Urea -- look at all those loosely bound hydrogen atoms! (© iStockphoto.com/theasis)

Humans produce 10 billion liters of urine every day, according to New Scientist. That’s a lot of raw material with which to power the world. So much in fact, that whatever power-producing process finds the best way to do it won’t even have to be that efficient. After all, we’re not talking about heading to the moon to mine He-3; there will always be more urine in the world tomorrow.

That ultra-renewable quality of the waste product first appealed to Gerardine Botte, a chemical engineer at Ohio University in Athens, in 2002. Botte was trying to think up sources of hydrogen to use in fuel cells, since hydrogen from fossil fuels is difficult to manage and hydrogen derived from water is too energy-intensive to make it worthwhile. But while water contains only two tightly bound hydrogen atoms, the urea in urine contains four loosely bonded hydrogen atoms, making the hydrogen separation process more efficient. Using an electrolytic cell with nickel-based electrodes, Botte was able to cut the 1.23 volts needed to split water down to only 0.37 volts for urea.

Chemist Shanwen Tao has taken a different track — using urine as the fuel itself, negating the need to break urea into hydrogen atoms. Again according to New Scientist, Tao’s fuel cell works something like this: A small cathode surrounded by water and air generates hydroxide ions, which are attracted to an anode. Once they’re there, the ions react with urea to make nitrogen, carbon dioxide and water — plus electrons that travel back to the cathode via an external circuit. There you go: a current powered by pee that Tao hopes could eventually run small devices like a radio. Imagine the possibilities of scaling up.

You can keep up with Stuff from the Science Lab through the official Facebook and Twitter feeds, or with me by following Stuff You Missed in History Class on Facebook and Twitter.