toxicity) through the use
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A Comparative Analysis LCA Tools Section 3 - Detailed Evaluation of the Selected LCA Tools
of a life cycle impact assessment method (LCIA). LCIAs include emission- and impact-category specific
conversion factors which allow the quantification and aggregation of individual raw emissions in terms of
a common reference emission (e.g., methane and dinitrogen monoxide are converted to units of carbon
dioxide equivalents). All the tools incorporate at least one LCIA, while EASETECH and SWOLF allow
the user to select from among several LCIAs.
The outputs format can impact the ease with which the user can manipulate and use the analysis to
crosscheck and compare results between the management scenarios modeled. All of the tools allow the
user to export data in a tabular spreadsheet format, which facilitates analysis and comparison of the results.
A summary of the results and data analysis generated from each of the tools is shown in Table 3-18. MSW-
DST was the only tool that could do optimization and perform a cost analysis; SWOLF developer plans to
implement optimization feature in a future version. Some tools such as EASETECH and WRATE can
analyze multiple scenarios simultaneously to facilitate result comparison.
Using the models' default/recommended LCIA methods, EASETECH (i.e. "EDIP97 wo LT") has the most
impact categories of all the tools, with fourteen, followed by MSW-DST with twelve, SWOLF (default)
and WRATE each with six, and WARM with one (as listed in Table 3-18). SWOLF allows user to add
additional impact categories and the associated impact factors from several databases (e.g. CML, ReCiPe)
included in the tool. Not all of the tools try to measure the same impact categories, and when they do they
do not always use the same set of impact methods. This results in different impact categories and multiple
impact category units, making comparison across tools difficult. This is evident in Table 3-19, which
compares the units of the LCIA results for four of the tools. This table does not include WARM, which
only calculates GHG impacts (CO2-Eq) and total energy usage (Million BTU). Other than global warming,
the only impact category analyzed across all tools is acidification, which is reported with different units in
every tool. While all tools measure toxicity, each tool distributes the impacts of toxicity differently. For
example, EASETECH and MSW-DST account for carcinogenic and non-carcinogenic human toxicity
separately while WRATE lumps them into a single category. Converting impacts into the same unit and
category for the sake of tool result comparison requires understanding the underlying impact method
calculations and is beyond the effort that most tool users are likely to invest.
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Section 3 - Detailed Evaluation of the Selected LCA Tools
Table 3-18. Comparison of Tool Analyses and Output Data Options
Tool Analysis/Output
Inventory emission results
provided in/exportable to
spreadsheet-based format
Allows selection of different
LCIA methods
Shows emission contributions
from each process
Presents the contribution of
each process to each impact
category
Allows selection/ adjustment of
normalization factor (i.e.,
person equivalents)
Out of range error feedback
Output data format
Does tool allow the LCIA
factor modification?
Impact assessment methods
used in analysis
Allows scenario optimization
or selects the "best case"
scenario
Provides side-by-side
comparison of different
scenarios
Allows execution of a Monte
Carlo simulation (sensitivity
analysis)
WARM
Yes
No
No
No
No
Yes
Can
view in
tabular
formats
No
NA
No
Yes
No
MSW-DST
Yes
No
Yes
No
No
Yes
Prints four
reports in xls
format: mass
flow,
recycling,
cost and
inventory
analysis
report, and
impact
assessment
report.
No
TRACI
Yes
No
No
SWOLF
Yes
Yes
Yes
Yes
No
No
Can view in
tabular
format;
Yes
Several LCIA
methods (e.g.,
CML EDIP
ReCiPe)
included
Nob
Nob
No
EASETECH
Yes
Yes
Yes
Yes
Yes
No
Can view in
tabular format
or export to
CSV. Can
group impacts
by process or
list raw
emissions.
Yes
7 Available
including
versions of
IPCC, ILCD
and EDIP
No
No
Yes
WRATE
Yes
Noa
Yes
Yes
Yes
Yes
Can view in
tabular and
graphical
formats (bar
charts and
spider chart),
also view
LCIs or
LCIAs, can
also chose to
normalize
data,
No
CML 2001
No
Yes
No
a. while the user can select from a default or CML 2001 options, the results appear the same
b. developer plans to include this feature in a future version
One potential use for materials-management tools beyond environmental evaluation is economic
evaluations. MSW-DST and SWOLF can estimate the economic impact of materials management, along
with the environmental impacts. These economic evaluations use many of the same mass and energy flows
as the environmental emissions estimates. The equations and methodology used in developing the earlier
MSW-DST tool form the framework being used to develop the SWOLF cost-estimate methodology, so the
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A Comparative Analysis LCA Tools
Section 3 - Detailed Evaluation of the Selected LCA Tools
resulting cost estimates are similar. Both tools report cost as an annualized cost, which is the annual
operation cost plus the capital cost divided by the expected lifetime.
Table 3-19. Comparison of Analyzed Tool Impact Categories and Associated Units
Impact
Global Wanning
Ozone Depletion
Human toxicity, general
Human toxicity
carcinogenic
Human toxicity non-
carcinogenic
Ionizing radiation
Smog formation
Eutrophication
Freshwater
Eutrophication
Marine Eutrophication
Ecotoxicity
Freshwater aquatic
ecotoxicity
Depletion of abiotic
fossil fuel resources
Depletion of abiotic
non-fossil fuel resources
Acidification
Terrestrial
eutrophication
PM
MSW-DST
kg C02-Eq
-
-
CTUa
CTUa
-
kg 03-Eq
kgN-Eq
-
-
CTUa
-
-
-
kg H+ moles-Eq
kg N-equivalent
kgPMlO-Eq
SWOLF
kg C02-Eq
-
-
-
-
-
kgNOx-Eq
kgN
-
-
-
-
MJ-Eq
-
moles H+ Eq
-
-
EASETECH
kg CO2-Eq
kgCFC-11-Eq
-
CTUa
CTUa
kgU235-Eq
kgNMVOC
kgP-Eq
kgN-Eq
CTUa
-
MJ
kg antimony-Eq
AEb
AEb
kg PM2.5-Eq
WRATE
kg CO2-Eq
-
kg 1,4-DCB-Eq
-
-
-
-
kgP04-Eq
-
-
-
kg 1,4-DCB-Eq
-
kg antimony-Eq
kg SO2-Eq
-
-
a. Comparative Toxic Units
b. Accumulated Exceedance (AE)
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A Comparative Analysis LCA Tools Section 4 - Applications of Tools from
a Decision-Maker's Perspective
4 Applications of the Tools from a Decision-Maker's Perspective
4.1 Relevant EOL Material Management Scenarios
A series of scenarios representing some of the most pressing EOL materials management questions decision
makers are currently encountering were modeled using these tools to assess their applicability and
practicality for US communities. The scenarios are selected based on observed industry trends and the
experiences of the authors. Table 4-1 lists the scenarios, associated major material handling processes, and
the question we attempted to answer with each of the simulations.
A hypothetical US community was developed (based on field experience and conditions relevant to the US
communities) to simulate specific material management challenges. The existing MSW management
system of the community is identified as the "baseline scenario" throughout the discussions presented in
this chapter. Unless otherwise specified, the baseline scenario is the starting point from which all of the
scenarios are derived. The baseline scenario that follows is provided to give the reader a point of reference
from which to compare the subsequent scenarios that have key assumption permutations (discussed in the
following subchapter).
Baseline scenario: A City consists of 40,000 single-family and 10,000 multi-family residences and 6,000
commercial entities. The EOL materials generation rate for a single-family residence
(2.5 people per home) and multi-family residence (2.07 people per home) is 2.04 kg per
capita per day. The average EOL materials generation for commercial establishments
is 10 kg per entity per day. This results in an annual EOL materials generation of
approximately 122,000 MTs of EOL materials. The City collects EOL materials from
all three sectors and transports the EOL materials to a City-owned landfill 70 km from
the City center. All the cells at the landfill are lined (single-composite liner) based on
Subtitle D landfill specifications. None of the cells is closed yet. Due to its size, the
City is not required to install a LFG collection system and LFG is emitted to the
atmosphere. The City does not have any provision in place for curbside recycling. The
City separately collects yard waste from the other EOL materials; 50% of the total
amount of yard waste is captured and sent to a composting facility 70 km from the center
of the city and 30 km from the landfill.
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
a Decision-Maker's Perspective
Table 4-1. EOL Materials Management Scenarios Evaluated Using the LCA Tools
Process
Baseline
Landfill
Organics
Collection
and
Processing
Material
Recovery
Collection
and
Transport
Thermal
Treatment
Landfill
Mining
Question
What are the environmental and economic impacts of the current EOL
materials management system?
What are the environmental and economic impacts of different LFG
management schemes (i.e., venting, flaring, LFG to electricity, and LFG to
electricity from a landfill operated as a bioreactor)?
What are the environmental and economic impacts of instituting a biological
organics management process for a source-separated organics stream (e.g.,
composting, AD)?
What are the environmental and economic impacts of increasing backyard
composting to reduce organics collection?
What are the environmental and economic impacts of different types of
MRFs (i.e., single stream, dual stream, mixed waste)?
What are the environmental and economic impacts of manual versus
automatic processes at MRFs?
What are the environmental and economic impacts of recycling plastic
compared to recycling glass?
What are the environmental and economic impacts of instituting a Pay-as-
you-throw (PAYT) collection scheme to encourage recycling and source
reduction?
What are the environmental and economic impacts of recycling versus
landfilling CDD?
What are the environmental and economic impacts of instituting an e-waste
collection system to capture and recycle e-waste currently being landfilled?
What are the environmental and economic impacts of using different fuels in
a collection vehicle fleet (i.e., diesel, CNG, biogas)?
What are the environmental and economic impacts of different levels of
recyclables collection vehicle automation (i.e., manual for dual-stream versus
automated for single-stream recycling)?
What are the environmental and economic impacts of having a centrally
located transfer station?
What are the environmental and economic impacts of instituting different
thermal treatment processes for EOL materials (i.e., incineration at a WTE
facility, gasification, and pyrolysis)?
What are the environmental and economic impacts of incinerating plastic for
energy recovery compared to recycling plastic?
What are the environmental and economic impacts of RDF production and
thermal treatment of as-discarded EOL materials versus RDF production and
thermal treatment of reclaimed materials from landfill mining?
Scenario Title
and Section
Number
Baseline Scenario
(4.4)
LFG Treatment
Options (4.5)
Source-Separate
Organics
Processing (4.6)
Backyard
Composting (4.7)
Materials
Recovery (4.8)
MRF Automation
(4.9)
Recycling Plastics
vs Recycling
Glass (4. 10)
Pay-as-You-
Throw(4.11)
CDD Recycling
(4.12)
E-waste
Collection and
Recycling (4. 13)
Collection
Vehicle Fuels
(4.14)
Collection
Vehicle Types
(4.15)
Transfer Station
(4.16)
Thermal
Treatment
Options (4. 17)
Plastic
Incineration vs
Recycling (4. 18)
RDF Recovery
Before and After
Landfilling (4. 19)
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
a Decision-Maker's Perspective
4.2 Basis for Material Composition Assumptions
The composition of the materials stream used for LCA has significant impact on the modeling results.
Therefore, it is important when comparing different tool results, such as this report does, that all of the tools
are using the same initial composition of materials. It should be noted that all the tools allow the user to
specify the percent composition or the amount of different material categories. The default EOL material
compositions of each of the tools were assessed to determine if they needed to be adjusted to reflect a
common composition. To assess the default tool material composition variation, materials were combined
into more general categories, consistent with the general categories used in the US EPA Facts and Figures
report (US EPA 2014). For example, plastic types (e.g., HDPE, PET, hard plastic, soft plastic) were pooled
into a single "Plastics" category.
Figure 4-1 presents the default materials composition of the tools as well as the composition of EOL
materials generated in the US in 2012 based on the US EPAUS EPA (2014). Figure 4-1 does not include
the composition for WARM as a default "mixed MSW" composition could not be found in the tool
documentation.
EPA 2012
Facts and
figures
DST-1
I Glass
I Metals
I Food Waste
I Plastics
I Paper and Paperboard
Rubber, Leather,
Textiles
I Wood
I Other*
DST-2 SWOLF EASETECH WRATE Yard Trimmings
Figure 4-1. Comparison of 2012 US EPA Fact and Figures and Tools' Default MSW Composition
Although many material categories are common among the tools, some of these categories have appreciable
proportional differences, (e.g., MSW-DST assumes 10% and EASETECH assumes 22% food scraps) and
some material categories typically present in the US EOL materials stream were not included (e.g., rubber,
leather, textiles, and wood are not included in MSW-DST). Additionally, although the material
compositions among the tools were relatively similar to US EPA (2014), an EOL materials composition
representative of US material generation was desired for a meaningful comparison of tool results for the
intended audience (decision makers of the communities in the US). Therefore, the material composition of
all the tools was adjusted to reflect the US EPA (2014) data.
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A Comparative Analysis LCA Tools Section 4 - Applications of Tools from
a Decision-Maker's Perspective
Many of the material categories in the US EPA (2014) report are not consistent with the material categories
presented in the tools. Assumptions were made to fit the US EPA composition categories into the most
similar categories in each tool. Table A-4 in (see Appendix A) provides the detailed EOL materials
composition from the US EPA (2014) from which the uniform EOL materials composition is derived. For
each material category in the US EPA (2014), the corresponding best-match EOL materials category for
the tool is also presented. The final column of the table defines whether the material is considered
"recyclable" for the scenarios which evaluate the impacts of recycling. The use of the US EPA (2014)
material composition presented the following challenges:
1. Because the US EPA report has more categories than the tools provide, many categories had to be
pooled together into the nearest appropriate category. This means that some material categories that
may have both recyclable and non-recyclable components had to be combined. For example,
multiple paper types included in the US EPA report were assigned to the "mixed paper, primarily
residential" category in WARM. Additional material category assignments are identified in Table
A-4.
2. When determining a best fit for a material not available in a tool, several characteristics and material
properties had be considered, for example, whether the material is likely to be clean or dirty,
recyclable or non-recyclable, combustible or non-combustible, or alone or mixed with other similar
materials in a mixed stream. Paper and plastic materials have the greatest number of unique specific
materials in the US-based EOL materials composition and consequently have the highest number
materials that do not match up with materials available for selection in each of the tools. For
example, the non-durable paper material category in the US EPA report composition had a
subcategory for paper plates and cups. None of the tools have comparable materials described so
specifically; therefore, more general materials had to be selected which were assumed to include
paper plates and cups. In EASETECH, "dirty paper" is the surrogate material for paper plates and
cups; in MSW-DST it is "paper non-recyclable"; in SWOLF it is "Paper-Non-Recyclable"; in
WARM it is "mixed paper (primarily residential)"; and in WRATE it is "unspecified paper."
3. The US EPA (2014) composition identifies plastics based on resin type (i.e., PET, HDPE, LDPE,
etc.) while EASETECH and WRATE classify plastics based on their use or characteristics (i.e.,
plastic film, soft plastic, hard plastic, packaging, etc.). Additionally, although MSW-DST and
SWOLF do classify plastics based on PET and HDPE resin types, the US composition is more
specific and includes plastics not included in MSW-DST. Therefore, the material category "plastic
non-recyclable" is used for all the other resin types in MSW-DST and SWOLF, as it is assumed
that these plastics most closely fit the non-recyclable category. With EASETECH and WRATE a
best effort is made to match up each plastic category with available materials which most closely
matched the description of the material used and the resin type provided in the US composition.
For example, the US EPA (2014) has a material category "durable goods" made of PET; therefore,
the material category "hard plastic" and "other dense plastic" were selected in EASETECH and
WRATE, respectively, to represent "durable goods." Some plastics seemed to match well between
the US composition and EASTECH and WRATE. For example, bottles and jars made of PET is a
material in the US EPA (2014). EASETECH and WRATE have plastic materials for, respectively,
"bottles" and "drink bottles" and these types of bottles are typically made of PET.
4. The rubber and leather composition category in the US EPA report was also not available in some
of the tools. If there were no comparable materials in the tools, a combustible materials category
was used as a surrogate for rubber and leather.
5. WRATE and EASETECH both have general categories for wood waste, whereas WARM has
categories for MDF and dimensional lumber and MSW-DST has no category for wood but does
have an undefined category called "CCCR" (which it appears to model similarly to wood since it
has a methane generation potential and heating value comparable to wood). All wood waste in the
US EOL materials composition was, therefore, assigned to the dimensional lumber category for
WARM and the CCCR category for MSW-DST.
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6. Carpet appeared to be the best fit material for textiles in WARM. WARM assumes residential
carpet to be composed efface fiber, woven backing, carpet backing adhesive, and a latex adhesive.
The face fiber comprises 45% of the total carpet weight, which makes up the largest single
component in carpet. The face fiber is comprised mostly of nylon (65%) and then PP and PET (US
EPA 2014). Nylon is a synthetic fiber that is used in making textiles; therefore, since the WARM
tool does not have a textile category, the carpet category was used as a surrogate for textiles.
7. The "other" and the "other wastes-miscellaneous inorganics" materials in US EPA (2014) do not
match well with the materials available in the tools. Since the "other" material is comprised
primarily of combustible types of materials and the "other wastes-miscellaneous inorganics" is
comprised of non-combustible (inorganic) materials, it is assumed that the materials these most
closely resembled are combustible and non-combustible materials. In WARM, a non-combustible
material is not available; therefore, clay bricks are used as a surrogate for "other" since this is an
inert, non-combustible material.
8. Some tools also have multiple materials that could be acceptable for matching a material in the US
composition. For example, in MSW-DST there are two material categories for HDPE plastic,
translucent and pigmented. Since the US composition data do not divide the category into more
specific categories, it is assumed that 50% of the material quantity in MSW-DST is translucent
HDPE and 50% is pigmented HDPE.
9. EASETECH and MSW-DST have multiple materials (grass, leaves, and branches) that could fall
under yard trimmings, so a representative composition of yard trimmings (50/30/20, which is the
default value for these materials in MSW-DST) is used to determine what percentage of each of
the materials is in the yard trimmings. EASETECH also breaks food scraps down into vegetable
waste and animal food scraps; therefore, a representative composition of vegetable and animal food
scraps (90/10) has been selected for EASETECH (Jones, 2002).
It should be noted that none of the tools can completely match the EOL materials composition as described
in the US EPA (2014). Depending on the objectives of the tool user, certain tools may be more amenable
to modeling certain materials. For example, as was described earlier, modeling plastics accurately using
WRATE and EASETECH is challenging if the user's EOL materials characterization data are provided in
terms of plastic resins (e.g., PET, HDPE). A surrogate materials assignment (i.e., the next closest material)
would, in general, be necessary to model a US-specific EOL materials stream due to the variability and
inconsistencies in the naming conventions of specific EOL materials.
As described earlier, EOL materials are generated from three sectors of the community (single-family,
multi-family, and commercial). The composition of materials from all three sectors was assumed to be the
same as the US EPA (2014) for the purpose of the simulations conducted in this study; in reality, the
materials compositions are dependent on the sector of origin. All three materials streams were simulated
individually for WRATE. The total materials mass calculated based on the annual materials generation
rates were used for WARM simulations. For MSW-DST, not all material fractions were available for
commercial, single-family and multi-family. This made it difficult to model a uniform composition across
all the sectors. To ensure a uniform composition, the categories in US (2014) which were only included in
the commercial or single-family categories were weighted more heavily in those fractions to make the
overall composition match. Because of the difficulty in matching compositions among the three streams,
multi-family streams were not modeled. Instead, single family population densities were increased to match
the average between single-family and multi-family at 2.83 people per residence. The population was
increased to 134,000 residents in single-family housing to account for the loss of the multi-family stream.
