Maine offers testbed for power from tides

Systems under development today rely on tidal stream turbines that are powered by current flows, just as windmills are spun by moving air.

Known as tidal in-stream or hydrokinetics, the process is a far cry from old-style tidal barrages that are more akin to dams and cost much more to build. The best-known plant of that type, built on France's Rance estuary, has been producing power for more than 40 years.

Ocean Renewable Power tested its prototype with different types of blades for much of the past winter in the frigid waters of Deep Cove. The tests were done aboard the barge Energy Tide 1, which is equipped with devices to measure turbine speed, tidal flow rate, voltage and electrical current. A bigger test came in April, when the barge was towed to the Western Passage between Eastport and Canada's Deer Island, where it generated electricity for the first time.

While the output was modest, the purpose was to demonstrate the feasibility of the turbine generator unit; Ferland said it passed that test with flying colors.

The commercial model would be roughly three times the size of the prototype and be placed in the water for testing as early as next year. By 2011, if all goes well, output could expand to 5 megawatts. Ocean Renewable Power's long-term goal is an array of turbines that would generate 80 to 120 megawatts.

Other sites, experiments
Only a handful of sites in the Lower 48 lend themselves to utility scale tidal generation, according to Bedard, including Eastport and a few areas along Washington's Puget Sound. Alaska, he said, has 95 percent of U.S. tidal resources and Canada also has huge potential, but the challenge lies in transmitting that power to markets where it is needed.

While Passamaquoddy Bay and the Bay of Fundy in the U.S. and Canada are prime proving grounds for tidal power, tests are also being run at other sites. The largest, a 1.2 megawatt generator, was deployed this year by Marine Current Turbines at Strangford Narrows in Northern Ireland.

Joel Page / AP Ocean Renewable Power uses this barge for its turbine testing.

Another developer, Verdant Power, placed turbines in New York's East River last year to test delivery of tidal power to a local supermarket and parking garage. The test was a success, but the project experienced problems with broken blades and has since installed new ones. Another urban site being explored is beneath San Francisco's Golden Gate Bridge.

In Maine, Portland-based Ocean Renewable Power is looking to generate revenue in three ways: It can provide its technology to other permit holders, generate power at its own sites, and take on the role of project developer for others who enter the market.

Because the technology is still in its infancy, techniques for building and deploying turbines are still being shaped.

"What we're doing is not in the shop manual," Lewis said. "We're writing the shop manual."

MORE FROM ENVIRONMENT

Environment Section Front

Nepal holds Cabinet meeting at Everest 'Adapt or die' becomes climate mantra India joins pledges to curb carbon Single Asian carp found in big fish kill Penn State prof welcomes climate inquiry University in climate flap details inquiry Crew plans to cut rope to free Hawaii whale Bhopal industrial disaster still haunts India An energy answer in the shale below? Catching up with South Pole adventurers Environment Section Front   Add Environment headlines to your news reader: