Fuel cells are like batteries, sort of. Both use chemical reactions to produce electricity. The difference is that when a battery exhausts its reactants, it goes dead. In some cases, you can recharge it, but you typically get less energy back with each recharge. A fuel cell, on the other hand, will make electricity as long as you keep supplying fuel. What kind of fuel? Depends on the cell, but most often it is hydrogen or methanol.
Researchers at the University of Bath, Queen Mary University of London, and the Bristol Robotics Laboratory want to use a different fuel: urine. According to the researchers, that’s one resource we will never deplete. The fuel cell is a type of microbial fuel cell which is nothing new. The breakthrough is that the new cell is relatively inexpensive, using carbon cloth and titanium wire. Titanium isn’t usually something you think of as cheap, until you realize that conventional cells usually use platinum.