Towards Net-Zero Aviation: A Critical Review of Sustainable Aviation Fuel Pathways and Scale-Up Constraints

Abstract

Aviation is one of the most difficult sectors to decarbonize because long-range flight still depends on high-energy-density liquid fuels. Sustainable aviation fuel (SAF) has therefore emerged as the principal near-term decarbonization option, but its real climate value depends on feedstock origin, conversion route, energy inputs, and deployment scale. This review synthesizes the state of knowledge on the major SAF pathways—including hydroprocessed esters and fatty acids (HEFA), Fischer–Tropsch (FT), alcohol-to-jet (ATJ), and power-to-liquid (PtL)—and compares their feedstocks, fuel yields, lifecycle greenhouse gas performance, production costs, certification status, and infrastructure readiness. Particular attention is given to the trade-offs among technological maturity, resource availability, land and water pressures, hydrogen demand, and electricity carbon intensity. The analysis also examines how policy instruments such as CORSIA and regional blending mandates shape investment signals and market formation. The review shows that no single pathway can satisfy future aviation demand on its own: mature lipid-based routes can support near-term growth, whereas deep long-term decarbonization will require large-scale expansion of residue-based and synthetic fuels. Progress in certification, feedstock governance, and industrial scale-up will be decisive for meaningful SAF penetration