The theory behind kite power is relatively straight forward. By flying a kite at a high angle-of-attack, in a cross-wind, “figure-eight” pattern you can generate very large forces in the kite tether. This is because by flying cross-wind, the kite can travel faster than the wind, and the force generated is related to the square of the relative wind speed,
F = ½ ρ CL A V2
Where, ρ is the air density, CL is the lift coefficient (based on wing profile), A is the swept area of the kite and V is the relative wind speed. The kite tether is connected to a large spool which turns as the kite is pulled back in the wind. The spool is then connected (through a drive train or direct drive) to a generator. When the kite has reached the end of its tether it is flown on the edge of the wind window at a low angle-of-attack. The kite can then be reeled back in, using much less energy than was produced on the way out. The cycle is then repeated.
Check out our current project progress here.