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Harnessing the power of underwater vibrations.

UP CLOSE image: Mike Clifford Says Characterizations and Stories Enliven Lectures and Deepen DiscussionsMichael Bernitsas is calmly describing his invention to two visitors when a graduate student bursts through the door of the University of Michigan conference room. “I think you should come see this,” urges the T-shirted intruder. Down the hall, past large models of submarines and propellers, Bernitsas follows his excited protégé into a long but cramped laboratory where water is sloshing out of an 8,000-gallon tank. The source of the agitation is an aluminum cylinder suspended in the water, rhythmically leaping for no apparent reason. “Whoa!” cries Bernitsas. “That’s the biggest motion I have ever seen.” The last time he witnessed something approaching such furious action in the device, the cylinder slammed against the tank’s inch-thick Plexiglas bottom and cracked it.

But Bernitsas is delighted by the violent oscillations. It signals hope for a nearly boundless source of clean energy, tapped in a way no one had ever considered before. Wherever rivers, tides, and ocean currents flow, Bernitsas foresees underwater cylinders bobbing up and down to generate cheap, dependable electricity. “If we manage to build these,” he predicts, “it’s going to be a big thing for the world.”

The phenomenon responsible for this energy is vortex-induced vibrations, and his patented invention is called VIVACE, for Vortex-Induced Vibrations for Aquatic Clean Energy. Whenever a current of water or air flows around an object, whirling eddies form in an alternating pattern, pushing and pulling the object perpendicular to the current. For this reason, an antenna on a moving car will wobble side to side.

Vortex-induced vibrations are the bane of any engineer trying to build a stable bridge, pier, or oil rig in flowing water. Bernitsas, 57, who was educated in his native Greece and then at the Massachusetts Institute of Technology, had built a distinguished but obscure career studying ways to reduce and control them. His research made him the 13th marine engineer to receive the Blakely Smith Medal for “outstanding accomplishment in the field.”

But it had never occurred to Bernitsas — nor apparently to anyone else — to harness these oscillations, until one afternoon in 2003, during a search for dissertation ideas. One of his students wanted to study renewable energy, while another, Kamaldev Raghavan, favored controlling vortices. Raghavan remembers the excitement in his normally understated professor when it suddenly dawned on Bernitsas that the vibrations he had been fighting might contain a solution to the world’s energy woes. Recalls Raghavan, “I was just happy because I had a research project.”

The idea of an entirely new source of renewable energy has lifted Bernitsas onto the global stage. VIVACE has been featured on National Geographic Television and in Popular Mechanics. “I can’t pick up my phone anymore,” he says.

Bernitsas says VIVACE could open up thousands of rivers and the entire Gulf Stream to hydrokinetic energy production and that a two-story-high array covering an area of the ocean floor the size of a running track could electrify 10,000 homes for less than the price of wind power.

Costs could fall further based on his lab’s latest refinements. With precise placement of sandpaper on the cylinder, much like fish scales, oscillations have leapt to tank-cracking levels. “You can’t believe what exciting results we’re getting by mimicking nature,” he says. Now he is testing racks of multiple cylinders in preparation for a U.S. Navy-funded test in mid-2010, probably in the Detroit River.

VIVACE is also a large educational project. Bernitsas currently has six of his seven Ph.D. students and 17 undergrads working on some facet of the invention. Several undergrads are testing fish tails for VIVACE cylinders. At present, the tails are just passive flappers; they cannot move to take advantage of oncoming vortices, as any well-schooled fish would do. “I’m not as smart as a fish,” quips Bernitsas, “but I’ll get there eventually.”

Don Boroughs is a freelance writer based in South Africa.




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