Defense officials say large, industrial wind turbines such as those proposed for Nantucket Sound can interfere with military radar systems if built in the radar’s line of sight, according to a report released yesterday.
Based on the report’s conclusions, the officials have asked for more analysis about whether the proposed 130-turbine Cape Wind project would interfere with an Air Force radar station in Sagamore.
The 62-page report, prepared for Congress by the Office of the Director of Defense Research and Engineering, specifically concludes that previous analysis of the effects on the PAVE PAWS radar station were ”overly simplified and technically flawed.”
The report calls for a more comprehensive study ”on an expedited basis.”
That conclusion stands in stark contrast to earlier correspondence from federal officials that found the Nantucket Sound project would pose no hazard.
In fact, whenever questions about radar interference were brought up before, Cape Wind officials would cite a 2003 letter from the Federal Aviation Administration that affirmed ”no hazard” to aviation, and a 2004 Air Force letter that said the project would ”pose no threat to the operation of the PAVE PAWS radar.”
The new Department of Defense findings echo similar a 2005 British report, which concluded that turbine blades can produce ”hole(s) in detection” for military radar systems.
”It validates the claims we’ve been making: that this is a very serious problem,” said Cliff Carroll, a wind farm opponent and co-founder of windstop.org. ”The real risks of this project are really starting to show themselves.”
For the Cape Wind developers, the radar question is just the latest in a series of thorny issues to emerge since the proposal was unveiled five years ago.
Among other concerns, Cape Wind proponents have had to answer to charges that the project – which would be the nation’s first offshore wind farm – would threaten birds, regional fishing and boat navigation.
The proposal remains the subject of an intense federal review by the Department of Interior.
Earlier this year, U.S. Rep. William Delahunt, the Cape’s congressman and a Cape Wind critic, asked federal officials to investigate how the 417-foot turbines would affect military and civilian radar. Of particular concern for Delahunt were potential effects at the PAVE PAWS station, which is located on the northwest corner of Camp Edwards and is one of just two fixed-site early warning radar systems in the nation.
Some have asked whether the turbines would create ”clutter” or an ”undesired reflected signal return,” according to the Defense report, when the radar signal returns to the Cape station. One of the findings of the Defense study is large turbine blades can ”appear to a radar as a ‘moving’ target of significant size if they are within the radar line of sight.”
While the report says there are potential technologies to minimize the effects on radar, it adds that ”only a few” have been proven.
Carroll, who has been pushing the issue of radar interference for more than two years, yesterday called the new report ”a huge deal.”
Cape Wind officials, however, took a cautious approach responding to the Defense report. ”We need to take some time to study this report,” said Mark Rodgers, a Cape Wind spokesman. ”I’m probably going to leave it there for today.”
Barbara Hill, executive director of Clean Power Now, a local organization that supports the wind farm proposal, said additional Defense analysis is important, as long as the process is open to the public and done in a timely fashion.
”This blip on the radar screen is just that,” Hill said, referring to many hurdles the renewable energy proposal has overcome during the review process. ”We will learn from this and we will get this built.”
Kevin Dennehy can be reached at firstname.lastname@example.org. David Schoetz can be reached at email@example.com.
(Published: September 29, 2006)
By Kevin Dennehy and David Schoetz, Staff Writers
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