ENERGY SECURITYKites Aim to Tap Unused High-Altitude Wind Power

By Tim Schauenberg

Published 28 March 2023

There is a growing interest in harvesting what are known as high-altitude winds. At a height of 200 meters (656 feet) and more, winds tend to blow stronger and more steadily than those closer to the ground. High-altitude winds remain a huge untapped source of renewable energy, but a race to the sky is well underway.

For a child, the simple act of flying a kite can be exhilarating; running and pulling at the line to send it ever higher into the sky where the winds dance to their own wild tune. 

Those same winds that captivate young imaginations are also working their magic on a growing body of researchers intent on harvesting what are known as high-altitude winds. At a height of 200 meters (656 feet) and more, winds tend to blow stronger and more steadily than those closer to the ground. 

These winds are so strong, in fact, that they could be used to generate more electricity than we need and significantly more than wind turbines on land can produce. A doubling of wind speed can theoretically generate up to eight times more power.

Moritz Diehl, who heads the Department of Microsystems Engineering at the University of Freiburg, said harvesting high-altitude winds is one of the “most promising” technologies for generating renewable energy in the future.

You see all the sky above conventional turbines, and you think all this wind energy is just blowing there and it’s not used,” he said.

Stephan Wrage, CEO of the German wind power company SkySails-Power, wants to change that and make the “largest yet untapped source of renewable energy worldwide” suitable for mass use.

And he’s not the only one. For years, engineers, various startups and international companies have been in a race to bring high-altitude winds down to Earth at low cost. Many have failed in their attempts and some have gone bankrupt. But others are on the verge of bringing their flying power plants to the market.

Flying Wind Turbines and Other Ideas
One of the first projects to attract attention was launched by the US energy company Altaeros in 2010. Their prototype was a generator attached to a helium balloon — in other words, a wind turbine without a heavy base and tower.

Tested in Alaska, it was connected to the ground by a cable. According to the company, it produced energy for about 50 households at an altitude of 600 meters. 

Around the same time, the German company SkySails developed a high-altitude kite to pull entire container ships. The idea was to save diesel used to run the engine, by up to 10%. 

Although the test with the kite worked, the shipping company went bankrupt and neither the kite nor the helium wind turbine conquered the market. But both prototypes pointed to one thing: harvesting high-altitude winds requires flying power plants.