Thursday, December 4, 2008

Fish-inspired power generator can work in slow-moving currents

Think like a fish not like a bird, say researchers trying to harvest energy from water currents. Their new fish-inspired power generator can work in slow-moving currents where traditional turbines are less effective.

Tidal streams and moving rivers in the United States could generate 140 billion kilowatt-hours per year, or about 3.5 percent of the nation's electricity demand, according to the Electric Power Research Institute (EPRI).

Most of the attempts to tap this potential have employed underwater windmills. These so-called tidal turbines use the force of lift to turn their blades.

"We live in air so we are used to lifting surfaces that support birds, sail boats and airplanes," said Michael Bernitsas of the University of Michigan.

In water, however, Nature has devised a different strategy. Most natural swimmers — from tiny sperm to giant whales — create vortices (or little whirlpools) that they push off of to propel themselves forward.

Bernitsas realized that these same vortices could be used to drive a generator. He and his colleagues have created a machine called VIVACE (Vortex Induced Vibrations for Aquatic Clean Energy), whose cylinders oscillate up and down in moving waters.

Read more about the generator at Live Science

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