High-altitude wind turbine: BAT

Harness Wind Energy At 2,000 Feet with BAT

Nothing about the grooved, inflatable body taking shape inside Greentown Labs in Somerville, Massachusetts, resembles a wind turbine. It looks more like a jetliner’s emergency ramp, or something you’d tie behind a boat and cling to desperately while bumping across the surface of a lake. But the 14-foot-long structure most resembles what it actually is–an air-filled wing.

Altaeros_Prototype_Flight

To be more precise, it’s a stabilizing fin, part of a tube-shaped, robotic airship designed to tap the power of high-altitude winds. The blade tips of today’s tallest conventional wind turbine, installed at a test center in Denmark this year, stretch to 720 feet. The fully autonomous, lighter-than-air BAT (short for buoyant airborne turbine) will climb as high as 2,000 feet, where winds blow stronger and steadier.

“There is more than enough energy in high-altitude winds to power all of civilization,” says Ken Caldeira, a Stanford University climate scientist, who co-authored a 2012 study that ballparked the potential at 1,800 terawatts–more than four times the estimate near the surface. “The question is whether technologies can be created that can reliably and affordably extract it.” Altaeros Energies, the company behind that BAT, is poised to prove that it’s already done so.

Provided, of course, the vehicle hasn’t sprung a leak. “We’ve been meaning to do this for a while,” says Adam Rein, the company’s lead director and co-founder, over the buzz of the air compressor. The fin had been pulled from storage, where it had been sitting deflated since test flights several months before. “We’re trying to understand how durable the material can be,” Rein says. “We have a vision of putting out a product that you could deploy, leave there for a year or two, pack down, and move to a new site or a new customer.”

While typical wind turbines of similar scale require a large crew and several days to install, the BAT is ready to fly and generate power the day it arrives. And instead of pouring concrete foundations and erecting a multistory tower, a few people with a truck can inflate the airship on site and attach it to a base station, which they secure to the ground with the same anchor ties used for telephone poles.

Logistical ease is critical to Altaeros’s initial customers: communities around the world too remote to access an electrical grid. Often, they must rely on diesel generators–one of the least-efficient power sources–because renewable energy systems are not economically feasible. In the Arctic, for example, there isn’t enough sunlight to justify solar power for months at a time, and a combination of permafrost and snowed-in roads complicates the installation of standard wind turbines.

How to Capture Energy at 2,000 Feet with BAT

BAT 2000feet

A The body, or shroud, of Altaeros’s Buoyant Airborne Turbine (BAT) is kept aloft by 1,000 cubic meters of helium. Four air-filled stabilizing fins passively steer the BAT into incoming gusts. The company worked with airship and spacesuit pioneer ILC Dover to develop its proprietary UV- and weather-resistant fabric.

B The first commercial BAT will house a 30-kilowatt turbine, which could power roughly a dozen homes. A larger version will fly a 200-kilowatt turbine. The BAT can also carry radio and cellular antennae or wireless Internet gear to create or extend voice and data networks.

C Three double-braided polymer tethers prevent the airship from drifting away. One contains copper conductors that transmit power, collected as high as 2,000 feet, down to a battery or the grid.

D The ground station, responding to sensor data from the BAT, helps the craft hunt for optimal wind conditions, around 30 mph. It can adjust the BAT’s altitude using three winches and rotates as the craft faces shifting air currents. The station can also reel the BAT all the way in if wind speed exceeds 75 mph.

For more information check: www.altaerosenergies.com

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