Airborne wind projects

US-based Joby Energy is testing a turbine system transported by a particular multi-wing structure that harnesses winds up to 10,000 metres. The 30 kW prototype should be tested at an altitude of 600 metres

High-altitude wind harnessing projects were already conceived over 40 years ago. In fact, between 7,000 and 15,000 metres, wind currents are exceptionally stable and reach very high speeds, 5 to 10 times higher than surface winds. But even at a 500-metre altitude, wind is twice as fast as on the ground. However, this has become a practical option only in the last few years, due to technological innovations. Indeed, wind developers are creating new models and are planning to send them high up in the sky, attached to large kites, in the near future.
One of these developers, US-based Joby Energy, is testing a turbine system transported through the air by a particular multi-wing structure that uses an advanced computer for orientation in order to follow the direction of the wind, also allowing it to land safely when the wind is low. According to its developers, the model can withstand strong winds, but in any case the security systems allow it to keep working even in case of failures and to land without any damage even if the tether should break down. The latter is used to transmit energy to the ground.

The prototype developed by Joby has a capacity of 30 kW, while the first commercialized model should reach 300 kW. The turbines can in theory fly at altitudes up to 10,000 metres but, for the time being, the US Federal Aviation Administration has established a maximum height of 600 metres.

According to the founder of Joby Energy, Joe Ben Bevirt, the total potential capacity of wind energy at high altitudes is 870 million MW, over 50 times higher than the capacity of surface winds, estimated at 17 million MW. In theory, this source is abundant and affordable in most parts of the world.

(June 2010)