Duke Energy Renewables, a commercial unit of the Charlotte-based company, has shown both the promise of wind energy and its ecological cost: Spinning turbines sometimes kill soaring eagles and other birds.
In 2013, Duke Renewables pleaded guilty in federal court to killing 14 golden eagles and 149 other migratory birds at two Wyoming wind farms. The case was the first criminal prosecution for killing birds at wind projects in the U.S.
Duke agreed to pay $1 million in fines and restitution, and to develop a plan to prevent more bird deaths at its four Wyoming farms. The high-tech solution Duke announced Tuesday will be installed at one of the farms where eagles were killed.
The technology, from IdentiFlight International, blends artificial intelligence with precision optics to detect approaching eagles and shut down turbines. Duke said it will be the first wind operator to commercially deploy the units.
Twenty-four units will be installed in Wyoming at the Top of the World wind farm, which is among Duke’s largest with 110 turbines on 17,000 acres. The IdentiFlight technology had previously been tested there.
Wind turbines are as tall as 30-story buildings.
The massive blades, wide as a passenger jet’s wings, appear to spin slowly but can reach 170 mph at their tips and create tornado-like vortices, the Associated Press has reported. Eagles, whose own wings can span more than seven feet, often don’t notice the blades as they scan the ground for prey.
Within seconds, Duke said, the IdentiFlight units can detect and identify the species of birds flying within about six-tenths of a mile. If an eagle’s speed and direction show a risk of collision, an alert shuts down the turbine in its path.
“Avian collisions with turbine blades have been an impediment to growth in the wind industry,” IdentiFlight president Tom Hiester said in a statement. “IdentiFlight was developed to address this problem and promote the successful coexistence of avian wildlife and wind energy.”
The American Wind Wildlife Institute, a nonprofit supported by industry (including Duke Energy Renewables) and environmental groups, said 60 percent of those killed at wind farms are songbirds and other small perching birds. Bats and birds of prey such as eagles, hawks and owls are also frequent victims.
The institute helped test the IdentiFlight system and said it is “excited by the promise of innovative technologies to produce meaningful reductions in wind energy impacts to wildlife.”
Duke Energy Renewables operates 20 wind farms across the U.S., chiefly in western states. The power, enough to power a half-million homes, is typically sold to customers including utilities, electric cooperatives and municipalities.