Peepee Power

There's a terrific new article in New Scientist about some of the ways scientists are working on turning pee into energy. There's a lot of pee in the world all going to waste, often at huge cost to the environment in terms of energy used to collect and purify waste water. Methods that can produce even small amounts of power from urine could be useful to help power office buildings or farms where there are a lot of people or animals all peeing in the same place, and smaller fuel cells could even also be used to power portable electronics, with no need to carry any fuel or batteries, just a water bottle.

There are three such methods discussed in the article, distinguished by their distance from the source. The urea in pee can be used to directly power a fuel cell, reacting at the anode with the hydroxide ions generated at the cathode. According to the scientists developing the technology, "an adult produces enough urine each year to drive a car 2700 kilometres on energy from the urea it contains." The urea in pee also makes electrolysis--the process by which electricity splits water molecules to produce hydrogen gas--more efficient, requiring a smaller electricity input to produce the same amount of hydrogen. Rather than using the urea directly, the hydrogen gas produced can be use to power other fuel cells. A third method doesn't need concentrated urine at all, but uses waste water streams to power fuel cells where bacteria produce the electricity. Metabolism requires a way to get rid of extra electrons and in organisms that breath air, oxygen takes the extra electrons, producing water. Many anaerobic organisms instead "breath" metal, putting their extra electrons generated from metabolizing the chemicals in waste water straight onto an electrode and producing electricity in microbial fuel cells.

As someone who has spent a lot of time thinking about how to produce hydrogen fuel from biological sources, I'm totally fascinated by this new take on "bioenergy." There is a lot of potential for capturing and converting some of our personal and industrial wastes into usable sources of energy, personalizing our energy sources depending on what is available and what is most efficient:

No one claims that urine will ever be the complete answer to our energy needs, but Botte argues that the more sources we have for our energy, the better. "We have gigantic energy needs. We are talking billions of megawatt-hours each year in the US alone," she says. "Trying to find one solution is not the answer. There is room for many technologies with different market shares."

There's not going to one magic fix to our energy needs, but biology and biological engineering can help us in reducing our inputs as well as reusing some of our outputs.

via NewScientist