The call of the running tide (OpEd, The Providence Journal, RI)

[jpak]

http://www.capecodtoday.com/blogs/index.php/Op-Ed/2007/06/14/the_call_of_the_running_tide

IN APRIL, Verdant Power, of Arlington, Va., installed the last four of six submerged tidal turbines in the East River off Manhattan. These are 35-kilowatt turbines, small compared with Cape Wind’s 3.6-megawatt wind turbines in the proposed Nantucket Sound project, but they are a prototype installation for an anticipated 100-turbine tide farm.

Marine Current Turbine, of Bristol, England, has been operating a 300-kilowatt tidal turbine off the Devon coast for four years, and a Norwegian company, Hammerfest Strom, has been operating a similar turbine in Norway. It is believed that enough tidal energy could be harnessed off the British coast to power 20 percent of Britain’s needs.

The Federal Energy Regulatory Commission has thus far issued preliminary permits for tidal installations at over 25 sites in the United States and is considering an additional 30 applications. Tidal power, like wind power, is on its way.

There are several designs for tidal turbines, but the most common resembles a wind turbine placed underwater to harness energy from the moving tides or, in the case of a river, from the moving current. The blades are much smaller, at about 20 to 50 feet long, because of the limited space between surface and ocean floor and, of course, water-flow considerations.

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