Pee Power: Urine Isn't Just "Waste," It's Useful Energy and Possibly Car Fuel

Dr. Geraldine Botte (center) with colleagues: waste power. (Ohio University)

I have built something of a specialty here at The Daily Green in writing about weird fuels. Well, sometimes the fuels themselves aren't that strange, but the source material -- from chicken feathers to used diapers, methane from cows, coffee grounds and sawdust -- certainly is.

I'm sure you were waiting for this one: hydrogen from urine, at a cost much lower than extracting it from water. Urine is, after all, the biggest waste product on Earth, produced by animals as well as humans. And disposing of it -- from factory farms as well as sewage plants -- is a big headache. So why not? Gas from the world's ubiquitous cows (a/k/a methane) is already generating electricity in Vermont, and we use pregnant mares' urine to treat menopausal women. Composting toilets are enjoying a hey day too.

The basic idea here is time-honored electrolysis. It works like this: A molecule of urea (a big part of urine) has four atoms of hydrogen and two of nitrogen. Messy and smelly as it might be, you can attach a nickel electrode to your basic urine pool and produce hydrogen gas to power the world's fuel cells. Farms could double as energy generators: Unlike us, cows and pigs don't move around so much (especially when they're factory farmed) so the urine is easy to collect.

Professor Geraldine Botte of Ohio University is working on the technology in miniature, but thinks it could be scaled up for commercial applications. According to a Discovery account, "A fuel cell, urine-powered vehicle could theoretically travel 90 miles per gallon. A refrigerator-sized unit could produce one kilowatt of energy for about $5,000 [a rough estimate]."

See Professor Botte talk about her work in this video:

Professor Botte's research, with Bryan Boggs and Rebecca King, was described in the Royal Society of Chemistry's Chemistry Communications. It's not that difficult to understand: "[T]he direct conversion of urine and urea to pure hydrogen via electrochemical oxidation with an inexpensive nickel catalyst." The process is not exactly arcane, just the unusual "feedstock."

On the telephone, the Venezuelan-born Professor Botte was charming and not without humor about the media deluge that produced a lot of amusing headlines. "They all talked about the ‘pee car,' but I wish we humans produced enough urine to run a whole car. Maybe we could run some minor applications, like the car stereo or something like that." We could run a car on ammonia, but let's leave that to another article.

Discovery's evocation of a car getting 90 mpg on pee is somewhat optimistic. The ideal application, Botte says, is a dairy farm, where cow waste is collected in giant lagoons that present a significant treatment and disposal problem (as well as a huge environmental problem and a big bottom-line cost). "Our research suggests you could provide hot water for 19 homes from a farm-based electrolyzer making hydrogen gas," she said. "And you can also provide heat and some electric power."

Once the urea is removed from the waste pool, Botte said, the farm is left with water that is significantly less polluted than it was, with irrigation as one possible use. Why didn't we think of this before? It's not like we have to take urine from the other vital missions it's performing for us. I'm ready to put a "urine power" bumper sticker on my car. Are you?

And from Popular Mechanics, Why Water Won't Improve Your MPG.