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Renewable Energy: 11 or 15 metre pole?

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    Hi, I have a VERY exposed site that I am hoping to put a 6kw turbine on , I have a annenometer measuring the wind at 11m for the last month and the average wind speed could turn out to be in excess of 8m/s. The site is also prone to violent gusts of more than 45m/s.
    my house is 20 metres from the proposed site. I have noticed that at a hub height of 11m we would have considerable flicker inside the house, a hub height of 15m would nearly eliminate any flicker.
    My concern is that there would be too much movement in a 15m mast on an exposed site like mine and the turbine may be damaged.
    Do I need to worry about this?
    Thanks
  2.  
    I am no expert on small turbine design but if the turbine has been tested on 15 mtrs towers then I would say it should be fine. All good strucures bend and flex so they do not break. 60mtr towers move a lot and the larger turbines cope fine. Average wind speed above 8m/s? LOVELY.
    Gusty.:thumbup:
  3.  
    Sorry forgot to ask, is your windy meter at 11 or 15? If its on 11 then a 15 will give you slightly more production.
  4.  
    Thanks gusty turbine, the meter is at 11m at the minute, I think we are 8m/s minimum! I've been comparing the data to a weather buoy about 22km away and they are pretty much identical, The buoy has an average speed of 9m/s!
    8m/s is great for a turbine but can get a bit tiresome when you have to live in it!! hoping a wind turbine is the silver lining!!
    • CommentAuthorGBP-Keith
    • CommentTimeMay 11th 2011
     
    15 metres every time. You will be wasting your money on the smaller pole and I bet you would always regret the choice.

    I think you will get flicker (strobe effect) on either height poles at some time of the year if it is south of your property because the blades deflect / cut (call it what you will) the sunlight across a region behind the blades.

    Neighbours? They are the ones to watch out for because they will not be appreciative of party lights through their windows.
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 11th 2011
     
    Easy enough to work out the flicker for your site and the higher the better every time, the big losses are closer to the ground and they are exponential.
    You may find that when the blade length is included you have to be more that 20m from a dwelling (depends what size turbine you are getting).
  7.  
    Neighbours are more than half a mile away, The pole is directly west of the house, and I noticed the sun was directly behind the weather station (11m) as I was sitting in my sunroom at about 6pm last week. I reckon at 11m it would give us 5-6 months of flicker per year. should be much less at 15m but I'll wait till the solstice to see how much it will affect us.
    Cheers
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 11th 2011
     
    Posted By: Wazzo Raybelle5-6 months of flicker per year

    Potential flicker, a lot of the time it is cloudy
  9.  
    Thanks, yes potential flicker, I'm hoping a 6kw +15m mast will be less than 20m, thats as far away from the house we can get!

    My biggest concern is that a 15m mast would have too much movement given the violent gusts we experience ( the southwest corner of our roof has been torn off several times over the years!!!)
  10.  
    Your roof does not flex (I hope):tooth:
  11.  
    15m and ask the manufacturer to design it so that it doesn't bend, that being their job after all.

    :wink:

    J
    • CommentAuthorwindy lamb
    • CommentTimeMay 11th 2011
     
    I wouldn't worry too much about the tower - but I would double check the foundation specification. It appearers that all (most) small wind turbine manufacturers design "a one size fits all" foundation, usually overengineered for most soil types and onshore locations, but if you are coastal with hard rock under shallow soil you need to get the manufacturers to confirm the foundation spec.
  13.  
    Thanks for that windy lamb,that is exactly the ground condition here.
  14.  
    Thanks for all the input, One more question on this, I'd be hoping to pick up a second hand proven 6kw, one I recently looked at was on a 9.5m pole in 2 sections, Is the 15m pole just an extra length added to this? or a completely different specced pole.

    thanks Wazzo

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