A Comparative Analysis of Life-Cycle Assessment Tools for End-of-Life Materials Management Systems
Jain, P., B. Dyson, T. M. Tolaymat, AND W. Ingwersen. A Comparative Analysis of Life-Cycle Assessment Tools for End-of-Life Materials Management Systems. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/232, 2015.
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 end-of-life (EOL) materials management options. The tools evaluated in this report are waste reduction mode (WARM), municipal solid waste-decision support tool (MSW-DST), solid waste optimization life-cycle framework (SWOLF), environmental assessment system for environmental technologies (EASETECH), and waste and resources assessment for the environment (WRATE). WARM, MSW-DST, and SWOLF were developed for US-specific materials management strategies, while WRATE and EASETECH were developed for European-specific conditions. 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 life-cycle assessment (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 material recovery facility (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 plastic,” “soft plastic,” or “drink bottles” in EASETECH while WARM allowed simulation of plastics by resin types similar to how EOL plastics are tracked for the municipal solid waste (MSW) stream in the US. While all of these tools 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 construction and demolition debris (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 greenhouse gas (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.