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 commodities.

(The economics work out at restaurant scale but not necessarily at household scale. If you deep fry a lot at home, you might be responsible for transporting your own grease to someone who wants it.)