For EASETECH, population is not considered, but only the total mass of materials generated, set at 121,000
MTs per year, consistent with other models. The parameters used to model the community across all the
tools are summarized in Table 4-2. It should be noted that not every parameter is relevant to every tool.
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Table 4-2. Global Assumptions for Baseline Scenario
Global Assumption - Description
EOL materials composition
Population
Single family
Multi family
Commercial
Material generation rate
MSW recycling rate
Yard waste collection rate
Collection bins, single-family
Collection bins, multi-family
Collection bins, commercial
Transport distance from end of material collection to
disposal in landfill
Transport distance from end of material collection to yard
waste composting facility
Transport distance from composting facility to landfill
Short-haul vehicle (diesel truck, 7.5 - 12 MT capacity)
Long-haul vehicle (diesel truck, 14-20 MT capacity)
Yard waste composting method
Landfill capacity
Landfill annual capacity
Landfill liner type
Landfill cover type
EOL materials decay rate (k)
Methane oxidation
LFG recovery
Parameter Units
Section 4.2
11 3, 000 people
2 1,000 people
6,000 entities
4.5 Ibs (2.04 kg) per person per d
0%, no existing recycling program
50% of the generated mass
2 bins, 360 liters each
2 bins, l.lm3 each, for every 5 residences
2 bins, l.lm3 each
70km
70km
30km
<50km
>50km
Windrows
2 million MTs
65,000 MTs/year
Composite
Clay
0.05 yr1 forEASETECH and SWOLF
0.052 yr1 for WARM
0.057 yr1 for MSW-DST
Tool default for WRATE
10%
No recovery
4.3 Additional Global Modeling Assumptions
To avoid repetition of common assumptions made throughout the scenarios evaluated, this section discusses
global assumptions that are assumed for all tools and modeling scenarios (unless otherwise noted). Global
assumptions are discussed from two perspectives; those that are assumed in the baseline scenario (as is
described in Section 4.4) and those that are generally assumed and could be applicable for any of the
scenarios (referred to here as global modeling assumptions). In some scenarios there will be instances when
there will be differences between the global assumptions and the assumptions specific to the scenario; those
assumptions are identified in the beginning of each scenario description.
Baseline assumptions are used to simulate the material management circumstances of a representative
community in the US and are based on industry standards, available information on US demographics,
reasonable estimates based on the experiences of the authors, and on the baseline scenario previously
described. Some of the assumptions are based on flexibility limitations of one or more tools. For example,
energy mix assumptions are based on the limitations of WARM, which cannot be adjusted to accommodate
a specific energy mix. WARM's 2010 energy mix assumptions were adopted for all of the tools for
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consistency, where possible. WARM uses a baseload fuel mix to calculate emissions resulting from
electricity consumption, as presented in Figure 4-2. This baseload energy mix was used to simulate the
emissions resulting from electricity consumption in all the tools.
Nuclear
19.6%
Hydro
6.2%
Other fossil
0.3%
Wind Gee-thermal
2.3% 0.4%
Other fuel
0.1%
Natural Gas
24.0%
Oil
1.0%
Figure 4-2. Baseload Energy Mix Used for Simulations
Figure 4-3 presents the marginal (non-baseload) energy mix estimated from WARM; because WARM
documentation does not provide the energy mix for marginal (or non-baseload) sources, the mix was
assumed to be derived from fossil fuels in the same proportions as those used in the WARM baseload
energy mix.
Other fossil
0%
Natural gas
34%
Figure 4-3. Marginal Fuel Mix Used for Simulations
The marginal energy mix presented in Figure 4-3 was used in MSW-DST and WRATE. However, the
marginal energy mix used for EASETECH was 100% coal; adjusting the marginal mix in EASETECH to
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reflect the WARM non-baseload energy mix could not readily be accomplished because processes which
directly simulate electricity generation from natural gas and oil-fired utilities are not currently available in
the tool. A 100% coal-derived marginal energy mix represented the mix closest to the marginal mix
presented in Figure 4-3. For SWOLF, all electricity produced was assumed to displace electricity based on
the tool's baseload mix, as the tool does not appear to allow the assignment of a unique displaced electricity
mix.
Collection container assumptions for specific bin types are based on the container types available in
WRATE (which are similar to those commonly used in the US). As discussed in Chapter 3, the collections
portion of WRATE is the most specific of all the tools, whereas the collection process in WARM is the
most general (e.g., is not specific to any bin type or collection vehicle type). Transportation distances are
assumed based on reasonable estimates and the truck types are based on what types are available in the
tools. In WARM, specific collection vehicles cannot be assigned; however, vehicles can be selected based
on a variety of parameter in the other tools. Vehicles most common to all tools (with the exception of
WARM) are used in the baseline assumptions. Since diesel fuel is most commonly used in US road
transportation, it is assumed these vehicles are diesel fueled. A set collections route is not established for
the tools since some tools cannot account for this; MSW-DST, SWOLF and EASETECH are the only tools
that can accommodate a collection route distance. Assumptions for short-haul distances (<50km) assume
a smaller vehicle than that used for longer-haul distances (>50 km).
The average size of the US landfill was based on the sizes included in WRATE, since many of WRATE's
underlying assumptions are based on landfill size. Only three landfill sizes can be selected in the tool, so
the US landfill size that is exempt from LFG collection (i.e., 2.5 million MT) is used to select the closest
landfill size in WRATE. The material decay-rate constant (k) cannot be adjusted in WRATE and the
underlying metadata are not reviewable through the tool. WARM has limited adjustability; k values are
limited to five predefined values. Although MSW-DST gives the option for a user-specified k value,
discussions with the developer revealed that this field is no longer used in the tool's calculations. The tool
default option of 0.052 yr1 and 0.057 yr1 was used for WARM and MSW-DST, respectively. A decay rate
of 0.05 yr1 was used for EASETECH and SWOLF, similar to WARM's value of k = 0.052 yr1. Methane
oxidation through the landfill's cover soil is assumed to be 10%. LFG is not collected in the baseline
scenario. EASETECH, MSW-DST and WARM are the only tools that allow the user to model the absence
of a LFG collection system; 0% LFG collection was selected for the other tools to simulate the absence of
LFG collection. The tool default landfill operational life (i.e. the timeframe over which EOL materials are
deposited in the landfill) was used for MSW-DST and SWOLF (i.e., 10 years) and for WRATE (i.e., 20
years). Landfill operational life assumptions are not used in EASETECH or WARM since all post-consumer
materials are modeled as being instantaneously placed in the landfill at year zero.
As specified in Subtitle D landfill rules, a composite liner (or equivalent) is required for MSW landfills in
the US; therefore, it is assumed that the landfill has a composite liner. A clay cap final cover was selected
for WRATE and SWOLF, while the model default cap was used for MSW-DST. Emissions associated with
constructing a final cover in EASETECH and WARM are not considered. Where possible, a windrow
facility was specified in the tools for composting yard waste, since windrowing is the management method
assumed in WARM.
Assumptions related to processes such as transportation distances, material recovery, and recycling that are
common for multiple scenarios are included in Table 4-3. The materials composition, population, material
generation rate, yard waste collection rate, energy mixes, collection bins, transport distances to the
composting facility and the landfill, and general long- and short-haul transportation vehicles are the same
as the baseline scenario and are therefore not repeated in this table.
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Information on the average residual rates for MRFs is approximated based on the data reported by Berenyi
(2007), which presents a range of residual rates for single- and dual-stream MRFs. For a mixed-waste
MRF, 20% of the incoming EOL materials are assumed to be recovered, which is comparable to the value
observed for other communities. Some of the tools allow the user to assign a material-specific substitution
ratio defined as the amount of recycled materials needed to replace a unit of virgin materials. The tools'
default substitution ratios were used for all the simulations as this parameter cannot be changed for many
of the tools.
Table 4-3. General Global Assumptions
Global Assumption - Description
Transport distance from the last collection point to treatment facility [including
MRF, SSO composting, thermal treatment (i.e., combustion/incineration,
gasification, pyrolysis)]
Transport distance from thermal treatment to ash landfill
Transport distance of MRF residuals management (to landfill disposal)
Transport distance of MRF recovered materials to remanufacturer plant
MRF residual rates:
Single stream
Dual stream
Mixed EOL materials stream
Substitution ratio
Parameter Units
70km
1km
30km
100km
12%
6%
80%
Tool default
4.4 Baseline Scenario
4.4.1 Scenario Description and Assumptions
To provide a common point of comparison across scenarios, the baseline scenario described in detail above
was simulated in each of the tools. Unless otherwise noted, all assumptions listed in this scenario are also
assumed in the other scenarios. When the scenario descriptions refer to a community, the community it is
referring to is the one described in Section 4.1. Figure 4-4 below provides a visual representation of the
materials flow for the baseline scenario showing the routes by which the EOL materials are generated,
transported, and managed.
Materials
Collection and
Transport from
Curbside
Yard Waste
Collection and
»
Transport from
Curbside
70 km-W Landfill N-30 kn
70 km-W
Yard Waste
Composting
30km
i
Transport of
Residuals
i
i Transport of
Compost
100 km-W
Compost Use
Figure 4-4. EOL Materials Flow with Composting of Yard Waste and Disposal of Remaining
Materials (Baseline Scenario)
4.4.2 Results and Discussion
As discussed in Chapter 3, each tool includes a different set of impact categories, often with different units
and different calculation methodologies (as discussed in Chapter 3). Therefore, it is difficult to compare
results from the different tools for most impact categories. In addition, WARM only provides GHG
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emissions. GHG emissions are common to all tools and calculated using similar methodologies, so GHG
emissions were used as the primary point of comparison among the tools.
Figure 4-5 presents process-specific (and net) GHG emissions for the baseline scenario for each tool. All
tools suggest that landfilling is the largest GHG-emitting process among all of the processes. The landfill
GHG emission estimate ranges from 8,000 MT CO2 eq (for EASETECH) to 179,000 MT CO2 eq (for
MSW-DST) neglecting carbon storage. Considering carbon storage, the landfill GHG emission estimate
ranges from 28,000 MT CO2 eq (for EASETECH) to 144,000 MT CO2 eq (for MSW-DST). All the tools
suggest that the GHG emissions contributed by the EOL materials collection, transport and composting
processes are negligible compared to that of the landfill. Composting emissions represent 1% or less of the
GHG emissions of landfilling. At most, collection and transportation together represent 10% of the GHG
emissions of landfilling for SWOLF and less than 5% for all other tools. MSW-DST and SWOLF provide
aggregated emissions for collection and transportation processes whereas EASETECH and WRATE
provide individual emissions for collection and transport processes. For consistency, collection and
transport emissions from WRATE and EASETECH were aggregated into one category for all the data
presented in the rest of the chapter.
It should be noted that the way data presented in Figure 4-5 is formatted is not necessarily the same
formatting that is output by each of the tools. For example, MSW-DST reports emissions values (LCIs) of
individual contaminants for each contributing process (e.g., CH4 values from landfill and transportation
are individually provided by the tool), but only one global warming impact value (MT CO2 eq)
aggregating all the processes (e.g., transportation, landfill, composting) is reported. The LCIA impact
values were distributed in the same proportions as the emissions from the LCIs to estimate the process-
specific emissions. Similarly, transportation and landfill disposal emissions factors from WARM (as
reported in documentation) were used to distribute the overall landfill emissions into LFG and
transportation-specific categories (including material placement into landfill). The GHG emissions were
distributed among processes to compare process-specific emissions across the tools.
Two categories of GHG emissions that occur from landfilling are biogenic and fossil. Biogenic emissions
are those associated with biodegradation of organic materials (e.g., LFG) whereas fossil emissions
corresponding to those released as a result of the combustion of petroleum-based materials or fuels (e.g.
from combustion of fuel used for EOL materials placement, raw materials extraction and manufacturing of
various materials used for landfill construction if considered by the tool). All the tools except WARM
provide fossil and biogenic GHG emissions. The fossil GHG emission constituted 3.7%, 1.5%, <1%, and
<1% of the overall GHG emissions for SWOLF, EASETECH, MSW-DST, and WRATE, respectively.
WARM GHG emissions corresponding to the combustion of fuel used for EOL materials transport to the
landfill and placement at the landfill are reported to be 0.04 MT carbon dioxide equivalent (MT CO2 eq)
per short ton (US EPA 2014). The fossil GHG emission for the community's entire EOL materials stream
is, therefore, estimated to be approximately 5,400 MT CO2 eq, which represents approximately 4% of the
overall landfill GHG emission estimate for WARM. As WRATE includes emissions associated with energy
and materials used for liner construction, fossil GHG emission amounting to less than 1% of the overall
GHG emissions suggests that the GHG emissions corresponding to liner construction are insignificant in
comparison to those associated with LFG emissions.
An additional consideration that should be taken into account for comparing GHG emissions from the
selected tools is carbon storage. As discussed in Chapter 3, carbon storage is equivalent to the biogenic
carbon dioxide emissions that would have been released if the materials were placed in an aerobic
environment; carbon storage lowers the net GHG emission estimate from landfilling. The results for
WARM and SWOLF incorporate the offsets of carbon storage, whereas EASETECH presents carbon
storage offsets separately. WRATE and MSW-DST (default) results do not include carbon storage.
WRATE assumes all carbon will eventuall be released from the landfill. MSW-DST does not include
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carbon storage in the model results, but carbon storage can be estimated using the tool post-processor. For
a meaningful comparison between tools, with the exception of WRATE, the global warming impact of
carbon storage is separately presented for each tool in the results of each applicable scenario as the green
bar located beneath the x-axis. Carbon storage estimates for WARM and SWOLF were added to the net
landfill GHG output to estimate the GHG emission if carbon storage is not accounted for solely to compare
results from these tools to MSW-DST, WRATE, and EASETECH.
200,000
150,000
_, 100,000
o-
01
ro
Q.
(D
(D
50,000
£ -50,000
-100,000
WARM MSW-DST SWOLF EASETECH WRATE
Baseline
Landfilling Collection and Transportation Composting Recycling Landfill Carbon Storage Net
Figure 4-5. Comparison of the LCA Tools' GHG Emissions Estimates for Baseline Scenario
Although WARM, MSW-DST, and SWOLF use the same first-order decay model to estimate LFG
generation, the variation in the results for GHG impacts for these three tools are primarily attributed to
variations in constituent-specific methane generation potentials used for these tools. The aggregated
methane generation potential used for MSW-DST and SWOLF are55% and 27% higher than the values
used for WARM; as mentioned earlier, the tool-default methane generation potentials were used for
modeling as a majority of the tools do not allow flexibility to modify these values. The carbon storage
estimate ranged from 36,500 MT CO2 eq (for MSW-DST) to 56,500 MT CO2 eq (for EASETECH). The
carbon storage for MSW-DST presented in Figure 4-5 assumes that the tool provides the carbon storage in
CO2 eq units and not in C eq as displayed in tool output; the conversion of C eq. to CO2 eq would have
resulted in an unreasonably greater carbon storage estimate when compared to those from the other tools.
Carbon storage has significant impact on the net landfill GHG emission estimate.
Acidification potential is the only impact category apart from global warming (i.e., GHG emission)
common to all tools except for WARM, which has only GHG emissions and energy as outputs. Unlike
GHG emissions, the units presented and methodology used differ across all tools. Because of differences
in units and methodology with acidification potential, the results across tools are not comparable with one
another. Figure 4-6 shows the relative fraction of acidification potential emissions by process all the tools
except WARM. All tools except SWOLF suggest that collection and transportation is the process with the
greatest acidification potential. SWOLF and EASETECH suggest that landfilling and composting have
significant acidification impacts. A wide variation in contributions by different sectors among different
tools potentially results from the lack of uniformity in assumptions and calculations among LCA tools.
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O
2,000,000
1,800,000
1,600,000
1,400,000
1,200,000
1,000,000
800,000
600,000
400,000
200,000
0
14,000,000
12,000,000
10,000,000
oT 8,000,000
+£ 6,000,000
i
4,000,000
2,000,000
0
MSW-DST
SWOLF
EASETECH
-5,000
WRATE
Landfilling Collection and Transportation Composting
Figure 4-6. Comparison of the LCA Tools' Acidification Impact Estimates for Baseline Scenario
Two (MSW-DST and SWOLF) of the five tools provide total cost as an output. Figure 4-7 compares cost
estimates from MSW-DST and SWOLF for the baseline scenario. Both tools use the same sets of cost
equations, leading to similar cost results. Interestingly, collection and transport, while contributing
insignificantly to GHG emission, has the greatest cost when compared to landfilling and yard waste
composting processes of the baseline scenario.
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MSW-DST SWOLF
Baseline
Landfilling Collection and Transportation Composting
Figure 4-7. Comparison of the LCA Tools' Total Annual Cost Estimates for Baseline Scenario
4.5 LFG Treatment Options
4.5.1 Scenario Description and Assumptions
As discussed in the previous section, uncontrolled LFG emission is the major contributor to the overall
GHG emission from the community's MSW management system; LFG is currently emitted to the
atmosphere. This scenario simulates the economic and environmental impacts of alternative LFG
management strategies such as active LFG collection and destruction via flaring, active LFG collection
coupled with electricity generation. The environmental and economic impact of operating the landfill as a
"bioreactor" to enhance the LFG production rate and the associated electricity generation were also
simulated. This section compares the environmental and economic impacts of the following three
alternative LFG management options. Figure 4-8 presents the flow of material for these options. The LFG
collection efficiency for all options is assumed to be 85%.
1. "LFG flare" option. The LFG is actively collected and combusted in a flare in the option. The
methane destruction efficiency of the flare is assumed to be 99.96%.
2. "LFG-to-electricity" option. LFG is actively collected and combusted in an internal combustion
engine to generate electricity. The generated electricity replaces the marginal electricity mix. The
methane destruction efficiency of the internal combustion engine is assumed to be 98.3%. The
energy conversion efficiency of the internal combustion system is assumed to be 34%.
3. "LFG-to-electricity with bioreactor" option. The landfill is operated as a bioreactor landfill to
enhance LFG generation. The LFG is actively collected and combusted in an internal combustion
engine for electricity generation. A decay rate "k" of 0.12 yr1 (i.e., the WARM default value for
bioreactor operation) was used for simulating the enhanced LFG generation from bioreactor
operation. All the assumptions of the LFG-to-electricity option including collection efficiency were
used for this option as well.
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[LFG Flaring/ |
LFG-to-Energy I
Materials
Collection and
Transport from
Curbside
Yard Waste
Collection and
Transport from
Curbside
f Landfill/ "X
70km-W Bioreactor N-30k
I Landfill ) \
J Yard Waste |
70 km-W _ . \
I Composting I
km
i
Transport of
Residuals
i
j Transport of
Compost
100 km-W Compost Use
Figure 4-8. EOL Materials Flow with Materials Disposal in Landfill or Bioreactor Landfill with LFG
Collection and Treatment with or without Electricity Generation
All of the tools have options to select different LFG management strategies. All tools have the option of
sending the LFG to a flare or to a gas-to-electricity system with user-specified values for methane
destruction and energy conversion efficiency. All of the tools except for WRATE also have the option of
selecting bioreactor landfill operation. The tool default k value of 0.12 yr"1 was selected for WARM and
MSW-DST. SWOLF's decay rate was manually adjusted to 0.12 yr1. The bioreactor option in SWOLF
appears to be under development and is expected to be included in a future version. This option would
allow the user to specify time-varying LFG collection efficiency to model methane emission from landfill.
WRATE does not have a bioreactor option or the ability to set an equivalent k value, so bioreactor operation
could not be modeled with WRATE. The results of these options were compared with the baseline scenario
(the scenario discussed in Section 4.4 where LFG is not collected).
