Efficiency in Extracting Wind Power

12 May
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Wind energy is one of the more efficient alternatives to fossil fuel energy. Wind power gives a significant Return On Investment (ROI) since it’s free energy that also has an endless renewable power source. 59% efficiency is the BEST a conventional wind turbine can do in extracting power from the wind.

Wind Power depends on:

• amount of air (volume)
• speed of air (velocity)
• mass of air (density)

flowing through the area of interest (flux)

Kinetic Energy definition:

  • KE = ½ * m * v 2

Power is KE per unit time:

mass flux

 Untitled  

Equation of Wind Power

Fluid mechanics gives mass flow rate

(density * volume flux):

  • dm/dt = ρ* A * v

Thus:

P = ½ * ρ * A * v 3

Betz Limit & Power Coefficient:

  • Power Coefficient, Cp, is the ratio of power extracted by the turbine to the total contained in the wind resource Cp = PT/PW
  • Turbine power output
  • PT = ½ * ρ * A * v 3 * Cp
  • The Betz Limit is the maximal possible Cp = 16/27
  • 59% efficiency is the BEST a conventional wind turbine can do inextracting power from the wind

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