Stunt kites to power high-altitude wind farm

It may seem as though the German plains are all but tapped out when it comes to wind energy production. To refute this theory researchers are sending stunt kites into the skies to harness the wind and convert the kinetic energy generated into electricity.

A kite makes its maiden voyage at the test site in Mecklenburg-West Pomerania. © Fraunhofer IPA

Kite surfing has risen to become a fashionable sporting activity, with the number of enthusiasts participating in this cross between wind surfing and stunt kite flying growing at a tremendous pace. When the wind catches the kite, the surfer is carried meters into the air; and the greater the leap, the bigger the thrill.

But a modern stunt kite is capable of being much more than a mere piece of sporting equipment – it has the potential to become a valuable energy producer. A stunt kite's aerial movements can be used to drive a generator, which in turn converts this kinetic energy into electricity.

This dynamic idea came to the founders of Berlin-based wind energy developer NTS GmbH. To make their concept a reality, they brought in the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart. The project partners intend to use their new method to harness the power of strong winds at altitudes of up to 500 meters.

Joachim Montnacher, an engineer at the IPA, explains how a ''kite power station'' works: ''The kites fly at a height of 300 to 500 meters, perfectly positioned to be caught by strong winds. Cables, about 700 meters in length, tether the kites to vehicles and pull them around a circuit on rails. A generator then converts the kinetic energy of the vehicles into electricity. The control and measuring technology is positioned on the vehicles.'' 

Compared to conventional wind farm technology that relies on rotors, this technology offers a wide range of advantages. Wind speeds at ground level tend to zero, but they increase dramatically the higher you go. At a height of 100 meters wind speeds are around 15 meters a second; at 500 meters they exceed 20 meters a second.