Environmental Impact Assessment: How the Effects of Wind Turbines Are Measured

Wind turbines are considered one of the cleanest and most sustainable methods of energy production. Unlike nuclear or fossil fuel-based energy, wind power doesn’t pollute the environment or contribute to climate change. Still, wind energy remains one of the most closely monitored, assessed, and regulated energy sectors. A key part of this regulation is the Environmental Impact Assessment (EIA), carried out when a wind farm is being developed. What does this process involve and how do we ensure that the energy we produce is safe for people and the planet? We asked the experts.

According to Neda Smalinskiene, a public health expert at the environmental consultancy "Ekosistema," the EIA is critical for determining whether a planned development meets environmental and health standards.

“Every human activity has an impact on the environment—positive or negative. The EIA allows us to identify whether the anticipated impact of a project exceeds allowable limits, such as for noise or shadow flicker. It also helps select the best available technologies, the most suitable site, and mitigation measures if needed,” explains Smalinskiene.

Assessing Noise and Shadow Flicker

When planning a wind farm, the first step is evaluating its potential effects on the environment and public health. This includes examining the project location, nearby residential areas, protected zones, cultural heritage sites, flora and fauna, terrain, and landscape.

The physical and technical characteristics of the proposed turbines are also assessed—especially important for nearby residents. How tall will the turbines be? How much noise and shadow flicker will they produce? What health impacts could arise?

Noise and flicker are modeled using specialized software based on technical specifications provided by turbine manufacturers. If calculations show that noise levels may exceed permissible limits in nearby areas, measures are proposed to mitigate the impact—such as reducing turbine output, especially at night.

Similarly, to manage shadow flicker, software calculates when turbine blades could cast moving shadows on nearby buildings, based on sunlight hours in Lithuania. Turbines can be automatically paused during critical times to ensure compliance.

A Detailed, Transparent Process

Independent experts conducting EIAs adhere to Lithuanian laws, including the Environmental Impact Assessment Law and other regulations, as well as globally recognized methodologies, modeling tools, scientific literature, and local/international experience.

“The EIA process is comprehensive, with oversight from multiple state agencies to ensure objectivity. Only qualified experts can conduct assessments, and results must conform to established legal norms,” says Smalinskiene.

The Environmental Protection Agency plays the leading role, with involvement from other authorities depending on the project’s location: municipal governments, the National Public Health Center, the Department of Cultural Heritage, the State Service for Protected Areas, and emergency services. Public participation is also a key part of the process.

“Agencies involved in each EIA vary depending on site-specific issues. For instance, if a proposed wind farm is far from protected or heritage areas, those respective institutions may not be required to participate,” explains Smalinskiene.

Ornithological Studies and Location Challenges

Ornithological surveys are the longest part of the process. At least a year before construction begins, the Lithuanian Ornithological Society monitors bird populations to determine whether the site is suitable. Even after turbines are built, monitoring continues for 3–5 more years.

Smalinskiene adds that public fears are often based on myths. “People have complained that cows stop giving milk or earthworms disappear—even before turbines are built! Some say they feel headaches or cramps. But in our experience, the chirping of birds can be louder than the turbines themselves on calm days.”

Many forget that municipalities often conduct feasibility studies and define optimal turbine zones in master plans long before developers begin EIA procedures.

“People sometimes ask for turbines to be built elsewhere, further from towns. But finding a suitable site isn’t easy. Developers must consider environmental factors, infrastructure, grid connection access, and more. Site selection and assessment begins well before the formal EIA, and it's a long, costly process,” says Smalinskiene.

She stresses that because the EIA evaluates only the most appropriate locations, changing the site later is usually unnecessary and impractical.