Munching microbes feed fuel cell

Researchers from the Ernst Moritz Arndt University in Germany have found a way to harvest the energy needed to power a fuel cell from chemical reactions that occur when E. coli bacteria consume sugar.

The researchers' prototype microbial fuel cell captures the hydrogen produced when the microorganisms metabolize carbohydrates like sugar in the absence of air. Most fuel cells use hydrogen as fuel, capturing the energy released when hydrogen reacts with oxygen to produce water.

The key to the researchers' prototype, which produces up to 1.5 thousandths of an amp and can run for hours at a time, is that the anode is coated with a conducting polymer. This layer allows hydrogen to diffuse through, but blocks larger molecules. It is also involved in an oxidation reaction that cleanses the anode of excreted metabolites that would otherwise gum up the works.

The fuel cell produces enough power to continuously run the 0.4 volt motor of a ventilator, according to the researchers.

It will take the least five years to produce practical microbial fuel cells, according to the researchers. The work appeared in issue 25 of Angewandte Chemie.