One of the drawbacks of the use of wind turbines is the massive amount of birds killed by them each year. It is estimated by Audubon that of this form of “green” energy is actually the most deadly. In the United States there are 49,000 wind turbines in 39 states. They are responsible for the death of 140,000 to 328,000 birds annually. Another study suggests that number is higher, and does not include the deaths of 800,000 bats annually.
In Canada there are 6,600 wind turbines that kill 54,000 birds annually. Nature Canada estimates that in ten years as wind energy increases ten-fold, bird kills will approach 500,000 on an annual basis.
There are various techniques that have been trialled to keep birds away from the blades of the turbines including radar, GPS, bright lights, and even dressing turbines up to mimic trees. Industry has even tried to produce “smart blades” that sense when a bird is approaching.
And it’s not just about the birds, as damage from bird strikes also compromises the blades which are difficult and expensive to repair.
But as Alex Fox in The Smithsonian and Mark Kinver with the BBC have reported a new study published in Ecology and Evolution has found that if just one of a wind turbine’s blades is painted black, the number of birds killed is greatly reduced. The study done in Norway found that turbines with one black blade killed 71.9 percent fewer birds.
At the Smøla wind farm in Norway “the researchers found that nearly 500 birds were killed by the site’s 68 turbines over a 10 year period. After finding a 2002 study suggesting a single black blade may help deter birds the team decided to try it out on four turbines beginning in 2013.”
The next year found only six birds killed by the painted turbines versus 18 killed by four unpainted turbines. How does this work?
“The researchers say the black blades may allow birds to visually recognize the spinning turbine as an obstacle by creating a “motion smear” that allows them to avoid the dangerous blades.”
There has not been a trial yet to learn if other colours like red might work as well as black on the blade, or how to handle the situation of a bird strike at night in the darkness where colour is not seen.
But any design improvement that mitigates bird mortality is worth pursuing as wind power becomes the popular choice to provide power.
Images: Renewableenergyworld, Naturalblaze