Australian wind farm operators are being urged to raise the wind speed at which turbines start spinning to prevent tens of thousands of bat deaths every year.
According to a study published in the journal BioScience, as reported by the Guardian, curtailment — raising the wind speed at which turbines start spinning — is an effective way to dramatically reduce bat deaths.
The average turbines begin at wind speeds of about 6.7 mph and reach maximum output at just over 33 mph. Research has found raising the wind speed at which turbines start by just over three miles per hour would reduce turbine-related bat deaths by 40%. That's a big number, considering Victoria's bat mortality is between 25,000 and 50,000 bats each year.
Emma Bennett, an ecologist who has been overseeing bird and bat surveys at wind farms since 2005, led a four-month trial at a Victoria wind farm that raised start speeds to just over 10 mph, which resulted in a 54% reduction in deaths. This was achieved with just a 0.16% reduction in energy output and only a 0.09% cut in revenue.
Bennett's trial results were published in 2022, but the strong evidence was met with little response from the industry. With federal onshore wind farm guidelines due soon, curtailment has been listed as a possible mitigating step.
Wind and other types of renewable energy are a great alternative to dirty energy. Unfortunately, bat habitats tend to be ideal locations for wind turbines, so as more wind farms are developed, the more endangered bats become.
"There's no other situation in Australia where we would be killing so many mammals accidentally, where we wouldn't change our behaviour," Bennett said, still optimistic, per the Guardian.
Renewable energy projects are key to cooling our planet and protecting the health and safety of all of us. Fortunately, there are other options in development that won't cut into revenue such as bladeless rooftop turbines and AI-based technology that detects animals.
A study showed painting one blade reduced fatalities by 70%. There has also been some success with using ultrasonic sounds to deter bats from turbine areas — a tactic that dropped death rates by 50%.
Professor Brendan Wintle, a University of Melbourne ecologist, told the Guardian the evidence showed Australia could have a cost-efficient renewable energy system that was good for nature, including bats. "It's just a matter of getting the planning right and getting the regulatory environment right to ensure that happens."
Professor Justin Welbergen, an ecologist and co-author of the BioScience paper, was quoted by the Guardian saying, "We all want more green energy that will benefit our climate and, by extension, biodiversity … including our bats."
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