New fuel cell to turn urine into electricity

Scientists have developed a low-cost, miniature microbial fuel cell that can turn urine into electricity, an advance that could revolutionise the way bioenergy is produced, especially in developing countries.
The research describes a new design of fuel cell that is smaller, cheaper and more powerful than traditional ones.
Researchers from University of Bath, Queen Mary University of London and the Bristol Robotics Laboratory developed a new design of microbial fuel cell that overcomes two limitations of standard cells - their cost and low power production.
"Microbial fuel cells have real potential to produce renewable bioenergy out of waste matter like urine," said 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," said Di Lorenzo.
Microbial fuel cells are devices that use the natural processes of certain bacteria to turn organic matter into electricity. There are other ways of producing bioenergy, including anaerobic digestion, fermentation and gasification.

However, microbial fuel cells have the advantage of working at room temperature and pressure. They are efficient, relatively cheap to run and produce less waste than the other methods, researchers said.
Microbial fuel cells can be expensive to manufacture. The electrodes are usually made of cost-effective materials, but the cathode often contains platinum to speed up the reactions that create the electricity.

Also, microbial fuel cells tend to produce less power than the other methods of bioenergy production.
The new miniature microbial fuel cell uses no expensive materials for the cathode; instead it is made of carbon cloth and titanium wire.
To speed up the reaction and create more power, it uses a catalyst that is made of glucose and ovalbumin, a protein found in egg white. These are typical constituents of food waste.
"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.

Doubling the length of the electrodes, from 4mm to 8mm, increased the power output tenfold. By stacking up three of the miniature microbial fuel cells, the researchers were able to increase the power tenfold compared to the output of individual cells.
"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," said lead author Jon Chouler, from University of Bath.
The study was published in the journal Electrochimica Acta.