Environmental and economic assessment of producing hydroprocessed jet and diesel fuel from waste oils and tallow

Animal fats and waste oils are potential feedstocks for producing hydroprocessed esters and fatty acids (HEFA) jet and diesel fuels. This paper calculates the lifecycle greenhouse gas (GHG) emissions and production costs associated with HEFA jet and diesel fuels from tallow, and from yellow grease (YG) derived from used cooking oil. For YG, total CO2 equivalent (CO2 eq.) GHG emissions of jet and diesel were found to range between 16.8-21.4 g MJ−1 and 12.2-16.9 g MJ−1 respectively. This corresponds to lifecycle GHG emission reductions of 76-81% and 81-86% respectively, compared to their conventional counterparts. Two different system boundaries were considered for tallow-derived HEFA fuels. In System 1 (S1), tallow was treated as a by-product of the rendering industry, and emissions from rendering and fuel production were included. In System 2 (S2), tallow was considered as a by-product of the meat production industry, and in addition to the S1 emissions, cattle husbandry and slaughtering were also included. The lifecycle emissions (CO2 eq.) from HEFA jet fuel for S1 and S2 were estimated to be 25.7-37.5 g MJ−1 and 67.1-83.9 g MJ−1 respectively. HEFA diesel lifecycle emissions were found to be 21.3-33.3 g MJ−1 for S1 and 63.4-80.5 g MJ−1 for S2. Production costs for these fuels were calculated using a discounted cash flow rate of return model. The minimum selling price was estimated to be 880 $ m−3-1060 $ m−3 for YG-derived HEFA, and 1050-1250 $ m−3 for tallow-derived HEFA fuels.