A city in Alaska is trialling the usage of flying wind turbines to take advantage of the stronger air currents found at higher altitudes.

The Altaeros Buoyant Airborne Turbine (BAT) looks like a cross between a windmill and a hollowed-out blimp, consisting of a segmented, tubular balloon pumped full of helium to confer it with sufficient buoyancy to float high in the air.

The blades of the Altaeros BAT are situated within the tube's hollow interior, while a set of sturdy tethers keep the device anchored to a relatively constant position above the ground.

The device was designed and built by Altaeros Energy, a start-up founded by MIT and Harvard alumni which has received a US$1.3 million grant from the Alaska Energy Authority to trial usage of the BAT over an 18-month period.

One of the turbines will be installed above the city of Fairbanks, Alaska at an altitude of just over 300 metres, where it will convey energy to the ground by means of cables connecting it to the grid.

Altaeros has already conducted successful trials of a 35-foot scale prototype of the BAT in Limestone, Maine. The device proved capable of ascending to heights of over 100 metres and harvesting power from more rapid air currents before returning to the earth in an automated cycle.

The technology could radically enhance the efficiency of wind turbines, given that air speeds are directly proportional to both altitude and energy harvesting. The air currents harvested by the BAT-Buoyant 300 metres above Fairbanks are expected to be between five to eight times stronger than those at sea-level, and Altaeros claims the device could reduce generation costs by as much as 65 per cent.

While engineers in the wind power industry are striving to devise new methods for raising the height of turbines, the use of airborne podiums could obviate the manifold challenges involved in building taller towers - an engineering task fraught with considerable difficulty.

BAT's developers see the flying turbines vastly increasing the convenience of wind power deployment by dispensing with the need to occupy extensive tracts of land and build fixed infrastructure assets.

"For decades, wind turbines have required cranes and huge towers to lift a few hundred feet off the ground where winds can be slow and gusty," said Ben Glass, inventor of the airborne wind turbine. "We are excited to demonstrate that modern inflatable materials can lift wind turbines into more powerful winds almost everywhere—with a platform that is cost competitive and easy to setup from a shipping container."

The turbines could also alleviate concerns about the the potential for intrusive or hazardous noise pollution created by wind turbines situated in close proximity to residential areas, and the impact of land-based towers upon terrestrial ecosystems.

In addition to achieving enhanced energy harvesting, the airborne devices are also capable of a swathe of other functions, including the provision of data coverage and telecommunication services, and the monitoring of local weather conditions.