快猫短视频

AN UNDERWATER fuel cell that runs on seawater and subsea sediment really can
generate small amounts of power indefinitely鈥攋ust as its inventor
hoped.

鈥淲e鈥檝e completed 220 days of continuous testing and the power level has been
constant throughout,鈥� says Leonard Tender of the US Naval Research Laboratory.

OSCAR, the Ocean Sediment Carbon Aerobic Reactor, taps into a natural voltage
gradient created by a pair of chemical reactions happening on the seabed.
Plankton release energy by using oxygen to break down organic matter in seawater
or sediment. Deeper down in the sediment there is no oxygen, so the plankton
rely on different chemicals. These two reactions set up a potential difference
between the seawater and the sediment a few centimetres beneath.

Tender and colleague Clare Reimers placed one electrode in the sediment and
another in the seawater. 鈥淓lectrons then flow from one electrode to the other
and that鈥檚 how we harvest the power,鈥� he says. Until recently, this was just a theory
(快猫短视频, 5 February 2000, p 10).

The cell鈥檚 power is more or less unlimited because the sediment is constantly
being flushed and replaced as plankton die. Tests in the Atlantic Ocean off the
coast of New Jersey have managed to generate 50 milliwatts of power from
electrodes covering just 1 square metre. You can see its power output right now
on a US Navy website at http://209.158.75.87/shorestation.htm.

Tender believes OSCAR will be ideal for powering oceanographic sensors whose
batteries now need to be replaced regularly.

Harold Bright, co-inventor of the idea, now manages the programme at the
Office of Naval Research. He says that he is funding a number of programmes to
tap energy from the sea. 鈥淏ut this is by far the most environmentally benign.鈥