WORKING PAPER 2020-21 © 2020 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION SEPTEMBER 2020 The potential of liquid biofuels in reducing ship emissions Authors: Yuanrong Zhou, Nikita Pavlenko, Dan Rutherford, Ph.D., Liudmila Osipova, Ph.D., and Bryan Comer, Ph.D. Keywords: maritime shipping, International Maritime Organization, GHGs, alternative fuels, climate change, life-cycle assessment, biofuels SUMMARY This study explores the potential contribution from different biofuel pathways in achieving the emissions reduction targets set by the International Maritime Organization’s (IMO) initial greenhouse gas (GHG) strategy. We screen a variety of potential liquid alternative fuels based on qualitative criteria, assess the potential GHG and air-pollution benefits of key candidates compared with distillate bunker fuel, and then discuss the compatibility of these fuels with marine engines. We also consider other barriers to their use, including feedstock availability, cost, and competition with other sectors. Of the fuels and feedstocks assessed, we identified five liquid biofuels with the potential to reduce shipping GHG emissions on a well-to-wake, life-cycle basis relative to conventional, distillate marine fuels: 1. Fatty acid methyl ester (FAME) biodiesel produced from waste fats, oils, and greases (FOGs) 2. Hydrotreated renewable diesel produced from waste FOGs 3. Fischer-Tropsch (FT) diesel produced from lignocellulosic biomass 4. Dimethyl ether (DME) generated by gasifying lignocellulosic feedstocks followed by catalytic synthesis 5. Methanol generated by gasifying lignocellulosic feedstocks followed by catalytic synthesis Overall, we find that feedstock is more important than conversion technology in www.theicct.org determining a fuel pathway’s GHG reductions. Additionally, regardless of feedstock, all fuels investigated will reduce particulate air pollution, and this is primarily due to their
[email protected] low sulfur content relative to conventional marine fuels.