Shadow Flicker and Wind Turbine Noise Wars

DN Staff

January 9, 2009

3 Min Read
Shadow Flicker and Wind Turbine Noise Wars

Two posts ago, I mentioned a dispute between abutters and a wind energy project where shadow flicker and noise were cited as potential problem. The tower started going up this week. So I wondered what shadow flicker is (I chose a link to a power company site with a seemingly credible technical explanation) and how loud wind turbines can be.Look no further than Youtube to appreciate the impact of wind turbine flicker, which are the shadows cast by rotating blades. It’s dramatic and I would not want it even a little bit passing over my house, windows, bedroom or property.

“If one of your kids were turning lights on and off like this, you’d be hollerin’ at them to knock it off,” exclaims one Wisconsin resident. His video offers evidence that no one should have to put up with this pollution of a sort. The video goes on to say the county established setbacks of turbine 1,000 feet that should take care of it. That would not seem to be the case.

One Larry Wunsch lives next to the Forward Energy Project in Wisconsin and produced a compelling video that looks at noise which he compares to that of jet engines. Indeed, his video would seem to bear that out. “Can you sleep listening to this? This is what we live with night after night,” says Wunsch. From the videos, he does not appear to be exaggerating.

Wunsch also describes shadow flicker - obviously a daytime-only condition when the sun is shining - as like lights being turned on and off.

Another enterprising videographer models flicker from a proposed wind farm that would pass over homes and a prison in Gartree, U.K. The author, who sounds reasonable and knowledgeable, says a two-kilometer setback rule should be adopted. In the U.S, 1,000 feet from dwellings is not uncommon or 1.5 times the height of the tower. Another remedy, he says, is deploying sensors to shut them down during the day, but that would clearly cut into wind turbines economics.

It’s hard to be against wind energy. I support it wholeheartedly, but find the narration in the videos while one-sided to be persuasive. Seeing is believing.

Turbines have to be carefully sited away from people and property. Of course, one also wonders what the impact is on wildlife and indeed that was the focal point of the original permitting discussions in Wisconsin focused on birds. But flicker looks to be hell on humans (some are claiming flicker can cause epileptic seizures). The truth probably lies somewhere in the middle between evidence from folks claiming flicker foul, often labeled as NIMBYs, and the American Wind Power Association (AWEA), which claims some allegations are “alarmist.”

The AWEA seems to have minimized the flicker problem (Page 2, first paragraph…I have a call into them to explore this) and says it can be mitigated by planting trees and calculating the hours flicker will cause annoyances each year. In these videos, that could a lot of very big trees, which are dwarfed by the turbine towers. And who wants to put trees directly in from their windows?

As for noise, turbines are “fairly quiet,” says the AWEA, which estimates wind turbines produce background noise of about 35 to 45 decibels at 350 meters.

What would Larry Wunsch say? I am trying to contact him as well, but questionably-sited wind turbines in Wisconsin where a full-fledged battle is being waged seem to have their detractors. One anti-wind energy site born out of the Wisconsin movement says 400-foot wind turbines produce turbulence that poses a hazard to EMS helicopters, attract lightning, dangerously throw ice and blades, destroys farmland and causes stray ground voltage that negatively affects cows.

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