America's growing wind sector may be easing the country's carbon footprint, but it's leaving a heavy imprint on local wildlife.
According to the American Wind and Wildlife Institute, an estimated three to five birds are killed every year per megawatt of wind energy. And new research indicates that wind farms could pose a threat to land-dwelling species, as well.
It's a far cry from President Trump's claim that wind energy "kills all your birds," but experts say they are beginning to pay more attention to how expanding wind facilities are affecting local wildlife.
"In the past decade, there's been a lot of incentive for wind energy development. The Department of Energy is calling for a 10 percent share of wind energy by 2020. With that development, we're seeing quite a few companies looking into buying land, and these lands are home to threatened and endangered species," said Mickey Agha, a graduate student at the University of California, Davis.
Agha authored a study on the impact that wind farms could have on wildlife, which was recently published in the Journal of Wildlife Management. It came about while working on a previous research project on tortoises in the California's Mojave Desert, he said. That project involved setting up cameras at a wind facility to study tortoise burrows. While looking through the tapes, scientists noticed that a host of animals passed through the site: coyotes, bobcats, foxes, skunks and even bears.
"Some of the developments are currently on undisturbed landscapes," said Agha, referring to sites that were being built on the first time. "And once you have the facility in place, infrastructure like roads and turbines add to the fragmentation of habitat. They could block migration routes for birds and restrict corridors that terrestrial wildlife use."
Birds are especially affected. Wind turbines are generally mounted on 300-foot towers and have wingspans that are twice that of a Boeing 747, spinning at around 200 mph. The operators of the first industrial-scale wind farm in the country — in Altamont Pass, Calif. — quickly began to notice that the turbines were killing numerous bird species, including red-tailed hawks and golden eagles, said Todd Katzner, a research wildlife biologist with the U.S. Geological Survey's Forest and Rangeland Ecosystem Science Center.
"Birds like golden eagles are essentially designed to soar on upward-moving wind curves," he explained, "and places with a lot of wind movement are also really good places to put wind turbines. Also, birds tend to not think about threats from things like spinning blades — their evolutionary history prepares them for threats from above, like other birds attacking, or from the ground. They aren't really used to things moving directly in front of them."
Roberto Albertani, associate professor of mechanical engineering with the Oregon State University College of Engineering, thinks he may have a solution to the problem. He recently received funding from the Department of Energy's Wind Energy Technologies Office to experiment with a network of sensors and cameras that he hopes will help reduce eagle fatalities in American wind farms. Working with a team of scientists, including Katzner, Albertani plans to set up a three-part system to test this technology.
"The project has three subsystems: detecting the eagle, providing a deterrent for the eagle and detection if there's a strike on the blade," he explained. "These are all integrated."
The system will be tested at the North American Wind Research and Training Center in Tucumcari, N.M., and the National Renewable Energy Laboratory's National Wind Technology Center in Boulder, Colo. It includes a camera mounted on the towers, which is programmed to identify eagles flying toward it. If it spots one, it will trigger the "deterrent" — images of people, which will hopefully scare the bird away. The turbines will also be equipped with vibration sensors so that if an eagle does collide with one, scientists can examine footage and determine the cause.
Collecting similar data for terrestrial animals is equally important, said Agha.
"What we need to know is what's happening on the ground. For instance — how are the vibrations and noise produced by the turbines going to impact the auditory cues of wildlife? It may also impact their ability to [inhabit] these areas. Future research should look at monitoring these facilities," he added.