Wind turbines and birds don’t go well together

Perched on the North Sea, one resource the Netherlands has a lot of is wind. Already since the Middle Ages, while other European countries chopped down their huge forests to generate energy, the Dutch were one of the first to widely employ windmills for that purpose. During the Dutch Golden Age, windmills were one of the major sources of energy for sawing wood, grinding wheat into flour, and most importantly pumping water from low-lying regions into canals and waterways, keeping the country dry. Today, with the Dutch government’s ambitious plans to meet the Paris Agreement and reduce CO2 emissions by 49% of the 1990 rate (approximately 228 million tons of CO2), more than 2,000 wind turbines dot the Dutch countryside, plus several bigger wind parks out at sea. However, while the Netherlands and other countries along the North Sea such as Norway and the United Kingdom are whole-heartedly embracing wind energy as a clean alternative to fossil fuels in the race to stall climate change, a new environmental problem has presented itself.

Each year thousands of birds collide with the 40- to 50-meter-long blades of the wind turbines, seriously threatening some bird populations. The same locations where wind turbines have been placed, due to the amount of wind, are also popular routes for bird migrations. Each spring millions of birds make their migratory journey from Northern Africa and Southern Europe to Northern Europe, or from the North Sea region to Scandinavia. The exact number of bird deaths is difficult to determine. Most of the cadavers are found in water, where most wind farms are located. However, according to Ralph Buij, ecologist at the University of Wageningen, mortality rates for the starling, marsh harrier and common tern are estimated at around 1% a year. Accumulated over ten years, those rates can be as high as 24%, depending on the species. The starling population is particularly sensitive: a slight increase, say an additional 5% rise in annual mortality, could kill 77% of the population within a decade.

In an effort to stop the avian carnage, scientists at the Norwegian Institute for Nature Research in Trondheim have discovered an ingenious solution, which includes painting one of the three blades or the base of the wind turbine black, which would deter the birds from flying directly into them. The idea to have a black blade was first suggested in an American study that discovered kestrels respond the best when there is a contrast between white and black. At the Norwegian wind turbine park of Smøla, the experiment has already been implemented. Every year, six to nine white-tailed eagles were killed by colliding with one of its 68 wind turbines. After painting one of the three blades of the wind turbine black, there were 70% fewer collisions.

In the Netherlands, the Dutch energy company RWE, together with municipal authorities, is currently exploring the possibilities of testing this method on a wind farm near Eemshaven with twelve wind turbines. The wind park generates an average of 190,000 megawatt hours, enough to supply 70,000 households with electricity annually. One of the problems is that wind turbine blades are manufactured to be white, so that a black blade requires a change in the production process.

Other alternative to prevent birds from flying into the blades is to shut down the turbines while the birds make their trek. In Spain, this has already been done; guards carefully monitor bird movements, and as flocks of birds approach, temporarily shut down the wind turbines. However, this is labour-intensive and expensive. Another option includes constructing higher turbines, above the altitude that birds fly. The blades of the higher wind turbines rotate slower than the shorter ones, so there are fewer bird casualties. Another possibility is to surround wind turbine farms with solar parks and to cut vegetation, so that birds have nothing to feed on. However, the most viable solution right now seems to be a simple one: a paint brush and black paint.

Written by Benjamin B. Roberts