A new hydropower prototype from the University of Michigan could end up using even slower river and ocean currents to generate energy. VIVACE, which stands for Vortex Induced Vibrations for Aquatic Clean Energy, can generate power from as little as 2 knots, making it more useful than most turbine and water mill systems out there, which need an average of 5 to 6 knots to operate efficiently. The system works by harnessing “vortex induced vibrations,” the thrumming caused by the flow of liquid or air over rounded objects. A cylinder placed underwater is subject to the current and starts to vibrate as liquid sticks and creates eddies on the object's opposite side. It's the same scientific principle that caused the collapse of the Tacoma Narrows bridge in 1940 .
"For the past 25 years, engineers—myself included—have been trying to suppress vortex induced vibrations. But now at Michigan we're doing the opposite. We enhance the vibrations and harness this powerful and destructive force in nature," said VIVACE developer Michael Bernitsas, a professor in the U-M Department of Naval Architecture and Marine Engineering.Just a few cylinders could possibly power an anchored ship or a lighthouse. An array of VIVACE cylinders about the size of a running track could produce energy at 5.5 cents per kilowatt hour and power about 100,000 houses. U of M is now working on possibly deploying a pilot project in the Detroit River within the next 18 months. [UMich via Gizmag ]