Advice Archives

Archive for the ‘Advice’ Category

Wind Speed Variability

Posted on: May 1st, 2008

The  wind speed is always fluctuating, and thus the energy content of the wind is always changing. Exactly how large the variation is depends both on the weather and on local surface conditions and obstacles. Energy output from a wind …]
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Obstacles

Posted on: April 11th, 2008

Obstacles to the wind such as buildings, trees, rock formations etc. can decrease wind speeds significantly, and they often create turbulence in their neighbourhood. The turbulence is more pronounced behind the obstacle than in front of it. Therefore, it is best to …]
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Roughness Class

Posted on: March 3rd, 2008

High above ground level, at a height of about 1 kilometre, the wind is hardly influenced by the surface of the earth at all. In the lower layers of the atmosphere, however, wind speeds are affected by the friction against …]
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Wake Effect

Posted on: January 13th, 2008

Since a wind turbine generates electricity from the energy in the wind, the wind leaving the turbine must have a lower energy content than the wind arriving in front of the turbine. This follows directly from the fact that energy can …]
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The Roughness Rose

Posted on: January 12th, 2008

If we have measured the wind speed exactly at hub height over a long period at the exact spot where a wind turbine will be standing we can make very exact predictions of energy production. Usually, however, we have to …]
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