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Trees, Forests and Wind Turbines — A Manufacturer’s View  

Author:  | Environment, Siting, Technology

High shear (different wind speeds at different heights) creates problems with power curves.

A 2.3 MW with 82.4 m rotor and 60 m hub height has 3.5% less apparent power at 10 m/s if sited near a 20 m forest with m = 0.25 than if sited in open terrain with m = 0.14 (where m is shear).

Bonus uses following rules of thumb for evaluation of possibility of power curve measurement:

  • Shear not to exceed 0.20
  • This shear expected possible if tree height does not exceed a horizontal level of:
    • Hub height − 0.67 rotor diameter for distance from trees less than 5 rotor diameters; up to
    • Hub height − 0.50 rotor diameter for distance from trees equal to 10 rotor diameters

Presentation by Bo Schou Nielsen and Henrik Stiesdal, Bonus Energy (now Siemens), 17 March, 2004

Download original document: “Trees, Forests and Wind Turbines – A Manufacturer’s View

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