German researchers achieve tenfold increase in bacterial fuel cell power

Brussels, 07 Jul 2003

Researchers in Germany are now able to generate ten times as much electricity using microbial fuel cells compared with previous designs, thanks to the use of a newly designed anode and help from the bacteria themselves.

A team from the Ernst Moritz Arndt University in Greifswald have designed an experimental fuel cell that generates electricity when bacteria, in this case Escherichia coli (E. coli), feed on sugar. The resulting output is enough to power a medical ventilator or similar appliance.

During fermentation, micro organisms such as E. coli convert sugar to alcohols, acids and carbon dioxide. When no air is present, hydrogen can also be produced. As with conventional fuel cells, this hydrogen is then used to generate electricity.

As reported in the scientific journal Nature, the researchers noticed that the power output of their prototype fuel cell appeared to be much higher than the hydrogen produced could account for alone. They believe the reason for this lies in the novel design of the charge gathering anode.

Earlier microbial fuel cells proved to be inefficient because their metal anodes became contaminated with by-products from the fermentation process. The new design uses a platinum anode coated with a conducting polymer called polyaniline, significantly slowing down its rate of contamination.

The team believes it is this coating that may also allow the E. coli bacteria to donate electrons directly to the anode, an explanation consistent with the observed increase in power generation. If so, and more research is needed before the theory can be proved, the German researchers may have inadvertently discovered the key to efficient generation of electricity from bacteria.

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