Wildlife & Biodiversity

Can painting a blade black save Great Indian Bustards from wind turbines?

A regulatory slowdown in wind power production could result from failing to address the harm caused by turbines to wildlife

By Jasleen Bhatti
Published: Thursday 29 July 2021

A new technology developed by the Norwegian Institute for Nature Research (NINR) has the potential to save the critically endangered great Indian bustard (GIB) from becoming extinct. It involves painting one of the three blades of a wind turbine black.

Just 100 of these massive, low-flying birds — the world’s heaviest flying birds — remain in the Thar desert. The area is the last breeding stronghold for the critically endangered species. Previously, it was primarily threatened by hunting and habitat destruction.

The most pressing threat to its future is a collision with overhead power lines. Despite its acclimatisation to wide horizons and grasslands, the GIB was unable to foresee or evolve to avoid this human-made threat.

The Indian government classifies semi-arid grasslands as revenue wastelands. In consequence, solar and wind energy projects have taken up most of the Thar. It is by far the best option we have to mitigate climate change and ensure the survival of human and wildlife populations on the planet.

RE adoption becomes an issue when wind farms, power lines, and other structures are situated in places where wildlife can be severely endangered. Wind turbines and steel towers are known to disrupt birds’ migration patterns and also increase their fatalities. 

According to the Union Ministry of New and Renewable Energy, collisions with turbines and electrocution on transmission lines are major causes of death for GIBs in the key wind power states of Rajasthan and Gujarat. According to the Wildlife Institute of India, almost 18, that is a fifth of the dwindling population of GIBs, die each year from collisions with power lines.

Earlier, the Forest Advisory Committee had made it mandatory for painting the vane tips of wind turbines with orange colour to avoid bird hits.

Considering the urgency of the GIB’s plight, the Indian Supreme Court (SC) ordered on April 20, 2021 that all powerlines in GIB habitat must be underground and bird diverters must be installed in the interim. A bird diverter is essentially a bright plastic disc that looks like a Christmas light and warns birds in flight from a distance so they don't collide. However, there is disagreement among scientists about their efficacy.

This SC rule applies not only to the bird’s current range but also to future habitats it may expand into, which offers a vital opportunity for the species to expand and prosper.

Enter NINR

The NINR has found that painting one of the three blades of a wind turbine black reduces bird mortality by 72 per cent. By implementing contrast painting at onshore and offshore wind farms, new wind farms could be built at sites previously not considered feasible, reduce public opposition, speed up permitting processes and increase the profitability of wind farms.

Statkraft’s 152.4 megawatt Smøla wind farm, located on a bird-rich island on Norway’s west coast, was studied for bird death data collected between 2006 and 2016.

In total, the wind farm has 68 wind turbines and provides 356 gigawatthour of electricity annually, enough to supply 17,800 Norwegian households. It is located in flat terrain, 10-40 metres above sea level.

In August 2013, a single blade of four turbines at the Smøla project was painted black. Avian fatalities were recorded for seven and a half years before and three and a half years after the painting.

Bird carcasses and feathers were found at the bottom of turbines at the wind farm by trained sniffer dogs, after which dead birds were observed and recorded by wind farm personnel and passers-by.

As a result of painting the turbines, the fatality rate was 71.9 per cent lower compared to the unpainted turbines.

How does a black blade reduce bird collisions?

NINR scientists explain why birds are susceptible to flying into rotating turbine blades and why a black blade makes the blade appear as a barrier.

In comparison to humans, birds have a narrow binocular frontal field of view and use their monocular and high-resolution lateral fields of view to detect predators, conspecifics and prey.

Birds may not always see obstructions ahead in assumed open airspace, increasing their risk of colliding. By providing ‘passive’ visual cues, birds may be better able to spot the moving blades, thus increasing their chances of evading collisions.

The birds perceive these moving white blades as ‘motion smears’ instead of motorised objects, the kind of a blur effect humans experience when waving a hand in front of their eyes.

Blackening one blade creates patterns that appear to be moving to the bird because its frontal vision is more tuned to movement.

The University of Maryland in the United States conducted a laboratory experiment with American kestrels in 2003. They compared the impact of various blade patterns (striped, stagger, and whole black) and coloured blades, to determine which was most clearly seen by the birds. In the end, it was observed that the whole black pattern was most visible.

NINR researchers recommend either replicating the study with more turbines or implementing the measure at new sites with collision fatalities monitored to determine if similar results are obtained elsewhere. These measures will be crucial in determining whether the effect can be generalised.

In order to mitigate impacts on birdlife and to help support the sustainable growth of wind energy in India, it is essential to gain greater insights into the expected effectiveness of promising mitigation measures.

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