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Urine: Waste product or future power source?

Researchers in the UK are looking into the use of urine as the ‘fuel’ for microbial fuel cells (MFCs), which use bacterial cultures to break down ‘food’ to create power. MFCs are a developing technology used to power autonomous robots.

An EPSRC Career Acceleration Fellowship Grant worth £564,561 has been awarded to Dr Ioannis Ieropoulos for a four year project to develop research into how waste could be used by Microbial Fuel Cells to generate energy.

Researchers at BRL have spent three and a half years developing EcoBot-III, funded by EU FP-6 -- a robot which can power itself by digesting waste (see: The early stage work of the EcoBot-III research was funded by EPSRC.

Dr Ieropoulos will take the concept of the Microbial Fuel Cells to the next level with a new team of researchers. They will work on scaling up the MFCs so that they can work together in a 'stack' -- a series of cells which are connected both electrically and in terms of the liquid feed-lines under a continuous flow system. Developing this will present a challenge for the researchers, as the liquid must be in a continuous flow, but still allow individual MFCs to remain isolated. However a stack of linked MFCs will be much more efficient and produce more energy than the same number of individual MFCs.

A unique aspect of their research will be to look at the use of urine as a waste material that could be used to power the MFCs.

Dr Ieropoulos explains, "Over the years we have fed our MFCs with rotten fruit, grass clippings, prawn shells and dead flies in an attempt to investigate different waste materials to use as a 'food source' for the Microbial Fuel Cells. We have focused on finding the best waste materials that create the most energy. Urine is chemically very active, rich in nitrogen and has compounds such as urea, chloride, potassium and bilirubin, which make it very good for the microbial fuel cells. We have already done preliminary tests which show it being a waste material that is very effective. Although it is early days for this research, we hope to work towards producing a prototype portable urinal which would use urine to create power from fuel cells. We envisage that this could be used for example at music festivals and other outdoor events."

The researchers are already in touch with a waterless urinal company who have seen the potential of the technology. Marcus Rose of Ecoprod Technique says, "Ecoprod Technique is a urinal company dedicated to the environmental benefits that our waterless urinal provides. We have talked to the researchers who say this product is the only type totally suited to complement this research. We are looking forward to helping with this unique project with the supply of Urimat -- The Waterless Urinal which the research team have chosen. This will be a valuable and interesting collaboration for the company to be involved in."

A further aspect of the EPSRC funded project is to develop the cathode side of the MFC so that the whole cell becomes self sustaining. Each MFC has an anode side and a cathode side which together as two half-cells complete the system to create power. Commonly bacteria are in the anode side, and chemicals or oxygen are in the cathode side, which complete the reactions (i.e. close the circuit). This research will develop the use of oxygen-producing organisms (such as algae) instead of chemicals in the cathode side of the MFC, thus moving towards a self-sustaining system -- the waste from the algae can -- for example -- be used to feed the bacteria in the anode side, i.e. using its own waste to produce energy.

Dr Ieropoulos says, "The award of this grant is a huge step forward and a great challenge for me and the team. I am thankful to the EPSRC for giving me this great opportunity to integrate the three areas of research -- creating stacks of MFCs, self sustainable cathodes and using waste products to produce energy. Advances in this area could provide a significant contribution to the challenges we currently face in terms of energy production and waste clean up. We hope this research will help change the way we think about energy and human waste."

The project builds on the success of the EcoBots I, II and III research carried out by Dr Ieropoulos, Professor John Greenman Professor and Professor Chris Melhuish, together with technical support from Ian Horsfield and other members of the BRL team.

Current research being carried out by Ioannis includes the collaboration with Wessex Water on wastewater treatment and MFCs, and a project looking at the materials and structures of the MFCs.