An anonymous reader writes "The research team from southwest England have built a robot which can move and transmit sensor data over a radio link powered solely by unrefined food including dead flies and apples.
The robot, known as Ecobot II, uses a Microbial Fuel Cell as its only power source. By "digesting" its own fuel, the aircraft could become autonomous and operate without the need for refueling, changing batteries or recharging from the mains. In the Microbial Fuel Cell microbes are used to extract electricity directly from food - in this case flies or apple."
Several people noted this previous article
on the same project.