Abstract:This paper reviews literature on technological, market, and policy factors affecting the growth of alternative aviation fuels. At present, they represent a minimal fraction of global aviation fuel used but are a critical tool for lowering GHG emissions from aviation. Even with electric and hydrogen power, substantial volumes of low-carbon liquid fuels are likely needed; these will draw heavily on biomass. Beyond hydroprocessed esters and fatty acid (HEFA) fuels, technologies, including lower carbon e-fuels, remain pre-commercial. More jurisdictions are providing incentives for alternative aviation fuel, and some on-road biofuels may be redirected towards aviation in a favorable market, because production processes for these fuels overlap. Biomass feedstocks at different demand levels need to be sourced and evaluated for unintended impacts. Research suggests alternative aviation fuels improve air quality impacts compared to conventional jet fuel. Key uncertainties in scaling alternative jet fuel remain, including ongoing concerns about land use change from biofuels, how to right-size incentives with no technology clearly dominant, what the long-term carbon budget is for aviation, and how to build fuel delivery infrastructure.