British model may hold key to solving wind energy, radar clutter problem.

• Author: Magnuson, Stew

Wanted: Flat ground with a clear line of sight to the horizon and few obstructions.

That is an ideal spot for a wind energy farm. Coincidentally, such topography is also ideal for military and Federal Aviation Administration radars.

The clean energy industry has found itself clashing with the Defense Department and FAA in recent years over the location of windmills, which are sprouting up across the nation from the prairies to the shores.

The crux of the problem is radar clutter. Both the moving blades and the towers they sit on can create false readings. Personnel monitoring screens at military bases, training facilities or other installations that watch U.S. airspace could mistake a windmill for an aircraft. Interference can also create blind spots that pilots of a hijacked airplane, or a small aircraft, could use to avoid detection.

Not only are the turbines becoming more numerous, they are becoming taller. The longer the blades, the more electricity they can produce at a cheaper kilowatt-per-hour cost. However, the increasing heights mean more radar clutter.

Industry advocates are now looking toward Great Britain to serve as an example of how the military and commercial interests can work together to solve the problem. That nation was recently forced to tackle the windmill radar clutter issue in both the technical and policy realms.

"What happened in the UK. is the US wind industry's model for the way we would like to see things proceed here," said Tom Vinson, director of federal and regulatory affairs at the American Wind Energy Association.

The British realized they had a problem when the government set a goal requiring that 20 percent of the nation's energy come from renewable resources by the year 2020, said Bill Troia, Lockheed Martin international business development manager for long-range radars. Offshore wind farms were a large part of the plan. Realizing that they were going to cause radar interference, the Ministry of Defence began rejecting almost all applications.

"It just so happens where you want wind farms is a perfect place for where you want radars--flat, open, good visibility to the horizon. That is also a good area for wind to come in," Troia said.

The United Kingdom is a relatively small nation where there is keen competition for this kind of real estate. Upgrading radar software was tried first, and in some cases, that eliminated the false alarm problem, but it didn't clear up the blind spot issue, Troia added.

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