China has successfully tested its new S4000 airborne wind-energy system at an altitude of 4,000 metres, completing a full demonstration cycle that included ascent, station-keeping, electricity generation and controlled recovery. The enormous helium-filled structure measures 67 by 40 by 23 metres and resembles an airship carrying lightweight wind-generation equipment. Once airborne, it remains tethered to the ground while harnessing stronger and more consistent high-altitude winds, with the electricity transmitted back through the tethering cable. The trial at a test site in northwestern China successfully examined the entire operating process, and developers said all major performance targets were achieved.
The S4000 can carry more than one tonne of airborne payload, is designed to provide output at 10 to 35 kilovolts and has a projected service life of up to 20 years. Systems of this type could eventually provide power in deserts, high-altitude regions, islands and other locations where building conventional wind-turbine towers and foundations is difficult or expensive. Higher-altitude winds can be stronger and more consistent, but the technology still has to demonstrate reliable long-term performance in storms, icing and other extreme conditions. The S4000 will now be used for extended high-altitude generation trials, with its operational data supporting development of the larger 5MW S6000 system. It is therefore more accurate to describe the achievement as a major step towards commercial deployment rather than a power station already operating commercially. Sources: Xinhua, CCTV/CMG, Hunan provincial authorities and Science and Technology Daily.
