Side Effects of Windmills

Wind power is a growing industry all over the world, but windmills may still cause problems. Also called wind turbines, these large power generators can create noise problems and pose a hazard to wildlife, and some consider them eyesores. The benefits of industrial wind turbines are significant, but it's important not to ignore their side effects.

Noise

• Wind turbines produce noise from their motors and from the aerodynamic effect of rotor blades. This noise is generally inaudible to the human ear, and so far, there is no evidence that it causes health problems. However, this noise can be annoying, which may increase stress levels in people who live close to the turbines. Modern wind turbine designs are much quieter than windmills of the past--according to the Chatham-Kent Public Health Unit, a wind turbine at 750 meters emits noise about equivalent to a home refrigerator.

Shadow Flicker

• When the sun is behind a windmill, it casts a shadow that appears to flicker in and out with the rotation of the blades. Shadow flicker can be annoying, especially for people close to the wind turbine, and causes problems in around 5 percent of people with epilepsy. Most wind turbines operate at a frequency below that which triggers epileptic symptoms, however. Enforced setback distances for turbines can help eliminate risks associated with shadow flicker.

Wildlife

• Wind turbines may pose a hazard to birds and bats, especially when turbines are located in migration routes. According to the American Wind Energy Association, high-tension lines, tall buildings and house cats all present a higher risk to birds. Bats collide with wind turbines at a lower rate than birds but are still sometimes killed. The installation of wind turbines can also fragment wildlife habitats.

Ice

• In temperatures below freezing, water in the air can condense on wind turbine blades and form ice. This reduces the effectiveness of the turbine. This ice may be thrown off of the blade and present a hazard to people and objects nearby. Older turbines are more likely to produce ice throw. Newer designs have reduced the danger of this problem. The risk of ice throw is why wind turbines are not used in mountains used for ski resorts and why setbacks for turbines should be carefully enforced.

Interference

• Industrial windmills may create electromagnetic interference, or EMI, when located between a signal source and the receiver. This interference chops up the signal and can prevent television and radio waves from being transmitted properly. The solution is usually to improve the receiver's antenna or install relays to transmit the signal around the turbines. Satellite and cable television are not affected by turbine interference. Wind turbines may also interfere with radar.