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This new urine-based fuel cell puts your liquid waste to good use

Harnessing the power of pee.

PETER DOCKRILL
18 MAR 2016
 

Scientists in the UK have developed a new kind of fuel cell capable of turning urine into electricity, and they say it's smaller, cheaper, and more powerful than existing microbial fuel cells. And best of all, it runs on something we're not exactly running out of – unlike rapidly depleting (and polluting) fossil fuels.

"Microbial fuel cells have real potential to produce renewable bioenergy out of waste matter like urine," said chemical engineer Mirella Di Lorenzo from the University of Bath. "The world produces huge volumes of urine and if we can harness the potential power of that waste using microbial fuel cells, we could revolutionise the way we make electricity."

 

Microbial fuel cells work by using the natural processes of bacteria to convert organic matter into electricity. They're not the only kind of bioenergy systems out there – others run on anaerobic digestion, fermentation, and gasification – but the benefits of microbial fuel cells are that they're efficient, inexpensive to run, and don't generate large amounts of waste. They also work fine at room temperature and under ordinary atmospheric pressure.

One of their drawbacks, however, is that they can be expensive to manufacture, but that's where the new fuel cell comes in. It's made from carbon cloth and titanium wire – both inexpensive materials.

To speed up its reaction, it uses glucose and ovalbumin – a protein found in egg whites – for a catalyst. As the researchers point out, these are typical constituents of food waste, providing an affordable surrogate to the rather exxy platinum cathodes used in traditional microbial fuel cells.

"We aim to test and prove the use of carbon catalysts derived from various food wastes as a renewable and low-cost alternative to platinum at the cathode," said Di Lorenzo.

The new system also addresses one of the other big criticisms of microbial fuel cells: low power production. By doubling the length of the electrodes in the fuel cell – from 4 mm to 8 mm – the scientists managed to increase power output by 10 times, and augmented this further by stacking the cells together in threes.

It's not the first time scientists have taken advantage of the properties of urine to generate electricity. In recent times, researchers have developed electricity-generating urinals and wee-powered socks to generate Wi-Fi signals (yep).

But the new fuel cell's low cost and its potential for miniaturisation could particularly come in handy in developing nations, where access to grid-based electricity can be hard or impossible to come by.

"Microbial fuel cells could be a great source of energy in developing countries, particularly in impoverished and rural areas," said one of the team, Jon Chouler. "Our new design is cheaper and more powerful than traditional models. Devices like this that can produce electricity from urine could make a real difference by producing sustainable energy from waste."

The research is published in Electrochimica Acta.

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