# Thread: Wind Farm Flicker Expert or mathematician needed

1. ## Wind Farm Flicker Expert or mathematician needed

Hi all,
Someone is proposing to build a wind farm near my house.
The three turbines would be in a straight line with my home the nearest being about 500mtr away.
I'm not against wind turbines but we already have a 1MW community turbine nearby and there is not enough capacity on the grid for an extra three.
There is more to it than this but I won't go into all the details.

Anyway, their expert says that there is no chance of flicker induced epilepsy etc.
Because with a maximum rotation of 34rpm and three blades the fastest flicker rate would be 1.5Hz.

So my question is this:
When looking through the blades, slightly off the axis of their alignment, it is possible to see the Sun through the up going blades of one turbine and the down going blades of another.
Also, all three turbines might going at slightly different speeds. For example 34, 33 and 32rpm.

Could this cause flicker at rates higher than the 1.5Hz which they predict?

TIA for any insight into this problem.
Last edited by coldraven; April 7th, 2013 at 11:38 PM.

2. ## Re: Wind Farm Flicker Expert or mathematician needed

I need to bump this.
My maths would indicate that looking through all three turbines would give a flicker rate of 1.5 x 2 x 2 = 6Hz but I would like to be sure.
My sunsets would never be the same again if this project goes ahead.
Thanks

Proposed view from my driveway

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## Re: Wind Farm Flicker Expert or mathematician needed

Standard rule of thumb is that flicker is pretty unlikely outside of 10 rotor diameters. So unless these are really big turbines with a rotor diameter above 50m then you should be fine.

4. ## Re: Wind Farm Flicker Expert or mathematician needed

How about noise? Are you going to hear these things spinning at 3 AM in the morning? They may be fine when new, but after a few years of deferred maintenance with worn bearings, I would expect these fans to be a nuisance.

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## Re: Wind Farm Flicker Expert or mathematician needed

I work for company which has some wind turbines and also hydro projects. A well made wind turbine should be very quiet and normally they don't go fast enough to trigger anyone's epillipesy. I prefer micro hydro though, because it has less impact on the local scenery and generates alot more power.

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## Re: Wind Farm Flicker Expert or mathematician needed

ps. I would be really flipped off if someone put that on my doorstep. Ideally wind farms should be put at sea where they don't bother anyone.

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## Re: Wind Farm Flicker Expert or mathematician needed

Originally Posted by mr john
... Ideally wind farms should be put at sea where they don't bother anyone.
You'd think so - I live on the coast and some locally are up in arms about exactly that. http://www.challengenavitus.org.uk/

8. ## Re: Wind Farm Flicker Expert or mathematician needed

Thanks for all the answers but where are the mathematicians when you need one?
I am going to object to this proposal, mainly on the grounds that I will be within the 35db sound envelope i.e. too loud.
However there are inaccuracies in their submission and I would like to highlight those, the flicker rate being one of them.

9. ## Re: Wind Farm Flicker Expert or mathematician needed

Originally Posted by coldraven
I need to bump this.
My maths would indicate that looking through all three turbines would give a flicker rate of 1.5 x 2 x 2 = 6Hz but I would like to be sure.
My sunsets would never be the same again if this project goes ahead.
Thanks

Proposed view from my driveway
They look extremely close to your property, and from what I've seen, flickering would be the least of your problems as when Den Brook wind farm was proposed, local residents decided to find out from other people across the UK and in one part of Norfolk (I think), a family actually moved out of their home because of a disturbed sleep pattern due to the blades noise "swishing".

http://en.wikipedia.org/wiki/Den_Brook_Wind_Farm

http://www.parliament.uk/briefing-papers/sn05221.pdf
Last edited by scouser73; April 5th, 2013 at 08:06 PM. Reason: Additional Information Posted

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## Re: Wind Farm Flicker Expert or mathematician needed

Originally Posted by mr john
ps. I would be really flipped off if someone put that on my doorstep. Ideally wind farms should be put at sea where they don't bother anyone.
Inclined to agree. On shore wind is just more trouble than it's worth. It's so difficult to get permission for even small numbers of small turbines. Here in the UK we've got better wind offshore and the sea is shallow. We should be, and are, building enormous arrays of huge turbines out to sea.

As for the flicker rate you'd see, that really depends. The rotation of the blades are highly unlikely to ever be synchronised, so you can't simply sum the frequencies. In reality you'd see an asynchronous flicker if you were looking through several swept areas.

35dB is very quiet, btw. I wouldn't worry about that.

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