Wind Power Density Calculator

How it works

P/A = ½·ρ·v³; v_hub = v_ref·(h_hub/h_ref)^α; P_turbine = C_p · ½·ρ·A·v³, C_p ≤ 16/27 = 0.593 (Betz)

The kinetic energy passing through a square metre per second grows with the cube of wind speed, so siting matters enormously: 8 m/s carries more than twice the power of 6 m/s. Wind also strengthens with height following a power law, which is why hub heights keep rising. No turbine can take it all — slowing the air completely would stop it flowing — and the Betz limit caps extraction at 59%; good modern rotors reach 0.45–0.50. Annual output depends on the whole distribution of speeds, summarised by the capacity factor.

Worked example

8 m/s at 10 m becomes 10.7 m/s at 80 m (α = 0.14): 749 W/m², an outstanding site. A 100 m rotor (7,854 m²) sees 5.9 MW of wind power and yields about 2.5 MW at C_p = 0.42; at 35% capacity factor that is 7,600 MWh a year.

Frequently asked questions