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Energy Department buoy off Virginia coast will use lasers to measure airspeeds

VIRGINIA BEACH, Virginia – Everyone knows gusty winds whip over the ocean off the coast here. Weather buoys out there measure speeds at the water’s surface.

But what about winds 100, 200 or even 600 feet above the ocean?

That is crucial, but so far unknown, information for companies looking to build offshore wind farms with turbines proposed to stretch close to 600 feet tall.

On Dec. 12, a ship carrying a new high-tech weather buoy motored out of Little Creek and about 23 miles into the Atlantic Ocean. The buoy will be moored in 80 to 100 feet of water for about a year to collect data.

The unique thing: It will use lasers to measure wind speeds at different altitudes.

“That’s really the missing information that’s critically important to the wind industry,” said Will Shaw, project manager at the Pacific Northwest National Laboratory, which developed the $1.3 million buoy for the U.S. Department of Energy.

Kind of like a police radar gun, the buoy will shoot a series of lasers into the air that will measure wind speed by tracking how fast tiny airborne particles, such as sea salt, are flying in the wind.

Generally, wind speeds are faster higher above the ocean surface because there is less friction between the atmosphere and the water.

The 10-ton bright yellow buoy – built in British Columbia and trucked several weeks ago to Virginia Beach – is 23 feet long, 8 feet wide and 10 feet tall. It’s designed to withstand normal storms but might be pulled from the ocean if threatened by a hurricane, Shaw said.

The buoy’s instruments are powered by a small wind turbine and solar panels; a diesel generator serves as a backup power source.

Its first mission will be to collect data for Dominion Virginia Power’s project to install two test turbines offshore. That project, backed by a $47 million federal grant, could set the stage for a large wind power farm.

Dominion last year won an auction to lease 113,000 acres of federal waters about 24 miles off Virginia Beach for a project that could include 200 turbines. The company has until 2018 to come up with a plan for a wind farm that officials have said could power up to 700,000 homes.

No offshore wind farms exist in the U.S. today, but 14 are in various stages of development, including the Virginia Beach site.

Data gathered by the buoy will be essential to learning how much electricity the turbines might generate, which is the key to evaluating the economic feasibility of wind power, said George Hagerman, senior research associate for the Virginia Tech Advanced Research Institute.

“This will reduce uncertainty,” he said. “They will have more confidence in their energy estimates.”

The data will also be used to check the accuracy of existing wind speed computer models.

Additionally, the buoy could help scientists and companies understand the intricacies of wind. One scenario to be explored is what kind of strain is put on turbines when the afternoon sea breeze blows toward land, while wind at higher altitudes blows in a different direction.

“That kind of phenomenon is of keen interest to the wind industry,” Shaw said.