If the poo-powered car doesn’t take things quite far enough for your, how does the pee-powered office sound? Far-fetched? Well, scientists think that pee could be the power source of the future.
According to coverage of the discovery in New Scientist, the secret comes from not actually using the pee directly: as with the poo-powered car, which uses bio-gas or methane produced from the decomposition of the waste, the idea of using urine as an energy source comes from harvesting the hydrogen contained within for use in fuel cells.
A team of scientists, lead by Gerardine Botte, have discovered that urea – the waste product in urine that stops it being plain old water – makes it significantly easier to ‘crack’ into hydrogen and oxygen than straight water.
Urea is comprised of four hydrogen atoms loosely bonded together, and accounts for around two percent of your urine by volume. Because the hydrogen atoms in urea are less strongly bonded than those in water, it requires less power to split them apart – meaning that the hydrogen can be harvested for significantly less energy investment than traditional water-based systems.
The energy requirement for hydrogen cracking has long prevented the technology from taking off: current small-scale systems for cracking water into hydrogen and oxygen require as much energy to perform the process as the hydrogen grants to the fuel cell, turning the equation into nothing more than a complicated battery.
By harvesting the hydrogen in urea, however, the scientists have been able to reduce the energy requirement from 1.23V to just 0.37V – meaning the dawn of the cheap hydrogen fuel cell could be upon us. By harvesting the waste urine from a 300-person office building, Botte theorizes that around 2 kilowatts of power could be generated – multiplied by larger offices, that’s a significant amount of power.
Another team of scientists, based at Heriot-Watt University in the UK and lead by chemist Shanwen Tao, have developed a method of using the urine directly within the fuel cell, generating hydrogen on the fly without the need for external power. Although the energy generated is currently minuscule, the team hope to be able to produce a commercially viable high-powered version in the near future – although convincing people to pee in their cellphone could be more of a challenge.
One thing is for certain: the future looks to have a certain yellowy tinge.