4.5.2 Results and Discussion
Figure 4-9 shows that all tools predict a decrease in GHG emissions impacts when methane destruction is
employed through a flare or through a gas-to-electricity system. Electricity generation further reduced the
impact or increases the benefit by offsetting the emissions associated with avoided electricity production.
The most dramatic effect is seen in the transition from not collecting LFG to flaring LFG due to avoidance
of the high global warming impact associated with methane emissions. As discussed previously, WRATE
estimate a greater reduction in GHG impacts than WARM, MSW-DST, and SWOLF due to methane
destruction through flaring or implementing a gas-to-electricity system.
Implementation of a bioreactor landfill (with LFG-to-electricity) does not significantly reduce overall GHG
emission over the LFG-to-electricity case because bioreactor landfills are generally assumed to release the
same amount of methane but over a shorter time horizon. For the bioreactor landfill case, EASETECH and
WARM predicts greater GHG emission than the LFG-to-electricity case, which is contrary to the
estimations from MSW-DST and SWOLF. This, probably, is a result of the differences in LFG generation
rate estimation algorithm used by these tools.
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200,000
150,000
v 100,000
rsi
o
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50,000
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1
-j.uu,uuu
^ 1 LJ_
^ to '
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Baseline (No
X LU
LU
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100,000
80,000
Baseline (No Gas Flare
Collection)
Collection and Transportation Composting Landfilling
LFG to Electricity
Landfill Carbon Storage
Bioreactor
Energy credit Net
Figure 4-10. EASETECH GHG Emissions Estimates with Offsets for LFG-to-Electricity Option.
All tools estimate a 45% to 75% reduction in GHG impacts through implementing a flare. Implementing a
gas-to-electricity system provides an additional 5% to 20% decrease in emissions due to electricity
production offset. Depending on the assumptions for LFG collection early in the system, operating the
landfill as a bioreactor either has a positive (MSW-DST, SWOLF) or negative (WARM, EASETECH)
effect on GHG impacts, as previously discussed.
Figure 4-11 presents the acidification impacts on different LFG treatment options. In general, the tools
suggest LFG flaring increases the acidification impacts over the baseline scenario with no LFG collection.
Increases in the acidification impact from LFG flaring are the result of an increase in sulfur dioxide
emissions (i.e., oxidation of numerous reduced sulfur compounds, some of which are not accounted for in
the acidification impact category), an increase in thermal nitrogen oxide emissions (resulting from oxidation
of nitrogen in ambient air), or both. All tools suggest reduced acidification impacts with LFG-to-electricity
option over LFG flaring option. This reduction is associated with offset associated with displacement of
marginal fuel mix with electricity generation from LFG. The magnitude of the impact and variations among
different LFG treatment options vary significantly among tools. For example, MSW-DST suggests that
LFG-to-electricity has a net negative impact (i.e., benefit) whereas all the other tools suggest a net positive
acidification impact. The large range in impact magnitude among tools is probably a results of variations
in the LFG composition and impact assessment methodologies used by these tools.
Figure 4-12 shows the estimated annual cost of operating a landfill based on MSW-DST and SWOLF
results. Surprisingly, both tools suggest no change in overall landfilling cost with LFG collection and
flaring option compared to the baseline scenario. The venting option was used for simulating the baseline
case (with no LFG collection). There are a few components such as gas wells that are common to venting
and active LFG collection system. These tools appear to assume mandatory installation of LFG collection
for cost estimation irrespective of whether the user specifies LFG collection. The overall landfill cost would
not change if these tools automatically include LFG collection system cost in the landfill cost. Both the
tools estimate reduction in landfill cost with LFG-to-electricity option, which is attributed to revenue from
the sale of the generated electricity. MSW-DST and SWOLF estimated 23% and 8%, respectively, lower
cost for LFG-to-electricity case over LFG flare case. The difference in the tools' default electricity sale
prices and internal combustion engine installation cost account for the difference in the cost estimated by
these two tools for options with electricity generation; tool defaults for these parameters were used for LFG-
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to-electricity simulations. MSW-DST assumes a 7.1-cent per kWh revenue for the sale of generated
electricity, whereas SWOLF assumes a 5-cent revenue. The cost of implementing a bioreactor landfill (with
LFG-to-electricity) is greater than that of a traditional landfill with LFG-to-electricity due to increased costs
associated with installing and operating a leachate recirculation system.
2,000,000
1,000,000
o
^ -1,000,000
+ -2,000,000
I
j/> -3,000,000
o
S -4,000,000
DO
-* -5,000,000
-6,000,000
-7,000,000
,CO'
rf>ev
MSW-DST
IT
U
5,000,000
4,500,000
4,000,000
3,500,000
3,000,000
2,500,000
2,000,000
1,500,000
1,000,000
500,000
0
.^r.CPXV
SWOLF
EASETECH
WRATE
Collection and Transport Composting Recycling Landfilling
Figure 4-11. Comparison of the LCA Tools' Acidification Impact Estimates for Different LFG
Treatment Options
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A Comparative Analysis LCA Tools
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$6,000,000
$5,000,000
o $4,000,000
T3
0)
$3,000,000
o $2,000,000
$1,000,000
$0
MSW-DST SWOLF MSW-DST SWOLF MSW-DST SWOLF
Baseline (No Flare LFG-to-Electricity
Collection)
MSW-DST SWOLF
Bioreactor
Figure 4-12. Comparison of the LCA Tools' Annual Landfill Cost Estimates for Different LFG
Treatment Options
4.6 Impacts of Source-Separated Organics Processing
4.6.1 Scenario Description and Assumptions
As can be seen in the previous section, the LFG contributed the most to the GHG emission among all EOL
materials management processes. Source-separation and diversion of organics from the landfill may
potentially reduce LFG GHG emissions. The community would like to understand the environmental and
economic impacts of source-separated organics (food and other organics) (SSO) collection and
management via composting or AD. Organics constitute a significant fraction of the EOL materials stream
with a high methane yield and a tendency to contaminate recyclable materials. Separating this EOL
materials stream can reduce the methane production in the landfill, make the recyclable streams more
recoverable, and produce useful byproducts in a composting facility or anaerobic digester where biogas
may be managed more efficiently than LFG produced in a landfill.
To analyze this scenario, three cases are considered. The first case is the baseline scenario (Section 4.4)
where organics are deposited in the landfill with other EOL materials; LFG from landfill is vented to the
atmosphere. A fraction of the organic (food scraps and soiled paper) in EOL materials stream is source-
separated and composted with yard waste (Figure 4-13a) in the second case. The third case includes the
same organic collection system as the second case, but rather than composting, the organics are processed
in an anaerobic digester to produce biogas, which is used to generate electricity (Figure 4-13b). Other than
these specific changes, all assumptions of the baseline scenario as applicable were used. All composting is
assumed to occur in windrow systems. Tools default decay rate (k) and methane generation potential for
AD were used. It was assumed that 50% of the food scrap and non-recyclable paper of the total present in
EOL materials will be collected and processed as SSOs. The SSOs for the composting option are assumed
to be collected with the yard waste stream. The SSOs for the AD option are collected and transported
separately.
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MSW-DST is excluded from this analysis as a SSO stream collection could not be modeled with MSW-
DST. It should be noted that an additional SSO material stream had to be created and modeled separately
from the rest of the EOL materials in EASETECH. WARM can model organic composting but not AD, so
it is excluded from the anaerobic digester analysis.
Materials
Collection and
Transport from
Curbside
Yard Waste and
Food Waste
Collection and
Transport from
Curbside
70km-J Landfill U-
30km
-70 km-
Yard Waste
and Food
Waste
Composting
Transport of
Residuals
i Transport of
Compost
100 km-W
Compost Use
(a)
Food Waste
Collection and
Transport from
Curbside
Materials
Collection and
Transport from
Curbside
Yard Waste
Collection and
Transport from
Curbside
Electricity
Production
70 kmW
Anaerobic
Digestion of
Food Waste
70 km-W Landfill U :
Transport of
Dig estate
Transport of
Residuals
30km--
100 km-W
Dig estate Use
-70 km-W
Yard Waste
Composting
Transport of
Residuals
Transport of
Compost
100km-W
Compost Use
(b)
Figure 4-13. EOL Materials Flow with Collection and (a) Composting, and (b) AD of Source-
Separated Organics
4.6.2 Results and Discussion
Figure 4-14 compares GHG emissions estimates from four relevant LCA tools for a system with and
without an SSO collection and processing program. Because the scenario modeled the entire EOL materials
stream, the effects on composting of food scraps are reported as one number in WARM, SWOLF, and
WRATE (as with AD) and cannot be separated from the effects of composting yard waste, which is included
in the default scenario. For this reason and due to the relatively minor impact of composting and digestion
compared to the impact of landfilling and carbon storage, these impacts of composting and AD are
combined into as a single "Composting and Digestion" category.
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As expected, all the tools suggest a decrease in GHG impacts with the progression from the baseline case
to composting to the implementation of an anaerobic digester, which stabilizes SSO and beneficially uses
the resulting biogas. Both EASETECH and WRATE GHG emissions estimates from the AD option are
only slightly smaller than that for the composting option. The offsets associated with electricity generation
from biogas recovery appear to have a negligible impact on GHG emissions.
200,000
-= 150,000
o-
01
O
u
13
13
SSO Anaerobic Digestion
Collection and Transportation Compostinging and Digestion Landfilling Landfill Carbon Storage NET
Figure 4-14. Comparison of LCA Tools' GHG Emission Estimates for Source-Separated Organics
Processing
Figure 4-15 presents system costs with and without an SSO collection and processing program. MSW-
DST could not model the separate organics stream. As expected, instituting an SSO collection and
composting or AD program is estimated to reduce the cost of landfilling due to materials diversion from
landfill. The cost for collection is also estimated to increase slightly potentially due to collection of SSOs
with the yard waste stream (in the SSO composting scenario), which the tool assumes to have a lower
density in the collection vehicle than that of MSW. The cost of landfilling is expected to decrease with
diversion of more organic wastes from the landfill. As expected, composting costs increase, but are
negligible compared to decrease in landfilling costs. Overall, the decrease in landfilling costs is greater than
the increase in composting and collection, making SSO AD and composting a net benefit. The cost of other
composting options such as in-vessel composting are expected to be greater than the windrow composting
option simulated in this scenario and may result in overall cost that are greater than the baseline scenario.
These alterative composting options offer advantages such as better odor control over the windrow
composting. The process cost for AD is estimated to be lower than for composting due to the revenue
generated from the sale of electricity generated from the resulting biogas.
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A Comparative Analysis LCA Tools Section 4 - Applications of Tools from
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$30,000,000
$25,000,000
$20,000,000
u
-a
01
T5 $15,000,000
~2 $10,000,000
.2
$5,000,000
$0
Baseline - No SSO SSO Composting SSO Anaerobic Digestion
Collection and Transportation Landfilling Composting
Figure 4-15. Comparison of Total Annual Cost Estimates from SWOLF for the System with and
without Source-Separated Organics Processing
4. 7 Impacts of Backyard Composting
4.7.1 Scenario Description and Assumptions
As discussed in the previous section, an SSO collection and composting program reduced the GHG
emission by 4% to 26% due to diversion of readily biodegradable organics from the landfill. Although the
program was estimated to reduce the landfill cost, it is estimated to increase the collection and transport
cost. One approach to realizing the benefit of reduced GHG emissions from SSO diversion from the landfill
while reducing the transport cost is instituting a backyard composting program. This section assesses the
environmental and economic impacts of implementing a community-wide backyard composting program.
Backyard composting programs typically involve community outreach such as advertisements, hosted
events, and subsidized home composting units (Composting Council, 1996). These programs reduce the
total EOL materials amount entering the MSW and yard waste collection streams by allowing residents to
manage organics such as yard waste and food scraps in their backyards. This option reduces collection and
transportation costs and emissions as the targeted EOL materials constituents are managed at the source
location.
The estimated average yard waste diversion from landfills by backyard composting is 14% of the total
amount of yard waste produced in the US (Sherman, 1996, Composting Council, 1996). This estimate is
corroborated by Oregon DEQ (2014), which observes comparable diversion (from landfill) of the state's
yard waste via backyard composting. Backyard composting in the simplest form, involves the combination
of brown material with green material; brown material being organic material high in carbon (e.g., leaves,
twigs, hay) and green material being high in nitrogen (e.g., grass clippings, vegetable and fruit peels, and
other food scraps). It is assumed that yard waste (comprises the bulk of the "brown" material) constitutes
50% (by wet weight) and food scraps (provides the "green" materials) constitutes the balance 50% of the
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mix for backyard composting for simulating this scenario. Thus, a diversion rate of 14% for yard waste and
14% of food scraps are assumed to simulate backyard composting.
The baseline modeling scenario assumes collection of 50% of the community's yard waste for composting.
Therefore, to simulate the community's change to implementing backyard composting, the amount of yard
waste going to community composting and the landfill is reduced. Additionally, the amount of food scraps
going to the landfill is reduced. It is assumed that 50% of the yard waste to be backyard composted comes
from yard waste that was originally being sent to community composting via curbside collection of yard
waste, and the other half of yard waste is from yard waste that is collected with the mixed MSW stream and
disposed of in the landfill in the default scenario.
To compare the impacts of a more aggressive backyard composting program, a scenario is modeled
assuming diversion of 50% of yard waste and 50% of food scraps to backyard composting. Table 4-4
summarizes the proportions of yard waste and food scraps managed in the baseline and backyard
composting scenarios. Both of these scenarios otherwise follow the global assumptions of the default
scenario. Figure 4-16 below provides a general visual representation of the materials flow for the backyard
composting scenario. Approximately 2,307 and 2,474 MTs of yard waste and food scraps, respectively,
are managed by backyard composting for the average scenario. Approximately 8,240 and 8,836 MTs of
yard waste and food scraps, respectively, are managed by backyard composting for the aggressive scenario.
Table 4-4. Yard Waste and Food Scraps Diversion Rates Used for Backyard Composting Scenario
Material
Management Method
Landfill
Community
composting
Backyard composting
Total
Yard Waste (%)
Baseline
50
50
0
100
Average
43
43
14
100
Aggressive
25
25
50
100
Food scraps (%)
Baseline
100
0
0
100
Average
86
0
14
100
Aggressive
50
0
50
100
EOL \
Materials J
Backyard
Composting
X^ j
~
Materials
Collection and
Transport from
Curbside
Yard Waste
Collection and
Transport from
} >(
) (
70 km-J
70 km-W
Compost Use
Landfill
Yard Waste 1
Composting 1
+30 km
i
Transport of
Residuals
i
i Transport of
Compost
100 km-W Com post Use
Figure 4-16. EOL Materials Flow with Backyard Composting of a Fraction of Source-Separated
Organics
It should be noted that several of the tools, including SWOLF, MSW-DST, and EASETECH, define the
system boundary as the point where waste must be handled by the local community. Using this system
boundary, backyard composting as well as other in-home activities such as, for example, rinsing containers
prior to placement in a recycling bin, are excluded. The emissions associated with backyard composting
include the emissions from the production, operation, and EOL management of the composting vessel; any
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additives to the composting process; and process-specific emissions such as methane and nitrogen oxide
emissions from the SSO biodegradation. One limitation of all of the tools except WRATE is the inability
to simulate backyard composting process that accounts for all these emissions. WRATE is the only tool
that includes a process to simulate impacts of backyard composting. For the other four tools, backyard-
composted yard and food scraps were simulated by removing the diverted food scraps and yard waste from
the system boundaries of the tool (in the previously described scenario-specific proportions). For tool
evaluation purposes, it was assumed that the backyard compost pile is managed to avoid anaerobic
conditions and associated methane generation. Potential costs and emissions of the actual backyard
composting process could not be, accurately, analyzed by these tools.
4.7.2 Results and Discussion
As expected, a backyard composting program results reduces GHG emissions from the landfill due to the
diversion of SSOs from the landfill (Figure 4-17). The effect for the 14% diversion rate are difficult to
perceive on the graph, but the reduction in GHG emissions for the 14% diversion scenario range from 3%
with WRATE to 16% with EASETECH. It should be noted that WARM, MSW-DST, SWOLF, and
EASETECH simulations were conducted by removing the diverted food scraps and yard waste from the
EOL materials stream, which is equivalent to assuming that no emissions occur from SSOs managed via
backyard composting. In reality, emissions have been reported from backyard composting of these
materials (Amliner et. al. 2008). The actual GHG emission would, therefore, be greater than those estimated
using WARM, MSW-DST, SWOLF, and EASETECH. The objective of using these tools that do not
include backyard composting as a process for simulating this scenario was to assess the upper range of
reduction in emissions associated with a decrease in the amount of SSOs collected and transported to landfill
(or composting facility) and avoidance of methane generation from SSOs diverted from landfill.
Backyard Composting 14%
Backyard Composting 50%
Baseline
Landfilling Collection and Transportation Composting Recycling Landfill Carbon Storage Net
Figure 4-17. Comparison of LCA Tools' GHG Emission Estimates for Backyard Composting
Figure 4-18 compares the annual EOL materials management cost for systems with and without backyard
composting. As expected, both MSW-DST and SWOLF estimate a decrease in the landfilling as well as
collection and transport cost with implementation of backyard composting. The decrease in collection and
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transport cost is more significant than that for landfilling. The cost presented in Figure 4-18 do not include
compost bin cost and the cost to promote and implement the program.
$30,000,000
$25,000,000
$20,000,000
" $15,000,000
$10,000,000
$5,000,000
$0
MSW-DST
SWOLF
Baseline Backyard Composting 14% Backyard Composting 50%
Landfilling Collection and Transportation Composting
Figure 4-18. Comparison of LCA Tools' Total Annual Cost Estimates for the System with Backyard
Composting
4.8 Impact of Materials Recovery
4.8.1 Scenario Description and Assumptions
The community would like to assess the economic and environmental impacts of enhancing materials
recovery by instituting a curbside recyclable collection program and building a complementary MRF. The
community would like to assess the impacts of the following MRF options: single-stream, dual-stream, and
mixed waste MRF. Four cases are compared in this analysis: the baseline scenario (which does not include
an MRF), a single-stream MRF, a dual-stream MRF, and a mixed-EOL-materials MRF. The type of MRF
implemented is assumed to affect the recycling participation rate, the material recovery rate, and the residual
rate (i.e., fraction of contaminated or unrecyclable materials) at an MRF. It is assumed that the overall
recycling rate achieved through dual-stream and single-stream collection is the same at 30%, but the capture
rate (i.e., the amount of recyclables sent to the MRF due to community participation) and MRF residual
rates differ. The following equation presents the relationship among the recycling rate, the capture rate, and
the residual rate.
Recycling Rate = Capture Rate * (1-Residual Rate)
The values of these parameters used for each scenario are shown in Table 4-5. Figures 4-19 and 4-20 below
provide a general visual representation of the materials flows for the single-stream/dual-stream and mixed-
waste MRF scenarios.
