Life cycle sustainability assessment of synthetic fuels from date palm waste

The use of biowaste feedstock is often suggested for sustainable production of synthetic fuels through gasification followed by the Fischer-Tropsch process. While the technical performance of this type of bioenergy system has significantly been investigated, comprehensive sustainability analyses are still required. The present study evaluates the life cycle sustainability performance of synthetic diesel and gasoline from Tunisian date palm waste, and compares it with that of conventional fossil fuels. Life cycle inventories are elaborated to subsequently characterise the performance of the synthetic biofuels under a set of 12 environmental, economic and social indicators. Both environmental and economic hotspots were found to be associated with the need for electricity and oxygen. Direct emissions to the air and the investment in the plant's power section were also found to significantly affect the environmental and economic performances, respectively. Potential social impacts were found to be mainly linked to the supply chain of equipment and infrastructure, while electricity arose as the most contributing operational element. Overall, the evaluated synthetic biofuels could be considered competitive with conventional fossil fuels and contribute to the achievement of sustainable development goals only if environmentally- and socially-friendly (renewable) electricity and oxygen sources are implemented and the scale and configuration of the plant are optimised.