The article explains briefly: fuel that is not from fossil sources. Essentially, organic waste converted to petrol-like hydrocarbons. Used frying oil from fast

The article explains briefly: fuel that is not from fossil sources. Essentially, organic waste converted to petrol-like hydrocarbons. Used frying oil from fast food is a large, consistent source. Ethanol from corn is also common in the US, but mostly for petrol meant for car. Not sure if there’s corn-based SAF but that would feel counter-productive (corn-based ethanol takes a lot of petrol to make). There seems to be issue with the relative portion of octanes, so it cannot be used in large portion in both car and aviation: I remember reading something about lead in petrol and “knocking”, ie the air-petrol mix exploding too early. I’m assuming that this engine handles that problem better, somehow. Given that lead is still in aviation gas, that would be beneficial in many ways.