Life cycle assessment applied to biofuels from sewage sludge: definition of system boundaries and scenarios

Europe is heavily dependent on imported oil for its mobility and transport. High population densities and an increase in sewage treatment facilities have resulted in a large increase in sludge production volumes in Europe and, consequently, disposal problems. The Demonstration of Waste Biomass to Synthetic Fuels and Green Hydrogen project, acronym TO-SYN-FUEL, aims to provide satisfactory answers to both of these environmental issues. The project implements a new integrated process to produce a fully equivalent gasoline and diesel substitute starting from sewage sludge. A Life Cycle Assessment will be performed in order to evaluate the environmental performances of the new integrated process to produce biofuels. This paper illustrates the process that has led the authors to define the LCA goal and scope considering both the feedstock and the end product point of view.