A more efficient but also cheaper type of microbial fuel cell that can use urine for fuel to generate electricity has been developed by British researchers.
The new fuel cell, developed by researchers from the University of Bath, Queen Mary University of London and the Bristol Robotics Laboratory, is smaller than earlier devices and more suitable for practical use as it overcomes two major problems of this type of fuel cell – that is their high 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, a member of the University of Bath team. "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."
To make the fuel cell produce more electricity, the researchers concocted a new type of catalyst made of substances commonly found in food waste – namely glucose and the egg-white protein ovalbumin. Instead of expensive cathode materials employed in earlier designs, the new cell uses cheap carbon cloth and titanium wire.
The researchers carried out a series of experiments to see how the length of electrodes would affect efficiency and found that increasing the length from four to eight millimetres results in ten times more power being generated. A further ten-fold improvement was achieved by stacking up three of the miniature microbial fuel cells.
"Microbial fuel cells could be a great source of energy in developing countries, particularly in impoverished and rural areas," said Jon Chouler, lead author of the study from the University of Bath. "Our new design is cheaper and more powerful than traditional models.”
Microbial fuel cells have certain advantages over other ways of producing bioenergy as they can operate at room temperature and regular air pressure. They are also relatively cheap to operate and produce less waste than other methods. However, large-scale adoption of the technology has been hindered by the high cost of some components. Previously, the cathode used to contain expensive platinum to speed up the electricity-generating bacterial processes. The new design doesn’t require any platinum.
Compared with other methods of bioenergy production, such as anaerobic digestion, fermentation and gasification, previous types of fuel cells were also much less efficient.