I doubt the military would endorse a 'body eating' robot. Right now we frown upon the desecration of human remains, so this would obviously be out of the question. And keeping a bio mass engine up and running sounds like a pain in the ass, but I'd take a generator setup, got a lot of feral hogs I could use. This also sounds close to one doomsday theory involving, nano robots, or others, that consume everything available in order to sustain and reproduce themselves. Eventually consuming near all carbon based items on the planet. I believe its called 'gray goo' theory.