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Navy, Snohomish Co. PUD discuss tidal energy projects September 3, 2009

Local residents last week had their first opportunity to ask questions about two renewable-energy pilot projects planned for the waters of Admiralty Inlet.

Officials from the Snohomish County Public Utility District and the Navy discussed their plans to harness tidal energy off Whidbey and Marrowstone islands at an event hosted by the Island County Economic Development Council, the Island County Marine Resources Committee and Rep. Norma Smith, R-Clinton.

The two projects have very different goals.

The Navy’s purpose is to comply with a renewable-energy mandate from Congress with a research project that will end with the removal of the underwater turbines after one year. Snohomish PUD is hoping its exploration of the potential of tidal energy in Admiralty Inlet will lead to a long-term – and lucrative – power-generation project.

“These are the ‘Kitty Hawk’ days of tidal energy,” said Craig Collar, the PUD’s senior energy resource development manager.

The PUD is studying how well the turbines perform, the economic feasibility of tidal power and how the turbines might affect the marine environment.

Snohomish PUD plans to install two turbines made by Ireland-based OpenHydro about 220 feet below the surface about a half-mile southwest of Admiralty Head. At peak performance, each unit is expected to produce about 600 kilowatts of electricity, enough to power about 500 homes.

Collar said the OpenHydro turbine is considered one of the most environmentally friendly designs on the market, as it is lubricated with salt water rather than a petroleum-based product, has a closed-fin design that prevents marine life from being harmed by spinning blades, and at 400 tons, the turbine’s weight anchors it to the sea floor, so no underwater drilling would be required.

“They are designed to be completely removable,” he said.

Island County Commissioner Angie Homola asked Collar how many turbines would be needed to match the approximately 100 megawatts produced by their Henry Jackson Dam facility in Snohomish County’s Sultan River basin.

Collar said the current tidal-energy project involves just two OpenHydro turbines. The PUD would need to install between 150 and 200 turbines to produce the same amount of power generated by the dam, he said.

In an interview after the meeting, Collar said that even if the pilot project yields promising results, he doubted the PUD would install any more than 100 turbines in Admiralty Inlet. And if it did, it would be done gradually, in phases, with the first batch of about 20 turbines installed no sooner than 2019.

“This could never be done any way but incrementally,” he said.

Howard Garrett, president of Orca Network, asked the presenters how much underwater noise the turbines would generate and whether a large number of turbines could slow tidal flow.

Scientists at the University of Washington’s Northwest National Marine Renewable Energy Center are trying to answer some of those questions.

Brian Polagye, a tidal expert and research assistant professor, said that while the impact of just a few machines would be unnoticeable, models have suggested that 100 machines could slow tidal flow by up to 1 percent.

“That’s measurable, but it’s not clear what the effects will be,” he said.

Another unidentified questioner asked what kind of land-based infrastructure would be needed to support the turbines. Collar said there wouldn’t be much as far as the pilot project is concerned, but if a major build-out takes place, the story might be different. He did not offer specifics.

As for the Navy’s plans, Brian Cable, a mechanical engineer at Naval Facilities Engineering Command, said Navy officials have focused their attention on two locations just off the east shore of Marrowstone Island.

Congress provided $5.6 million for the Navy research project. Research gathered could yield information about tidal energy that could eventually allow some bases to generate their own power.

“Energy independence on a Navy base is a security factor that is important,” Cable said.

The Navy will also be installing a different type of turbine than the OpenHydro design. Instead, they will be using turbines built by U.S. based Verdant Power. Closely resembling wind turbines, Verdant Power’s design uses a tri-frame platform. Like the OpenHydro model, it uses weight to anchor it to the sea floor.

The Navy plans to install two platforms and a total of six turbines that will power one building and the lights in a parking lot at the Navy’s ammunition depot on Indian Island, which is just southeast of Port Townsend. Each turbine supplies up 40 kilowatts of electricity.

Before either pilot project can move forward, the agencies need to complete an extensive permitting process.

The Navy must adhere to the requirements outlined in the National Environmental Policy Act, while Snohomish PUD must obtain federal, state and local permits. Both agencies hope to have their projects under way by 2011.

Justin Burnett, Whidbey Examiner


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