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Materials
Collection and
Transport from
Curbside
SS/DS
f ^\ Recyclables
( ) ^- Collection and
V Materials /
>i v' Transport from
Curbside
Yard Waste
Collection and
Transport from
Curbside
r ^
^Single-stream A
^ MRF J
.[ Yard Waste ]
70km-W _
1 Composting 1
1 Ferrous 1
/" 1 Recycling J
30km
Fransport of
Residuals
i
i
i Transport of
Recyclables
30km
Transport of
Residuals
Transport of
Compost
Figure 4-19. EOL Materials Flow with Materials Recovery via a Single/Dual-St
Program
Transport of
Materials
Collection and
"" Transport from
Curbside
f EOL A
y Materials J
Yard Waste
Collection and
transport from
curbside
_A Mixed Waste | |
70 km '1 MRF J
Transf
of Res
A Yard Waste |
-70 km M r
1 Composting 1
Recyclables
°rt , 30km-W Landfill
duals 1 1
Transport of
Compost
1 Aluminum 1
1 Recycling 1
| Paper |
1 Recycling 1
f Plastics I
1 Recycling 1
k [ Glass 1
1 Recycling 1
W Compost Use
ream Recycling
1 Ferrous 1
/" 1 Recycling J
1 Aluminum 1
1 Recycling 1
1 Paper 1
1 Recycling 1
I Plastics 1
1 Recycling 1
V | Glass 1
1 Recycling 1
N Compost Use
Figure 4-20. EOL Materials Flow with Materials Recovery via a Mixed-Materials Recycling
Program
Table 4-5. Material Capture Rate, Residual Rate, and Recycling Used for the MRFs Analyzed.
Recovery Stream
Capture rate
Residual rate
Recycling rate
No MRF
0%
0%
0%
Dual Stream
MRF
32%
6%
30%
Single Stream
MRF
34%
12%
30%
Mixed EOL
Materials MRF
100%
80%
20%
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A Comparative Analysis LCA Tools Section 4 - Applications of Tools from
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It should be noted that, except for SWOLF, there are major limitations in modeling EOL material
management scenarios using different MRF technologies/recyclable collection strategies. WARM does not
account for the emissions associated with MRF operation; GHG emissions resulting from the
implementation of different MRF options were estimated through the fractionation of specific material
categories to recycling and landfilling based on the capture rates. EASETECH only includes a paper MRF;
this MRF was modified for all scenario options. A mixed-EOL materials and a separate-stream MRF can
be selected in MSW-DST, but the residual rate of the separate-stream MRF cannot be adjusted; because the
separate-stream MRF residual rate is set at 10%, the emissions resulting from the use of this facility are
only included in the single-stream results. WRATE has multiple MRF options that can be selected, but the
capture/residual rates cannot be adjusted from tool default values. Only SWOLF has MRF processes with
adjustable capture/residual rates for dual-stream and single-stream recyclable collection, as well as mixed-
EOL materials recyclable recovery.
EASETECH has no general "recycling" process, but has a set of specific remanufacturing processes. All
recyclable materials in EASETECH are sent to the most appropriate process, though some are not identical.
For instance, the plastics in EASETECH are not identified by resin, but the two recycling processes
available for plastic are specific to either PE-based resins or PP-based resins. An additional plastic recycling
process handles multiple resins but it is specific to Sweden. The material re-use process is identified by
resin, but the plastics categories are identified by type, i.e. "soft plastic," "hard plastic," "drink bottles", etc.
It is not possible to direct the appropriate resin to the appropriate remanufacturing process. Since PE-based
resins represent the largest component of the recyclable plastics stream (US EPA, 2014), all recycled
plastics have been modeled as being directed to the PE remanufacturing process.
4.8.2 Results and Discussion
Figure 4-21 compares GHG emission for three MRF scenarios along with the baseline scenario for each
tool. All tools' results suggest GHG emission reduction with enhanced materials recovery. The tools
estimate that any type of material recovery has a lower GHG emission than no material recovery. The only
exception is that WRATE predicts a higher impact from a mixed-EOL-materials MRF than from not
recovering materials. This is because of the impact WRATE attributes to processing a large material stream
and recovering only 20% of the material for recycling. Some of the additional GHG impact that WRATE
estimates comes the energy required to move residuals twice - once from the collection point to the MRF
and then again from the MRF to the landfill. EASETECH report nearly identical performance from either
dual-stream or single-stream recycling schemes. All tools estimate an increased impact due to additional
material transportation, but in all cases this is more than offset by the impact of recycling. SWOLF predicts
the most significant increase in collection and transportation impacts. The version of SWOLF evaluated
had an error in the dual stream process which created erroneous results, and is excluded from GHG impacts
results.
For three of the five tools (WARM, MSW-DST, and EASETECH), single- and dual-stream MRFs showed
a lower impact than a mixed-EOL-materials MRF due to the higher overall recycling rate. However,
SWOLF predicts a lower impact for a mixed-waste MRF, which may be due to the increased complexity
of source-separated recycling collection systems, which may require additional vehicles, drivers, and
routes.
Figure 4-22 presents the annual EOL materials management system cost estimates by MSW-DST and
SWOLF for each of the MRFs assessed. Because source separation increases the number of collection
vehicles/routes, collection for single-stream and dual-stream MRFs is higher than for mixed-EOL materials
and no-recycling collection. Both tools estimate an increase in the materials management system cost due
to the increase in costs associated with additional materials processing and transport. The benefit offered
by the sale of recyclables is not adequate to offset the added cost. It should be noted that the tools' default
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market price for recyclables was used for the simulations. The prices of some of the commodities (e.g.,
PET) are much higher than the MSW-DST defaults. For example, the MSW-DST default market price for
PET is $17/ton, whereas recycled PET (baled) price in the US in February 2015 was $270 per ton. The
estimated benefit from the sale of recyclables is much lower than that based on current market pricing.
MSW-DST and SWOLF allows the user to specify the market price of various commodities.
The commodity prices vary greatly depending on factors beyond the control of the solid waste community
and have a significant impact on the materials recovery and recycling economics. For example, recent
decline in crude oil price has been reported to result in significant decline in recyclables market value and
their use in remanufacturing. For a given materials stream and commodities market prices, these tools can
be used to assess the MRF construction and operating and maintenance cost above which materials recovery
would not be economically viable.
200,000
150,000
_ 100,000
o-
01
O 50,000
u
I o
V)
! -50,000
£
₯ -100,000
- J-JU/UL/U
-200,000
^ 1 LJ. X LLJ
I | 1 1 1
,> LLJ
Baseline (No MRF)
^ |
1 1
00
^
LL. X LLJ
n u &
(J LJJ LJJ
Mixed Waste MRF
Collection and Transportation Composting MRF Recycling Landfilling Landfill Carbon Storage NET
Figure 4-21. Comparison of LCA Tools' GHG Emission Estimates for Different Materials Recovery
Options
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$40,000,000
$35,000,000
$30,000,000
$25,000,000
$20,000,000
8 $15,000,000
| $10,000,000
£
** $5,000,000
$0
-$5,000,000
MSW-DST SWOLF MSW-DST SWOLF MSW-DST SWOLF
Baseline (No MRF) SS MRF Mixed Waste MRF
Collection and Transportation Recycling Landfilling MRF Composting Net
Figure 4-22. Comparison of LCA Tools' GHG Emission Estimates for Different Materials Recovery
Options
4.9 Impacts of MRF Automation
A municipality would like to compare the economic and environmental impacts of different levels of MRF
automation. Specifically, the community would like to compare the impacts of using only manual sorting
with using the highest level of automation available. The community believes that automatic sorting may
reduce costs by reducing the labor cost at the facility, reducing occupational exposure potential, and
increasing processing rate. The community is also concerned about potentially higher contamination rates
due to greater levels of automation.
This scenario could not be readily simulated using any of the five LCA tools under consideration at this
time. SWOLF does have options to adjust the level of automation of a MRF, but the version evaluated did
not have this MRF component fully implemented and does not output different results based on different
levels of automation.
4.10 Impacts of Recycling Plastics vs Recycling Glass
4.10.1 Scenario Description and Assumptions
A community would like to understand the relative environmental and economic benefits of recycling
different materials, such as plastic and glass, to improve its recycling outreach program. Plastic is generally
more valuable to recycle and acquiring the raw materials used in plastic production has a greater
environmental impact than acquiring those used to produce glass. However, the community wants to
compare the overall GHG benefit of increasing plastic recycling vs increasing glass recycling.
To capture the effects of recycling plastic vs glass, two scenarios are compared, one in which 121,000 MTs
of plastic are recycled and one in which 121,000 MTs of glass are recycled. The scenario is outlined in
Figures 4-23 a and b. EOL materials collection is modeled with 100% capture rates, and the same 12%
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residual rate is applied from each single-stream MRF scenario modeled. The EOL materials stream for the
plastic scenario includes only recyclable plastics in the same relative proportions as the default scenario.
The glass stream is modeled as 100% clear glass. Figure 4-23 presents a visual representation of the flow
of materials in the plastics and glass recycling scenarios, respectively.
Materials
Collection and
Transport from
Curbside
70knrM MRF
Transport of
Residuals
Transport of
! Recovered
Plastics
-30 km-I
Landfill
100 km-M
Plastics
Recycling
(a)
Materials
Collection and
Transport from
Curbside
70 km-M MRF
Transport of
Residuals
Transport of
Recovered
Glass
---30 km-I
Landfill
100 km-W
Glass
Recycling
(b)
Figure 4-23. EOL Materials Flow for (a) Plastics and (b) Glass Recycling Scenario
While glass types are consistently modeled across all tools, limitations with plastics categorization in some
of the tools have been described previously. The goal of the plastic scenario is to only analyze recyclable
plastic, but this is difficult to designate in EASETECH and WRATE, which include plastic categories that
may include a mixture of both recyclable and unrecyclable plastic (see the types of plastic categories
presented in Appendix A for each of these tools). A best effort was made to include recyclable fractions in
proportions that represent the US EOL materials stream.
As is mentioned in other scenarios, MSW-DST cannot set a residual rate for the MRF process, so the capture
rate is adjusted to reflect the 12% of plastics and glass that are not captured by the MRF. This may result
in differences in transport emissions since MSW-DST models these EOL materials as if they are collected
in a mixed-EOL materials collection stream rather than with other recyclables. It should be noted that the
tool MRF limitations described in the "MRF Types" scenario are applicable to this scenario as well.
Because WRATE does not allow the adjustment of the MRF residual/recovery rates, no MRF was included
in WRATE model runs for this scenario.
4.10.2 Results and Discussion
Figure 4-24 compares GHG emission estimates for plastic and glass recycling for various tools. As
expected, the reduction of GHG emission with recycling plastic is far greater than with recycling the same
mass of glass. Crude oil extraction, refining, and eventual plastic manufacturing are more resource intensive
than are the same processes leading to glass manufacturing. The "other" categories are mainly comprised
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of GHG emissions from material collection and transportation and MRF operation, but also include
emissions resulting from the landfilling of MRF residuals. The "other" category is higher for plastic
recycling than glass recycling with the exception of EASETECH (which does not account for the density
of materials). This difference is a result of the bulk density of plastic being lower than that of glass; mass
is transported less efficiently, requiring more trucks and creating a higher impact. All tools estimate a larger
impact from materials recovery for plastic than for glass.
8
100,000
S. -50,000
LO
u -100,000
Q.
I -150,000
LU
Recycling Other -Net
Figure 4-24. Comparison of LCA Tools' GHG Emission Estimates for Plastics and Glass Recycling
It is important to discuss the results from the perspective of the current methods and metrics used by
communities to track the sustainability of their EOL materials-management systems. As discussed earlier,
communities across the US use recycling rate as the primary metric to assess the sustainability of their EOL
materials-management system. The recycling rate is calculated simply based on the amount of the materials
recycled and generated. It does not consider the materials-specific properties and or the recycling
application. Recycling rate, if used for decision making in this scenario, would suggest that the community
would realize the same environmental benefits irrespective of whether it recycled glass or plastics. These
results, however, suggest that the recovery of certain materials (e.g, plastics in this case) provides a much
larger environmental benefit than those of others (e.g., glass in this case).
The primary reason that the environmental benefits of recycling plastics is much greater than those
associated with recycling glass is that the emissions from manufacturing plastic products (from crude oil
extraction through consumer products [e.g., plastic containers] manufacturing) are significantly greater than
those from manufacturing glass consumer products such as glass containers. Although the tools evaluated
in this report primarily focus on the EOL phase of materials management, data used/results of some of these
tools (e.g., source reduction feature of WARM) can be used to assess the environmental impacts through
all phases of the life cycle of materials. The environmental benefits of reducing the manufacturing plastic
products would be greater than those achieved by recycling post-consumer plastics. Using WARM, the
GHG emissions reduction achieved by recycling 1 short ton of PET is 1 MT CO2 eq, whereas that achieved
by avoiding (i.e., source reduction) production of 1 short ton of PET is 2 MT CO2 eq. With their informed
choices, consumers can potentially reduce environmental impacts (associated with all the four phases of
the life cycle of materials) to a greater extent than those that can be achieved with just the EOL stage of
materials management.
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Figure 4-25 compares the cost estimates for plastics and glass recycling for SWOLF and MSW-DST.
Contrary to expectations, both tools estimate that it economically more favorable to recycle glass than it is
to recycle plastic. Based on the mass balance of plastic types and the default prices of plastic, SWOLF
suggests a net cost of about $12 per MT of plastic recycled compared to $6 per MT for glass. The tool
default market price of recyclable materials was used for simulations. The MSW-DST default market value
of many plastics (e.g., $17 per short ton PET) was found to be significantly lower than the current market
price ($270 per short ton of PET in February 2015 as published by www.secondarymaterialspricing.com)
of these commodities. The MSW-DST default glass price ($14 per short ton for mixed glass) was found to
be greater than the current market value of glass (prices published by www. secondarymaterialspricing. com
suggest that it cost approximately $17 per short ton in February 2015 to get rid of glass due to lack of
demand for recycled glass). Based on the current pricing, recycling plastics would probably be more
beneficial economically than recycling glass. As discussed earlier, recycling plastics would have greater
environmental benefits than recycling glass. Expending the community's resources on enhancing plastics
recovery as opposed to glass recovery would, therefore, be more beneficial economically and
environmentally.
A large discrepancy between the MSW-DST default market pricing of materials, which are potentially
reflective of market conditions at the time of tool development, and current prices suggests the importance
of having tool that dynamically updates cost and price data or at least let users specify this data to reflect
the current market conditions for reliable economic-impact assessment.
I Recycling BMRF -Net
Figure 4-25. Comparison of LCA Tools' Plastics and Glass Recycling Cost Estimates per MT
Material Collected
4.11 Impacts of PAYTProgram
4.11.1 Scenario Description and Assumptions
A community would like to assess the impacts of implementing a PAYT (PAYT) program. In a PAYT
program, residents are charged based on the amount of mixed EOL materials they discard as waste for
disposal, incentivizing generating less mixed EOL materials through recycling, composting, reuse, and
source reduction. The results of implementing a PAYT system are variable, but tend to increase recycling
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and decrease EOL materials generation, pushing total EOL materials diversion up from 30% to an average
of 50% (Folz and Giles, 2002).
Figure 4-14 below shows the materials flow for the PAYT scenario, showing the beginning point where
EOL materials are generated, transported, and managed. To model the effects of implementing a PAYT
program, two options are evaluated in this scenario: before and after PAYT. Before PAYT differs from the
baseline scenario in that it has a recycling program in place with single-stream collection and a single-
stream MRF, since municipalities considering PAYT likely already have a recycling collection program in
place. The program assumes a capture rate of 50% of recyclable materials. This results in an overall
diversion rate of approximately 30%. Implementing PAYT is assumed to drive the diversion of recyclables
and yard waste up to 90%, bringing the overall diversion rate to 50%. The specific diversion rate of
recyclables and yard waste and the overall EOL materials stream before and after PAYT are summarized
in Table 4-6. The MRF is modeled as a single-stream MRF and therefore includes the tool MRF limitations
discussed in the MRF Types scenario.
Materials
Collection and
Transport from
Curbside
SS/DS
Recyclables
Collection and
Transport from
Curbside
Yard Waste
Collection and
Transport from
Curbside
70km-W
70km-J
70km-W
: Landfill 1"^ ]
) 30km
Transp
Residu
: Single-stream |
MRF J
: Yard Waste |
Composting I
ort of
als
Transport of
Recyclables
30
Transport of
Residuals
Transport of
)0km >
km
Compost
1 Ferrous
/" 1 Recycling
f
Aluminum
1 Recycling
f Paper
1 Recycling
f
Plastics
1 Recycling
V f Glass
1 Recycling
(
n W Compost Use
Figure 4-26. EOL Materials Flow with a PAYT Program Implemented with a Single/Dual Stream
Materials Recovery Program
Table 4-6. Materials Diversion Rates Assumed for the PAYT Scenario.
Diversion of
recyclables and
yard waste
Total waste
stream diversion
Before
Implementing
PAYT
50%
30%
After
Implementing
PAYT
90%
50%
None of the tools offer a built-in option to implement PAYT, so the results are modeled by altering material
capture rates. It should be considered that implementing PAYT requires a method of metering EOL
materials disposal, either through purchasing tags to place on the collection containers, limiting the volume
of waste container available (e.g., through providing different container sizes), or directly weighing the
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EOL material before it is collected. There are cost associated with PAYT program implementation, which
are important decision-making considerations for communities considering PAYT. None of the tools
include the cost of implementing PAYT or offer flexibility for user to specify these cost. Although the
impact of these cost can be simulated indirectly by altering the materials collection or transportation cost,
such adjustments are expected to be beyond the technical expertise of users with limited LCA experience.
4.11.2 Results and Discussion
Figure 4-27 compares GHG emission estimates from different tools before and after the PAYT
implementation. As expected and in all cases, increasing diversion due to PAYT decreased total GHG
emissions by increasing the emissions averted as a result of recycling. Carbon storage decreased due to a
decrease in landfilled organics (e.g., paper and vegetative waste), but this reduction in carbon storage is not
as great as the increase in recycling-averted emissions offsets.
150,000
100,000
VN 50,000
o
(J
^ 0
rc -50,000
-100,000
(D
-150,000
-200,000
CCL
<
00
Q
00
^
LJ_
I
0
00
Before PAYT
\SETECH
LJJ
WRATE
WARM
00
Q
00
^
LJ_
I
0
00
After PAYT
\SETECH
LJJ
WRATE
Collection and Transport MRF Composting Landfilling Recycling Landfill Carbon Storage NET
Figure 4-27. Comparison of LCA Tools' GHG Emission Estimates for the System with and without
PAYT Program
4.12 Impacts of ODD Recycling
4.12.1 Scenario Description and Assumptions
A community would like to compare the economic and environmental impact of recycling and landfilling
CDD materials. CDD is typically disposed of in a CDD landfill, often without LFG collection or a
composite liner. These materials, such as concrete, wood, and bricks, are often readily recycled either onsite
or following processing at a CDD MRF. Some communities require a certain quantity of CDD recycling
for major construction and demolition projects.
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To model this scenario, an EOL materials stream is developed that only includes CDD materials, since this
material stream is typically separately managed from the MSW stream. The CDD composition assumed for
simulating this scenario is presented in Figure 4-28. Figure 4-29 (a) and (b) presents the materials flow for
the CDD landfilling and recycling scenarios, respectively.
Wood flooring
10%
Dim lumber
9%
Drywall
23%
Asphalt shingles
6%
MDF
Mixed metals
4%
Mixed organics
1%
Clay bricks
11%
\_Concrete
11%
Asphalt concrete
16%
Figure 4-28. CDD Materials Composition assumed for CDD Recycling Scenario
CDD
Collection and
Transport from 70km
Curbside
(a)
CDD
Collection and
Transport from
Curbside
70 km-J
CDD MRF
Transport of
Residuals
Transport of
Recovered
CDD
30km->
Landfill
100 km-J
CDD
Recycling
(b)
Figure 4-29. EOL Materials Flows for CDD (a) Disposal, and (b) Recycling Scenarios
WARM is the only tool that includes multiple CDD materials and models the recycling of CDD materials,
so it is the only tool used to analyze this scenario. This scenario compares the effect of landfilling and
recycling CDD that has been processed by a CDD MRF, and no residual is assumed from the recycling
process. All recycled material is assumed to be reused. The transport distances to a CDD landfill and a
CDD MRF are the same as the distances to an MSW landfill and an MSW MRF, respectively, as depicted
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in previous scenarios. It should be noted that WARM does not include the emissions associated with CDD
MRF operation. Also, WARM does not provide the option to recycle wood flooring or mixed organic
material, although mixed organic material can be composted in WARM.
