A screening life cycle metric to benchmark the environmental sustainability of waste management systems.

The disposal of municipal solid waste (MSW) can lead to significant environmental burdens. The implementation of effective waste management practices, however, requires the ability to benchmark alternative systems from an environmental sustainability perspective. Existing metrics--such as recycling and generation rates, or the emissions of individual pollutants--often are not goal-oriented, are not readily comparable, and may not provide insight into the most effective options for improvement. Life cycle assessment (LCA) is an effective approach to quantify and compare systems, but full LCA comparisons typically involve significant expenditure of resources and time. In this work we develop a metric called the Resource Conservation Efficiency (RCE) that is based on a screening-LCA approach, and that can be used to rapidly and effectively benchmark (on a screening level) the ecological sustainability of waste management practices across multiple locations. We first demonstrate that this measure is an effective proxy by comparing RCE results with existing LCA inventory and impact assessment methods. We then demonstrate the use of the RCE metric by benchmarking the sustainability of waste management practices in two U.S. cities: San Francisco and Honolulu. The results show that while San Francisco does an excellent job recovering recyclable materials, adding a waste to energy (WTE) facility to their infrastructure would most beneficially impact the environmental performance of their waste management system. Honolulu would achieve the greatest gains by increasing the capture of easily recycled materials not currently being recovered. Overall results also highlight how the RCE metric may be used to provide insight into effective actions cities can take to boost the environmental performance of their waste management practices.