Wisconsin wind projects face restrictions to protect rare cave bats

State environmental regulators are proposing permit changes to reduce or avoid killing rare cave bats that may be affected by wind energy projects.

Around a decade ago, the Wisconsin Department of Natural Resources began requiring measures for certain projects to minimize impacts to cave bats under permits that allow harming or killing a protected species. The requirements were put in place for four bat species that had been listed as state threatened or federally endangered due to white-nose syndrome.

The deadly fungal disease that looks like white fuzz on the nose of bats was first detected in New York in 2006. Since then, white-nose syndrome has killed more than 90 percent of northern long-eared, little brown and tri-colored bat populations.

So far, wind projects have been exempt from measures to protect bats due to a lack of research on ways to minimize their impacts, according to Stacy Rowe, the DNR’s endangered resources energy liaison. Now, she said studies have shown that curtailing turbines or reducing speeds are effective at limiting or preventing bat deaths.

“The numbers are high enough to where it’s a pretty big concern nationwide with bats. We are not the only state looking at putting in restrictions,” Rowe said. “The Fish and Wildlife Service at a national level has voluntary restrictions for bats, and other states nationwide are starting to put in more restrictions as well.”

States like Minnesota, Illinois, Maine and New York require some curtailment of wind facilities. Research estimates up to nearly 1 million bats are killed each year by wind projects nationwide, including almost 400,000 bats in the Midwest.

The state’s proposed changes would affect existing and proposed wind developments. Wisconsin has 480 wind turbines representing 828 megawatts in capacity, according to a map from the U.S. Geological Survey.

Wind turbines would have to adjust speeds, use sensor technology

Wind developers would be required to raise cut-in speeds, which Rowe said means slowing blade speeds down, in priority areas where maternity roosts exist or bats hibernate during the winter. The slower speeds would be required at night during the bats’ active season from April 1 through Oct. 31.

Outside of those areas, wind projects must either use year-round sensor-based technology that would change speeds when bats are detected or slow turbine speeds to lower levels than what’s required in bat priority areas at night during their active season. Monitoring would also be required for two to four years to determine whether the conservation measures are reducing bat deaths.

Michael Whitby is director of the bats and wind energy program at Bat Conservation International. Whitby, who authored a study on curtailment research, said the state’s proposal is largely in line with federal guidance for wind developers. He added bat fatalities would likely be reduced by an average of 50 percent.

“Wisconsin’s implementation of this should greatly reduce bat fatalities in the state,” Whitby said.

Whitby said most bat activity occurs at lower wind speeds when turbines aren’t producing as much electricity. Even so, the proposal is likely to result in energy losses and less revenue for utilities or energy companies.

While shutting down or curtailing turbines protects bats, research found it also results in an annual loss in energy production ranging from less than 1 percent to 10 percent. Whitby said the state’s proposal would likely reduce energy losses to less than half a percent each year. However, he noted wind developers have been resistant to curtailing turbine operation due to concerns about the viability of projects.

Representatives with Alliant Energy and We Energies, which own wind projects in Wisconsin, said they’re reviewing the agency’s proposal.

“We share their goal to protect wildlife and ensure it is balanced with the need to provide customers across the state affordable, reliable and clean energy,” We Energies spokesperson Brendan Conway said in an email.

Wisconsin needs more wind to reach net-zero emissions by 2050

Amy Barrilleaux, spokesperson for Clean Wisconsin, said bat collisions with wind turbines are not insignificant. Even so, she said research shows fossil fuel plants pose an even greater threat to birds and bats.

“We know from studies that fossil fuel power plants, like coal and gas plants, are about 35 times more dangerous to birds on a per gigawatt basis than wind energy. I think the same holds true for bats,” Barrilleaux said. “While there are impacts to bats and birds from wind turbines, doing nothing is worse.”

Wisconsin needs around 21 gigawatts of wind energy to meet rising energy demand and reach net-zero emissions by 2050, according to a 2022 study commissioned by Clean Wisconsin and RENEW Wisconsin. Barrilleaux noted that climate change and habitat loss are also top threats to bats, adding Wisconsin is far behind Midwest states for wind capacity.

State regulators and bat advocates say they support the shift to carbon-free electricity, including John Griffin, senior director for urban wildlife programs with the Humane Society of the United States. He said conservation measures seek reasonable changes that reduce impacts to both energy generation and bats, noting they provide important ecological services.

“The pollinating that they do, the insect control that they do, it’s just an enormously beneficial thing,” said Griffin.

The DNR is accepting public comments on the proposed changes until Jan. 2.