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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Bug-Powered Battery on the Ocean Floor
2 July 2002 (All day)
Collecting data on the ocean floor may soon get a lot easier, thanks to a fuel cell that runs off organic detritus in the mud at the bottom of the sea. Instruments powered by the new device could operate forever (at least in principle) without the hassle of swapping batteries.
Scientists have known about the untapped potential at the ocean bottom for decades. Mud-loving microbes convert organic matter into electron-rich molecules, building up an electric potential between the soil and the electron-poor water above. Earlier this year, a team of researchers reported that electrodes in laboratory aquaria--after being colonized by a certain type of bacteria--carry a flow of electrons that can power a pocket calculator (Science, 18 January, p. 483).
Now, some of these researchers have plopped the device into shallow harbor waters off Oregon and New Jersey. Led by Leonard Tender of the Naval Research Laboratory in Washington, D.C., and Clare Reimers of Oregon State University in Newport, the team built electrodes from two graphite disks, each about 14 centimeters in diameter and drilled with small holes to increase the surface area for chemical reactions. One disk they buried in sediment, the other they placed in the water above. Bacteria growing on the buried plate pumped electrons into the electrode as they consumed organic matter (which is continually replenished by falling detritus from above). Oxygen molecules in the water plucked available electrons off the upper electrode, creating a current that provided about 0.02 milliwatts of power--enough to power simple ocean sensors, the researchers report in the 1 July issue of Nature Biotechnology.
Engineer Paul Chandler of the Monterey Bay Aquarium Research Institute in California, who designs oceanographic equipment, says that sensors are often not placed in remote areas because of the cost of replacing batteries, and this discovery might expand the areas that scientists can study. "The need is there, the energy resource is out there, and it looks like we can learn how to exploit it," he says.