No-one should ever drink and drive, but there may soon be a good reason to drink a lot before you fill up your car – researchers at Ohio University have worked out a way to efficiently extract hydrogen from urine. It could provide a cheap, renewable fuel source for vehicles and, finally, a good use for the most abundant waste on Earth.
The electrolytic system that Gerardine Botte and her team have developed is clever on a number of counts. It helps preserve ever-more precious supplies of fresh water while providing a means of cleaning up the effluent from sewage plants. The abundance of wee in the world makes large-scale production of hydrogen as fuel a more viable prospect. And, most importantly, it’s actually a lot easier and cheaper to extract hydrogen from pee than water.
The hydrogen atoms in urea – the main constituent of urine – are less tightly bonded than those in water. So much less power is needed to break the molecule apart. Botte developed a nickel-based electrode that efficiently oxidises urea with a voltage of just 0.37V, compared to the 1.23V needed to split water. Once the charge passes through it, pure hydrogen evolves at the cathode, with nitrogen and a trace of oxygen and hydrogen collecting at the anode.
It’s now just a matter of scaling up the technology, according to Botte. And working fast – urea’s biggest drawback is that it hydrolyses into ammonia very quickly.
And if the idea of a piss-powered car seems a little hard to accept, keep in mind that urine has a long and proud history of serving mankind. Aztec physicians used it to clean wounds. It’s been used in the manufacture of saltpetre for gunpowder. And, most famously, German alchemist Hennig Brand discovered phosphorus while trying to create the Philosopher’s Stone from urine. So, wheels that run on wee isn’t such a stretch.
See the Ohio University video here.