Patterning wind turbine blades reduces avian fatalities

Wind farms are often in the news for the wrong reasons – they kill soaring birds, and are particularly adept at killing raptors, despite the raptor’s legendary vision.

Following on from the successful pioneering experiment in Norway, BBU initiated a similar “blade-painting” experiment in Hopefield, South Africa, in close collaboration with Umoya Energy in early 2023, with approval from Civil Aviation.

To field test this new mitigation in Africa the idea was to paint two broad “Signal Red” stripes on a single blade at four turbines (design based on McIsaac 2001).

Sixteen months’ monitoring of the four patterned turbines and 16 control (un-patterned) turbines have shown dramatic results: no further birds were killed by the patterned blades in 16 months, but birds continued to be killed at the control turbines – at the same rate as measured before any painting took place.

Even more exciting was the fact that there were no more raptors – the group most vulnerable to collision with spinning blades – killed at the patterned blades (7 before painting, 0 after painting). This, despite at least five species of raptors (Black Harrier, Jackal Buzzard, two species of kite, and Rock Kestrels) active and breeding on or around the wind farm, whilst raptors continued to be killed at the control turbines. 

This constitutes only the second time this passive mitigation has been tested, following the pioneering Norwegian experiment in Smola where a solid black blade showed similar results (72% reduction in fatalities for all birds, 100% reduction in eagle deaths).

This augurs well for future experiments with red, or black, patterned blades to be trialled in different environments and with different species. Should they, too, prove successful, then newly approved wind farms may be able to order pre-patterned blades to reduce raptor deaths dramatically at a fraction of the cost of present AI solutions.