Most eastern bat species are declining, and several – including some that occur right here in Virginia – are listed as endangered or threatened. Bats provide important ecosystem services, including consuming insect pests and acting as pollinators. Bat populations are declining due to habitat loss, climate change, and worsening air quality, among others factors. Additionally, over the past decade, there have been reports of hundreds of thousands of bat deaths related to wind turbines, with the highest concentrations in the Midwest and Great Plains regions.
There are many thoughts as to why bats are attracted to the area around the turbines. Some potential factors include the noise produced by the wind turbines, the concentration of insects in the open spaces around, and various bat roosting and mating practices. Most bat deaths occur on low wind speed nights.
Does this mean wind projects must be stopped because of the impacts to bats? Absolutely not! Growing collaborative scientific research has provided us with a number of operational best practices that can be implemented to significantly reduce the number of bat fatalities seen each year. Some of these best practices include:
- Increasing the turbine cut-in speed (the speed at which the turbine first begins to rotate). This has been shown to decrease bat fatalities by up to 50%!
- Feathering turbine blades (which stops the blades from turning) when wind speeds are low. Some members of the American Wind Energy Association have already committed to this best practice to curtail impacts to bats.
- Predicting bat behavior and adjusting accordingly. Bats are only active at night and peak fatalities occur in the late summer and fall.
- Avoiding, to the greatest extent possible, installing wind projects within areas of intact forest in which bats are known to roost. These bats are likely to preferentially feed in the open areas around the turbines.
There have also been developments in acoustic devices that have the potential to deter bats from flying near turbines, though the effectiveness of these devices are in question. The impacts of ultraviolet light are also being evaluated as a potential option.
It is clear that there is an unfortunate correlation between wind turbines and bat deaths. Fortunately, this is something the wind industry has already acknowledged and is well underway to rectifying. The most important takeaway is that there are best practices that can be implemented with minimal impacts to the productivity of wind producers. Encouraging the wind industry to adopt these practices and supporting the scientific community as they continue to find solutions is the best route forward. Wind remains a clean and cost-effective energy resource, which should continue to develop in the most responsible way possible.
Resources for further research: