Pee-power toilet to light up disaster zones
By Matthew Stock A toilet that uses urine to generate electricity will soon light up dark corners of refugee camps after being tested by students in the UK. The pioneering toilet, the result of collaboration between global aid agency Oxfam and the University of the West of England in Bristol, uses live microbes which feed on urine and convert it into power. Led by Professor Ioannis Ieropoulos, the scientists developed microbial fuel cells that use bacteria grown on carbon fiber anodes that feed on urine, breaking it down and generating electricity which is stored in a capacitor. They used up to 24 of these microbial fuel cells in 2013 to prove that urine could produce enough electricity to power a mobile phone. For the pee-power toilet they are using 288 fuel cells, though a thousand-unit cell stack is planned for the next version of the device. Ieropoulos believes it's the abundant, free supply of urine that makes the pee-power toilet so practical for aid agencies to use in the field. "We were challenged by Oxfam to think about lighting urinals that they would use in refugee camps. So this is the result of that conversation. And it's basically a live trial to demonstrate the microbial fuel cell technology over a long period of time; how it can continuously generate electricity from urine in real time," he said. The prototype cubicle resembles toilets used in refugee camps by Oxfam to make the trial as realistic as possible. The microbial fuel cells that convert the urine into power are stacked underneath the urinal and can be viewed through a clear screen. Conveniently located near the University of the West of England's student bar, the toilet was successfully tested by students who found it produced enough electricity to power four LED light bulbs in the cubicle. Ieropoulos even theorized that the student's urine could prove particularly potent: "We're hoping to see some improved performances from people coming out of the bar after the consumption of certain beverages. But we have seen, at least in the lab, we have seen that there is a difference between the morning sample compared to the later in the day sample, because it's more concentrated." The experiments in Bristol began about 14 years ago. In that time the harvesting of electricity from urine has advanced rapidly through several generations of microbial fuel cells. The latest models use ceramic cylinders with a continuous stream of urine passing through them, with the electricity collected by an energy harvesting board. "Traditionally in the microbial fuel cell we would have two half cells and a membrane separating the two cells. In this case, the microbial fuel cell chassis and membrane is the ceramic material. So the outside is the bacterial anode, or the negative terminal of the fuel cell; and the inside is the positive cathode. The ceramic is there to allow to exist as a microbial fuel cell, but also to allow ions to flow through from the anode to the cathode," explained Ieropoulos, adding that it's the continuous cascade of urine through a series of fuel cells that keeps up the electricity production by constantly 'feeding' the bacteria. Andy Bastable, head of water and sanitation at Oxfam, said the pee-power toilet could vastly improve women's safety in deprived countries that often have poorly lit sanitation zones. "By lighting bits of the camp using this technology we can create a safe environment so that women can go out, use the toilets at night, do things at night in a safer environment," he said. Oxfam hopes to have the first toilet sent out to a refugee camp within the next six months, and after testing will be rolled out more widely, initially in camps, but possibly also in other places without electricity. "This urine bio-fuel cell technology could be used for many things, such as charging mobiles phones, any applications involving low electricity current like dosing pumps. It could be used outside of the camp environment; in any poor community that doesn't have electricity at night it would be a game-changer for them," added Bastable.
