Using radar to control wind turbines and reduce bird kills: does it work? 

One of the major criticisms of wind energy facilities is the deadly impact of the fast-whirling blades on birds. Most notoriously, thousands of golden eagles have been killed at the Altamont wind farm; however significant numbers of bird deaths have occurred at many other wind facilities.

Now, wind farm developers are touting radar systems similar to those used by the U.S. Air Force and NASA. In aviation, the technology detects large flocks of incoming birds and is sold to avoid bird collisions with aircraft. At wind facilities, avian radar in theory offers the potential reduce bird kills by shutting off turbines before birds reach the blades.

Just how effective these systems are at wind facilities, however, remains debatable.

Avian radar manufacturers praise the technology.

But a check of several prominent manufacturers’ websites found only visual “simulations” of turbines halting as faux-flocks fluttered through the stilled blades. If the radar is effective, as wind industry officials who have installed radar at major wind facilities claim, where are the videos documenting this technology in action?

Amateur videos documenting bird kills from wind turbines, however, are plentiful on the Internet.

Pattern Energy, developer of the proposed Ocotillo Express wind facility in Imperial County, California, has stated that it intends to use avian radar similar to the Merlin Avian Radar System currently installed at its Gulf Wind Project on Kenedy Ranch in Texas—a major migratory flyway.

In an online article for Pattern Energy, Environmental Manager Rick Greiner said one advantage of the radar system used for the 283.2 megawatt Gulf Wind Project is its ability to run continuously with a neighboring system, not just during bird migratory periods as most other systems do.

“During spring migration,” said Greiner, “each wind farm moves its radar to the southern edge of its site to see birds coming. In the fall,” he says, “we move the radars to the north.”

For the past two years, Pattern Energy has hired outside companies to conduct research to see if the radar is successfully reducing the number of birds and bats killed by the turbines. In the first year, Greiner said the annual mortality rate was 2-4 birds per megawatt and 7-9 bats per megawatt.

Even if that figure is accurate, however, the facility still killed many hundreds of birds in its first year. But Greiner notes, “Our bird rate is low to average and bats are average.” The National Wind Collaborative estimates 3-6 birds per megawatt per year is the average killed in the U.S.

Some eyewitnesses have cast doubt on whether turbines are really being shut off when flocks of birds fly through.

Serious questions are being raised over Pattern’s claim that radar offers a solution beyond diminishing deaths by detecting large flocks of birds. The company aims to rely on the radar as part of the Golden Eagle protection plan at the Ocotillo Wind Energy Facility as well, even though evidence of radar’s effectiveness in protecting individual large birds appears lacking.

According to the plan drafted in March 2011, Ocotillo Express, LLC says it will use the radar system to monitor Golden Eagles that fly within the project area and “curtail turbines when eagles are at risk of collision.” In addition to the radar, OE LLC will have a staff biologist at the project site to monitor the movements of eagles and other wildlife year round for the first five years the facility is in operation.

But in an interview with Stu Webster, director of permitting and environmental affairs at Iberdrola Renewables earlier this month at the company’s proposed wind site in McCain Valley, California, ECM asked whether radar has been proven effective.

“We have experimented with radar,” replied Webster, who contends the technology has shown promising results for detecting large migration patterns. “There has been some discussion on using it to detect single targets,” he added.

Asked if radar has been proven effective at detecting single targets such as eagles, however, Iberdrola’s representive answered, ”No.”

Why, then, does Pattern expect decision-makers to approve its Ocotillo facility based on unproven technology?

ECM has repeatedly requested responses from Pattern Energy, but the company has declined all interview requests.

By Pattern’s own description in project documents, however, its plan makes no claim of effectiveness to save eagles, but rather states that it will allow “opportunities to learn and test hypotheses regarding the effectiveness of such equipment in reducing mortality.”

These plans proposed by wind energy developers aren’t convincing wildlife advocates that wind turbines no longer pose a danger to birds, especially when there is evidence proving otherwise.

In an online article from the Industrial Wind Action Group, David Newstead, the president of the Coastal Bend Audubon Society, relates how he watched a flock of huge White Pelicans fly into the Kenedy Ranch wind facility, yet turbines did not shut off.

“We watched as the pelicans continued soaring between us and the turbines. It appeared that they were getting closer and closer to the next turbine,” he wrote. “We watched as the last bird in the group was struck and literally “erased” from the air (a blade is about the width of a city bus, and moving about 180 mph). It was flying at or just below hub height, and was hit on the downstroke.”

Newstead observed, “This raises some very serious questions about the “radar shutdown” system which is so highly touted by Iberdrola and Pattern Energy as state of the art. The American White Pelican is one of the largest birds in North America, weighing nearly twenty pounds and with a nearly nine-foot wingspan. The turbines obviously did not shut down when this flock approached.”

Findings from a 2008 study, Wind Farms and Radar, by JASON, the Mitre Corporation, brings to question whether these systems work at all. The study found that wind turbines with “tip speeds of 6-7 times the wind speed” interfere with existing radar fielded by the DOA, FAA and other agencies.

This discovery has not gone unnoticed by those opposed to the proposed Ocotillo Wind Energy Facility.

In an email to ECM, wildlife biologist Jim Wiegand, vice president of Save the Eagles International, suggested that wind turbines could also throw off the Merlin radar system, rendering them ineffective at reducing bird mortality rates.

“Their system, because of turbine interference or clutter, will most likely be completely useless when the turbines are spinning,” said Wiegand.

Just how many birds wind turbines have killed is hard to pinpoint. According to an online article for Politifact Tennessee, Albert Manville, a biologist for the U.S. Fish and Wildlife Service (USFWS), estimated that more than 400,000 birds are killed every year in the U.S. by wind turbines, but cautioned that the number was not exact.

“It’s an estimate, and that’s really all you can say about it, frankly,” he said.

The National Wind Coordinating Collaborative, an agency that includes representatives from the wind industry and the USFWS, gives a lower estimate. It concludes that there are three to four birds killed per megawatt per year and with current capacity at 50,000 megawatts, that number totals about 150,000 to 200,000 birds per year.

The number is apt to climb, however, as numerous new wind facilities come online in the future across the nation.

Critics argue that independent studies need to be conducted before wind developers claims that radar systems reduce bird kills can be documented or disproved.

“With this system, many birds still are killed,” Wiegand concluded. “If the radar system does not work in Texas, it will not work at Ocotillo.”

The wildlife expert noted that an eagle or falcon can travel four miles in a minute—thus a 60-second shut down time is inadequate. Radar would also not detect small birds such as the Least Bell’s Vireo on the site, he predicted.

He also questioned the accuracy of body counts, since the industry will control mortality studies.

“You will only know what they decide to reveal. So they will proclaim what a success the radar is,” predicted Wiegand.

“Radar is a wind industry ploy used to sell their deadly turbines,” said Wiegand, who asked why radar has not been installed at Altamont—the deadliest wind facility for eagles—if it is genuinely effective.”