Wind

[lurker]

My mate lives in the "catchment" he is rather good at fixing cars.
I went round there to sort my wheels one dull winter afternoon and came away with something akin to sea sickness. Bear in mind I am deaf & can't hear a bluddy thing and the noise itself does not effect me.

As you can imagine his home is now worth FA.

Evidently he is a NIMBY :roll:

 

[Digit]

As you can imagine his home is now worth FA.

No, no, no! I'm sure he can find some green enthusiast who'd love to live there! :roll:

Roy.

 

[CraigyBoy]

The blade flicker that you mention, along with the noise, is a much under appreciated problem, as such flickering can be a trigger for epileptic seizures.

Roy.

This should not be ruled out, but a lot of research has been done in this area, and it is currently considered highly unlikely. Epilepsy in action did a survey in 2007 and one person did say that they had a seizure whilst looking at a wind turbine, however that person didn't suffer from photosensitive epilepsy, so it's difficult to conclude if the wind turbine was the cause.

Research has shown that epilepsy can be triggered by flashing lights in 3-5% of people who suffer from epilepsy. The frequency of the flicker needs to be between 5 and 30Hz. To be safe, the recommendation for people who suffer from photosensitive epilepsy is not to be subjected to flashing lights over 3Hz. All large wind turbines are designed to operate at <1Hz (i.e. <3 flashes a second if there are 3 blades), hence it is very unlikely that a single wind turbine could trigger a seizure. There could be a possibility of multiple flashes from a farm, but as they would normally be all pointing in the same direction, a single point (i.e. where you're standing) would be unlikely to get flashes from multiple turbines at the same time. Again, I don't believe there is any evidence that this has ever caused a problem, but I may be wrong, and I'm sure we would have heard if there was real evidence of somebody being effected.

In addition to this, the likelihood of a seizure is directly related to the % of the field of vision that the flashing occupies. Sitting closer to a large TV is more dangerous that sitting further back. As flashing would be caused by reflections of the sun, there would be pinpoint lights as opposed to "fullscale flashing" like in a disco. This further reduced the likelihood.

The other type of flickering, shadow flicker, e.g. where a turbine blade obscures the sun has not been shown to cause epileptic fits/seizures regardless of the cause of the flickering.

I'm not saying that it can't happen, I'm simply providing more information so that you can objectively consider the issue for yourselves. If you don't want to think for yourself, then you will probably prefer the following article presented in the Daily Mail that provides sensationalist headlines with vague references to a single expert. Don't worry, this article will not bother your brain with any results or evidence gathered from independent sources, or peer-reviewed controlled experiments. However if you have already made your mind up, this single article will provide the hard and fast "proof" that you will need whilst talking sh*te to strangers in the pub tonight! ;-)

http://www.dailymail.co.uk/news/article ... tists.html

Happy Friday!
Craig

 

[Digit]

that a single wind turbine could trigger a seizure.

I would have made that point if you hadn't Craig. But have you ever been tested for Epilepsy? Do you know how the test is/was conducted.
As someone who once suffered from the condition I can assure you that both light flicker (reflection) and shadow flicker, will trigger a seizure in certain people.
I have had seizures due to headlights on the motorways, walking past tall picket fences with the sun low behind, and even from a spinning lathe chuck!

Roy.

 

[CraigyBoy]

I would have made that point if you hadn't Craig.

Err, but you didn't. Instead you provided a statement without caveat or context. Anyhoo ...

OK, I'm happy to accept your personal experience and retract the "regardless of the source of the flickering" part of my post. However I maintain that shadow flicker from a wind turbine is highly unlikely to induce an epileptic seizure. For this to happen:

- it needs to be windy (not uncommon)
- it needs to be sunny (rare in the UK!!)
- somebody with photosensitive epilepsy need to be close enough to the turbine to be in the shadow of the blades (typically within 10x the rotor length of the base i.e. very close)
- the turbine needs to be rotating fast enough to generate flicker that is in the range of the observers photosensitive range (highly unlikely given the design parameters stated above)
- if the point above is not met, then the observer needs to be in the shadow created by >1 turbine. This is usually not allowed by planning regulations as flicker is an annoyance to everybody,m not just epileptics!
- more than 25% of the visual cortex needs to be stimulated (i.e. a large part of the field of vision needs to be effected)

... and this is before you take into consideration background illumination, background contrast, wavelength of light that effects the particular person etc etc.

Unlike reflective flicker, somebody with a diagnosed condition would have to deliberately get within close range of a turbine, stay there for long enough to be effected, and do nothing to remove themselves before it starts to effect them.

To the best of my knowledge, there is currently no UK or US shadow flicker standard. There may be a European one now, but this is very recent. I wasn't able to find it using google for a few minutes, but some reports made mention of it. If this was a major issue, why are there no standards?

Can you find any evidence of a single person who has had a seizure caused by shadow flicker from a wind turbine? And by this I mean real evidence as opposed to pseudo-science leaflets claiming that there is a risk - yes I've already agreed there is a risk, but there is a risk that my house will get hit by a meteor this weekend. That is also unlikely! Unlike some people, I am very open to the possibility that I am totally wrong, and I will consider all inputs in an unbiased manner, but so far, there is precious little evidence to support this.

Cheers Craig

 

[Digit]

Err, but you didn't. Instead you provided a statement without caveat or context.

So? I also didn't bother to explain that the noise varied dependent on whether the blades were on the up wind or the down wind side of the tower, and neither did you.

Roy.