Report details turbines' risk

Federal department says wind farms could interfere with radar systems that monitor missiles, air traffic

BY MARK HARRINGTON
Newsday Staff Writer

November 1, 2006

Clusters of high-standing wind turbines similar to one proposed off the South Shore could pose security risks by compromising radar systems for missile-defense and air-traffic control systems, a recent U.S. Department of Defense report concluded.

The study, prepared at Congress' request, draws on previous reviews of the effects of wind farms by the British Ministry of Defense, which found the turbines can have "a significant impact on the operational capabilities of military air defense radar systems," as well as a U.S. Defense Department review at a turbine field in upstate Fenner, N.Y., in April and May.

The Defense Department study notes that wind turbines, particularly the towering type clustered in wind farms, can lead to radar system effects known as clutter, shadowing and tracking interference. Together they "increase the difficulty in detecting and tracking targets flying at low altitude in the immediate vicinity of the wind turbines."

Shadowing masks a radar "target" when it's directly behind a wind farm, while clutter refers to inaccurate bounce-back signals from the turbines. Both can lead to tracking interference, an inability of a radar system to "initiate and maintain the track of an aircraft."

Because the report doesn't mention the proposed Long Island Power Authority project by name, it's difficult to assess the possible impact on the 40-turbine project planned for the waters off Jones Beach.

A spokeswoman for the Federal Aviation Administration said the agency was aware of the report, but couldn't comment on its possible impact on that project because the FAA has not yet received an application for it. A Defense Department spokesman wasn't available for comment.

LIPA spokesman Bert Cunningham said the utility's "initial assessment is there is no impact on our project," but he noted contractor FPL Energy awaits an official response from the Air Force.

Babylon Supervisor Steven Bellone, a wind-farm critic, said of the study, "Clearly it's another issue of concern and highlights the fact that this is still new technology." The town recently passed a resolution seeking to force LIPA to compare the estimated $500-million wind farm with alternatives such as updating existing plants.

But advocates for the wind industry called the report "incomplete" because it underplays technologies that can mitigate the impacts of wind farms on some radar systems.

"Decades of experience tell us that wind and radar can coexist," said Randall Swisher, executive director of the American Wind Energy Association, in a statement.

In addition to air-defense problems, the report raises concerns about wind farms' potential to disrupt air-traffic control radar systems. In one passage, the Defense Department discloses uncovering "proprietary information for at least one" U.S. air traffic control radar system that provided "documentary evidence that a large wind farm in the radar line of sight does cause significant loss of primary radar tracking capability for aircraft flying over that wind farm." It declined to identify the system or its location.

Another problem with the turbines is caused by the movement of the massive blades, the Defense Department said, causing them to "appear to a radar as a 'moving' target of significant size if they are within the radar line of sight."

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