The federal government will decide next month whether to allow a higher number of accidental bird and bat deaths at two Maui wind farms.
Auwahi Wind Energy is asking the U.S. Fish and Wildlife Service to allow an “incidental take” of 140 ope’ape’a, or Hawaiian hoary bats, up from the 21 bats it’s currently allowed to take.
Kaheawa Wind Power II, meanwhile, is requesting to increase its incidental take of adult hoary bats from 11 to 38 and nene from 30 to 44.
The final programmatic environmental impact statements for four Hawaii wind farms, including Auwahi and Kaheawa, were published Aug. 2. After a 30-day evaluation period, the U.S. Fish and Wildlife Service will issue separate final decisions on each of the four permit requests. The process has been ongoing for the past couple of years, after it became clear that the wind farms were going to exceed the number of permitted bat fatalities.
Located on Ulupalakua Ranch land in Kanaio, the 21-megawatt Auwahi wind farm came online in December 2012 and includes eight turbines and an 11-MW battery storage system. It’s run by American Electric Power, which acquired it from Sempra Renewables earlier this year. The incidental take permit and license that Auwahi got from the federal and state governments in 2012 is good through 2037.
The 21-MW Kaheawa Wind Power II project, meanwhile includes 14 turbines and 10 MW of battery storage on the slopes of the West Maui Mountains near Maalaea. Its federal and state permits were issued in January 2012 for a 20-year term; the wind farm started operating in July 2012. The facility is run by TerraForm Power and Younicos, previously SunEdison/First Wind, according to the state Energy Office.
When both wind farms got their permits, the risk that wind projects posed to bats in Hawaii “was largely unknown and underestimated,” Auwahi stated in its habitat conservation plan. The number of accidental deaths allowed at the wind facilities was “based on the available information at the time.” But since then, technology and research methods have improved, and more bat fatalities have been observed than expected. Both wind farms have upped their low wind speed curtailment, a method that keeps the turbines operating only when the wind reaches a certain speed.
In August 2014, KWP I and II increased their low wind speed curtailment from 5 to 5.5 meters per second. In the four years after that, no bat fatalities were observed within the KWP II search area, though within the same time period, KWP II reduced its search area and also began using canine-assisted searches. As of June 2018, three bat fatalities have been observed at KWP II, along with four nene from 2012 to 2017.
In 2015, Auwahi began voluntary low wind speed curtailment with a cut-in speed of 5 meters per second. In 2018, the cut-in speed was increased to 6.9 meters per second from August through October, which was estimated to reduce fatalities by 59 percent.
“Auwahi Wind has observed 25 bat fatalities since operations began in 2012,” said Melissa McHenry, managing director of external communication for AEP. “It’s too early to quantify the benefits of voluntarily applying low wind speed curtailment at 6.9 m/s in 2018, but preliminary indications are good.”
If Auwahi is allowed to increase its incidental take, McHenry said that Auwahi will minimize risk to bats by applying year-round low wind speed curtailment and even more significant curtailments at night. The wind facility will adjust this practice, including the months and turbines to which it’s applied, “to ensure that it is working to reduce the impact on bats,” McHenry said.
She added that Auwahi has worked to reforest 130 acres of bat habitat in Puu Makua on Maui, sponsored U.S. Geological Survey bat research, conducted predator control and petrel burrow monitoring on Haleakala and funded nene pens in the national park.
“Additional mitigation is expected to include creation of a f1,752-acre bat foraging habitat with forested hedgerows and water features, research level monitoring, and a bat occupancy study on leeward Haleakala,” McHenry said.
Like Auwahi, the Kaheawa wind farms have had to invest in mitigation efforts, including installing predator-free enclosures for Newell’s shearwaters in West Maui. If KWP II is allowed to increase its take, the wind farm plans to support research on the life history, occupancy, habitat usage and foraging habits of bats; continue to fund nene mitigation at an existing pen at Piiholo Ranch or fund nene mitigation at Haleakala Ranch; and expand the current low wind speed curtailment of 5.5 meters per second to year round from sunset to sunrise.
Rob Weltman, president of the Sierra Club Maui Group, which has been following and commenting on the process, said that the Sierra Club wants to see the wind farms provide managed roosting and foraging areas for bats and expand the search area and frequency of searches for carcasses.
The Sierra Club also supports increasing cut-in speeds at all wind farms to the 6.9 meters per second that Auwahi experimented with, while monitoring to ensure the changes in speeds reduce the observed rate of fatalities by half.
Weltman said the Sierra Club doesn’t believe fines are enough; the companies “must commit to curtailing operations to the extent required” to reduce fatalities and avoid jeopardizing the survival of the bats.
“While reforestation for bat habitats is a good thing to do, we don’t know yet what the effects of that work will be on the bat population, while we do know that bats are being killed by the wind turbines,” he said. “Wind energy production is renewable and a valuable contributor to Maui’s electricity needs, but optimal output has to be weighed against the consequences to endangered native species.”
Fern Duvall of the state Department of Land and Natural Resources said that “it’s obvious that climate change is upon us” and Maui needs clean energy resources. But at this point, “we just don’t know enough about the long-term effects” of wind farms on bat populations.
“We want to have more green energy, but there are downsides, and it really does need to take careful consideration so that we do not cause irreparable harm to these really Hawaiian, endemic species,” said Duvall, the program manager of DLNR’s Native Ecosystem Protection Management Maui Nui program.
Duvall explained that because so little is known about the population of the hoary bats in Hawaii, it’s hard to say how much of an impact the wind farms are having on their population.
He said that low speed wind curtailment is a “very good” step toward reducing the risk, though he added that the reforestation efforts might need to be increased. Recent information shows that bats may use up to 3,000 acres, and the value of the reforested areas depends on how much habitat space and food they provide.
“Unfortunately, the real problem is we are learning as we go forward, and we don’t know if we have the luxury of learning as we go forward at the rate we go forward,” Duvall said.