The Weirdest New Source of Alternative Energy: Underwater Vibrations

Researchers say this longtime bane of offshore drilling is more cost-efficient than wind and solar.

By Andrew Grant|Wednesday, February 25, 2009
A prototype underwater generator shows the
fluid dynamics that will produce power from
slow-moving currents using metal
rods suspending near the ocean
or river floor.
Image courtesy of NOAA

The latest frontier for renewable energy is the ocean floor. A novel method of generating power uses a network of metal rods to tap into the currents that flow along the bottom of the ocean (and along riverbeds as well). Water swirls as it flows past the rods, making them vibrate. This phenomenon is painfully familiar to oil companies, which spend large sums of money minimizing such vibrations in order to stabilize offshore drilling equipment. “Everyone was obsessed with suppressing this motion,” says Michael Bernitsas, the University of Michigan engineer who developed the technology. “At some point it dawned on me that maybe we can do the opposite: Enhance it and harness the energy.”

Many proposed ocean energy projects rely on turbines that require sustained strong currents, but Bernitsas’s device can run efficiently on water flows of just a few miles per hour. He says that the cost of water-flow power production is less than that of solar or wind and that current-based generators can be arranged in large networks to power thousands of homes.

Although his technology has proved itself in the lab, Bernitsas still needs to find the best materials to withstand the elements in a real underwater environment. Vortex Hydro Energy, Bernitsas’s company, plans to install a prototype—about the size of a large car—in the Detroit River by the end of the year.

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