Laddermill
A laddermill kite system is an airborne wind turbine consisting of a long string or loop of power kites. The loop or string of kites (the "ladder") would be launched in the air by the lifting force of the kites, until it is fully unrolled, and the top reaches a height determined by designers and operators; some designers have considered heights of about 30,000 feet (9144 meters), but the concept is not height-dependent. The laddermill method may use one endless loop, two endless loops, or more such loops. A laddermill kite system had been built and flown by  Dave Santos of kPower, Inc. Introduction. In a 2007 "road map" report on renewable energy adopted by the European Parliament, laddermill technology was listed among various "promising and challenging" new energy sources into which revenue from emissions trading could be reinvested. Operating modes. There are currently two operating modes considered: Design. A "rotating loop" "LadderMill" project is designed and developed by the Dutch ex-astronaut and physicist Wubbo Ockels. As quoted from his website: The LadderMill is the response to the challenge for exploiting the gigantic energy source contained in the airspace up to high altitudes of 10 km. The  concept has been developed with the aim to convert wind energy at altitude in electricity on the ground in an environmental and cost effective manner.