used to power mechanical devices. But the device being promoted as the next big thing in wind energy by the California-based firm Makani Power brings to mind something with roots stretching even further back into ancient history – the kite. Described by its developers as a tethered wing, the Makani Airborne Wind Turbine (AWT) was created to harness wind at much higher altitudes than can be reached by ground-based turbines.

Wind speeds are much higher and more consistent at 800 to 1,950 feet, where the AWT operates. In flight, the wing is guided by an onboard computer to follow a circular path. As this happens, direct-drive generators collect the traction force of the air as it meets the wing. This energy is then transmitted to a ground station through the tether. Because the wing can circle at upwards of 10 times the wind speed, electricity can be generated under conditions that would be far less conducive to wind power using conventional techniques.

After five years of development, Makani’s prototype was tested last year. The company has already secured $15 million in funding from Google and an additional $3 million from the Department of Energy’s Advanced Research Projects Agency, looking ahead to the ultimate goal, as with wind lens, of deploying this technology offshore.

Makani isn’t the only innovator generating excitement with a model airborne turbine. Altaeros Energies is a company based in Massachusetts, which, like Makani, was formed by MIT graduates. Its airborne turbine is lifted by an inflatable helium shell in a method reminiscent of the aerostat technology used to launch satellites.