Library filed under Shadow Flicker
In late February 2009 the Minnesota Department of Health (MDH) received a request from the Office of Energy Security (OES) in the Minnesota Department of Commerce, for a “white paper” evaluating possible health effects associated with low frequency vibrations and sound arising from large wind energy conversion systems (LWECS). MDH agreed to evaluate health impacts from wind turbine noise and low frequency vibrations. In discussion with OES, MDH also proposed to examine experiences and policies of other states and countries. Below are the Introduction and Conclusions of the white paper released in May 2009. The full report can be accessed by clicking on the link at the bottom of this page.
This suit was filed against the Village of Libertyville (IL) and DPR Investments LLC shortly after a business-scale wind turbine was erected and became operational within 600 feet of residential properties. The Entegrity 50 kilowatt, 120-foot turbine is owned by DPR Investments doing business as Aldridge Electric Company. Complaints of noise, shadow flicker and blade flicker were heard right after the turbine started turning. On July 24, 2009, the Court issued a compromise ruling stating that the turbine was affecting neighboring residents and restricted the turbine hours of operation to weekdays from 9 a.m. to 3 p.m. (see: http://www.windaction.org/news/22373 )
As the state pushes wind energy and communities create guidelines to accommodate it, those living in the shadow of Mark Richey's wind turbine wonder if the effort is at their expense. The Richey turbine meets the general spirit of the state's guidelines as well as the city's current wind turbine bylaw, under which Richey received a special permit that allows a turbine in an industrial zone to be at least 300 feet from a residential zone. ...As the city takes a closer look at its wind ordinance, neighbors are arguing that the rules most officials are accepting as well thought out are out of sync with reality.
Jason LaCroix, 14 Hill St., told councilors of the "human effect" the turbine has caused in the neighborhood. He recently purchased and put in a new glass door on his house. He had to take it out after he saw the shadows of the turbine's rotors on his wall reflecting off the glass. On his rooftop deck, the turbine is "virtually eye level," he said. The flicker study done for the Richey turbine wasn't accurate and minimized what impact it would have on the Back Bay neighborhood.
Newburyport has its own laser light show, or an equivalent thereof, from an unlikely source: the new industrial-sized wind turbine that recently was turned on in the industrial park. At night, from the middle of the northbound lane of Route 1, the twirling blades catch the red beacon light atop the massive structure, and the light shoots out along the blades. It's pretty spectacular, but not if the light is shooting right into the window of your home.
A northern Missouri man has filed a lawsuit against farm equipment maker Deere & Co. and a wind energy company alleging nearby wind turbines have hurt his property values and made him ill. Charlie Porter filed the lawsuit in the 4th Circuit Court of Missouri against Deere and The Wind Capital Group, a St. Louis-based wind energy company.
In Fond du Lac County, Wisconsin, in spite of what wind developers and wind lobbyists assert, 1000-foot setbacks are not a sufficient distance between homes and wind turbines that are 40 stories tall. There are indeed problems with noise and shadow flicker at this distance. Ask people in the town of Byron in Fond du Lac what they think of the 1000 foot setback. Duration: 2 minutes 37 seconds
Flicker in the yard and in the house, rural Maine. Duration: 2 minutes 19 seconds
Wind turbines are known to produce shadow flicker by interruption of sunlight by the turbine blades. Known parameters of the seizure provoking effect of flicker, i.e., contrast, frequency, mark-space ratio, retinal area stimulated and percentage of visual cortex involved were applied to wind turbine features. The proportion of patients affected by viewing wind turbines expressed as distance in multiples of the hub height of the turbine showed that seizure risk does not decrease significantly until the distance exceeds 100 times the hub height. Since risk does not diminish with viewing distance, flash frequency is therefore the critical factor and should be kept to a maximum of three per second, i.e., sixty revolutions per minute for a three-bladed turbine. On wind farms the shadows cast by one turbine on another should not be viewable by the public if the cumulative flash rate exceeds three per second. Turbine blades should not be reflective.
Large scale shadow flicker is a phenomenon, not experienced by people on an “industrial scale”, with football field-sized shadows moving across their home or through their local views. This report prepared by physicist Rick Bolton examines the problems with the shadow flicker modeling at a proposed site in New York State. A portion of the report is provided below. The full report can be accessed by clicking the link on this page.