RENNES -- In the corner of his lab at the University of Rennes 1, Frederic Barrière demonstrates a battery powered by the symbiosis of small plants and bacteria. A small light-emitting diode connecting to the two poles of the device illuminates, proving that the system produces an electric current.

Barrière, a chemistry researcher with France's National Centre for Scientific Research (CNRS), explains that the battery functions very simply, producing a modest amount of electricity by utilizing living microorganisms. The technique isn't powerful enough to run something like an electric car, but it still has exciting potential. The system is currently undergoing trials, for example, in sewage treatment plants to not only clean the water but also produce electricity.

The microbiological battery, which Barrière developed alongside a young doctorate student, is an impressive variation on a device that's already been around for more than a century: fuel cells.

"Classic" fuel cell batteries operate with electrodes that are immersed in hydrogen and oxygen. They rely on expensive catalysts, like platinum, to initiate chemical reactions on the electrodes' surfaces. Barrière's "organic" version uses live material – bacteria – as the catalyst. Unlike platinum, bacteria are abundant – and cheap.

Instead of breathing oxygen into the air, the microorganisms breathe the metal of the electrode, which in turn circulates electrons in the battery and produces the electric current. Impressively, the bacteria – when placed in their optimal, oxygen-free environment – instinctively attach themselves to the appropriate electrode.

Strange brew

To catalyze electricity production, the only thing necessary is to feed a thin layer of the bacteria. This "fuel" can be a mix of organic compounds commonly found in waste products. A pilot plant in Australia is even operating with the liquid effluent of a brewery.

Such a system could be of great benefit in waste treatment plants, which tend to be large electricity consumers. In efforts to make this bio-battery even more efficient and ecological, it may be possible in the future to apply the system to the roots of photosynthetic plants, which capture the carbon dioxide omitted by the bacteria while also providing the carbohydrates the bacteria feed on.

Read the original article in French

Photo - shatt0r