By Sid Perkins
Some types of bacteria living in seafloor mud can generate enough electricity to power small electronic devices, field tests have shown. The months-long trials may herald a new generation of fuel cells that can supply reliable low-voltage power to future networks of ocean-bottom sensors in long-lived instruments for which changing batteries would be impractical, if not impossible.
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Many microbes live in the sediments that accumulate at the bottom of the ocean, says Leonard M. Tender, a chemist at the Naval Research Laboratory in Washington, D.C. As these bacteria consume the ooze’s organic carbon, which comes primarily from the decayed remains of marine organisms, they produce waste products that include negatively charged ions. As a result, there’s a voltage difference of up to 0.8 volts between the top few centimeters of seafloor sediment and the seawater immediately above it.