4.12.2 Results and Discussion
Figure 4-30 compares GHG emissions for CDD landfilling and recycling estimated using WARM. WARM
predicts a substantial savings due to recycling this material, compared to the relatively small benefit
resulting from landfilling CDD. This increased benefit results from the avoidance of emissions released
from virgin material production, whether the specific CDD material is used to offset its own virgin
production (e.g., asphalt concrete recovered and incorporated into a pavement mix to offset the production
of asphalt concrete created from virgin material) or the virgin production of another material (e.g. crushed
concrete used to offset virgin aggregate production).
o-
01
u
0N -20,000
-40,000
% -60,000
Q.
- -80,000
I
13 -100,000
-120,000
CDD Landfilled
Collection and Transportation
I Recycling
WARM
Landfillins
CDD Recycled
Landfill Carbon Storage Net
Figure 4-30. Comparison of WARM GHG Emission Estimates for the CDD Landfilling and
Recycling Options
4.13 Impacts ofE-Waste Collection and Recycling
4.13.1 Scenario Description and Assumptions
A community would like to evaluate the economic and environmental impacts of instituting an e-waste
curbside collection system to capture e-waste that is not otherwise captured by drop-off programs. E-waste
is generally regarded as a high-value material stream and has been reported to pose a major challenge to
the solid waste community (Townsend 2011). Many communities have instituted a variety of drop-off
programs to promote e-waste recycling.
Two cases are considered to better understand the benefits and costs of a curbside e-waste collection
program. The first case assumes that e-waste is collected with the mixed MSW stream and landfilled. The
second case assumes that e-waste is source separated and collected as a separate stream, passing through
the closest approximation to a pre-sorted material MRF available in each tool. Figure 4-31 (a) and (b)
presents flow diagrams for the e-waste landfilling and recycling scenarios.
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Collection and
Transport from
Curbside
70 km-W
Landfill
(a)
Collection and
Transport from
Curbside
70 km-M
MRF
Transport of
Residuals
Transport of
Recovered
Materials
30km->
Landfill
100 km-M
E-waste
Recycling
(b)
Figure 4-31. EOL Materials Flow with E-waste (a) Disposal, and (b) Recycling Scenarios
Only WRATE and WARM have categories for modeling e-waste. WARM's "personal computers" category
was used to model the e-waste management in this scenario. WRATE has several categories of e-waste.
SWOLF has a category for e-waste, but this was not fully implemented at the time of this report. MSW-
DST and EASETECH do not have a material category for e-waste and thus cannot be used to analyze this
scenario. WARM assumes that all personal computers are sent to a specialized e-waste MRF. Unlike
WARM, WRATE does not have a specialized MRF for e-waste, so a "civic amenity center" (equivalent to
a presorted drop-off center) is used. WRATE does not include an LCI for recycling e-waste, so for the
recycling scenario, landfill emissions were not included for the e-waste diverted from landfilling. WARM
accounts for the virgin material manufacturing emissions that are avoided by the recycling and recovery of
materials from e-waste.
4.13.2 Results and Discussion
Figure 4-32 shows the results of the LCA analysis for GHG impacts for WARM and WRATE. Both tools
show a greater overall impact from e-waste landfilling than e-waste recycling. Since WRATE does not have
an LCI for recycling e-waste, the reduction in GHG impacts in the recycling case is much greater for
WARM than for WRATE. Other impacts, including collection and transportation, are small compared to
the reduction in emissions WARM predicts for recycling e-waste and to the reduction in landfilling
emissions that WRATE predicts.
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0.5
o.o
-2.5
-3.0
WARM WRATE WARM
Landfilling
Other Recycling Landfilling Net
WRATE
Recycling
Figure 4-32. Comparison of WARM GHG Emission Estimates for the E-Waste Landfilling and
Recycling Options
4.14 Impacts of Collection Vehicle Fuels Type
4.14.1 Scenario Description and Assumptions
A community would like to assess the economic and environmental impacts of replacing the existing EOL
materials collection fleet with an alternative fuel vehicle fleet. Diesel is the predominant fuel used in
collection vehicles. Many municipalities, however, are considering switching to collection vehicles
powered with an alternative fuel, such as CNG, in order to reduce fuel expenses and reduce environmental
impacts.
Modeling this scenario requires collection and transportation processes which can simulate a variety of fuel
types for equivalent or substantially similar vehicle types. Three fuel types - diesel (i.e., the default base
case), CNG, and biodiesel - are used to analyze the impacts of fuel-type changes.
Only WRATE has the necessary default functionality to model alternative fuels vehicles. WRATE allows
the user to select a diesel-, CNG-, or biodiesel-powered materials collection fleet. Model default vehicle-
specific and fuel-specific parameter values were used for the simulation. The tool does not account for any
of the economic costs. It appears that SWOLF will ultimately have an option for modeling CNG as a fuel
for collection vehicles, but this feature is not yet implemented and could not be included for this simulation.
It should be noted that the impact of the fuel types could be evaluated using MSW-DST by modifying the
default vehicle emissions to reflect those associated with CNG or biodiesel vehicles. As compilation and
modifications of tool-default LCIs data to simulate a scenario like this are likely to be beyond the technical
expertise of the targeted audience of this report, this scenario was not modeled using MSW-DST.
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4.14.2 Results and Discussion
Figure 4-33 compares the GHG emission estimates for EOL materials collection for three fuel types. The
results show that a slight decrease in GHG impacts using CNG as a fuel source over diesel and a 74%
decrease in impacts with biodiesel. While CNG does reduce GHG emissions slightly, the carbon emitted is
considered fossil carbon, leading to a similar impact as diesel. The impact of switching to biodiesel, which
potentially contains and releases equivalent amounts of CO2 upon combustion amount as diesel, is
significant as much of the CC>2 emissions of biodiesel is from biogenic sources. Although GHG emissions
can be significantly reduced with the use of a biodiesel fleet, the GHG emissions associated with collection
and transportation are relatively insignificant compared to other materials-management processes such as
landfilling as shown in several scenarios presented earlier.
2,500
Diesel
CNG
Biodiesel
Figure 4-33. Comparison of LCA Tools' GHG Emission Estimates for Different Collection Vehicle
Fuels Options
Figure 4-34 shows the acidification emissions predicted by WRATE for the collection vehicle fuels
modeled. Unlike the GHG impacts, the acidification emissions for the CNG fuel scenario are an order of
magnitude lower than the other fuel scenarios. This appears to be due to the relatively lower amount of
acidic gases (e.g., sulfur dioxide) formed by the combustion of CNG compared to diesel or biodiesel fuel.
Since WRATE does not have a cost-estimation feature, the economic impacts of switching to a different
fuel type for collection vehicles cannot be evaluated using EOL materials LCA tools.
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2,500
^ 2,000
8
1,500
I 1,000
500
Diesel
CNG
Biodiesel
Figure 4-34. Comparison of WRATE's Acidification Impact Estimates for Collection Vehicle Fuels
Options
4.15 Impacts of Collection Vehicle Types
The community would like to compare the economic and environmental impacts of using different types of
collection vehicles for EOL materials collection. Specifically, the community would like to compare
manual collection vs automatic collection of curbside recyclables. Automatic collection vehicles reduce the
number of employees required to collect EOL materials while increasing the cost and operational
complexity of the collection vehicle, and the community would like to assess the impact of vehicle
automation and the associated loss of jobs.
This scenario could not be modeled using any of the five LCA tools under consideration. MSW-DST has
several types of collection vehicles available, but it is not clear what the category names in MSW-DST
correspond to in the tool's documentation. WRATE includes several vehicle types with manual and
mechanized loading options. However, economic impacts, which are the primary objective of this scenario,
cannot be evaluated using WRATE. Although user can adjust parameters such as number of workers and
vehicle time per house in MSW-DST and SWOLF to simulate the environmental impact and change in
materials collection and transport cost associated with collection vehicles used, neither MSW-DST nor
SWOLF include options to readily choose commercially-available collection vehicles with varying levels
of automation.
4.16 Impacts of a Transfer Station
4.16.1 Scenario Description and Assumptions
The community would like to compare the economic and environmental impacts of constructing a centrally-
located transfer station. Depending on the distance between collection routes and the landfill, it is often
economical to build a transfer station that allows collection vehicles to tip and transfer EOL materials to
more fuel-efficient vehicles for (typically long-distance) transport to the materials-management facility.
To model this scenario, simulations with and without a transfer station were conducted. All baseline
scenario, including transportation distances in the case without a transfer station, were used. In the case
with a transfer station, the transfer station is assumed to be located 30 km from the center of the city and
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50 km from the landfill. This is a total of 80 km compared to 70 km for the baseline case without a transfer
station. It is assumed that the additional distance is necessary to accommodate locating the transfer station.
It is assumed that a long-haul truck will be used to transport EOL materials from the transfer station to the
landfill. Figure 4-35 below shows the material flows for the centrally-located transfer station scenario.
Materials
Collection and
Transport from
Curbside
Yard Waste
Collection and
Transport from
Curbside
30 km-J
Transfer
Station
70 km-W
Yard Waste
Composting
Transport to
Landfill
Transport of
Residuals
Transport of
Compost
50 kmM
Landfill
30 km
100 kmM
100 kmM Compost Use
Figure 4-35. EOL Materials Flow for Transfer Station Scenario
WARM does not model variations in the collection process such as a transfer station or alternative vehicles
with different fuel efficiencies and thus cannot be used to model this scenario. EASETECH does not have
a transfer station process, so the paper-sorting facility is used as a surrogate for a transfer station. DST and
SWOLF both have options to include a transfer station and to include different fuel efficiencies for transport
vehicles. As stated in the general assumptions, it is assumed that trucks with a capacity of 14 to 20 tons are
used for long-range transport. The truck option most closely resembling this capacity is selected in each
tool. For SWOLF, a "medium-duty" truck is assumed to be used. MSW-DST automatically assumes a
"typical" transport vehicle is used if a transfer station option is selected. The tools' default fuel efficiency
was used for simulations.
4.16.2 Results and Discussion
Figure 4-36 shows that all the tools suggest that a centrally-located transfer station reduces GHG emissions
associated with EOL materials transportation. Collection and transport emissions overall are reduced, even
though the total distance the EOL materials travel is greater, because the vehicles used to transport the
materials from the transfer station to the landfill are more fuel efficient. The only processes affected by
adding a centrally located transfer station were collection and transportation and the transfer station process.
The emissions of the transfer station are small compared to other categories.
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200,000
150,000
O 100,000
50,000
ra
o.
£ 0
-50,000
I
-100,000
MSW-DST SWOLF EASETECH WRATE MSW-DST SWOLF EASETECH WRATE
Default
Collection and Transportation
Centrally located TS
Composting Recycling
Figure 4-36. Comparison of LCA Tools' GHG Emission Estimates for the System with and without
a Transfer Station
Figure 4-37 shows the cost estimated by MSW-DST and SWOLF before and after adding a transfer station.
The annualized cost includes the annual operating and maintenance and capital costs, amortized over the
life of the facility. Both models estimate a decrease in collection and transport cost with the implementation
of a centrally located transfer station. Both models estimate that the savings in collection and transport more
than offset the cost of operating the transfer station. SWOLF estimates a larger operating cost than MSW-
DST.
$35,000,000
$30,000,000
$25,000,000
$20,000,000
$15,000,000
$10,000,000
$5,000,000
$0
MSW-DST SWOLF
Default
Collection and Transportation Composting
MSW-DST
SWOLF
Centrally located TS
Landfilling Transfer station
Figure 4-37. Comparison of LCA Tools' Total Annual Cost Estimates for the System with and
without Transfer Station
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4.17 Impacts of Several Thermal Treatment Options
4.17.1 Scenario Description and Assumptions
The community would like to understand the economic and environmental impacts of different thermal
treatment strategies, including traditional incineration (WTE), gasification, and pyrolysis. These processes
can recover energy from an EOL materials stream and reduce the mass and volume of EOL materials
disposed of in a landfill.
Simulations results from four cases are compared. The first case is the baseline scenario in which all EOL
materials except for yard waste are collected in one stream and landfilled. The second case is similar to the
baseline scenario, with the exception that the mixed EOL materials stream is incinerated at a WTE facility
instead of being placed in an MSW landfill. The ash from this facility is then landfilled in an ash landfill.
The third case simply replaces the WTE process with a gasification process. The fourth case replaces the
gasification process with a pyrolysis process. The tools default values are used for all energy-recovery
parameters such as energy content and electricity conversion. The energy mix displaced by the electricity
in this process is the same as the mix presented in the global assumptions. Figures 4-38 and 4-39 represent
the materials flow for a WTE process and for a pyrolysis/gasification process for energy recovery,
respectively. The main difference between the thermal treatment types is that the pyrolysis and gasification
facilities must treat the incoming material stream (e.g., adjust moisture content, remove unsuitable
materials) for effective thermal processing. Most mass-burn WTE facilities (currently the most prevalent
type of WTE facility in the US) require little to no pre-preprocessing.
I Electricity I
I Production I
Materials
Collection and
Transport from
Curbside
Yard Waste
Collection and
Transport from
Curbside
70 km-
WTE
(Preprocessing
Onsite)
J
70 km-W
I
Yard Waste
_ .
Composting
Transport of
Residuals to
Landfill
Transport of
Recovered
Ferrous
Transport of
Recovered
Aluminum
Transport of
Compost
30km--W Ash Landfill
100 km
100km
Ferrous
Recycling
Aluminum
Recycling
-100kmM Com post Use
Figure 4-38. EOL Materials Flow for Thermal Treatment Scenario
4-42
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
a Decision-Maker's Perspective
. Collection and .[ RDF Process!
i ^ , 70km-W
Transport from 1 (Onsite)
f EOL ^
V Materials J
Yard Waste
^ Collection and _, ,
Transport from
1 Electricity 1
1 Production 1 Transport of
t Landfill
/ ' s
ng I Pyrolysis or
1 Gasification
v J
1 J
1 Yard Waste 1 Transport of
1 Composting I Compost
30km--W Ash Landfill
^1 Ferrous 1
100km H
1 Recycling J
.1 Aluminum 1
100km H
1 Recycling J
c ^\
Figure 4-39. EOL Materials for Pyrolysis or Gasification Treatment Scenario
All of the tools can model the default scenario and WTE facility case; however, WRATE is the only tool
that can be used to model a gasification and a pyrolysis process. All other assumptions are the same as the
default scenario.
4.17.2 Results and Discussion
Figure 4-40 shows the results of the five LCA tools for GHG emissions impacts. All tools estimate a lower
impact for WTE processes than for landfilling because the baseline landfilling process does not include
LFG collection, resulting in methane emissions. EASETECH estimated an order of magnitude higher
emissions savings from operating a WTE facility. WRATE predicts lower GHG emissions for gasification
and pyrolysis than for landfilling, but a greater reduction for WTE than for the advanced thermal treatment
processes. The GHG emissions for pyrolysis and gasification are greater than WTE mass burn because both
gasification and pyrolysis require the materials to be transformed into an RDF more suitable for the process.
The RDF production process rejects some of the materials as residual, which is then landfilled where it may
generate methane. This leads to a higher GHG emission compared to the WTE mass-burn scenario. Both
gasification and pyrolysis produce syngas as a process output. WRATE assumes that the syngas is used
for electricity generation. Syngas can also be used for other applications such as vehicle fuel production,
which may offer a greater environmental offset than that for electricity generation.
4-43
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
a Decision-Maker's Perspective
S o |
§ °° to
^ LLJ
Baseline (Landfilling)
5 i
1 i
OO T^ (J
Q O LLJ
§ °° to
^ LLJ
Incineration
LLJ LLJ LLJ
< < <
555
Gasif. Pyro.
Collection and Transportation Recycling Landfilling HWTE Landfill Carbon Storage Net
Figure 4-40. Comparison of LCA Tools' GHG Emission Estimates for the Baseline Scenario and
Different Thermal Treatment Options
Figure 4-41 presents the annual cost estimated for landfilling and WTE from SWOLF and MSW-DST. It
is not clear why MSW-DST estimates lower collection and transportation costs for the incineration case.
SWOLF estimates a higher collection and transportation cost, probably to account for the impact of
transporting ash and recovered metals twice. MSW-DST estimates a slightly greater revenue through the
recovery of metals than SWOLF. MSW-DST estimates a significantly larger cost for operating the WTE
incinerator than does SWOLF. Based on the tool development timeline, the cost data used in SWOLF are
expected to be more recent and updated than those used in MSW-DST.
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
a Decision-Maker's Perspective
$30,000,000
$25,000,000
$20,000,000
$15,000,000
to
8
"S $10,000,000
"S
3
I $5,000,000
"S
£ $0
-$5,000,000
MSW-DST
SWOLF
Baseline (Landfilling)
Collection and Transportation Recycling
MSW-DST
SWOLF
Incineration
Landfilling HWTE -Net
Figure 4-41. Comparison of LCA Tools' Total Annual Cost Estimates for the Baseline Scenario and
Different Thermal Treatment Options
4.18 Impacts of Plastics Incineration vs Recycling
4.18.1 Scenario Description and Assumptions
Plastics have a high heating value, making them a valuable fuel for a WTE facility, but they are also a
valuable commodity if recycled. The community with a WTE incineration facility would like to understand
the economic and environmental impacts of recycling versus incinerating plastics. To analyze the effects
of the incineration and recycling of plastic, two scenarios are compared, one in which 121,000 tons of
recyclable plastics are combusted with electricity production and one in which 121,000 tons of recyclable
plastics are recycled. The EOL materials stream includes only recyclable plastics in the same relative
proportions as the default scenario. Electricity produced from WTE plastic incineration displaces the same
electricity grid mix specified in the global assumptions section. Figures 4-42 and b represent the material
management flows for the scenarios where plastics are recycled and plastics are combusted, respectively.
The goal of this scenario is to model the management of recyclable plastics only, but this is difficult to
designate in EASETECH and WRATE, which may include some categories that contain both recyclable
and unrecyclable plastic. A best effort is made to include recyclable fractions in proportions that represent
the US EOL plastics stream. Also, it should be noted that EASETECH does not have a process that
simulates the disposal of fly ash; EASETECH only includes a bottom ash landfill process. This could lead
to differences in the results of EASETECH compared to other tools for EOL materials incineration.
As is mentioned in other scenarios, it is not possible to adjust the MSW-DST residual rate for the MRF
process, so the MRF capture rate (i.e., the total mass of plastics being sent to the MRF) is adjusted to force
the correct amount of plastics being sent to recycling. This could result in substantial differences in
transportation emissions, especially considering that MSW-DST models materials as if they are collected
4-45
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
a Decision-Maker's Perspective
in a mixed-EOL materials collection stream rather than with other recyclables. Modeling plastic
incineration in SWOLF and WARM was relatively straightforward since the plastics categories are based
on resin type, which are consistent with the composition used for this scenario.
