After a glance at the jars of muddy water in Daniel Bond’s lab fridge, you might suggest the University of Minnesota microbiologist throw them out. But the muck is worth a closer look. It may hold the key to developing clean energy.

The jars contain Geobacter sulfurreducens, an electricity-producing microbe that feeds on organic material (even sewage) in sediment at the bottom of oceans and lakes for energy. When breaking down molecules, electrons flow from the bacterium to metals, such as iron, in the soil, creating an electrical current. Geobacter already helps clean up sites polluted by toxic heavy metals: When reduced by the microbe, the metals precipitate into solids, which are easier to remove.

Bond studies how the microbes generate current and how to make them do it better. Others are designing devices, called microbial fuel cells (MFCs), to harness bacteria’s power. Though some prototypes exist, the technology faces major hurdles. “So far we can do tricks, like make a light bulb burn, or run a toy robot,” says Bond, “but we can’t economically put it to use on a larger scale yet. We need a way to get more power.”

Researchers have made small-scale progress. The Naval Research Laboratory’s microbe-powered weather buoy in the Potomac River monitors air and water conditions. And in 2007, Foster’s Brewing Company installed an MFC at its brewery near Brisbane, Australia. The “beer battery” produces energy from brewery wastewater, treating it in the process. It generates only about two kilowatts of power, but beer lovers should still lift a pint to toast sustainable brewing and the magic of microbes.

This article originally appeared in Plenty in February 2008.

Copyright Environ Press 2008.

Magic muck
Muddy water may hold the key to producing clean energy.