Wind power depends on the wind speed raised to the third power (wind speed cubed). The equation describing this follows:
WPD=1/2*P*V3
Please note in P it is (volume * wind density) not area. So if you try to do calculations on a drag based VAWT you have to take volume into consideration. In HAWT's (Horizontal Axis Wind Turbine) the volume of the blade is ignored because they have very little volume.
This means that an increase in wind speed from 13 mph (5.8 m/s) to 15 mph (6.7 m/s) will increase wind power production by 54 percent.
