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7th July 2010 06:51 PM
Unregistered Hi Farlo

You are probably rigth about that. I assumed that it was an offshore wind farm.

Peter R
7th July 2010 06:49 PM
Farlo Hi Peter, wind is more affected in altitude, so the effect at around 100 m of a large wind farm will be sensible several miles away (however 30% is surprising). Close to ground level the situation is different because the wind is slower and less steady anyway. It all depends on roughness between the farm and the spot. If plenty of trees, buildings, hills... the difference will be negligible. If very flat land or open water like Rodsand, the extra turbulence will travel much longer. http://www.talentfactory.dk/en/tour/...lter/index.htm for speed simulations and http://www.talentfactory.dk/en/tour/wres/park.htm for park effect.
7th July 2010 06:45 PM
Unregistered
Separation between turbines in farms

Quote:
Originally Posted by Roger View Post
Floyd,
My guess would be there is virtually no effect.
Why?
Look at the separation between the wind turbines in the wind field.
At what one of those units cost, I'm pretty sure that they place them so
the upwind turbine does not negatively effect any turbines downwind.
So, the distance between them is probably greater than some calculated or
actually physically tested distance at which the upwind turbine affects the
efficiency and output of the downwind turbines.
There are several reasons that wind turbines are placed pretty close:

1) Infrastructure: The expenses to the power cable to "Rødsand II" is approx. 300 million dKr (50 million dollars). If the wind turbines were dispersed further, the expenses would be higher. Wind turbine service are another example of expenses that would go up, and you will also need infrastructure at land

2) The right bottom structure, (low) water depth

3) Aesthetics


Peter R
7th July 2010 04:58 PM
Unregistered
It will most like affect affect wind

The Nysted wind farms consist of "Rødsand I" (166 MW total -erected 2003) and "Rødsand II" (215 mW total - under construction). Rødsand I and II are approx 3 km (or 2 miles) from each other and estimates are that "Rødsand II" will reduce the power procution from "Rødsand I" up to 30% (depending on wind direction). As these windfarm have different owners this has caused some discussion about compensation. Experts within the field estimates that there will be a windshadow more than 20 km away from a large windfarm.

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

I could link to some additionals sources for information, but the ones I know are in danish.

A personal experience: I have sometimes sailed approx 5-10 km from Rødsand I, and I feel the wind is more gusty than before 2003.

"Your" windfarm is smaller than Rødsand I - but I still think there will be a difference.

Peter R
7th July 2010 03:51 PM
Farlo This is true and you tend to rig larger now, but modern sails have also a bigger wind range. You don't really need sails every 0.5 m² like in the old days. I guess their ability to handle unsteady wind has grown in proportion. Anyway I remember people already complaining in the early 90's (mostly inland spots) with gear of that time. It seems that wind was very steady before WS actually started.
7th July 2010 02:06 PM
Unregistered
Quote:
Originally Posted by Farlo View Post
Hi Floyd, for over twenty years I've heard sailors insisting the wind is not as steady as it used to be. Even in South of France or places like Tarifa you ear this from time to time. Is it because the trees around their spot have grown, or new buildings have emerged, or the general skill level has improved? It doesn't seem to be related to wind farms. For sure a certain amount of energy is taken out but will there be a sensible effect at ground level two miles away? I doubt. Offshore wind tends to reaccelerate and stabilize a few hundred meters from the beach, unless there are mountains around.
or kit is more affected by unsteady wind.
20 years ago tops of sails had more drive and power and they were biased more towards the bottom of their wind range
today tops of sails have relatively little drive and power and the sails are biased towards the top of their wind range.
6th July 2010 11:39 PM
Farlo Look at this Danish site: http://www.talentfactory.dk/en/tour/...lter/index.htm and plot wind speed after an obstacle. You will find that in most practical cases wind speed at ground level is unaffected after two miles (same as if there was no obstacle). I guess the extra turbulence created by the obstacle disappears as well provided that wind speed is unaffected within ten meters above the ground.
6th July 2010 11:11 AM
davide Hard to tell if it is significant but it must have an effect. Some energy is created out of the wind and the wind slows down ... Trees, buildings, ugly turbines ... put down enough and the wind will stop.

Maybe we should start a stop-wind-energy campaign, Turbines do have a huge footprint and who knows what environmental consequences will result when they become more widespread ...
5th July 2010 11:44 PM
Farlo Hi Floyd, for over twenty years I've heard sailors insisting the wind is not as steady as it used to be. Even in South of France or places like Tarifa you ear this from time to time. Is it because the trees around their spot have grown, or new buildings have emerged, or the general skill level has improved? It doesn't seem to be related to wind farms. For sure a certain amount of energy is taken out but will there be a sensible effect at ground level two miles away? I doubt. Offshore wind tends to reaccelerate and stabilize a few hundred meters from the beach, unless there are mountains around.
5th July 2010 10:58 PM
Floyd PS
Our turbines are just about at sea level.
If they do have an effect there`s going to be some sad sailors in Tiree;biggest Windfarm in Europe is planned for there !!!
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