The impending restrictions on the sulfur content and greenhouse gas emissions of marine fuels represent a challenge for the maritime shipping industry and an opportunity for alternative fuels that may have lower environmental impacts but are not currently economically competitive. This study developed an integrated screening model to compare the technological, economic, and environmental performance of 33 “drop-in” marine biofuel blendstock supply chains, considering nine agroforestry residues and three thermochemical technologies. The biofuel production was modeled for 500 tonne per day “first-of-a-kind” biorefineries to reflect near-term production. Supply chains were modeled for biofuel production in both Brazil and Sweden to explore the impact of regional differences on the biofuels’ break-even prices and their life cycle emissions of greenhouse gases, SO2, and NOX. This study indicates that in the immediate term, marine biofuels from lignocellulosic feedstocks may have a minimum fuel selling price three or more times higher than current fossil marine fuel prices. Biofuels made from agricultural residues saw a 40–100 kg/GJ decrease in life cycle GHG emissions, but forestry residue emissions depended highly on biogenic carbon dioxide accounting. SO2, and NOX emissions were dominated primarily by combustion, which for SO2 were estimated to be much lower than fossil fuels, due to the negligible sulfur content of the biomass. Overall, no single biofuel was a clear winner in terms of economic and environmental performance in the model, but space is opened for deeper research, as the new regulations come into effect.
