By Charlie Bermant
Peninsula Daily News
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The two-year project — funded by a $746,000 federal Department of Energy grant and under the auspices of the University of Washington — is testing three different technologies that will be used to map underwater areas and provide an accurate representation of the ecosystem prior to turbine installation in 2013.
Snohomish County Public Utility District plans to install two large turbines about 200 feet below the surface of Admiralty Inlet between Whidbey and Marrowstone islands.
The pilot project would harness tidal power to generate 100 kilowatts of electricity, or enough to power between 50 to 100 homes.
“The main purpose of this project is to use different acoustic technologies to calculate and evaluate all the fish and invertebrates who inhabit this area,” said John Horne, a 49-year-old UW fisheries and aquatic resources professor who is supervising the project.
“We will compare the data and see how these technologies can be used together or separately.”
Once assembled, the data will be used to determine the best location for the turbines.
On Wednesday morning, a crew of oceanographers on the RV Jack Robertson retrieved the devices while a smaller craft with reporters and photographers circled around the site.
Horne now will spend the next several months analyzing the accumulated data.
The components — known as the echo sounder, acoustic camera, wave, acoustic Doppler and multibeam sonar — all use sound waves to paint a precise picture of underwater life, sending out signals that are reflected back to the source.
“The images that come back are generated by sound but are very visual and very close to what we see in pictures,” Horne said.
The components, on three separate underwater platforms, are self-contained with power sources and data storage capacity and are submerged for one month at a time.
During that time, the data is collected during 12-minute bursts every second hour.
Horne said a real-time connection is not possible without a direct cable connection, since wireless data transfer technology doesn’t have the necessary bandwidth to transmit through water.
The platforms were timed for recovery, releasing an orange buoy Wednesday morning that the crew used to locate the equipment for retrieval.
The UW data will help determine two aspects that need to be determined prior to turbine installation: the turbines’ impact on underwater wildlife and vice versa.
Horne said it is important to understand what conditions are like before the turbines are installed so as to evaluate potential impacts.
Once the turbines are in place, the acoustic devices will monitor and adjust conditions, Horne said.
“There could be the tendency for some of the larger sea animals to attack the devices, and we need to understand those probabilities,” he said.
“We want to understand how the turbines will change migration patterns and if they will actually attract fish.”
In December, a separate UW study said nearly two years of monitoring showed that Admiralty Inlet is an ideal place for tidal energy generators.
UW oceanographer Jim Thomson said researchers measured currents of up to 8 knots, or 9 mph, faster than initially expected.
Thomson also said then that data collected so far showed the site wasn’t used much by marine species.
Jefferson County Reporter Charlie Bermant can be reached at 360-385-2335 or at firstname.lastname@example.org.