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X-Wind technology (spoken: Cross-Wind) is a High Altitude Wind Energy System which combines automatically steered kites, grounded rail systems and/or cable car technology on linear or circular track. This technology allows to harness the energy of wind at an altitude of up to 500m/1.500 feet.
The concept was developed by Uwe Ahrens, a German Aerospace-Aviation Engineer. In 2006 he partnered with investment capital firm NTS GmbH to develop the idea.
A feasibility study made by the Technische Universität Berlin shows the capability of energy production by NTS power plants. A legal study and discussions with the German Federal Ministry of Transport "Bundesverkehrsministerium", the aviation authorities Bun-desluftfahrtamt and Deutsche Flugsicherung led to a positive feedback toward obtaining a special permit to run the NTS X-Wind plants.
NTS received permission and approvals to start the first test flights by July 16, 2011. A 400m linear test track is in operation since November 2011. Closed loop prototype is under construction at Mecklenburg-Vorpommern, Germany.
The steering units to steer the kites safely are mounted on the ground vehicles. Four tethers are steering the kite. Each one of these tethers is capable to pull down the kite safely.