On a recent day in August in a field near Munich, Germany, a group of engineers launched a kite-like electric plane into the air and watched for the first time as it flew in figure eights in the sky. The device is one of a handful to take a different approach to wind energy: Instead of a traditional wind turbine with a massive tower and huge blades (that’s anchored to the ground), it shrinks the system into a tiny footprint and sends it into the air.
“The most important factor is that we need 10 times less material, so we can reduce costs quite dramatically,” says Florian Bauer, co-CEO of KiteKraft, the German startup developing the technology, which recently completed a stint at the tech accelerator Y Combinator. The cost could be as little as half that of conventional wind energy. The carbon footprint of building the devices is also lower.
As the kite flies autonomously, driven by the wind, eight small onboard rotors turn and generate energy that is sent down a thin tether back to the ground. In essence, Bauer says, it does the same work as the tips of the blades on large wind turbines, which convert the most energy in the system because they move the greatest distance as they’re pushed by the wind. But the new technology, which came out of research at the Technical University of Munich, does that work without the same need for massive infrastructure.
Wind turbines are typically huge; one recent model designed to work offshore has a rotor that’s 728 feet across, with each blade nearly as long as three space shuttles. If KiteKraft’s tech is eventually used offshore, “you just need a ground station for the kite like a floating buoy,” Bauer says. “There’s no foundation required, like a huge tower that goes to the seafloor.” While wind power is already cheap—building new wind farms is already cheaper than running existing coal plants in many locations—reducing the cost could make its renewable energy even more accessible.
Some other companies are also working on aerial wind power, though KiteKraft says that its technology is unique in that it can be commercially viable both at a small scale and in larger deployments. The startup plans to work first with microgrids—each kite is rated between 20 and 100 kilowatts—that haven’t been able to use wind energy in the past, such as remote islands where transporting traditional wind turbines isn’t feasible, or where there isn’t room or community support for large wind installations. (Another advantage of the kites: From a distance, they’re barely visible in the air.) The technology is also better suited for places prone to hurricanes, since in high winds, the kite can be lowered to the ground rather than risking any damage.
After tweaking its current prototype, the company plans to begin pilot tests in microgrids. It will use that data to help prepare for larger installations. “Once you figure out how to make it cost-efficiently, how to make the software so that everything works well together, we just need to scale up the kite,” says Bauer.