UW: Admiralty Inlet promising spot for tidal power

A small area near the Keystone ferry terminal in Admiralty Inlet could be a sweet spot for generating electricity from the tides, University of Washington researchers say.

The spot about 180 feet below the surface near the terminal on Whidbey Island has fast currents and little aquatic life, says Jim Thomson, an oceanographer with the university's Applied Physics Laboratory.

"It's a boring, dark, rocky bottom," Thomson told The Herald of Everett. "That's good."

Three power-generating tidal turbines could be installed there by 2011 as part of a pilot project, Snohomish County Public Utility District officials say. The district said Tuesday that the demonstration turbines would be designed, built and installed by an Irish company, OpenHydro, which has installed some tidal turbines off the coast of Scotland.

A UW research vessel spent last week probing the spot between Whidbey Island and Port Townsend using high-tech equipment, including a robotic underwater camera. It collected data about water speed, depth and marine populations.

The researchers found the area has fast water, a flat sea-bottom and few fish. Currents rush through the passage at up to nearly 6 mph, except for slack water for about 10 minutes once every 12 hours.

"It's a very energetic site," said Brian Polagye, a UW researcher.

The researchers will spend the rest of the year revisiting the site as part of a $100,000 study paid for by the U.S. Department of Energy.

At maximum capacity, the three turbines could supply about 1 megawatt, or enough power for about 700 homes, according to the PUD.

The 33-foot-wide turbine design selected by the PUD rotates just 10 times a minute and doesn't have exposed blade tips, which should minimize the effect on marine life, officials said. An underwater cable would connect to power lines on Whidbey Island.

The turbines don't have a price tag yet but are being designed to minimize maintenance. They also won't require any pilings, pinnings or drilling, so they can be relocated if needed, and environmental damage should be minimal, said Craig Collar, a senior manager of energy resource development with the PUD.

"This is a very straightforward device, very robust," Collar told The Seattle Times.

If the trial is successful, a larger turbine farm in Admiralty Inlet could be built.

The U.S. Navy also is planning a tidal power installation, off nearby Marrowstone Island, which could be installed in 2010, officials have said.