Wind power threatens hoary bats
New report details threat to bats from windmills
A new report predicts a great and rapid decline to hoary bats, unless a way is found to reduce the bats’ fatalities at wind electricity generating facilities in North America. The hoary bat population could decline by 50 percent in the next five years, according to the report.
Hoary bats are the most widespread bat species in North America, ranging from northeastern Canada all through the U.S. They can even be found in Hawaii. We tend to associate bats with caves, but hoary bats like to hang out in trees, blending in with their surroundings by curling up in such a way as to resemble dried leaves.
The insectivores are solitary, meaning that they don’t hang out in groups or families. They also migrate. We know that hoary bats can reach heights of 8,000 feet on their migration flights, but scientists and bat experts are still in the dark on their migration range and patterns. As they are solitary and migrate, instead of whiling away the colder months of the year hibernating in close proximity to other bats, they are not susceptible to white-nose syndrome, which has caused great declines in the populations of about two dozen other North American bat species.
In flight, hoary bats are pretty good at avoiding trees and buildings, but the blades of a wind turbine can be too fast for their echolocation to detect, leading to collisions with the blades of the turbines. Between 76,000 to 152,000 hoary bats are killed each year by collisions with wind turbines. Windmills are also dangerous for birds, mostly raptors such as red-tailed hawks, turkey vultures, and eagles.
The report comes out at a time when the mantra of electrify, electrify, electrify is coming from folks like environmentalist Bill McKibben, who are trying to get the U.S., indeed, the entire world, to decarbonize. Last night I read a book review by McKibben in The New York Review of Books of Saul Griffith’s new book, Electrify: An Optimists Playbook for Our Clean Energy Future. McKibben is gung ho for Griffith’s prescription of electric cars, electric heaters, electric stoves, and electric everything else in our modern world. McKibben agrees with Griffith that people would rather have their spleens surgically removed than to sacrifice (drive less, turn the thermostat down, etc.) to avoid a climate crisis. So if folks won’t reduce on their own, we have to figure out a way that makes their cars, homes, and buildings carbon neutral.
And as McKibben points out, reducing driving or running the thermostat lower only reduces carbon output. It doesn’t get you to zero, which can happen if you electrify everything. Another point I might add is that electrifying everything—cars, hot water heaters, even aircraft—decarbonizes folks who disregard the science or the problem of global heating.
A great deal of decarbonization is and will be solar, but there will be more and more wind generation as well. Windmills have been around for a long time. After all, Don Quixote attacked them, thinking they were giants, and Cervantes wrote that over 400 years ago. In the 1800s Cape Cod boasted 1000 windmills, and there were thousands more throughout the eastern United States.
Yet these were not the mega-generating behemoths that are being built today. Even the mega-generating behemoths of a few years ago are not the mega-generating behemoths of today. In the last two decades the height of the windmill’s hub, the top of the tower around which the blades spin, has grown from around 190 feet to 295 feet, with their rotors encircling a diameter of 380 feet, well longer than a football field, including the end zones.
We have wind turbines close to where I live. Driving along the freeway and watching them turn, the big blades don’t look as though they are moving very fast. Most of them rotate at around 15 to 20 times a minute, not the lazy image of Don Quixote, but nothing that seems bat killingly fast.
But let’s do some arithmetic. If the end of the blade goes around 20 times in a minute, that means that it takes three seconds to go around once. Pi times the diameter gives us the circumference, which turns out to be 1194 feet. So the end of the blade is traveling 1194 feet in 3 seconds. converting to miles per hour: (3600/3) x (1194/5280) = 271 mph. That’s pretty fast! Faster than anything that hoary bats ever evolved to deal with.
The Energy Department predicts that from 2020 to 2030, the amount of electricity from wind will almost double and almost triple by 2050. That means thousands more bat killing windmills blades all over the country.
Solutions include siting electricity generating windmills (Please don’t call them wind farms!) away from bat flight paths, migration corridors, and habitat. The wind generating industry is also working with conservationists on better ways of running the turbines. One development is what is called turbine “curtailment,” which is the practice of slowing or stopping the windmill blades when bat collision is likely.
If you’d like to find out more about hoary bats, bats in general, and what you can do to help them, check out Bat Conservation International.