On August 23, the Land Board voted to accept a supplemental environmental impact statement for the Auwahi wind farm on Maui and approve a new Habitat Conservation Plan for the take of an additional 119 endangered Hawaiian hoary bats over the course of its incidental take license, which expires in 2037.
The company’s original plan allowed the facility to take only 21 bats. As of June 30, it had taken 46.
Last month, Environment Hawai‘ireported that the state Endangered Species Recovery Committee had approved the plan after the company made several amendments to address the committee members’ concerns about proposed bat take minimization and mitigation measures.
To minimize the number of bats killed by the wind turbines, located on Ulupalakua Ranch, the company last year began curtailing night operations until wind speeds reached at least 6.9 meters per second. This practice, known as low wind speed curtailment (LWSC), has been proven to significantly reduce bat take. Other wind farms throughout the state use LWSC, but none have raised their cut-in speeds (the speed at which turbine blades start spinning) as high as Auwahi has.
The Kawailoa wind farm on O‘ahu, which has also had a higher than expected level of bat take and is also in the process of amending its HCP, has chosen to minimize bat take through the use of acoustic deterrents aimed at driving bats away from the spinning blades.
Rather than adopt the same practice, Auwahi has chosen to wait and see the results of Kawailoa’s use of the deterrents.The O‘ahu wind farm is the first in the country to use them commercially.
“We are very excited about deterrents. It’s part of our adaptive management …We’re interested in the effects to other wildlife,” Auwahi’s Marie VanZandt told the board.
Because the Auwahi site is extremely windy, the company would need to determine whether acoustic deterrents are suitable. “We want to understand how microphone propagation changes in different conditions,” she said.
Land Board member Chris Yuen asked about ultraviolet light deterrents, which have been tested on Hawai‘i island.
VanZandt said UV deterrents are still being tested by the Department of Energy, but there is nothing commercially available.
Yuen said he’d like to see the take of bats minimized as much as possible. He noted that the Land Board had included a condition in the plan for the proposed Na Pua Makani wind farm on O‘ahu requiring the use of deterrents if and when they are determined to be effective and feasible.
VanZandt explained that the environ- mental conditions at each wind farm site differ, as do the strategies they can use for take minimization. “Some have a lower wind profile, some have a higher one. … Some can’t implement higher cut-inspeeds. Na Pua Makani did not commit to using low wind speed curtailment as high as we proposed,” she said.
She pointed out that on the U.S. mainland, the Fish and Wildlife Service, which must also approve bat take levels by wind farms, has decided that facilities that use a cut-in speed of 6.9 meters/second don’t even need to secure an incidental take permit because the bat take is likely to be very low.
Should LWSC prove ineffective, the company has committed to using deterrents, she said.
Yuen asked how it would determine if curtailment is ineffective.
VanZandt explained that Auwahi’s fiveyears of data on bat activity at the site when LWSC was not being used provides a baseline.
Yuen said that he was concerned about deeming LWSC effective if it merely reduced take below the historical baseline. “Are you saying the curtailment would be considered effective if it reduced take to below five a year? … If we had a deterrent technology that might reduce it to, say, one, and it was commercially available and cost effective [the] HCP does not require you to use that technology,” he said.
He then asked if she had any objection to the board including in its approval a condition on deterrents similar to the one imposed on Na Pua Makani.
She said she doesn’t believe Auwahi would have any objection. She added that the way the plan is structured, the wind farm has an incentive to keep take as low as possible. Once the level of take hits certain thresholds, the company has to expend resources to mitigate the increased take.
“What’s been your experience so far with 6.9” meters per second as the cut-in speed? board chair Suzanne Case asked.
VanZandt said the wind farm had an average of three observed bat deaths before using the higher cut-in speed. Last year,it only had one. Because take levels are so low, it’s difficult to determine if the LWSC scheme is effective or not, but it shows promise, she said.
Even so, Yuen recommended that the Land Board approve the plan with the following amendment: If the Department of Land and Natural Resources’ Divi- sion of Forestry and Wildlife determines that a commercially available deterrent would be effective in reducing bat take at the site at a reasonable cost, the agency will require Auwahi to implement that deterrent. If Auwahi disagrees with DOFAW’s assessment, Yuen said, DOFAW’s recommendation would then be brought to the Endangered Species Recovery Committee, and then the Land Board, for approval.
In addition to Kawailoa’s use of ultrasonic deterrents, Yuen noted that in Texas, they’re being put on 250 turbines. “This may be something that’s coming. … It’s starting to work and may be theway to go in the future,” he said. — Teresa Dawson
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