Bat deaths from turbines are well-documented, and represent one of several issues the wind industry must address head-on sooner rather than later.
How many bats are killed by wind turbines each year? There have been several studies, and estimates vary. It has been estimated, for example, that each of the 86 wind turbines on Wolfe Island just outside Kingston kill an average of 30 bats a year.
John Goodrich-Mahoney, a senior project manager with the Electric Power Research Institute, a research group based in California and funded by North America¬ís big utilities, says the mortality rate per turbine can run as high as 50 per year.
With more than 20,000 turbines installed across North America ¬ó and growing ¬ó the numbers start to add up.
The turbine deaths are a concern, but bats are battling another great threat these days, a fungal infection that causes a condition called white nose syndrome.
How this fungus infects and causes bats to become sick is still a bit of a mystery, but its impact is clear: more than a million, if not millions, of bats have been killed since the disease surfaced in 2006. It was detected in the Bancroft/Minden area of Ontario a year ago.
Both turbine deaths and fungus-related deaths could have a big impact on the economy. Bats are a natural pesticide because they gobble up flying insects that threaten crops. Fewer bats means more insects more insects means greater application of nasty industrial pesticides to keep bug populations under control.
A study published in this month¬ís issue of the journal Science estimated that bats save the agricultural sector many billions of dollars a year in pest-control services ¬ó in fact, as much as $53 billion US. It warned that over the next five years the sector will begin feeling the financial impact of bat deaths.
¬ďThat¬ís why there¬ís a lot of focus on bats right now,¬Ē says Goodrich-Mahoney. ¬ďAnything that can reduce mortality is of interest.¬Ē
Goodrich-Maloney has taken the problem into his own hands. A couple of years ago he came up with the idea of a bat detection system that could be installed within the nacelles of wind turbines. Each system would consist of four ultrasonic microphones that could detect bat echolocation calls near the sweep area of a turbine¬ís blades.
Ground-level field tests have so far been encouraging. The next step, likely to start this year, is to mount the ultrasonic microphone system onto the nacelle of a GE wind turbine located at the U.S. Department of Energy¬ís National Renewable Energy Laboratory in Colorado.
A tiny remote-controlled helicopter will be modified to make bat calls as it flies around the turbine. ¬ďThen we¬íll see if we can detect the calls,¬Ē says Goodrich-Maloney, explaining that the system will be designed to eventually integrate with the control system of a turbine. This would give turbines the capability of automatically slowing down or completely stopping blade rotation whenever bats are detected nearby.
¬ďWe¬íre not going to be able to save all the bats, but we¬íll be able to reduce the bat deaths significantly,¬Ē he says.
Major wind-turbine manufacturers such as Siemens and Vestas are watching the research closely because they know that the system, if it works as promised, represents the best way to protect bat populations without reducing the productivity of wind projects.
It¬ís conceivable that future generations of wind turbines will have some variation of Goodrich-Maloney¬ís system built directly into a turbine¬ís nacelle.
Of course, it won¬ít solve every problem. Wind farms still need to be sited carefully, away from the migration routes of birds and at a reasonable distance from homes.
And even then, there is a small contingent of the population that dislikes wind power ¬ó period. There¬ís no arguing with them.
It¬ís not a perfect source of energy, but as one of many clean options it is far better¬ó and more sustainable over the long run ¬ó than continuing to rely on fossil fuels, particularly coal.
You can¬ít make everyone happy. You can, however, continue to improve on what you have to address the problems that are addressable. Goodrich-Maloney¬ís bat detection system is but one example of innovation in action.
But there are more. The machines are getting quieter, more efficient, and less expensive to maintain. Efforts to anticipate and respond to changing wind conditions are becoming more advanced and effective. And options for storing and dispatching wind energy on demand are becoming more affordable.
The trend is encouraging.