The Pumping cycle is an alternative technique to onboard generation. It consists in pulling the tether with a very strong force while reeling it out; the mechanical power is then converted to electricity on the ground, by a generator attached to the winch. As the cable cannot be extended infinitely, a reel-in phase is necessary. During this phase the force in the tether is kept to the minimum possible value, in order to minimize energy consumption.

Groups basing their work on the Pumping Cycle :

Ampyx Power, http://www.ampyxpower.com
Enerkite, http://www.enerkite.com
KITEnrg, http://http://www.kitenergy.net/
Skysails Power, http://www.skysailspower.com
SwissKitePower, http://www.swisskitepower.ch
T.U.Delft, http://www.kitepower.eu

Publications related to the Pumping Cycle :

B. Houska and M. Diehl. Optimal Control for Power Generating Kites. In Proc. 9th European Control Conference, pages 3560–3567, Kos, Greece, 2007. (CD-ROM).

M. Loyd. Crosswind Kite Power. Journal of Energy, 4(3):106–111, July 1980.