Our municipal sewage plant generates its own electricity using methane. They told me they generate enough that they don’t have to buy power except from a black start.
And from what I recall a major city we did work in was doing the same thing. This isn’t unusual I don’t think. The methane is generated anyway as you treat the waste so its just a matter of capturing it and burning it in an engine which drives a generator.
This would be cool in a vehicle. A turd powered F250 Super Doody.