The cleaner option for energy production from a municipal solid biowaste

Abstract The environmental performances of four market-available thermochemical and biochemical processes for energy production from municipal solid biowaste have been compared by means of a combined utilisation of Life Cycle Assessment and Material Flow Analysis. The thermochemical options are those of co-combustion and co-gasification with an unsorted residual municipal waste. The biochemical options are those of anaerobic digestion, with energy cogeneration from the obtained biogas or biomethane. The production of 1 MJ of primary energy from the biowaste fed to these treatment plants has been assumed as the functional unit. The study identified the life cycle stages where a specific improvement can better contribute to a remarkable increase of the environmental performances of each of the examined energy production scenarios. A sensitivity analysis investigated the effect of the local electric energy mix, taking into account its evolution until 2030. The results indicate that anaerobic digestion is the biowaste-to-energy process with the best environmental performances, particularly when energy generation is obtained from the combustion of biomethane produced by biogas upgrading (with improvements up to 167% for Global Warming Potential and up to 107% for Non-Renewable Energy Potential).