Materials
Collection and
Transport from
Curbside
70 km-J
MRF
Transport of
Residuals
Transport of
Recovered
Plastics
30km->
Landfill
lOOkm-M
Plastics
Recycling
(a)
Materials
Collection and
Transport from
Curbside
70 krrH
WTE
(Preprocessing
Onsite)
Transport of
Residualsto 30km-
Landfill
Ash Landfill
Electricity
Production
(b)
Figure 4-42. EOL Plastics Flow for (a) Recycling, and (b) WTE Scenarios
4.18.2 Results and Discussion
As seen in Figure 4-43, all tools predict a greater GHG emission from incinerating than from recycling
plastics. All tools predict a negative net GHG emission for recycling, and only EASETECH predicts a
negative net emissions for incinerating plastic. A large variation among tools results for incineration
scenario is, probably, a result of differences in the marginal energy mix used for modeling as well as the
variation in electricity generation process LCIs among tools. As discussed earlier, 100% coal was assumed
as the marginal fuel mix for EASETECH, whereas several fossil fuels were included in the marginal energy
mix for the other tools. EASTECH and WRATE electricity generation process LCIs are based on Euorpean
data whereas WARM, MSW-DST, and SWOLF LCIs are based on the US-specific data. Because recycling
results in additional transportation and processing emisisons compared to incineration, the "other" category
is included but is small compared to the impacts of WTE mass burn and recycling. Because plastic is
primarily derived from fossil carbon, incineration of plastic releases fossil carbon.
Figure 4-44 shows the economic impact of plastic incineration compared to recycling. Since this scenario
models only the plastic part of the EOL materials stream, collection and sorting are not included as the
additional landfilled residual amount could not be removed from MSW-DST MRF output. Both tools
predict a greater revenue for incineration than for recycling. This is due to the inclusion of lower value
plastics such as film plastic and polypropylene, which are considered part of the "non-recyclable-plastic"
4-46
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
a Decision-Maker's Perspective
stream and are not recycled, for WTE. This fraction lowers the net value of the recycled products. However,
these non-recyclable plastics have high energy content, which contributes to the electricity generation if
incinerated for energy recovery. The SWOLF tool is not fully developed and these costs may be revised in
future versions.
200,000
^ 150,000
"ii 100,000
O
u 50,000
tS -50,000
ra
|- -100,000
13 -150,000
I
13 -200,000
-250,000
WARM MSW-DST SWOLF EASETECH WRATE WARM MSW-DST SWOLF EASETECH WRATE
Plastics Incineration Plastics Recycling
Collection and Transportation Recycling Landfilling Combustion MRF NET
Figure 4-43. Comparison of LCA Tools' GHG Emission Estimates for Plastics Incineration and
Recycling
o
-500,000
-1,000,000
-1,500,000
-2,000,000
-2,500,000
-3,000,000
-3,500,000
-4,000,000
-4,500,000
-5,000,000
tt
8
-a
01
S
o
MSW-DST
SWOLF
Incineration
MSW-DST
SWOLF
Recycling
Recycling Incineration
Figure 4-44. Comparison of LCA Tools' Economic Benefits Estimates for Plastics Incineration and
Recycling
4-47
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A Comparative Analysis LCA Tools Section 4 - Applications of Tools from
a Decision-Maker's Perspective
4.19 Impacts of RDF Recovery Before and After Landfilling
The community would like to compare the economic and environmental impacts of RDF production. RDF
can be produced from fresh incoming EOL materials or from materials deposited in a closed landfill.
Landfill mining is a process that can be used to reclaim older landfill cells to acquire additional landfill
airspace or to provide community assets such as parks or land for future development (Jain et al. 2013, Jain
et al. 2014). Mining landfill cells and screening out fines can produce an RDF with greater energy content
than fresh MSW due to the absence of higher moisture content materials such as food scraps. An additional
benefit of RDF production from the mined materials over RDF production from fresh incoming material is
that a smaller materials stream would need to be processed as a majority of the biodegradable organics (e.g.,
food scraps), which have relatively lower energy content, are stabilized.
To model this scenario, two cases are considered. The first case assumes the same EOL materials
composition as the baseline scenario, but one which passes through preprocessing at a WTE facility that
recovers metals for recycling and produces RDF that is combusted to produce electricity. The rest of the
residual material and generated ash is sent to a landfill (Figure 4-45 a). The second case assumes that the
EOL materials are deposited in the landfill and mined (after stabilization of biodegradable organics) to
produce RDF. It is assumed that the mining process produces three broad categories of materials: those
suitable for recovery (i.e., aluminum and ferrous materials), those suitable for RDF production, and residual
for landfilling (Figure 4-45 b). RDF is combusted at a WTE facility. In setting up the scenarios to simulate
RDF production and landfill mining, it was observed that none of the tools could readily simulate the landfill
mining scenario due to a lack of processes specific to landfill mining. Therefore, the RDF production and
landfill mining scenarios were not further evaluated. It should be noted that some of these tools can be
modified to include landfill mining process LCIs and can be used to model this scenario; Jain et al. (2014)
used EASETECH to assess the environmental impacts of landfill mining. As mentioned earlier, process-
specific LCIs development and programing to modify the existing tools to include new processes is
expected to be beyond the technical expertise of community decision makers.
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
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I Electricity I
I Production I
Materials
Collection and
Transport from
Curbside
Yard Waste
Collection and
Transport from
Curbside
70 km-
WTE
(Preprocessing
Onsitefor RDF
Production)
J
70 km-W
I
Yard Waste
_ .
Composting
Transport of
Residuals to
Landfill
Transport of
Recovered
Ferrous
Transport of
Recovered
Aluminum
Transport of
Compost
30km--W Ash Landfill
100km
100km
Ferrous
Recycling
Aluminum
Recycling
-100kmM Com post Use
(a)
Materials
Collection and
Transport from
Curbside
70 km-W
Landfill
30km
Transport of
Residuals
Yard Waste
TdlU VVdbLC X
Collection and [ Yard Waste
^t 70km-W .
Transport from I Composting
Curbside ^
m Transport of
Residuals
Landfill Mining
and Production of
RDF Following
Biodegradation of
Organics ^
Transport f ^
30 km ^ j
Transport of
Ferrous
Transport of
Aluminum
_^ Electricity
Production
^\ Ferrous
~fF\ Recycling
^i Aluminum
H Recycling
Transport of
Compost
-100 km-
M Com post Use
(b)
Figure 4-45. EOL Materials Flow with (a) RDF Production before Disposal, and (b) RDF Production
after Disposal followed by Landfill Mining
4.20 Summary and Discussion
Table 4-7 presents a summary of scenarios that could be simulated with each tool. Out of total 31 scenarios
planning for this evaluation, WRATE readily simulated 25, EASETECH readily simulated 19, MSW-DST
and SWOLF simulated 17 each. SWOLF developers plan to add features that would allow it to run 7
additional scenarios. As discussed earlier in this chapter, some of the simulations were conducted by
selecting a similar process due to lack of availability of the process of interest in the tool(s), or
adjusting/approximating parameters (e.g., diversion rates for PAYT scenario). Such
approximations/adjustment may be difficult for a user with limited LCA or technical background, and may
also result in an inaccurate assessment. None of the tools except WARM could simulated the impacts of
alternative management option for CDD materials. None of the tools except WRATE could simulate
impact of alternative fuel vehicle fleet. None of the tools could readily simulate impacts of automation
levels of materials collection and recovery operations or impacts of landfill mining. It should be noted that
some of these tools can be modified to include process LCIs and can be used to model several of the scenario
4-49
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
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that could not modeled using features; Jain et al. (2014) used EASETECH to assess the environmental
impacts of landfill mining. As mentioned earlier, process-specific development and programing to modify
the existing tools to include new processes is expected to be beyond the technical expertise of community
decision makers.
Table 4-7. A List of the Scenarios that could be Evaluated Using the LCA Tools
Scenario
Title and
Section
Number
Baseline
Scenario
(4.4)
Landfill Gas
Treatment
Options
(4.5)
Source-
Separate
Organics
Processing
(4.6)
Backyard
Composting
(4.7)
Materials
Recovery
(4.8)
MRF
Automation
(4.9)
Options
Landfill with no
LFG Treatment
Flaring
LFG-to-
Electricity
LFG-to-
Electricity with
Bioreactor
Collection and
Composting
Collection and
AD
Decreased
organics
collection due to
home composting
Single stream
MRF
Dual stream MRF
Mixed waste
MRRF
Various levels of
manual vs
automated work
Recycling Plastics vs Recycling
Glass (4. 10)
Pay-as-You-Throw (4. 1 1)
CDD
Recycling
(4.12)
Landfilling of
CDD
Recycling of
CDD
WARM
^
^
^
^
^
^
^
^
^
^
^
^
^
MSW-
DST
^
^
^
^
^
^
^
^
^
SWOLF
^
^
^
^
^
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A Comparative Analysis LCA Tools
Section 4 - Applications of Tools from
a Decision-Maker's Perspective
Table 4-7 (contd.). A List of the Scenarios that could be Evaluated Using the LCA Tools
Scenario Title
and Section
Number
E-waste
Collection and
Recycling
(4.13)
Collection
Vehicle Fuels
(4.14)
Collection
Vehicle Types
(4.15)
Transfer
Station (4. 16)
Thermal
Treatment
Options (4. 17)
Plastic
Incineration vs
Recycling
(4.18)
RDF Recovery
Before and
After
Landfilling
(4.19)
Options
Landfilling of
e -waste
Recycling of e-
waste
Diesel
CNG
Biodiesel
Vehicles with
different
mechanisms
for waste
collection
Adding a
centrally
located transfer
station
Mass burn
WTE
Gasification
Pyrolysis
Plastic
incineration
Plastic
recycling
RDF
production
from fresh
MSW
RDF
production
from landfill
mining
WARM
^
^
^
^
^
^
^
MSW-
DST
^
^
^
^
^
^
SWOLF
Sa
Sa
s
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A Comparative Analysis ofLCA Tools Section 5 - Summary
5 Summary
5.1 Summary of 7bo/s Salient Features Comparison
The decision-making domain of communities in the US typically begins when materials are taken out of
the use phase and become a waste to be managed by the community's EOL materials management
department or their franchised haulers; the community's decision-makers can indirectly influence processes
upstream (e.g., promotion of backyard composting) of the EOL phase. We identified 29 tools that can
potentially be used by communities for the LCA of MSW materials. As the decision-making domain of
communities includes only the EOL phase of materials collection and management, only the tools that were
specific to EOL management of materials in the US or the ones that allow users to customize the tools to
simulate US-specific EOL materials management approaches were selected for comparative evaluation.
The tools selected for evaluation were WARM, MSW-DST, SWOLF, EASETECH, and WRATE. Only
the standard version of WRATE was evaluated in this report; the expert version of this tool offers more
flexibility and costs more than the standard version.
These tools were evaluated based on such criteria as LCA scope (e.g., materials and processes included),
impacts analyzed (e.g., environmental, social, economic), and other general attributes (e.g., training and
tutorials available, documentation thoroughness, ease of use, frequency of update). The tools were
evaluated based on a review of tool documentation and use of these tools to simulate the LCA of a variety
of materials-management scenarios. These scenarios represent several currently pertinent materials-
management-specific challenges that decision makers of US communities must address. These simulations
were not only useful in illustrating the applications of LCA in decision making but also helpful in
identifying the limitations of these tools.
All the tools evaluated have been developed in the last two decades with WARM being the oldest and
SWOLF, which is still under development, being the newest. All these tools (except SWOLF) have been
updated since the release of the original version. WARM has been updated most frequently (14 times)
since it its initial release in 1998. Table 5-1 compares salient features of these tools. WARM and MSW-
DST are available for free while there is an annual licensing fee of £1400 for WRATE and a one-time fee
of 5,000 for EASETECH. The EASETECH license is provided free to the registered user and the training
cost (provided by DTU) for consultants, authorities, and developers to become registered users is 5,000.
Fewer than 230 licenses/copies each of EASETECH, MSW-DST, and WRATE have been
sold/distributed internationally since their development; there are approximately 300 unique users on the
WARM update mailing list. As a point of comparison, there are over 39,000 local governments (counties,
municipalities, and townships) existed in the US in 2012 (Hogue, 2013) that may benefit from these tools.
As shown in Table 5-1, all tools included features to compare environmental impacts of the commonly
practiced EOL materials (specifically MSW) management options in the US, such as recycling, composting
of biodegradable materials, incineration, and landfilling. However, some management options and material
streams could only be analyzed with specific tools. For example, only WARM can analyze impacts
associated with source reduction and the management of CDD materials; pyrolysis can be analyzed only
using WRATE. It should be noted that Table 5-1 includes the process for atool if it can be readily simulated
using the tool even if it is not available as default option. For example, a single-stream MRF is not
specifically included in WRATE but it can be modeled using other similar process. Only MSW-DST and
SWOLF assess the cost to construct, operate, and maintain a facility.
Tools offered varying degrees of flexibility in simulating slight variations of materials-management
options. For example, the impact of progressively expanded LFG collection system can be assessed by
varying LFG collection efficiency in MSW-DST; WARM is not suitable for this assessment. Another
example of tool-specific flexibility is assessing the impact of replacing a diesel fleet with a CNG fleet for
-------
A Comparative Analysis ofLCA Tools Section 5 - Summary
materials collection. This can only be analyzed with WRATE or the future version of SWOLF, as the other
tools do not include CNG as a fuel option. The advantage of flexibility is that the user can simulate site-
specific conditions, the disadvantage is that a greater number of user-specifiable parameters add tool
complexity. In general, EASETECH appeared to be the most flexible and WARM the least flexible in
terms of the number of user-specifiable parameters. It should be noted that the standard version of WRATE
was evaluated in this study and the expert version is designed to offer greater flexibility.
Tools varied in the scope of emission sources included in process-specific LCIs. For example, WARM's
landfill process excludes emissions associated with landfill leachate and landfill construction while
WRATE includes emissions associated with these aspects. WARM does not consider emissions associated
with facility construction in general. Examples of these emissions include emissions associated with
manufacturing/production (including raw materials extraction) of materials (e.g., steel, concrete,
geosynthetics, and equipment) and energy (e.g., electricity, diesel) used for materials-management
facilities.
Tools varied in the impact categories analyzed and not all tools included the same impact categories, as
shown in Table 5-1. For example, WARM only analyzes the GHG impacts, whereas other tools include a
wide range of impact categories such as climate change, ecotoxicity, acidification, and eutrophication.
5-2
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A Comparative Analysis ofLCA Tools
Section 5 - Summary
Table 5-1. Comparison of Salient Features of EOL Materials Management LCA Tools
Consideration
Procurement Cost
Latest Update
Construction and Operating
and Maintenance Cost
Estimates
WARM
Free
2015
-
MST-DST
Free
2002
^
SWOLF
Free to non-
commercial.
Cost for
commercial
use is not
yet
determined.
2015
^
EASETECH
5,000
2014
-
WRATE
£1,4007
Year (Std
version)
2015
-
Material Categories
MSW
CDD
Electronic Waste
Source Reduction
^
^
^
^
^
-
-
-
^
-
V'l
-
^
-
-
-
^
-
^
-
Materials Collection
Bin/cart options
Drop-off
CDD Collection
SSO
-
-
-
-
^
^
-
-
^
^
-
^
-
-
^
-
^
^
^
^
Materials Transport
Multiple Fuel Options
Multiple Vehicle Options
Multiple Modes (e.g., Rail, Ship)
Multiple Road Options
Transfer Station
-
-
-
-
-
^
-
^
-
^
^
-
^
^
^
^
-
^
^
-
^
^
^
^
^
MRF
Single Stream
Dual Stream
Mixed EOL materials
-
-
-
^
-
^
^
^
^
^
-
-
^
^
^
Landfill
MSW Landfill
Ash Landfill
Carbon Storage
Leachate
LFG- Generation Rate Adjustable
LFG-Flaring
LFG-to -Electricity
LFG Direct Beneficial Use
^
-
^
-
^
^
^
-
^
^
^
^
^
^
^
-
^
^
^
^
^
^
^
-
^
^
^
^
^
^
^
^
^
^
-
^
^
^
^
-
5-3
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A Comparative Analysis ofLCA Tools
Section 5 - Summary
Table 5-1 (contd.). Comparison of Salient Features of EOL Materials Management LCA Tools
Consideration
WARM
MSW-
DST
SWOLF
EASETECH
WRATE
Emerging Technologies
Gasification
Pyrolysis
AD
-
-
-
-
-
-
^!
-
^
-
-
^
^
^
^
Incineration
Mass Burn
Refuse-Derived-Fuel
Incineration without Energy
Recovery
^
-
-
^
^
-
^
^
^
^
-
^
^
^
-
Composting
Windrow Composting
In-vessel Composting
Backyard Composting
^
-
-
^
^
-
^
^
-
^
^
-
^
^
^
Tool Output
Simultaneous Comparison of
Multiple Scenarios
Process-specific emissions
-
-
^
-
^
-
^
^
^
Impact Categories2
Global Warming
Ozone Depletion
Human Toxicity, General
Human Toxicity Carcinogenic
Human Toxicity Non-Carcinogenic
Ionizing Radiation
Smog Formation
Eutrophication
Freshwater Eutrophication
Marine Eutrophication
Ecotoxicity
Freshwater Aquatic Ecotoxicity
Depletion of Abiotic Fossil Fuel
Resources
Depletion of Abiotic Non-Fossil
Fuel Resources
Acidification
Terrestrial Eutrophication
PM
^
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
^
-
-
^
^
-
^
^
-
-
^
-
-
-
^
^
^
^
-
-
-
-
-
^
^
-
-
-
-
^
-
^
-
-
^
^
-
^
^
^
^
-
^
^
^
-
^
^
^
^
^
^
-
^
-
-
-
-
^
-
-
-
^
-
-
^
-
-
1 planned but not included in version evaluated
2 SWOLF has an editable impact assessment method section that could add or remove categories. Note EASETECH has multiple impact assessment
methods available.
5-4
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A Comparative Analysis ofLCA Tools Section 5 - Summary
5.2 Observations from the Tools Application for Evaluating Materials
Management Options
The following observations were made from the application of the tools for various materials management
scenarios simulated using these tools:
1. A majority of the US-specific EOL materials management options could be simulated (with
appropriate assumptions in material categories and classification) using WRATE and
EASETECH due to the flexibility offered by these tools. Simulating a stream of materials
representative of the US (US EPA 2014), which is the datasetthe US communities' decision makers
are expected to rely upon, was challenging, especially using EASETECH and WRATE due to
variation in materials nomenclature. For example, plastics in WRATE and EASETECH are labeled
based on use (e.g., drink bottles), and characteristics (e.g., hard plastics in EASETECH), whereas
the US EPA Facts and Figure track plastics by resin type (e.g., PET, HDPE). This discrepancy in
classification styles is also important because some items (e.g., drink bottles) have compositions
that may substantially vary over time.
2. Not all the planned scenarios could be simulated with all the tools. For example, the environmental
impact of landfill mining could not readily be analyzed with any of the tools.
3. Several commonly practiced materials management options either are not included in the many of
the tools or not referred to by the names used by the EOL materials-management community in the
US. For example, none of the tools, except SWOLF, specifically includes single-stream curbside
collection and single-stream MRF as options. Although most of the materials-management
processes may reasonably be simulated using these tools, use of names inconsistent with industry-
standard terminology or processes complicates their use by users with limited LCA background.
4. Due to the wide variation in impact categories analyzed among tools, the only impact category that
could be compared among the tools was global warming (i.e., GHG emission). Also, the units for
none of the comparable impact categories included in the tools (except WARM) are the same to
allow comparison of these impacts among the tools. For instance, the unit for eutrophication in
EASETECH is kg P-eq while the unit in MSW-DST for the same category is kg N-eq, making it
difficult to quantitatively compare the results across tools.
