A Microbial Fuel Cell stack prototype continuously produced electricity from human urine over a period of eight months powering four LED lights fitted within a previously unlit communal ablution block.
A group of researchers from the Bristol BioEnergy Centre at the University of West England (UWE Bristol) developed the technology for deriving biological electricity from human urine through the Pee Power® mini-plant, created as part of the international Reinvent the Toilet Challenge championed by the Bill & Melinda Gates Foundation.
The mini-plant prototype, consisting of a bank (stack) of microbial fuel cells, was installed at an informal settlement accommodating more than 2 000 people in Durban last year, generating what the team terms “urine-tricity” – direct electric power from urine collected from the urinal stands which successfully lit up the communal ablution block.
Microbial fuel cells contain microorganisms that break down organic material in urine and as a result produce electrical energy. The devices have positive and negative terminals like regular batteries, but unlike lead-acid batteries, their energy production does not get depleted as long as the organisms have a source of waste to decompose – this could be urine or another source of organic waste.
Pee Power developers at the Bristol BioEnergy Centre also hope it will play a role in purifying polluted wastewater flowing into rivers around the world, and that it can be scaled up from its current prototype design to units which could generate even more electricity. They envision this technology being deployed throughout the developed and developing world as a source of free off-grid electricity and wastewater treatment. If connected to wastewater treatment plants, the effluent by-product could be used for the production of biofertiliser, and the cells could also be used on a smaller scale by homeowners to treat wastewater and produce electricity in their backyards.
The device was trialled at the Glastonbury Festival in the United Kingdom and at two schools in Kenya and Uganda. Its development has been funded by the Gates Foundation, United Kingdom’s Engineering and Physical Sciences Research Council (EPSRC) and the European Union.
At the Durban testing site, the aim was to use a smaller prototype plant than had been previously trialled, increase the power output and improve electronics hardware for better interfacing with applications including LED lights and mobile phones.
The PRG, which has collaborated with the eThekwini Municipality for more than two decades, has drawn in several collaborative research projects that have positioned Durban as a leading site for the testing of sanitation solutions that will conserve water, reduce water pollution and the need for intensive wastewater treatment, and valorise human waste products by transforming them into new resources, such as fertiliser.
The PRG’s collaborative research has involved exploration of the production of fertiliser from wastewater treatment works, the separation of urine and faeces in urine-diversion toilets, and redesigned toilets that reduce the volume of water lost to flushing – an important advance especially in a water-scarce country. The PRG is currently testing almost 20 prototypes under the Reinvent the Toilet Challenge.
Collaboration takes place with several national and international organisations, institutes and foundations, including the Gates Foundation, the Water Research Commission, overseas universities and research institutes, and several disciplines, units and centres within UKZN.
Words: Christine Cuénod