Energy recovery from municipal solid waste: a life cycle assessment approach

The aim of this study is the comparison of four different municipal solid waste (MSW) management scenarios: mechanical pre-treatment of a part of mixed MSW followed by biological stabilization of wet fraction and incineration of medium-high calorific value fraction in a waste-to-energy plant (scenario 1); direct waste-to-energy of total mixed MSW (scenario 2); mechanical pre-treatment of total mixed MSW followed by incineration of the low calorific value waste fraction in a waste-to-energy plant and co-combustion of the high calorific value waste fraction in a cement plant (scenario 3); mechanical pre-treatment of total mixed MSW followed by biological aerobic stabilization of the low calorific value fraction and co-combustion of high calorific value fraction in a cement plant (scenario 4). The evaluation and comparison of the four described scenarios was carried out applying Life Cycle Assessment (LCA) approach. Results showed that scenario 3 collects the highest number of best values in the following impact categories: acidification, eutrophication, heavy metals, energy resources and solid waste. Scenario 1 has the highest number of worst values for the environmental indicators, except for the Greenhouse effect, which has worst value in scenario 2 and the best value in scenario 4. Finally, the sensitivity of the results to the variation of some parameters assumed in the inventory analysis resulted in rather small changes in the indicator values and the overall scoring of the scenarios was not affected by such changes.