5. Not all the tools provided process-specific breakdowns of emissions (e.g., materials placement and
compaction, LFG) from the major processes (e.g., landfill). The process-specific emissions
distributions presented in Chapter 4 were estimated using tool outputs and documentations.
6. LFG and carbon storage had the greatest influence on the overall GHG impact for landfill and
remanufacturing credit (i.e., emission offset associated with avoiding virgin materials production
due to substitution by recovered materials for product manufacturing has the greatest influence
on overall GHG emissions from materials recovery and recycling processes). All the tools,
except WRATE, include (or give the user the flexibility to include) carbon storage. Including
carbon storage reduces the net GHG emissions estimate for landfill. WARM's remanufacturing
credit was significantly greater than the other tools. Due to variations in the magnitude of these
parameters, net emissions varied significantly among tools in some scenarios simulated.
7. Although the magnitude of impact varied among tools, the tools results, in general, provided
consistent qualitative interpretation of environmental benefits as expected for various materials-
management options simulated. For example, although the magnitude of reduction in GHG
emission with LFG flaring varied among tools, all the tools, as expected, showed a decline in
GHG emissions with LFG collection and flaring.
8. Although the tools evaluated in this report primarily focus on the EOL phase of materials
management, data used/results of some of these tools (e.g., source reduction feature of WARM)
can be used to assess the environmental impacts through all phases of the life cycle of materials.
5-5
-------
A Comparative Analysis ofLCA Tools Section 5 - Summary
5.3 Data Gaps and Considerations for Future Research
Additional research effort is needed to develop approaches and tool(s) that decision makers can use to
characterize trade-offs among the environmental, economic, and social impacts of EOL materials
management on community sustainability. Some considerations for future revision of the existing tool(s)
or new tool development are as follows:
1. As discussed earlier, specifying a material stream representative of the US EPA (2014) was
challenging due to variation in materials nomenclature. The materials category nomenclature
should be consistent with that used for the US EPA Facts and Figure report and
categories/descriptions used by the communities to track EOL materials. The tools should include
a description of materials along with examples of materials included in each material category.
2. The tool architecture should allow easy revision to accommodate updated LCIs of individual
processes and inclusion of new materials (e.g., electronics) and emerging materials management
technology (e.g. pyrolysis) as data become available; pyrolysis in WRATE is based on data from
a single facility. Regular updating and maintenance of the LCIs in each tool is needed, as some
of the data and assumptions in the tools evaluated appeared outdated. Developing a dedicated
web portal (such as http://www.lcacommons.gov/) that allows communities to share data (e.g.,
cost, process-specific energy and materials usage) that can be used for updating tool(s) inputs
(cost, LCIs, and characterization factors) should be considered.
3. The tool(s) should be designed for users with varied educational levels and skill sets. Due to its
ease of use, WARM is the most commonly used tool among the tools evaluated in this report.
However, WARM offers limited flexibility (e.g., allows specification of only limited number of
inputs by the user). A tool that can readily be used by the community decision makers, facility
operators, engineers, and regulators at varying level of complexity and flexibility on multiple
platforms (e.g., mobile devices, computers, online calculators) would be expected to have more
prevalent use and impact on the communities' decision making. As presented above, there are
over 39,000 local governments that may benefit from such tools.
4. The tool(s) should consider all phases of a product or process. Although tools specific to EOL
management materials were the focus of the evaluation presented in this report, future tools
should consider manufacturing and use phases of the materials for use by consumers to assess
the impacts of materials consumed and those associated with reduce consumption (i.e., source
reduction) or the impacts of consumption. This feature would expand analysis boundary of the
current waste LCA tools; only WARM includes manufacturing phase while other tools include
only offset for materials remanufacturing using recycled products.
5. None of the selected tools evaluates the social impacts of EOL materials-management options.
Only MSW-DST and SWOLF assess the economic impacts of materials management, and these
tools only produce an estimated annualized cost. The economic impacts are only limited to the
cost of constructing, operating, and maintaining materials-management facilities and do not
account for overall economic impacts, such as job creation. Also, the current tools only analyze
environmental and economic impacts in isolation and do not account for interaction or trade-off
between environmental and economic impacts, e.g., long-term economic benefits from enhanced
ecosystem services associated with emission reduction that requires an investment of community
resources.
5-6
-------
A Comparative Analysis ofLCA Tools Section 6 - References
6 References
Amlinger, F., Peyr, S., and Cuhls, C. (2008). Green house gas emissions from compositing and mechanical
biological treatment. Waste Management & Research, 2008: 26, 47-60.
Barlaz, M.A. (1998). Carbon Storage during Biodegradation of Municipal Solid Waste Components in
Laboratory Scale Landfills. Global Biogeochemical Cycles, 12 (2), 373-380.
Berenyi, E.B. (2007). Materials Recycling and Processing in the United States: Yearbook and Directory.
5 Ed. Government Advisory Associates, Inc.
Composting Council, (1996). National Backyard Composting Program Training Manual. The Composting
Council's National Backyard Composting Program. The Composting Council, Alexandria, VA.
Dumas, R. (1999). Energy Use and Emissions Associated with Electric Energy Consumption as Part of a
Solid EOL materials management Life Cycle Inventory Tool. Prepared by Robert D. Dumas
Department of Civil Engineering North Carolina State University, July 8, 1999.
Folz, D., and Giles, J. (2002). Municipal Experience with "Pay-as-You-Throw" Policies: Findings from a
National Survey. State and Local Government Review, 34(2) (Spring 2002): 105-115.
Gentil, E., Damgaard, A., Hauschild, M., Finneveden, G., Eriksson, O., Thorneloe, S., Kaplan, P., Barlaz,
M., Muller, O., Matsui, Y., Li, R., and Christensen, T. (2010). Models for waste life cycle
assessment: Review of technical assumptions. Waste Management, 30(2010), 2636-2648.
Hogue, C. (2013). Government Organization Summary Report: 2012, Government Division Briefs, US
Census Bureau. http://www2.census.gov/govs/cog/gl2_org.pdf accessed on July 5, 2015.
Jain, P., Townsend, T., Johnson, P. (2013) "Case study of landfill reclamation at a Florida landfill site."
Waste Management. 33(1): 109-116. doi:10.1007/sl2665-012-2054-8.
Jain, P., Powell, J., Smith, J., Townsend, T., and Tolaymat, T. (2014). Life-Cycle Inventory and Impact
Evaluation of Mining Municipal Solid Waste Landfills. Environmental Science & Technology,
2014, 48(5), 2920-2927, DOI: 10.1021/es404382s.
Jones, T.W. (2002). Using Contemporary Archaeology and Applied Anthropology to Understand Food
Loss in the American Food System. Bureau of Applied Research in Anthropology, University of
Arizona Tucson, AZ
Oregon DEQ (2014) 2013 Oregon Material Recovery and Waste Generation Rates Report. Environmental
Solutions Materials Management Program Oregon Department of Environmental Quality.
Sherman, S., (1996). Backyard Composting: Eight Case Studies. Applied Compost Consulting, Berkeley,
CA.
Tchobanoglous, G.; Kreith, F. (2002). Handbook of Solid EOL Materials Management, Second Edition.
McGraw Hill Inc.
Tchobanoglous, G.; Theisen, H.; Vigil, S. (1993). Integrated Solid EOL materials management-
Engineering Principles and Management Issues; McGraw-Hill Inc. 79, 293-294.
Townsend, T. (2011). Environmental issues and management strategies of waste electronic and electrical
equipment. Journal of Air & Waste Management Association, 61:587-610.
US EPA (1995). Decision-Maker's Guide to Solid EOL Materials Management, Volume II. EPA530-R-
95-023, August 1995. http://www.epa.gov/osw/nonhaz/municipal/dmg2/
US EPA (1996). New Source Performance Standards for Municipal Solid Waste Landfills. 40 CFR 60
Subpart WWW, 12 March 1996.
US EPA (2009). Sustainable Materials Management: The Road Ahead. EPA530R09009, June 2009.
https://www.fas.usda.gov/info/IATR/072011 Ethanol IATR.pdf.
US EPA (2012a). Sustainable and healthy communities. Strategic Research Action Plan 2012-
2016. Office of Research and Development, Sustainable and Healthy Communities, United States
Environmental Protection Agency, EPA 601/R-12/005, June 2012.
US EPA (2012b). Landfilling. WARM Version 12, Documentation. http://l.usa.gov/UyBqY4. Accessed
21 April 2014.
US EPA (2014/ Municipal Solid Waste Generation, Recycling, and Disposal in the United States: Facts
and Figures for 2012. EPA-530-F-14-001, February 2014.
-------
A Comparative Analysis ofLCA Tools Section 6 - References
USGS (1998). Materials Flow and Sustainability. USGS Fact Sheet FS-068-98, June 1998.
Winkler, J. and Bilitewski, B. (2007). Comparative Evaluation of Life Cycle Assessment Tools for Solid
EOL materials management. EOL Materials Management, 27: 1021-1031.
6-2
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A Comparative Analysis ofLCA Tools
Appendix A
Appendix A
Table A-l. Tool Descriptions and General Attributes
Attribute
Tool
Description
Developed by
Year
Developed
Year of latest
update
Availability
WARM
WARM can be used to
estimated GHG emissions
from various EOL
materials management
practices source
reduction, recycling,
combustion, composting,
and landfilling for a
variety of EOL materials
constituents. The tool
was created to help EOL
materials planners and
organizations track and
voluntarily report
greenhouse gas (GHG)
emissions reductions
associated with the EOL
materials management
options.
US EPA
First released in 1998.
Last updated June 2014
Online. Web-based
MSW-DST
This LCA tool is
designed to aid EOL
materials planners in
evaluating the economic
and environmental
aspects of integrated
MSW management
operations including
collection, transfer,
materials recovery,
composting, WTE, and
landfill disposal.
Developed by RTI, Inc.
under a contract from the
US EPA
2000
Current model released
June 20 15
Online
SWOLF
This tool is designed for
planners and researchers
for modeling the
economic and
environmental impacts of
EOL materials
management. It includes
collection, transport,
disposal, reuse, and
advanced treatments such
as AD, and gasification.
Department of Civil,
Construction, and
Environmental
Engineering at North
Carolina State University.
Unreleased
Unreleased
Unreleased. Will be
EASETECH
This tool is designed for
EOL materials planners
for evaluating LCA of
integrated EOL materials
management operations
including transportation,
composting, resource
recovery, and landfilling
based on resources
consumption and
environmental emissions
from these operations for
MSW.
Technical University of
Denmark (DTU)
EASE-WASTE was
released in 2008.
EASETECH began
development in 2010.
Current version (2.0.0,
Internal Institute Version)
released August 2014.
Must receive training at
WRATE
WRATE can be used for
LCA of integrated MSW
management operations
including collection,
transportation, materials
recovery and recycling,
composting,
combustion, AD, and
landfill disposal based
on resources
consumption and
environmental emissions
from these operations
for EOL materials.
Colder Associates (UL)
Ltd and ERM on behalf
of the Environment
Agency of England and
Wales (software owned
by Colder Associates)
First released in April
2007
Major update to the tool
occurred in 2010, most
recently updated in
March 20 14.
Online. Afterpayment
A-l
-------
A Comparative Analysis ofLCA Tools
Appendix A
Attribute
Is there a
trial version?
Cost
Prevalence of
Use
Training
User Support
Tools
WARM
calculator and Microsoft
Excel spreadsheet are
available on the US
EPA's webpage
Not applicable as the tool
is available online for
download for free.
Free
There are 300 users on
WARM update mailing
list. The US EPA has
been contacted by 250-
300 unique users in the
last 5 years.
Not available.
User guide and
documentation available
on tool's website;
provides detailed
information on the tool
and background
information on processes
and materials.
In the material tonnage
portion of the tool, the
user is alerted if mass
MSW-DST
None.
Unknown
Approximately 190
licenses (including 21 for
trial version) have been
distributed as of July 1,
2015
Serf -guided tutorials.
Walk through tutorial,
informational tips at the
top of each page of the
tool. User guide and
extensive documentation
are available on tool's
website.
Available documentation
primarily presents
background data used for
the tool.
SWOLF
available to the public
online.
No trial version, tool will
be free and available for
public download for non-
commercial purposes.
Expected to be free for
non-commercial uses.
There will be a royalty-
based fee for commercial
uses.
Unreleased
Developers expect to
release online video
lectures, and hold an
annual training session.
Unreleased. The
developers plan to release
a user's guide for each
module, online courses,
and in-person training.
EASETECH
DTU to receive a copy of
the program.
None.
Free for researchers,
5,000 for the course and
software for a
commercial license.
As of June 2015, 161
licenses have been issued
(31 license 1 for
commercial and 130 for
academic users)
5 -days mandatory
training course to receive
a copy of the tool.
Support from tool
developers (up to 5 hours
for commercial users).
EASETECH
Documentation Manual. 7
example training
exercises. Access to
additional tool versions as
they are released.
As part of the mandatory
training, users are taken
WRATE
the demo version can be
activated into the
Standard version.
Free demo with limited
functionality (e.g., only
allows five processes for
the entire system,
limited user-specified
inputs, inability save a
project or print the
report).
Standard version annual
license costs £ 1,400.
From 2008 through
20 13 there were 229
annual licenses
purchased.
One day of training
costs approximately
$560; variable training
options available on
request.
Electronic copy of user
manual, access to
training (subject to
additional fee), help
desk access (for users
that have attended
training), and "Help
contents" look up within
the tool.
The 264 page user
manual and the "Help
A-2
-------
A Comparative Analysis ofLCA Tools
Appendix A
Attribute
Number of
User Specific
Inputs (as an
indicator of
ease of use) -
assuming the
most
simplified
EOL
materials
management
scenario is
landfilling
System
requirements
WARM
balances are unequal for
the two scenarios being
compared. The tool
documentation provides
detailed explanation for
how the tool assesses
impacts.
The user must enter the
tonnage of material under
the appropriate
management method for
a baseline and a
comparative scenario of
material management.
The web-based tool
requires one of the
following browsers:
Firefox (version 3 or
higher), Chrome, Safari,
or Internet Explorer
(version 6 or higher).
MSW-DST
In the case of modeling
residential EOL
materials, the tool can be
run without any user
specific inputs since all
default values are
provided. If a second
residential stream or
commercial EOL
materials stream were to
be modeled, the
population, generation
rate (Ibs/person-day), and
collection points, or
density (people/house)
are necessary inputs. For
multi-family dwellings,
only the population and
generation rate are
needed.
There is no published list
of system requirements
for the current version of
MSW-DST. Past versions
requirements are:
Pentium II PC compatible
machine with at least a 16
GB hard drive, 5 12 of
SWOLF
The user must enter
tonnage and designate the
processes modeled.
Default values for all
processes are provided.
The version evaluated in
this report is not the final
version of the tool and
does not include a
published set of system
requirements. The version
evaluated runs on the
Microsoft Excel
EASETECH
through the example
exercises in order to gain
hands-on experience.
The user must enter the
tonnage of the material
handled in the modeling
scenario. Default values
can be used for all the
other parameters
However, the user must
create the specific EOL
materials management
scenario being modeled
by specifying material
flows through the
process(es) of interest.
The tool user manual and
documentation does not
provide a description of
the minimum system
requirements necessary.
Separate software
packages are provided for
32- and 64-bit operating
WRATE
contents" within the tool
both provide tool screen
captures, labels, and
descriptions on how to
operate the software and
set up and run scenarios.
The tool's built in error
detection calls attention
to and identifies errors
so the user can easily
troubleshoot.
At a minimum, the user
must enter the name of
the EOL materials flow,
EOL materials quantity,
number of EOL
materials containers, and
transportation distance
to the EOL materials
management/treatment
facility. The user must
specify material flows
through the process(es)
of interest, and
depending on the EOL
materials management
scenarios chosen there
may be additional user
inputs that must be
entered.
The tool was developed
to run on IBM PC
computers and under
Microsoft Windows 7,
the speed of the
microprocessor should
be at least 1 GHz with 1
GB of RAM, and a
A-3
-------
A Comparative Analysis ofLCA Tools
Appendix A
Attribute
WARM
The excel-based tool
(Version 13) requires the
Microsoft Excel
application version 2003,
2007, or 20 10.
MSW-DST
RAM, 400MZ processor.
Machines with less
memory or processing
capacity may be used but
will result in slower run
times for the MSW-DST.
SWOLF
application (believed to be
compatible with Excel
versions 97 and later).
EASETECH
systems.
WRATE
minimum of 100 MB of
hard drive space is
necessary to run the
software.
A-4
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A Comparative Analysis ofLCA Tools
Appendix A
Table A-2. Tool Documentations Details
Tool
Documentation
Thoroughness
of
documentation
Transparency
- Qualitative
Data
Transparency
-Quantitative
Data
Documentation
of degree of
WARM
Background data
clearly documented.
Twenty-nine (29)
(388 pages)
documents
describing the data
for individual
materials and
management
practices - available
on the US EPA
WARM website for
the user to review.
Data typically
derived from
process-specific
field data or
secondary research
of multiple similar
processes.
User can observe
and verify most
equations used to
determine modeling
results from
calculations
presented in tool
documentation.
Documentation
identifies partial or
MSW-DST
The most recently
updated version of the
tools background
documentation provides
a detailed explanation of
the tool's LCI
development; however,
there are instances when
the documentation is
inconsistent with the
current tool version.
Data typically derived
from process-specific
field data or secondary
research of multiple
similar processes.
User can observe and
verify most equations
used to determine
modeling results.
The documentation
acknowledges that
SWOLF
Unknown, the
documentation is not yet
available to evaluate.
Unknown, the
documentation is not yet
available to evaluate.
Unknown, the
documentation is not yet
available to evaluate.
The current spreadsheet
version makes all inputs
and assumptions visible,
and the final version is
expected to do the same.
Unknown, the
documentation is not yet
EASETECH
Data used are clearly
documented. Each process in
the tool program has a
documentation tab which
provides information on the
date the process was created,
the date it was updated, the
name of the process developer,
process data quality index
scores and descriptions, a
general technology description
and references to where the
data was obtained. However,
not all process documentation
tabs are complete. Additional
information on some of the
more complex processes is
found in the tool
documentation manual.
Data typically derived from
process-specific field data or
secondary research of multiple
similar processes.
User can observe and verify all
equations used to determine
modeling results. All processes
can be opened and the
equations and parameters
edited.
Each process has a
documentation tab which
WRATE
The background data are
clearly documented.
Information such as data
sources and contact
information, type of data
collected (e.g.,
averages), a data quality
indicator are viewable by
the user. Additional
background
documentation details on
the process, assumptions
made, calculations, and
references are available
for some processes.
There are some instances
when documentation is
not available due to
broken hyperlinks.
Data typically derived
from process-specific
field data or secondary
research of multiple
similar processes.
User can observe and
verify most equations
used to determine
modeling results.
A data quality indicator
associated with each
A-5
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A Comparative Analysis ofLCA Tools
Appendix A
Tool
Documentation
data
uncertainty
WARM
proxy data, if used.
Tool and
documentation do
not provide a
qualitative or
quantitative
measure of data
uncertainty.
MSW-DST
results are not 100%
precise. Tool and
documentation do not
provide a qualitative or
quantitative measure of
data uncertainty.
SWOLF
available to evaluate.
EASETECH
allows the provisions of data
quality indicators scores for
reliability, completeness,
temporal correlation,
geographic correlation and
technological correlation.
However, a significant number
of the processes do not include
data quality indicator scores.
WRATE
process is available in
WRATE. The indicator
is a visual bar that shows
the level of
completeness and quality
of the dataset.
