The traction force of the kite is converted into energy in a periodically oscillating cycle.
In the generation phase, the kite is operated in figure-of-eight manoeuvers transverse to the incident wind generating a high cable tension. At the same time, the tether is slowly reeled off a drum which is connected to the generator. In a retraction phase, this process is reversed, using the generator as motor to reel in the tether. Using a low-traction flight mode of the kite and reeling in at high speed, only a fraction of the energy produced in the generation phase is consumed.
Energy is generated by the generator that is attached to the winch, when the kite is unwinding the line from the winch.
The following animation shows the path, that a kite (or a kiteplane) is flying during pumping operation:
The following video shows a kite, flying a figure of eight in crosswind, to generate a high force on the winch for maximal power generation:
- Cheap (no tower needed, the generator is on the ground, can be heavy and is easy to maintain);
- high power density (a peak power of 20 kW with a 20 m² kite was already achieved, theoretically a power density, that is ten times higher is possible);
- high safety (the kite is lightweight and soft, not much happens, if it crashes into the ground).
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