Great. People have figured out how to convert basic human organ function into electric energy. "The act of breathing-of moving the ribs to draw air into the lungs and expel it-can generate about a watt of power," according to an article by Henry Fountain in today's NYT Science Times. "And if the potato actually gets up off the couch and walks briskly across the room, each heel strike can produce even more power, about 70 watts' worth. That energy could be put to work, charging a cellphone, say, or a medical sensor in the body. The problem is how to harvest it."