The Admiralty Inlet characterization is being conducted by the Northwest National Marine Renewable Energy Center, in which the UW leads research on tidal energy. Once the turbines are in the water, likely in 2013, researchers will monitor environmental effects. So far, researchers say, the data support the notion that the Admiralty Inlet is well suited for a tidal energy installation from an engineering perspective. This observational data will help determine precisely where to put the tidal turbines, and establish potential environmental effects once they are in the water. The monitoring tripod holds instruments to track water quality, ambient noise, currents, temperature and salinity, and to record marine mammal calls and electronic tags on passing fish. Even so, it can barely stay put on the ocean floor. With added ballast for stability, the device weighs 850 pounds in water. The UW team has been measuring currents continuously at the proposed site for almost two years, using a monitoring tripod the size of a small refrigerator. This reduces the effect on animals' hearing, which is good, but it also means less noise for marine mammals to detect turbines and avoid them. The data suggest that Admiralty Inlet tends to lessen sound. UW researchers used sound from a Washington state ferry to learn how turbine noise would spread from the project site. 'It's similar to when you're bicycling downhill and the air rushes past your ears.'Ĭhris Bassett, a UW doctoral student in mechanical engineering, is testing approaches that would allow underwater microphones to work in fast-moving water. 'When currents were more than about 2 knots the instruments are hearing considerable self-noise,' Polagye said. Strong currents complicated the task of measuring how sound travels in the channel. One area of concern is how underwater noise generated by the turbines could affect marine mammals that use auditory cues to navigate and communicate with each other. The pilot site lies roughly 200 feet below the surface of Admiralty Inlet, where the UW team has measured currents of up to 8 knots, or 9 miles per hour. And it's too deep for conventional scuba diving.' The currents are so fast that it's hard to operate vehicles and maintain equipment. 'These kinds of tidal channels where water is going very fast only happen in a few areas, and have not been well studied. 'There's surprisingly little known about the oceanography of these very fast waters,' said collaborator Jim Thomson, a UW assistant professor of civil and environmental engineering and an oceanographer in the UW's Applied Physics Laboratory. To do this, the UW team must assess a new technology that operates in a little-explored environment. 'We want to monitor the effects of this particular project, but also understand the processes so we can apply the findings to other potential tidal energy sites,' Polagye said. The turbines would generate an average of 100 kilowatts of electricity, enough to power 50-100 Washington homes during the pilot phase. The Snohomish County Public Utility District, just north of Seattle, received a $10 million grant from the Energy Department for the tidal project now in the final phase of obtaining permits. 'The results of this pilot project will help decide if this is an industry that has potential for going forward at the commercial scale, or if it stops at the pilot stage,' Polagye said. He believes the Pacific Northwest installation will have the most comprehensive environmental monitoring of any tidal project so far.

'There really isn't that much information, anywhere, about the environmental effects of tidal turbines,' Polagye said.Īlthough European countries have more experience with tidal energy devices, they are not as far ahead on environmental monitoring, Polagye said.

Polagye and colleagues are involved in environmental monitoring before and during a planned deployment of two 30-foot-wide turbines in Admiralty Inlet, the main entrance to Washington state's Puget Sound. Brian Polagye, UW research assistant professor of mechanical engineering, will present recent findings this week in an invited talk at the American Geophysical Union's annual meeting in San Francisco. University of Washington researchers are devising ways to site the tidal turbines and measure their environmental effects.

Tidal power stations operate by using