SAF (sustainable aviation fuel)
Sustainable aviation fuel is jet fuel made from non-fossil feedstocks such as used cooking oil, agricultural waste or, eventually, captured carbon and green hydrogen. It is chemically similar enough to be blended with conventional kerosene, currently up to 50%, and needs no engine changes, cutting lifecycle CO2 by 60–80% depending on the pathway. Supply is tiny and it costs two to five times as much as regular fuel. In the EU the ReFuelEU regulation obliges fuel suppliers to blend 2% SAF from 2025 rising to 6% in 2030, and the UK has a similar mandate, so European charters already carry a small SAF cost. Operators sell voluntary SAF top-ups, often via book-and-claim.