Studies conducted by the British Ministry of Defence in 2005 and obtained by the Times concluded turbine blades can produce ''hole(s) in detection'' in air defense radar systems, sometimes causing aircraft to become obscured from view. While British researchers are trying to develop computer software to reduce the turbines' impact on radar, the technology currently does not exist.

U.S. military officials have said little about their research, but the federal government recently froze a permit for a wind park in southeastern Wisconsin until the Air Force is sure turbines won't interfere with a nearby radar station.

U.S. Rep. William Delahunt was briefed this month by Pentagon officials on the radar issue and said available evidence has reaffirmed his national security concerns over Cape Wind Associates' proposed wind farm.

''They're losing airplanes from radar (in Britain),'' said Delahunt, the Cape's congressman and a Cape Wind opponent. ''These are unanswered issues and they can't be dismissed.

''I know they haven't been answered,'' he added, ''because I've been told by the Department of Defense.''

The Quincy Democrat has asked the Committee on Homeland Security to investigate how Cape Wind's project would affect radar, calling it a potential threat to the PAVE PAWS radar station in Sagamore, as well as civilian radar.

Delahunt said he has sent documentation on his concerns to numerous other congressional committees. Recipients include a conference committee debating a Coast Guard bill that would ban wind turbines within 1½ miles of shipping and ferry lanes - mainly because of maritime radar concerns. If approved, that bill would likely kill the Cape Wind proposal, an ambitious plan to build 130 417-foot turbines on Nantucket Sound.

While Cape Wind officials are following the Pentagon study closely, spokesman Mark Rodgers said they remain confident radar technology will be developed to address any interference concerns.

''For those wind farms where they are finding (radar) is a problem,'' he said, ''I'm sure there will be technology to address those concerns.''

Michael Hay, a renewable energy specialist for the British Wind Energy Association, said the industry group will resume tests with the British military into new technologies in May. ''It seems these problems can be overcome, not through changing of the wind projects, but an upgrading of the radar equipment,'' he said. ''It looks like something we can solve without any major costs.''

But Cliff Carroll, a Cape Wind opponent, said the technology doesn't exist. And that, he said, should be a concern not just for the military, but for those who rely on the three regional airports that surround Nantucket Sound.

For more than a year, Carroll, a co-founder of windstop.org, has pushed federal officials to look at the British radar experience. Now, he predicts, the radar issue will sink the Cape Wind project.

''If you go by the UK standard, this thing never would have gotten off the drawing board,'' he said. ''It's the wrong place. ... It's toast.''

While Carroll's prediction remains to be seen, U.S. military officials are certainly paying closer attention to wind projects - onshore and offshore.

Earlier this year, a panel of defense and Homeland Security agencies started looking into the effects of modern windmills on military readiness. The study was required as part of the 2006 Defense Authorization Act, and includes representatives from the Air Force, Army, Navy, Missile Defense Agency and U.S. Northern Command.

Defense leaders are saying little about the study. ''Until this report is submitted to Congress, it would be premature to talk about specifics of what the team is discussing,'' said Maj. Susan Idziak, an Air Force spokeswoman.

Cape Wind officials say the company has already received approvals from both the Federal Aviation Administration and the Air Force.

In particular, Rodgers cited a 2004 FAA letter that affirmed ''no hazard'' to aviation, as well as a 2004 Air Force letter that said the Nantucket Sound project would pose ''no threat to the operation of the PAVE PAWS radar.''

''As far as we're concerned,'' Rodgers said, ''this has been looked at by the FAA.''

Earlier this month, the FAA notified a Chicago developer that a plan to build 133 turbines in Wisconsin may pose a ''presumed hazard'' to air traffic and the nearby Horicon military radar station.

''Therefore, the operational impact on the Air Force mission of the proposed wind farm development can't be fully assessed at this time,'' Fred Souchet, an FAA specialist, wrote to Forward Energy Center, the project's developer.

Rodgers said the Cape and Wisconsin projects cannot be compared because of different geographical positions relative to nearby military radar.

The Wisconsin project is within the ''sight-line'' of the military radar system - meaning radar beams would strike turbines directly without topographical interference such as hills.

The main beam of the Air Force radar station in Sagamore, however, would shoot above the line of turbines, Rodgers said.

Kevin Dennehy can be reached at David Schoetz can be reached at .
source:http://www.capecodonline.com/special/windfarm/radarrisk30.htm
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