Well for lack of a better place I composted this topic here where the fellow run all his power needs off methane and compost. I probably would work on you boat HKalan :-). THis is a vid back from the 70's. This guy was way before his time.
Well yeah, it would be under something like nature energy or something but don't have a catagory for that. THe bacterial farting making gas would be the wind:-), plants decomposing I guess would come under solar. I know a fellow here that gets his compost piles up to 85 degrees celcius. I think Jean Pain had green houses run on this stuff in the middle of a cold french winter.