If you’re a tinkerer, you can run an engine with lots of different “junk” fuels. Used motor oil, antifreeze (GEET) wood chips/scraps (gasifier) methane from a digester.
The captured exhaust heat can also make hot water.
hah...the LAST thing I am is a tinkerer....my brain is not normal, many things are easy to me that are hard or impossible to others, but some things that are easy to many others...like any kind of mechanical tinkering - or slalom skiing - vex me to no end.