Having already put its Google Wallet where its mouth by backing a solar power tower plant in California to the tune of US$168 million, Google has now turned to wind power. According to a report from Bloomberg Businessweek, the search giant has acquired Makani Power, a California-based startup whose Airborne Wind Turbine (AWT) technology first caught our interest in 2011.

The Makani Power acquisition comes from Google X, Google’s not-so-secret research and development arm that focuses on "moonshot" technologies, such as the Google driverless car and Google Glass. This is apparently the first time Google has acquired a company for Google X, but it’s not the first time it has invested in the wind power company. Google was a primary investor providing $10 million in funding to Makani Power in 2006, following up with another $5 million the following year.

Makani Power also received a grant in 2010 from the Department of Energy’s Advanced Research Projects Agency (ARPA-E) to help in development of its Wing 7 prototype. This is a 30 kW scale model of Makani’s planned 600 kW utility-scale devices that are designed to fly at altitudes of between 250 and 600 m (800 and 1,950 ft) and transmit electricity to the ground via a tether.

The tethered wings are outfitted with turbines that operate like conventional wind turbines, with air moving across the blades forcing them to rotate and drive a generator to produce electricity. However, Makani says fitting them to a flying wing provides increased performance in low winds, allowing the turbines to produce about twice the power of a traditional wind turbine of the same size, while requiring less materials to build.

Makani says their superior low wind performance means its AWTs would be economically viable in areas where conventional wind turbines aren’t. While the technology would by slightly cheaper to run than conventional wind turbines in good wind areas, Makami says their cost of energy would be half that of conventional turbines in typical onshore or offshore sites. The AWTs are intended to be installed in arrays over large areas, flying in a circular path and spaced approximately one tether-length apart to ensure they don’t become tangled.

On its website, Makani says it recently completed the first-ever autonomous flight demonstrating all flight modes, including launch, hover and landing. It also confirmed the Google acquisition, saying the extra resources provided by the deal will help them accelerate development of the technology with the goal of making wind energy cost competitive with fossil fuels.

Video of the recent fully autonomous flight of the Wing 7 prototype can be seen in the following videos. The first shows the flight at 5x normal speed from a distance, while the second provides a closer view.

Sources: Makani Power, Bloomberg Businessweek