A-6
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A Comparative Analysis ofLCA Tools
Appendix A
Table A-3. MSW Type Materials Included in Tool Scope
MSW Materials Included
WARM
MSW-DST
SWOLF
EASETECH
WRATE
Paper
Corrugated containers,
magazines/third-class mail,
newspaper, office paper,
phonebooks, textbooks,
mixed paper (general),
mixed paper (primarily
residential), mixed paper
(primarily from offices)
Newspaper, office paper,
corrugated cardboard, phone
books, books magazines,
third class mail, other paper
(#1-5), paper - non-
recyclable.
Corrugated cardboard,
newsprint, office paper,
magazines, office paper, 3rd
class mail, non-recyclable
paper, mixed paper, folding
containers,
paper bags
Newsprints, magazines,
advertisements, books/phone
books, office paper, other
clean paper, paper and carton
containers, dirty paper, dirty
cardboard, other clean
cardboard.
Paper and card: unspecified
paper, newspapers,
magazines, recyclable paper,
other paper, card packaging,
other card
Plastic
HOPE, LDPE, PET, LLDPE,
PP, PS, PVC, PLA, mixed
plastics
HOPE - translucent, HOPE -
pigmented,PET, other plastic
(#1-5), plastic, non-
recyclable
Film plastics, translucent
HOPE, pigmented HOPE,
PET containers, plastic -
non-recyclable, Plastic -
other #1 polypropylene
Soft plastic, plastic bottles,
hard plastic, non-recyclable
plastic, plastic products
(toys, hangers, pens).
Plastic film: unspecified
plastic film, bags, packaging
film, and other film plastics;
Dense plastic: unspecified
dense plastic, drinks bottles,
other bottles, other
packaging, other dense
plastic
Textiles
NA
NA
Textiles, rubber/leather
Textiles, shoes/leather
Unspecified textiles,
artificial textiles, natural
textiles
Metals
Aluminum cans, aluminum
ingot, steel cans, copper
wire, mixed metals
Ferrous metal: Ferrous cans,
ferrous metal, Ferrous - non-
recyclables
Aluminum: Aluminum,
other-aluminum (#1-2),
Aluminum - non-recyclable
Ferrous Cans, Ferrous Metal
- Other,, Aluminum Cans,
Aluminum - Foil, Aluminum
- Other, Ferrous - Non-
recyclable, Al - Non-
recyclable
Beverage cans (aluminum),
aluminum foil and
containers, food cans
(tinplate/steel), plastic-
coated aluminum foil, other
metals.
Ferrous metal: unspecified
ferrous metal, steel food and
drink cans, other ferrous
metal;
Non-ferrous metal:
unspecified non-ferrous
metal, aluminum drinks
cans, foil, other non-ferrous
metal
Glass
Glass
Glass - Clear, Glass -
Brown, Glass - Green, Glass
- non-recyclable.
Glass - Brown, Glass -
Green, Glass - Clear, Mixed
Glass, Glass - Non-
Clear glass, green glass,
brown glass, non-recyclable
glass.
Unspecified glass,
packaging, non-packaging
glass, green bottles, clear
A-7
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A Comparative Analysis ofLCA Tools
Appendix A
MSW Materials Included
WARM
MSW-DST
SWOLF
recyclable
EASETECH
WRATE
bottles, brown bottles, jars
Organics
Food scraps (non-meat),
grains, bread, fruits and
vegetables, dairy products,
yard trimmings, grass,
leaves, branches, mixed
organics
Yard waste: grass, leaves,
branches.
Food scraps
Yard Trimmings, Leaves;
Yard Trimmings, Grass;
Yard Trimmings, Branches;
Food scraps - Vegetable;
Food scraps - Non- Vegetable
Vegetable food scraps,
animal food scraps, yard
waste/flowers, animal
excrements and bedding
(straw), wood, many types of
garden waste.
Unspecified organic, garden
waste, food scraps, organic
pet bedding/litter, other
organics
Electronics
Personal computers
NA
E-waste
Batteries
Waste electrical and
electronic equipment:
Unspecified WEEE, white
goods, large electronic goods
(excluding CRT TVs and
monitors), CRT TVs and
monitors, other WEEE
Tires
Tires
NA
Rubber/Leather
Rubber
Non-MSW Waste: Tires,
Other
Mixed recyclables; mixed
MSW
Residential: Miscellaneous
combustible, Miscellaneous
non-combustible.
Commercial: Combustible
compostable recyclable,
Combustible Non-
compostable recyclable,
Non-combustible non-
compostable recyclable,
Combustible compostable
non-recyclable, combustible
non-compostable non-
recyclable, Non-Combustible
Non-compostable, non-
recyclable.
Misc. Organic, Misc.
Inorganic, wood, wood -
other, Diapers and tampons,
Aerobic Residual, Anaerobic
Residual, Bottom Ash, Fly
Ash
Milk cartons (carton/plastic),
Juice cartons (carton/ plastic
/aluminum), kitchen towels,
other combustibles, vacuum
cleaner bags, cigarette butts,
ceramics, cat litter, other
non-combustibles.
Absorbent hygiene products:
unspecified absorbent
hygiene products, disposable
nappies, other (sanpro and
dressings);
Combustibles: unspecified
combustibles, shoes,
furniture, other
combustibles;
Non-combustibles :
unspecified non-
combustibles, inorganic pet
litter, other non-
combustibles
Hazardous household waste
NA
NA
NA
NA
Specific hazardous
household: unspecified
hazardous household,
A-8
-------
A Comparative Analysis ofLCA Tools
Appendix A
MSW Materials Included
WARM
MSW-DST
SWOLF
EASETECH
WRATE
clinical waste, paint/varnish,
oil, garden herbicides and
pesticides
CDD Materials Included
Dimensional lumber,
medium-density fiberboard,
wood flooring, clay bricks,
concrete, drywall, asphalt
shingles, asphalt concrete,
fiberglass insulation, vinyl
flooring, carpet
NA
Wood, Wood Other
Wood, stones/concrete, soil,
small stuff (May -July garden
waste), garden
waste/soil/stones and foreign
objects, small stuff (Aug
garden waste), small stuff
(Sept-Apr garden waste),
branches, plants, grass and
leaves, tree, grass, (these
may also be considered as
MSW organics), stone
Wood (unspecified wood,
wood packaging, non-
packaging wood); non-
combustibles: bricks, blocks,
plaster (all one category),
fine material <10mm:
unspecified fine material;
non-combustibles: soil;
combustibles:
carpet/underlay
Other materials included
Industrial waste/ processed materials
Fly ash
No
Aerobic Residual, Anaerobic
Residual, Bottom Ash, Fly
Ash
Ash
Processed materials:
compost PAS 100, compost
APEX, home compost, other
compost, RDF, fiber,
stabilite, bottom ash, bottom
ash ferrous, bottom ash non-
ferrous, air pollution control
residue;
Non-MSW waste: waste oils,
wheat straw, meat and bone
meal, AWDF (rendered
hoofs, bones, blood, etc.),
untreated willow
Bio solids
No
No
Biowaste
Non-MSW waste: sewage
sludge (dry basis)
A-9
-------
A Comparative Analysis ofLCA Tools
Appendix A
Table A-4. US EPA (2014) Materials Composition with the Most Similar Category Found in Each LCA Tool
2012 US Facts and
Figures Category
Paper & paperboard
Nondurable
Newspaper/mechanical
papers
Books
Magazines
Office-type papers
Standard mail
Other commercial
printing
Tissue paper and towels
Paper plates and cups
Other non-packaging
paper
Disposable diaper tissue
Container & packaging
Corrugated boxes
Gable top/aseptic cartons
%
-
-
3.34
0.34
0.59
1.89
1.44
1.06
1.4
0.51
1.6
0.02
-
11.75
0.22
WARM
-
-
Newspaper
Textbooks
Magazines/3 rd
class mail
Office paper
Magazines/3 rd
class mail
Magazines/3 rd
class mail
Mixed papers
(primary
residential)
Mixed papers
(primary
residential)
Mixed papers
(general)
Mixed papers
(primary
residential)
-
Corrugated
containers
Mixed papers
(primary
residential)
DST
-
-
Newspaper
Books
Magazines
Office paper
3rd class mail
Magazines
Paper-
nonrecyclable
Paper-
nonrecyclable
Combustible
compostable
recyclables
(commercial
stream)
Paper-
nonrecyclable
-
Corrugated
cardboard
Combustible
compostable
recyclables
(commercial
stream)
SWOLF
Newsprint
Office paper
Magazines
Office paper
3rd class mail
3rd class mail
Non-recyclable
paper
Non-recyclable
paper
Mixed paper
Diapers and
sanitary products
Corrugated
cardboard
Folding containers
EASETECH
-
-
Newsprints
Books, phone
books
Magazines
Office paper
Advertisements
Magazines
Dirty paper
Dirty paper
Other clean paper
Diapers, sanitary
towels, tampons
-
Cardboard
Milk cartons
(carton/plastic)
WRATE
-
-
Newspapers
Other paper
Magazines
Recyclable paper
Other paper
Unspecified paper
Unspecified paper
Unspecified paper
Other paper
Disposable
nappies
-
Card packing
Unspecified paper
Recyclable
-
-
y
y
y
y
y
y
n
n
y
n
-
y
y
A-10
-------
A Comparative Analysis ofLCA Tools
Appendix A
2012 US Facts and
Figures Category
Folding cartons
Other paperboard
packaging
Bags and sacks
Other paper packaging
Glass
Durable goods
Container & packaging
Beer and soft drink
bottles
Wine and liquor bottles
Other bottles and jars
Metals
Durable goods
Ferrous metals
Aluminum
Lead
%
2.19
0.03
0.38
0.58
0.87
-
2.2
0.74
0.8
-
5.81
0.61
0.57
WARM
Mixed papers
(primary
residential)
Mixed papers
(general)
Mixed papers
(primary
residential)
Mixed papers
(general)
-
Glass
-
Glass
Glass
Glass
-
-
Steel cans
Aluminum ingot
Mixed metals
DST
Combustible
compostable
recyclables
(commercial
stream)
Combustible
compostable
recyclables
(commercial
stream)
Combustible
compostable
recyclables
(commercial
stream)
Combustible
compostable
recyclables
(commercial
stream)
-
Glass-clear
-
Glass-clear
Glass-clear
Glass-clear
-
-
Ferrous metal
Aluminum
Non-combustible
non-compostable
SWOLF
Folding containers
Mixed paper
Paper bags
Mixed paper
Glass-clear
Glass-clear
Glass-clear
Glass-clear
Ferrous metal -
other
Aluminum - other
E-waste
EASETECH
Milk cartons
(carton/plastic)
Other clean
cardboard
Other clean paper
Other clean
cardboard
-
Clear glass
-
Clear glass
Clear glass
Clear glass
-
-
Metal (non-
aluminum)
Beverage cans
(aluminum)
Other metals
WRATE
Unspecified paper
Other card
Unspecified paper
Other card
-
Non-packaging
glass
-
Clear bottles
Clear bottles
Jars
-
-
Unspecified
ferrous metal
Other non-ferrous
metal
Unspecified
ferrous metal
Recyclable
y
y
y
y
-
y
-
y
y
y
-
-
y
y
y
A-ll
-------
A Comparative Analysis ofLCA Tools
Appendix A
2012 US Facts and
Figures Category
Other nonferrous metals
Nondurable goods -
aluminum
Containers &
packaging
Steel-cans
Steel-other steel
packaging
Al-beer and soft drink
cans
Al-other cans
Foil and closures
Plastics
Durable goods
PET
HOPE
PVC
LDPE/LLDPE
PP
PS
%
0.23
0.08
-
0.74
0.15
0.52
0.05
0.18
-
0.14
0.49
0.09
0.79
1.56
0.28
WARM
Mixed metals
Aluminum ingot
-
Steel cans
Steel cans
Aluminum cans
Aluminum cans
Aluminum ingot
-
-
PET
HOPE
PVC
LDPE & LLDPE
(50/50)
PP
PS
DST
recyclable
(commercial
stream)
Non-combustible
non-compostable
recyclable
(commercial
stream)
Aluminum
-
Ferrous cans
Ferrous metal
Aluminum
Aluminum
Aluminum
-
-
PET
HOPE (50/50
translucent/pigmen
ted)
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
SWOLF
Aluminum non
ferrous
Aluminum - other
Ferrous cans
Ferrous cans
Aluminum cans
Aluminum cans
Aluminum - foil
Pet containers
HDPE-
translucent/pigme
nted
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic- other #1,
polypropylene
Plastic - non-
recyclable
EASETECH
Other metals
Beverage cans
(aluminum)
-
Food cans
(tinplate/steel)
Food cans
(tinplate/steel)
Beverage cans
(aluminum)
Beverage cans
(aluminum)
Aluminum foil
and containers
-
-
Hard plastic
Hard plastic
Hard plastic
Hard plastic
Hard plastic
Hard plastic
WRATE
Other non-ferrous
metal
Other non-ferrous
metal
-
Steel food and
drink cans
Other ferrous
metal
Aluminum drink
cans
Aluminum drink
cans
Foil
-
-
Other dense
plastic
Other dense
plastic
Other dense
plastic
Other dense
plastic
Other dense
plastic
Other dense
plastic
Recyclable
y
y
-
y
y
y
y
y
-
-
y
y
n
n
n
n
A-12
-------
A Comparative Analysis ofLCA Tools
Appendix A
2012 US Facts and
Figures Category
Other resins
Non-durable goods-
plates and cups
LDPE/LLDPE
PLA
PP
PS
Non-durable goods-
trash bags
HOPE
LDPE/LLDPE
Non-durable goods-all
others
PET
HOPE
PVC
LDPE/LLDPE
PLA
PP
PS
%
1.22
-
0.01
0.01
0.08
0.33
-
0.09
0.32
-
0.22
0.21
0.09
0.46
0.01
0.48
0.08
WARM
Mixed plastics
-
LDPE & LLDPE
(50/50)
PLA
PP
PS
-
HOPE
LDPE & LLDPE
(50/50)
-
PET
HOPE
PVC
LDPE & LLDPE
(50/50)
PLA
PP
PS
DST
Plastic
nonrecyclable
-
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
-
HOPE (50/50
translucent/pigmen
ted)
Plastic
nonrecyclable
-
PET
HOPE (50/50
translucent/pigmen
ted)
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
SWOLF
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic- other #1,
polypropylene
Plastic - non-
recyclable
Film plastics
Film plastics
PET containers
HDPE-
translucent/pigme
nted
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
EASETECH
Hard plastic
-
Hard plastic
Hard plastic
Hard plastic
Hard plastic
-
Soft plastic
Soft plastic
-
Hard plastic
Hard plastic
Hard plastic
Soft plastic
Hard plastic
Hard plastic
Hard plastic
WRATE
Other dense
plastic
-
Other dense
plastic
Other dense
plastic
Other dense
plastic
Other dense
plastic
-
Bags
Bags
-
Other dense
plastic
Other dense
plastic
Other dense
plastic
Other film plastic
Other dense
plastic
Other dense
plastic
Other dense
plastic
Recyclable
n
-
n
n
n
n
-
y
n
-
y
y
n
n
n
n
n
A-13
-------
A Comparative Analysis ofLCA Tools
Appendix A
2012 US Facts and
Figures Category
Other resins
Plastic containers &
packaging -bottles and
jars-PET
Plastic containers &
packaging - natural
bottles-HDPE
Plastic containers &
packaging-other
containers
HOPE
PVC
LDPE/LLDPE
PP
PS
Plastic containers &
packaging-bags, sacks,
wraps
HOPE
PVC
LDPE/LLDPE
PP
PS
%
0.22
1.11
0.31
-
0.56
0.02
0.02
0.11
0.03
-
0.28
0.02
0.91
0.26
0.06
WARM
Mixed plastics
PET
HOPE
-
HOPE
PVC
LDPE & LLDPE
(50/50)
PP
PS
-
HOPE
PVC
LDPE & LLDPE
(50/50)
PP
PS
DST
Plastic
nonrecyclable
PET
HOPE (50/50
translucent/pigmen
ted)
-
HOPE (50/50
translucent/pigmen
ted)
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
-
HOPE (50/50
translucent/pigmen
ted)
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
SWOLF
Plastic - non-
recyclable
PET containers
HDPE-
Translucent
HDPE-
translucent/pigme
nted
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Film plastics
Film plastics
Film plastics
Film plastics
Film plastics
EASETECH
Hard plastic
Plastic bottles
Plastic bottles
-
Hard plastic
Hard plastic
Soft plastic
Hard plastic
Hard plastic
-
Soft plastic
Soft plastic
Soft plastic
Soft plastic
Soft plastic
WRATE
Other dense
plastic
Drink bottles
Other bottles
-
Other packaging
Other packaging
Other packaging
Other packaging
Other packaging
-
Bags
Packaging film
Packaging film
Packaging film
Packaging film
Recyclable
n
y
y
-
y
n
n
n
n
-
y
n
n
n
n
A-14
-------
A Comparative Analysis ofLCA Tools
Appendix A
2012 US Facts and
Figures Category
Plastic containers &
packaging-other
packaging
PET
HOPE
PVC
LDPE/LLDPE
PLA
PP
PS
Other resins
Rubber and leather
Rubber in tires
Other durables
Clothing and footwear
Other nondurables
Textiles
Wood
Other
%
-
0.33
0.27
0.13
0.43
0
0.38
0.12
0.15
1.2
1.4
0.31
0.1
5.71
6.31
1.83
WARM
-
Pet
HOPE
PVC
LDPE & LLDPE
(50/50)
PLA
PP
PS
Mixed plastics
-
Tires
Carpet
Tires
Tires
Carpet
Dimensional
lumber
Tires
DST
-
Pet
HOPE (50/50
translucent/pigmen
ted)
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
Plastic
nonrecyclable
-
Miscellaneous
combustible
Miscellaneous
combustible
Miscellaneous
combustible
Miscellaneous
combustible
Miscellaneous
combustible
Combustible
compostable
recyclables
(commercial
stream)
Miscellaneous
combustible
SWOLF
Film plastics
Pet containers
HDPE-
translucent/pigme
nted
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Plastic - non-
recyclable
Rubber/leather
Rubber/leather
Rubber/leather
Rubber/leather
Textiles
Wood
Misc. Organic
EASETECH
-
Hard plastic
Hard plastic
Hard plastic
Soft plastic
Hard plastic
Hard plastic
Hard plastic
Hard plastic
-
Rubber
Combustible
Shoes, leather
Combustible
Textiles
Wood
Combustible
WRATE
-
Other packaging
Other packaging
Other packaging
Other packaging
Other packaging
Other packaging
Other packaging
Other packaging
-
Tyres
Carpet/underlay
Shoes
Other
combustibles
Unspecified
textiles
Unspecified wood
Other
combustibles
Recyclable
-
y
y
n
n
n
n
n
n
-
n
n
n
n
n
n
n
A-15
-------
A Comparative Analysis ofLCA Tools
Appendix A
2012 US Facts and
Figures Category
Other wastes-food
Other wastes-yard
trimmings
Other wastes-
miscellaneous
inorganics
%
14.52
13.54
1.55
WARM
Food scraps (non-
meat)
Yard trimmings
Clay bricks
DST
Food scraps
Grass, leaves &
branches
(50/30/20)
Miscellaneous non-
combustible
SWOLF
Food scraps -
vegetable & and
animal (90/10)
Yard trimmings -
leaves, grass,
branches
(50/30/20)
Misc. Inorganic
EASETECH
Vegetable food
scraps & animal
food scraps
(90/10)
Leaves and grass
& branches
(80/20)
Noncombustible
WRATE
Food scraps
Garden waste
Unspecified non-
combustibles
Recyclable
n
n
n
A-16
------- |