Clean Energy From Wind Turbines On Kites? Google Thinks So.

A Makani Airborne Wind Turbine launches in Alameda, CA | Photo: Makani Power

It sounds like a flight of fantasy: mount wind turbine generators on gigantic kites, then fly them a thousand feet off the ground to generate power. But one company pushing this literal "blue sky" concept got a huge real-world vote of confidence recently: Google bought them.

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Google's acquisition of Makani Power is still in the works. The buyout hit the renewable energy trade press suddenly this week after a feature story in Business Week describing the search engine giant's science-fictiony Google[x] research arm, which is also responsible for the self-driving car and Google Glass projects.

Makani Power's website seems to be suffering under heavy traffic in the wake of the BusinessWeek story, but the working models of its tethered flying turbines seem to do better under pressure. The Makani Airborne Wind Turbine (AWT) is essentially a "flying wing"-style light aircraft, tethered to a ground anchor by a composite fiber cable. When the AWT is aloft, small wind turbines mounted on the blade-like wing convert the energy of the air rushing past the wing into electrical power. That power is conducted down the tether to a ground station.

In standard operation, the AWT is designed to loop in large more or less vertical circles at the limit of its tether, somewhere between 800 and 1,950 feet off the ground. If the wind slackens, the AWT's turbines serve double duty as propeller engines to keep the unit aloft. Having gotten promising results with a 30-kilowatt model of the AWT, Makani is working on a 600-kilowatt version. Acquisition by one of the richest tech companies on the planet can only help.

Multiple exposure image shows AWT in its looping flight path | Photo: Makani Power

Regular readers of ReWire may well wonder whether this type of wind turbine offers less potential threat to birds and other wildlife. The short answer? We don't know. The AWT wing is designed to resemble a standard wind turbine blade in an aerodynamic sense, and so it can be seen as a single-bladed wind turbine without a pole. Deploying the AWT at 1,000 feet or more above the ground will reduce risk from the blade to birds that don't usually fly that high, but then there's the added danger from the tether as well, which could move fairly quickly in its upper reaches and not be all that visible. Makani's tests are being conducted in the San Francisco Bay Area on open lands, but the company's long-term goal is offshore deployment. That means wildlife injured by the AWTs would fall to the ocean, and detection by wildlife biologists tallying the technology's impact would be essentially impossible.

But that's handwaving on ReWire's part. If the technology advances, we'll be interested to hear what the biologists have to say. In the meantime, Makani's tech is pretty interesting for its gee-whiz factor alone.

About the Author

Chris Clarke is a natural history writer and environmental journalist currently at work on a book about the Joshua tree. He lives in Joshua Tree.
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