Wind energy and radar: A safety risk

Posted on November 17th, 2011 by

While of course the wind farm may be one of those projects with such overwhelming policy benefits (and political support) as to trump all other considerations, even as they relate to safety, the record expresses no such proposition. — U.S. Court of Appeals

Federal agencies and 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.

The fact is that our air space has been made less safe by turbines and our national security has been compromised because of a reckless policy of siting wind towers within 50-miles of radar installations.  FAA and 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, they’ve bowed to the pressure.

Radar interference and mitigation

U.S. 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 signal strength greater than a Boeing 747, so when the radar repeatedly sees the large return it cannot detect an 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. 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 and 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 aircraft 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 the concerns and agreed to a delay.

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

Today, the Travis AFB Midair Collision Avoidance (MACA) pamphlet warns that wind farms southeast of the base interfere with radar. Unless an aircraft is flying with its transponder on (‘squawking’) it can’t be seen. (See image on right or click here to access the MACA . )

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.

Despite the apparent flaws, the “Travis solution” is touted as the gold standard for mitigating turbine interference.

FAA’s inadequate reviews

Last month, a U.S. federal appeals court found that the FAA failed to adequately analyze whether Cape Wind, the controversial proposal to erect 130 utility-scale turbines offshore in Nantucket Sound, would pose a hazard to air navigation.

The project’s proponent vigorously defended the agency’s review claiming that for over eight years the FAA repeatedly found the project would pose no hazard. But the record clearly shows otherwise.

In May 2010, the FAA issued identical Determinations of No Hazard for each of the Cape Wind turbines. These determinations were conditioned on implementing a tiered mitigation plan that incrementally upgraded nearby radar systems to correct for any interference the turbines would produce.  While the upgrades would limit the impact of the spinning blades, the FAA acknowledged that the ‘fixes’ would reduce the resolution of the radar. Like Travis, aircraft flying in the area might go undetected or false objects could appear. If, after the turbines go online, the interference was found to be a safety risk, the FAA recommended revising airspace procedures to restrict air traffic to transponder only – also like Travis.

Remarkably, this is not the first time the FAA’s No Hazard determinations on wind turbines were overturned by the Courts. In 2008, a near identical finding to the Cape Wind case was reached by the Federal Appeals Court. In that case, Clark County, NV challenged the FAA over turbines proposed to be built several miles from the County’s planned airport.

Why compromise? has interviewed radar specialists familiar with the mitigations implemented at Travis and those proposed near Nantucket Sound and elsewhere. These experts are very clear that the reduction in radar resolution poses a serious risk to air safety and should not be permitted.

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. The larger question is why? Why are our agencies and military services allowing these compromises and why are the courts — and not the agencies themselves — being called upon to correct their actions? Indeed, politics are playing a role in these compromises along with a general disinterest by many in Washington to consider both the good and bad of renewable energy.

The Court had it right when it stated: “While of course the wind farm [Cape Wind] may be one of those projects with such overwhelming policy benefits (and political support) as to trump all other considerations, even as they relate to safety, the record expresses no such proposition. 

Written by Lisa Linowes, Executive Director of the Industrial Wind Action GroupThe opinions expressed in this article are solely those of the author, Lisa Linowes.

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