Soon The Ocean Will Be Generating Power Near Seattle

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Sunrise on Puget Sound and Seattle, Washington.

At the end of last week, the Federal Energy Regulatory Commission gave the go-ahead for a 10-year project testing our ability to generate electricity from the movement of the ocean.

The license permits Public Utility District No. 1 of Snohomish County to install two underwater turbines in the Admiralty Inlet near Seattle, Washington. The turbines will be provided by OpenHydro, and should produce 300 kilowatts a piece. Each turbine is nearly 20 feet high and will be mounted to the sea floor by triangular bases, about 200 feet underwater. They’re designed to generate power over a range of water flow velocities regardless of which direction the tide is flowing. Two 7,000 foot cables will carry the electricity they generate to shore.

This makes tidal power a bit different from wave power, which usually relies on buoys that ride ocean waves and translate that kinetic force into electrical generation.

The Admiralty Inlet is the main connection between the maze-like Puget Sound, which sits alongside the city of Seattle, and the Strait of Juan De Fuca. The Strait, in turn, runs between Washington State’s shoreline and Vancouver Island, and on out to the Pacific Ocean.

Because the Inlet is narrow, and the place where most of the water enters Puget Sound, it naturally speeds the water fast enough to make it a prime spot for driving underwater turbines.

As a pilot, the Admiralty Inlet Tidal Project will be very small; at a total of 600 kilowatts, it will be a tiny fraction of the 454,000 kilowatts generated by the nearby wind farm at Walla Walla. Tidal power is also much more of a work-in-progress than wind power, with only about five projects around the world as of 2010. That also makes it rather expensive source of power: $440 per megawatt-hour, according to Bloomberg, versus $82 per megawatt-hour for coal.

But the immaturity of the technology is also the problem the Admiralty Inlet project aims to help solve. There’s really no regulatory framework or set of established best practices for deploying tidal power generation, so FERC included a range of requirements in the license to protect fish, wildlife, and natural resources — as well as ensuring the safety of passing ships and a nearby undersea fiber-optic cable that runs from the US to Japan. The license also gives the public utility the job of studying the turbines’ impact on fish, sea mammals, and plant life, as well as any effects on the surrounding marine ecology and the water’s temperature and chemical makeup.

“The Admiralty Inlet Project is an innovative attempt to harness previously untapped energy resources,” said Cheryl LaFleur, FERC’s acting chairman. “I look forward to the results of the experimental project and congratulate Snohomish for undertaking it.”