Fuel cells work by using a catalytic material to oxidize hydrogen and make an electric current flow between two electrodes. Microbial fuel cells, on the other hand, use bacteria instead of one electrode which is normally made of platinum or cheaper, alternative materials. They process the fuel and produce naturally-occurring chemical reaction that produce electricity.
Dr. Georgia Antonopoulou, a biochemical engineer from the University of Patras in Greece, has discovered that whey coming from cheese factories can be used by cultures of bacteria contained in microbial fuel cells to generate electricity. Whey is a lactose-rich organic material, and it is usually disposed. Factories have strict regulations to treat the whey before disposing the whey, since it can constitute an environmental hazard. Just one small feta facility throws away as much as 4,000 tons of whey per year, as dr. Antonopoulou says.
In theory microbial fuel cells can run on almost any kind of organic matter, says Chris Melhuish, head of the Bristol Robotics Laboratory, England. “All you have to do is match the microbial culture with the type of stuff you want to use as fuel,” he says. Dr Melhuish has been trying to power robots on domestic waste-water, but it is tricky. Ideally you would want to use cheap raw-waste products, he says. But traditionally the fuel cells work best with a refined fuel in the form of solutions containing synthetic sugars, such as glucose.
The bacteria that would digest the whey has been obtained from a waste-water plant. Dr. Antonopoulou has demonstrated that by using the bacteria she processed it is possible to produce as much power as from refined fuel.
A previous stage of research made the fuel cells harvest only a few milliwatts, also having a low efficiency – only 2%. This was because a second set of microbes, withing the whey itself, absorbed the electrons produced by the first. After killing the second set of microbes, the efficiency jumped to 25%.
Further researching and funding from third parties should help dr. Antonopoulou a lot in this quest. She needs to increase the surface area of the electrodes within the fuel cell, and that requires a special material, which needs money to be discovered. Such materials have already been discovered, but had only been applied to batteries and solar cells so far.