Another stupid part of this: used cooking grease has positive market value! Quite a few companies, even in expensive places like Palo Alto, will happily supply you, for free, with barrels and such to hold your grease, and they'll come empty them when they're full, and I think you can even often negotiate to get paid to give these companies your grease. It gets recycled into various non-tasty but still useful commodit…
In the old days people would convert diesel trucks and cars to run on "biodiesel" which was lightly processed used cooking oil. You could tell who did that because their cars always smelled like french fries.
No.
Biodiesel is fuel made directly from vegetable matter; typically it needs a ""special"" engine to run, or is blended in a low ratio with ordinary diesel (B7 in the UK and EU).
Processed cooking oil is made into HVO.
This can be used as a direct 1:1 replacement for ordinary diesel without engine modifications. Very green! Unsurprisingly, HVO has a higher price than biodiesel.
https://en.wikipedia.org/wiki/Hydrotreated_vegetable_oil
HVO is easily available in the UK and is typically bought by bus companies and delivery companies seeking to improve their green footprint.