Sustainable aviation fuel pathways: Emissions, costs and uncertainty

Abstract

Previous life cycle assessment (LCA) and techno-economic analysis (TEA) show significant variations in greenhouse gas (GHG) emissions and costs of sustainable aviation fuel (SAF). This study conducts a meta-analysis to examine uncertainty sources and their impacts on GHG and cost performances of various SAF pathways, using data harmonized for the U.S. context. Pathways include hydroprocessed esters and fatty acids (HEFA), Fischer–Tropsch (FT), bioenergy combined with carbon capture and storage (BECCS), alcohol-to-jet process (ATJ), pyrolysis, and power-to-liquid (PtL) with direct air capture (DAC). Harmonization reduced uncertainties for all SAF pathways except PtL-DAC, where the H₂ source is the main uncertainty. FT-BECCS, HEFA-UCO and PtL-DAC pathways show negative GHG emissions (−9.8 to −122.4 g CO_2eq/MJ), while pyrolysis and HEFA show lower costs (0.4–0.7 $/L) than fossil jet fuel (0.75 $/L). Background process data significantly influence GHG variability across all the pathways and mainly contribute to cost variability in HEFA (except HEFA-Tallow) and FT pathways, whereas foreground process data have larger or comparable impacts on cost variations in ATJ and PtL-DAC pathways. Eco-efficiency analysis reveals notable trade-offs among SAF pathways, with some HEFA pathways offering potential co-benefits.