RISING TIDES

Tapping into tides for electricity
Bob Drogin, November 25, 2010 (LA Times via seattle Times)

"…[T]he little gray barge strains against a raging morning tide…[that] will drain nearby rocky inlets and fishing harbors by 20 feet — as high as a two-story house — only to flood them again six hours later…[U]nder the stern, horizontal turbines spin in the swirling current. The huge mechanism…is America's most ambitious effort yet to produce electricity by harnessing the gravitational pull of the moon and sun on the sea…

"…Ocean Renewable Power…aims to link a larger turbine system to eastern Maine's power grid next fall in the country's first small-scale commercial use of tidal energy…Tapping the tides is the latest niche in the search for affordable, renewable energy…Widespread use may be years off, but advocates say tides and other hydrokinetic systems, from ocean waves to free-flowing rivers, ultimately could meet up to 10 percent of America's electricity needs, more than hydropower dams now supply."

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"Pilot projects or studies are under way in Washington's Puget Sound, in Alaska's Cook Inlet, off the coasts of Florida, California, Oregon and Hawaii, in New York's East River, along the Mississippi River and elsewhere…[T]he technology for marine and hydrokinetic power remains in its infancy, and costs are prohibitively high. Ireland, Denmark, Portugal, South Korea, China, Australia and other nations have been testing the waters for years. Commercial operations are rare…Canada may be closest…[It] is investing $75 million for three pilot projects in the upper Bay of Fundy, home to the world's highest tides. The first test turbine weighs 400 tons, has a peak capacity of one megawatt and looks like a sunken windmill…[They hope] to gather enough data by 2015 to determine whether tidal power is technically feasible, environmentally safe and economically viable.

"In theory, the U.S. resource is immense. Waves and currents are relatively reliable in some areas, and tides ebb and flood twice a day like clockwork. As a result, they are more predictable resources than wind or solar power…[but] tides with sufficient range and velocity run only in the nation's northeastern and northwestern corners, mostly Maine and Washington, plus Alaska…Waves are consistently high only on the Pacific coast north of Point Conception, Calif., and in Hawaii."

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"Several developments suggest a surge of U.S. interest…The Federal Energy Regulatory Commission reported this month that it has issued 140 hydrokinetic preliminary permits for proposals to tap tides, waves or river currents, up from a handful a few years ago…Working with the Navy, for example, Ocean Power Technologies last month connected a small test buoy in the swells off Oahu to the power grid that serves the Marine Corps Base Hawaii, marking a first for a wave-energy device in U.S. waters…

"Tides in Maine's rugged Cobscook Bay, at the mouth of the Bay of Fundy, flow [fast]…Ocean Renewable Power, based in Portland, Maine, launched its first cross-flow turbine… in 2007…[I]t worked…The company built a bigger unit…for $2.5 million…Testing resumed Oct. 1 in a fast-flowing channel flanked by wooded hills and rocky cliffs…The environmental impact still isn't clear. University of Maine researchers are trying to assess risks to fish, diving seabirds, seals and other creatures in a pristine ecosystem…[T]he Snohomish County [Washington] Public Utility District…[has] plans to install two large turbines to gather tidal data one-half mile offshore and 200 feet deep…"