National Geographic: A new fuel cell is putting a twist on alternative energy from biofuels: The implanted device draws power from chemicals in living animals. Dubbed a glucose biofuel cell, the implant gets its juice from glucose–aka blood sugar–and oxygen, both of which are naturally present in the fluids between a body’s cells. In a recent study, researchers created a test version of their glucose biofuel cell and implanted it in a white lab rat named Ricky. The rat sported the device …