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RESEARCHERS at Bristol University, UK are working to develop stacks of microbial fuel cells that could one day generate electricity by cleaning waste water.

Armed with a $900,000 grant from the EPSRC, robotic researcher Ioannis Ieropoulos will spend the next four years developing a microbial fuel cell already used to power autonomous robots. Waste is fed into a cell and broken down by microbes into treated waste, producing electricity in the process.

Previously the team has tested all manner of wastes from grass clippings to dead flies – but found that urine shows the most potential.

“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,” Ieropoulos says.

With this in mind, the wastewater industry looks to be an attractive source of ‘fuel’. The team will use its grant to scale-up its technology into stacks of microbial fuel cells that can handle a continuous flow of waste. These will be connected both electrically and in terms of liquid feed lines. This should make the system more efficient so it produces more energy than the same number of isolated cells.

Ieropoulos tells tce that his findings show that scale-up can be achieved by miniaturisation of individual units followed by multiplication of these smaller units in what he describes as a “continuous optimisation process’.

A working prototype is expected in five years with an industrial-scale unit turning waste water into energy much further down the line.

In the short-term, the team plans to collaborate with makers of urinals to see whether the concept could be used to generate electricity at music festivals.