Wind is a green alternative to fossil fuels, but its complex environmental impact may stand in the way of widespread use and acceptance.
Many studies around the world have reported high incidence of bird mortality as they crash into windmills. In Gujarat and Karnataka, two of India’s top states for harnessing wind energy, turbine operators have reported carcasses of more than 50 birds over a period of three years1. Despite some ecological downsides, governments are being compelled to embrace wind energy as a sustainable source of power.
However, experts are now urging the Indian government to redefine policies that place wind farms in the ‘green’ category, exempting them from environment impact assessments.
While many large birds of prey, including vultures and raptors, have a broad visual field to comprehensively cover the sky and the ground, they also have a large blind spot above and below their heads2. As most fly with their heads tilted down, the area immediately in front of them is a blind region, making them vulnerable to visible structures, including wind turbines and power lines. Studies show that among the bird species affected by windmills, predatory birds such as raptors are at the greatest risk of collision. Raptors control populations of small mammals, reptiles and other birds around the windmills. In their absence, says ornithologist Ramesh Kumar from the Bombay Natural History Society, the balance of the local ecosystem is undermined.
A 2018 study3 showed that reduced raptor numbers in wind turbine areas led to increase in the numbers of its prey, the endemic fan-throated lizard Sarada superba. The lizard population had a lower body weight and reduced colouration due to a limitation on resources.
Some studies show that infrasound windmill noise (frequencies below the lower limit of human audibility) may affect birds and rodents4, 5. More nuanced studies are needed to establish the effect of windmill noise on the behaviour of organisms.
According to an environmental assessment report proposed by New Delhi-based Centre for Science and Environment (CSE) in 2013, the initial stages of site clearance and construction can have temporary and permanent impact on the land area, including fragmentation of habitats, large-scale deforestation and soil erosion. Also, if built in ecologically sensitive areas, wind projects can affect decades of eco-restoration efforts.
Animals affected by the infrasound, ecosystem changes and human activity, start avoiding the area. This is a significant problem for those species which have no other sites to inhabit, according to ecologist Maria Thaker from the Indian Institute of Science.
Making wind energy safer
“Green energy and ecological conservation do not have to be mutually exclusive,” Thaker points out.
Mapping the ecological sensitivity of the area, for example factoring in the major migration or nesting sites of birds, may inform smarter decisions about where to build wind farms. “Many wind corridors are in ecologically vulnerable areas,” Thaker adds. Instead of building large turbines, it makes better sense to build smaller ones, spaced out so that birds can fly safely through the gaps.
Ideally, a complete environmental impact assessment should be made before a wind farm is built. However, their classification as ‘green category’ industries exempts them from the need for clearances from regional forest authorities, says Shikha Lakhanpal, a researcher at Bangalore-based Ashoka Trust for Research in Ecology and the Environment (ATREE).
“Almost all European countries, US, UK, China, and Sri Lanka require an EIA for their wind projects,” says Sujith Singh, lead researcher of the CSE report.
While EIA is not mandatory in India, the wind sector does need to follow certain guidelines issued by the Ministry of Environment and Forests (MoEF). If the wind power project lies in a forest or national park/sanctuary, it needs clearances from the State Forest Board, the State Pollution Board, and the National Board for Wildlife. Also, wind projects are subject to the Scheduled Tribes and other Forest Dwellers Act, 2006 if scheduled tribes or other traditional forest dwellers reside on that land. However, the report sites the example of wind power project in Bhimashankar in the Western Ghats that violates these guidelines. Singh adds, “As the wind plants are not air polluting, the State Pollution Board often overlooks the projects.”
Recently, the Ministry of New and Renewable Energy proposed a set of lease rules for the off-shore wind projects which mandates cancellation of lease if the projects cause “environmental damage to underwater flora and fauna”.
M. V. Ramanamurthy, a scientist at the National Institute of Ocean Technology (NIOT) in Chennai, says that NIOT along with National Institute of Wind Energy is conducting an assessment of the environmental impact of India’s first offshore wind power project in Gujarat. “The results of the study would be available in six months.”
The Indian government has set an ambitious target of 60 GW wind capacity by 2022. Strategic planning to spread out wind mills rather than filling up empty spaces with wind farms could go a long way to balance energy and conservation.
“While we cannot undo the mistakes, we do not have to keep repeating them,” Thaker says.
1. Kumar, S. R. et al. Avian mortalities from two wind farms at Kutch, Gujarat and Davangere, Karnataka, India. Curr. Sci. (2019) doi: 10.18520/cs/v116/i9/1587-1592
2. Ed Yong. Vultures blind to the dangers of wind farms. Nature News. (2012) doi: 10.1038/nature.2012.10214
3. Thaker, M. et al. Wind farms have cascading impacts on ecosystems across trophic levels. Nat. Ecol. Evol. (2018) doi: 10.1038/s41559-018-0707-z
4. Zwart, M. C. et al. Wind farm noise suppresses territorial defense behavior in a songbird. Behav. Ecol. (2016) doi: 10.1093/beheco/arv128
5. Hamura, T. et al. Chronic exposure to low frequency noise at moderate levels causes impaired balance in mice. Plos One (2012) doi: 10.1371/journal.pone.0039807
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