Better Plan, Wisconsin

F is for FLICKER

Why is Wind Turbine Shadow Flicker a Problem?

If you ask a wind developer, he'll tell you shadow flicker isn't a problem.

If you ask people inside of the 86 turbine wind farm near the town of Byron in Fond du Lac and Dodge Counties, they'll tell you about what they are experiencing. And they'll tell you to bring a video camera.

This video shows the effect of shadow flicker on their homes.

The town of Union's large wind ordinance recommends a setback of at least 2640 feet to minimize the impact of shadow flicker.

(Download the entire ordinance by clicking here)

From the Town of Union Ordinance: Findings on Shadow Flicker:

"Adverse health effects from wind turbine noise can be exacerbated by the rotating blades and shadows from the wind turbines.As wind turbine blades rotate in  sunny conditions, they cast strobe-like shadows on the windows of nearby homes and buildings causing shadow flicker that cannot be avoided by occupants. Shadow flicker can cause some people to become dizzy, nauseated or lose their balance when they see the movement of the shadow. Shadow flicker from wind turbines at greater than 3Hz poses a potential risk of inducing photosensitive seizures. Therefore, wind turbines should be sited such that shadows from wind turbine blades do not fall upon the windows of nearby dwellings or within 100 feet of dwellings for any considerable period. The Wind Energy Handbook recommends a setback of 10 rotor diameters to avoid shadow flicker on occupied structures. (See Acoustic Ecology Institute special report 2008; Burton 2001; UK Noise Association 612006, Graham Harding 2008 and Dr. Nina Pierpont 31212006 andBl112006)

If placed too close to a road, the movement of the wind turbine blades and resulting shadow flicker can distractdrivers and lead to accidents. (See NRC May 2007 report,pg.263) Wind turbines have been known to throw ice and debris from the turbine blades. According to Professor Teny Matilsky from the Department of Physics and Astronomy at Rutgers University, ice throws from large wind turbines can reach up to a distance of 1750 feet and blade throws can reach 2500 feet.