Going to Bat for Bats

January 3, 2020

If we’re going to deploy renewable energy systems, we need to learn from the mistakes of the past and be pro-active about emerging issues.
One such issue is the impact of wind energy on bats.
It’s not the Armageddon anti-winders would have you believe – but it is real, and combined with other, greater threats, like loss of habitat, pesticides, and emerging diseases, it’s a challenge for conservationists.

Fortunately, there is a powerful motivation on the part of researchers and wind developers to find solutions, and results are extremely promising.

NRG Systems:

Hinesburg, VT, USA – A trial of NRG Systems’ Bat Deterrent System at the Pilot Hill Wind Project in Illinois yielded an overall reduction in bat fatalities of 67 percent, and greater reductions with species commonly affected by wind projects. The results of the trial were announced on March 27, 2019, by EDF Renewables, the developer/owner of the Pilot Hill Wind Project, at the AWEA Wind Project Siting and Environmental Compliance Seminar in Albuquerque, New Mexico. Located in Kankakee and Iroquois counties, the 175MW Pilot Hill Wind Project was made possible by a 20-year power purchase agreement with Microsoft Corporation and has been in commercial operation since 2015.

Testing of NRG’s ultrasonic acoustic Bat Deterrent System was conducted at Pilot Hill between August and October of 2018. Fifteen out of the facility’s 103 turbines were outfitted with Bat Deterrent Systems. A 5.0 m/second cut-in speed curtailment was simultaneously applied at the deterrent-equipped turbines. Michael Azeka, Director, Environmental Strategy at EDF Renewables, said, “Our goal with this trial was to gauge the efficacy of combining curtailment with NRG’s Bat Deterrent System to reduce bat mortality at wind turbines. The results of this trial are very encouraging and suggest that this approach to minimizing bat impacts is a compelling one for the wind industry.” There are several bat species present at Pilot Hill, including multiple migratory tree species. The testing revealed a significant reduction of 72% with Silver-haired Bats, 71% with Hoary Bats, and 94% with Big Brown Bats. Eastern Red Bats proved harder to deter, with 58% reduction in mortality for the two treatments together.

At the moment, raising cut-in wind speed is the most widely used method for reducing bat mortality at wind turbines. While effective, many wind plants in North America experience a significant loss of energy production when this curtailment is implemented. Brogan Morton, Senior Product Manager at NRG Systems, said, “The Pilot Hill trial is especially encouraging because it suggests that we can minimize bat impacts while increasing the amount of energy produced at wind plants struggling with this crucial issue. This is a win for all parties involved, including developers, conservationists, and, most importantly, the planet.”

The Pilot Hill trial was preceded by a two-year study at the Los Vientos Wind Energy Facility in Texas, which saw an overall reduction in bat fatalities of 54 percent. NRG’s Bat Deterrent System is currently available in North America. The company plans to hold trials of the technology in Europe in 2019.

A solution to protect Hoary bats is welcome, because the species is vulnerable at wind development sites. New study below.


“Drawing on data accumulated through Bat Hub monitoring, our paper reports evidence that the hoary bat is declining in the Northwest,” said Rodhouse, one of NABat’s key architects. “The study also looked for, but did not find, evidence of decline for the little brown bat, which has been heavily impacted in eastern North American by white-nose syndrome.”

White-nose syndrome is a fungal condition that does not affect people but is devastating to bats. It was first identified in 2006 and has killed millions of bats in North America, mainly in the continent’s eastern half.

“White-nose syndrome was documented in the Northwest in 2016 and may not yet have caused regional impact to the little brown bat,” Rodhouse said. “However, the discovery of hoary bat decline is consistent with the hypothesis that the longer history of wind power development, spread over a larger geographic area, has impacted that species through collision and barotrauma. These hypotheses can be evaluated and updated over time within the OSU-Cascades Bat Hub framework of collaborative monitoring.”

Barotrauma refers to injuries caused by rapid changes in atmospheric pressure such as may occur around the blades of a wind turbine. Examination of dead bats collected near turbines often reveals signs of the internal hemorrhaging associated with barotrauma rather than collision.

“The rate of hoary bat decline is worrisome and, if persistent over the next few years, represents a major threat to long-term persistence of the species in the region,” Rodhouse said.

Pantagraph – Bloomington, IL

Preliminary results from a study involving a wind turbine at Heartland Community College in Normal indicate that using software that turns off turbine blades at lower wind speeds can cut bat mortality in half.

“We’re killing less bats, significantly less bats,” said Janet Beach-Davis, associate director of Heartland’s science lab. “We’re really happy.”

Heartland’s wind turbine has been in operation for seven years. Early studies were hampered by crops and dense vegetation around the turbine, making it difficult to find bats that had been killed. About five years ago, a large area in the “kill zone” around the turbine was switched to mowed grass and some gravel, said Beach-Davis.

“We’re confident with the data we’ve got now,” she said.

In 2017 and 2018, Beach-Davis and Illinois State University zoology professor Angelo Capparella, searched each morning for dead bats around the turbine. Generally, she handled weekdays and Capparella handled weekends.

They went out early in the morning, before scavengers could get to any carcasses.

The searches took place from Aug. 1 through Oct. 31 — prime time for bat migration.

Walking five times around the turbine, in ever-smaller circles, they would look for dead bats.

In 2017, they found 15 bats.

In 2018, special software was installed that prevented the blades from turning unless wind speeds were at least 5 meters per second — roughly 11 mph — during migration season.

That year, only eight bats were found dead.

Bats “don’t like to fly when it’s windy,” explained Capparella.

Bats eat mosquitoes, moths and other insect pests, but they are under a lot of threats beyond wind turbines.

White Nose Syndrome, a fungal disease, has hit bats hard in the United States and Canada.

Loss of habitat and declining food sources are other problems.

With spraying and other methods used to control insects in agriculture, “you’ve got a landscape of death from an insect standpoint” in the Midwest, said Capparella.

With so many challenges hitting together, “they’re just getting hammered,” he said. Capparella said 90% of the population of Little Brown Bats has been lost.

Jim Hubbard, executive director of facilities and public safety for Heartland, said, “We haven’t done any analysis of how much energy we’ve lost,” but said mitigation efforts are the right thing to do.

Audubon Society:

Audubon strongly supports properly sited wind power as a renewable energy source that helps reduce the threats posed to birds and people by climate change. However, we also advocate that wind power facilities should be planned, sited, and operated in ways that minimize harm to birds and other wildlife, and we advocate that wildlife agencies should ensure strong enforcement of the laws that protect birds and other wildlife.

3 Responses to “Going to Bat for Bats”

  1. rhymeswithgoalie Says:

    Traditional FF power and urban/industrial sprawl have been killing birds and bats for decades. Anti-wind talking points conveniently ignore this history.

  2. ecoquant Says:

    As @rhymeswithgoalie suggests …

  3. Brent Jensen-Schmidt Says:

    Take measures, no worries.
    Meanwhile bats, and every other living thing, are headed for deeper shit, way way deeper than wind farm kills. Like extinction for example. Side priorities, especially important ones like maintaining the ambiance of the view, are trivialities.

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