While I don’t see this powering the entire world as we know it any time soon this article is about some interesting research. Researchers at Case Western Reserve University have created an implantable biofuel cell that can provide power from an insect. The fuel cell is based around two enzymes reactions which break down sugars and ultimate release electrons.
Read the article for all the details on the testing and output measurements. I don’t know about you, but the thought of a cockroach with a tiny spy camera on its back kind of creeps me out.