Dec. 15, 2008 -- Currents can be powerful enough to tip canoes, damage docks and even topple bridges. The force of all that moving water can also provide a clean, affordable and unobtrusive source of renewable energy, says engineer Michael Bernitsas, of the University of Michigan in Ann Arbor. Bernitsas has invented a device, named VIVACE, that converts river and ocean currents into electricity. Like fish, the device takes advantage of powerful phenomena called vortex-induced vibrations. These vibrations occur when water flows past a round or cylindrical object. Swirls of water form downstream from the object and in an alternating pattern on either side of it. That causes the object to oscillate, or vibrate, up and down. Vortex-induced vibrations also occur in air. And they have been responsible for some high-profile disasters, including the 1940 collapse of the Tacoma Narrows Bridge in Washington. Related Content: Project Earth Discovery Blog: PowrTalk Discovery Tech: 10 Fuel-Efficient Cars "We always try to suppress vortex-induced vibrations because they are very destructive," said Bernitsas, who has designed offshore mooring systems for oil companies. "It dawned on me that instead of suppressing those vibrations, maybe we could enhance them, control them, and harness the energy from currents." Spinning electricity out of water is not a new idea. Hydroelectric plants harness the power of falling water. Turbines tap into currents. But these techniques are limited to systems that contain lots of fast-moving water flowing at speeds of at least five knots. (One knot is equivalent to just under one mile per hour.) However, the vast majority of ocean currents around the world flow slower than three knots. Most river currents are slower than two knots. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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