Comparative LCA of two approaches with different emphasis on energy or material recovery for a municipal solid waste management system in Gipuzkoa

Two alternative approaches for an integrated municipal solid waste management system (MSW-MS) have been confronted in the province of Gipuzkoa, in the north of Spain, during the last decade. While one of them prioritizes energy recovery from mixed residual waste in an incineration plant, the other approach gives precedence to material recovery of separately collected waste. Which system would present a lower environmental impact and be more desirable from a sustainability perspective? Answering this question is hindered by the fact that recovered energy and materials are not directly comparable or directly substitutable with each other. Based on the powerful framework provided by life cycle assessment (LCA) methodology, this work performs a comparative LCA of overall environmental impacts of these two alternative approaches, showing that comparisons of alternative systems in terms of direct energy recovery or direct material recovery should be avoided in favor of other indicators already proposed in the LCA framework, such as the Cumulative Energy Demand category from Ecoinvent, or the global warming potential and the Abiotic Resources Depletion categories from the CML 2001 method. Applying the LCA framework, this work shows that when a high share of waste is collected separately, and processes assumed in the background system are adequately characterized, especially the production of the electricity mix, then prioritizing material recovery provides better results even in environmental categories tightly related to fossil energy consumption, such as the global warming potential impact category. (C) 2015 Elsevier Ltd. All rights reserved.