Sustainable aviation fuel (SAF)
Drop-in jet fuel made from biomass, waste or captured carbon and hydrogen, certified to blend with fossil Jet A-1 and cut lifecycle emissions.
SAF must meet ASTM D7566, after which it is treated as conventional jet fuel. Eleven production pathways are approved, with blend limits of up to 50% today (100% SAF flights have been demonstrated). Main routes:
- HEFA: hydroprocessed esters and fatty acids from used cooking oil, tallow and vegetable oils; more than 90% of current supply but feedstock-limited.
- Alcohol-to-jet: from ethanol or isobutanol.
- Gasification + Fischer-Tropsch: from municipal solid waste or forestry residues.
- Power-to-liquid: synthetic kerosene from green hydrogen and captured CO2, a type of e-fuel.
Lifecycle reductions are 50–90% versus fossil jet fuel (CORSIA default values). SAF production was about 1 Mt in 2024, roughly 0.3% of global jet fuel demand (IATA), at prices 2–3 times fossil kerosene for HEFA and 4–8 times for power-to-liquid.
The EU ReFuelEU Aviation regulation mandates SAF shares at EU airports of 2% in 2025, 6% in 2030 (including 1.2% synthetic fuels), 20% in 2035 and 70% in 2050. The UK mandate starts at 2% in 2025 rising to 22% in 2040. In the US, tax credits under the Inflation Reduction Act and its successors support production.
Related terms
All terms →- Biofuel
A liquid or gaseous fuel derived from biomass, such as ethanol, biodiesel or renewable diesel, used mainly in transport to replace petroleum fuels.
- E-fuels (power-to-X)
Synthetic fuels made from electrolytic hydrogen, sometimes combined with captured CO2 or nitrogen, such as e-methane, e-methanol, e-kerosene and e-ammonia.
- Green hydrogen
Hydrogen produced by splitting water in an electrolyser powered by renewable electricity, with near-zero direct CO2 emissions.
- Direct air capture (DAC)
Engineered systems that extract CO2 directly from ambient air using chemical sorbents or solvents, producing a concentrated stream for storage or use.
- Lifecycle emissions
Total greenhouse gas emissions of a product or power source across its full life, from raw material extraction and manufacturing through operation to decommissioning.