Wind energy and radar: A National Security Risk

Lisa Linowes|September 25, 2011

U.S. air space has been made less safe by turbines and our national security compromised because of a reckless policy of siting wind towers within 50-miles of radar installations. Military radar experts in the field know the damage that’s been done. But with the debate surrounding energy policy dominated by politics and money, the military has bowed to the pressure.

Military leaders are under pressure to not disrupt White House green energy policies even while green energy technology is disrupting our navigation aids and impairing U.S. national security.

Stetson Mountain turbines

Washington has a track record of muzzling military testimony to protect its pet policies and political friends. Last week, Air Force Gen. William Shelton admitted he was pressured by the administration to change his testimony regarding LightSquared’s network and its adverse impact on military space-based navigation systems. We applaud Shelton for not backing down.

But the military has not been honest about the effect wind turbine technology has on our national radar systems.

The fact is that our air space has been made less safe by turbines and our national security compromised because of a reckless policy of siting wind towers within 50-miles of radar installations.  Military radar experts in the field know the damage that’s been done. But with the debate surrounding energy policy dominated by politics and money, the military has bowed to the pressure.

Radar interference and mitigation

The military services and federal agencies have conducted numerous studies on the radar question, as have multiple international military and private interests. Not all studies agree on levels of severity and potential mitigations, but all agree that large scale industrial wind turbines have the potential to negatively affect military installations, radar, and navigation aids.

The problem is easy to explain, but difficult to resolve.

Since radar technology is designed to detect moving objects, spinning turbine blades create interference which degrades the signal. Wind towers carry a signal strength greater than a Boeing 747, so when the radar repeatedly sees the large return it cannot detect actual aircraft in the same area.

Large expenditures of time and funds have been allocated in pursuit of technical mitigations but so far the results are controversial. According to Raytheon lead radar engineer, Peter Drake, radar mitigation technology does not yet exist. “…These things [turbines] inside of 20 miles, look like a 747 on final approach,” Drake said. The trick, he adds, “…is to somehow make them disappear, while still being able to see a real 747…we have not figured that out yet.”

By 2008, nearly 40% of our long-range radar systems were compromised by wind turbines. Today, more than twice the wind capacity is installed and the problem of radar interference persists.

Proper siting of turbines, while politically cumbersome, is the only tried and true form of mitigation. But this means denying wind developers access to land areas covered by radar.

Radar interference at Travis Air Force Base

The problem of radar interference first cropped up in the United States in early 2007 near Travis Air Force base in California. Two wind proposals were before the Solano County Planning Commission that would erect over one-hundred new turbines in the area. The spinning blades resulted in smaller planes appearing to drop off the radar while others appeared when they weren’t actually there.

Both Travis and the Solano County Airport Land Use Commission urged a delay in approving the projects, citing air safety and the need for more time to study the effects the towers had on navigation.

In his letter to the County, Colonel Steven Arquiette, commander of the 60th Air Mobility Wing at Travis warned the turbines would create significant interference with the base's radar and could lead to potentially serious flight safety hazards.

The county heeded their concerns and agreed to the delay. Commissioner John Moore was particularly firm when he said "...Nothing happens unless the Air Force's problem gets fixed."

Travis held firm on its objections until a year later when enXco, one of the project proponents gifted $1 million to the base for technical mitigations. 

Col. Arquiette was told by his superiors to accept the money and withdraw his complaints despite the fact that the mitigation offered little more than a ''detuning" of the radar signal to lessen the impact of the towers.

enXco's project was built but the radar problem was never resolved.

The Travis AFB Midair Collision Avoidance (MACA) pamphlet was updated this year with a warning that states the wind farms southeast of the base interfere with radar. Unless an aircraft is 'squawking' it can't be seen. See image on right or click here to access the MACA .Travis AFB Midair Collision Avoidance Pamphlet

Squawking refers to turning the aircraft’s transponder on to allow communication between the aircraft and the secondary radar system installed at air traffic control facilities.

The strategy of requiring areas to be transponder-only airspace could work but relies on pilots complying with the warning. Recreational pilots may not remember to comply or their aircraft might not be adequately equipped. And worse, drug runners or — in this post-9/11 world — terrorists, might prefer they not be seen. The first thing the 9/11 hijackers did after seizing control of our passenger planes was to turn off the transponders.

Remarkably, participants at the radar forum at AWEA’s Annual Conference last May touted the Travis solution as the gold standard for mitigating turbine interference. You be the judge.

Shepherds Flat wind and long-range radar

The radar problem at Travis involves airport surveillance radar. This type of radar is used by air traffic control and has a range of about 60 miles. Long range radar monitors in-route air traffic control used for homeland defense and NORAD. The mile distance for long range radar is distance of 250 miles.

A year ago, the unmanned Air Force radar facility located in Fossil, Oregon became the source of significant controversy when the Pentagon objected to the proposed $2 billion Shepherds Flat1 wind energy facility. The project's 338 GE turbines totaling 845 megawatts would be built in the line of site of the radar sweep .

Fossil's radar monitors the U.S. border along the Pacific northwest including the territory north, over the Canadian border, and south into California.

Oregon Senators Ron Wyden and Jeff Merkley were outraged and tried pressuring the military into silence. They joined nine other senators in writing to Defense Secretary Robert Gates requesting a resolution of the conflict and insisting the Department failed to search hard enough for practical solutions.

Sen. Wyden also lobbied for $8 million in the 2011 appropriations to cover the cost technical mitigations akin to what was implemented at Travis.

Outcome TBD

Windaction.org interviewed long-range radar specialists familiar with the mitigation proposed for the Fossil radar. The technology known as "Scan Step" involves installing a digital processor that, with software, will work to lessen the effect of turbine clutter. The process results in targets becoming invisible. In fact, aircraft the size of the space shuttle could fly through the radar swept area undetected.

The processor underwent its first test in the field last spring. Word back was that it failed all tests. None of the FAA or DOD engineers we've spoken to believe Scan Step technology will work in the way people have been led to believe. No one doubts there will be a loss in radar resolution. Critical questions still pending are: 1) What level of radar reduction will be deemed acceptable? 2) Who will decide the level of reduction that will be permitted? and 3) Will the public be informed as to the extent Shepherds Flat has compromised our national security?

When Windaction.org asked a staff member of the Senate Armed Services Committee what would happen if Step Scan didn't work, his response was an abrupt: "It has to."

Indeed! Shepherds Flat is slated to go in service in 2012.

The cases at Travis AFB and Fossil should raise red flags. But unlike the LightSquared example, the military is comfortable whitewashing the turbine issue and  hiding behind technical mitigations that don’t work. Our national security and air safety have been compromised by wind turbines and U.S. taxpayers are unknowingly funding the degradation of our radar through federal renewable programs. It’s time the military had the courage to step up and speak the truth to the American people.

1. The Shepherds Flat wind facility was the subject of the White House memo that complained the project received $1.2 billion in governmental subsidies covering 65% of the cost and risk for the project while its equity sponsors incurred only about 11% and an estimated return on equity of 30% -- a hefty return for a project where the American public is absorbing the bulk of the investment risk.

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