Sorry for being a smarty pants. Actually Solar, wind, steam are all valid.
Do look up info on the bicycle generated stuff. I have a couple websites on this and will look them up,
The bike is attached to an alternator (car type) which in turns generates the battery. I wanted a couple of these especially in an bunker/shelter situation as a form of pragmatic energy producing exercise. Also attach to treadmills . . . which could also serve to exercise your dog!
