Airborne Wind Energy - Aeronautics on a String
3:54 PM on Mar 28, 2012
Aeronautics doesn't have to be about aeroplanes. Altaeros Energies, an MIT spin-off, has demonstrated an airborne wind turbine (AWT) that uses lighter-than-air technology adapted from tethered aerostats.
It's 35ft-diameter subscale prototype has just demonstrated it can lift an off-the-shelf wind turbine to 350ft altitude, where it produced more than twice the power generated at conventional tower height, Altaeros says.
Photo: Altaeros Energies
Transported and deployed from a docking trailer, the prototype climbed to 350ft, produced power at altitude and landed in an automated cycle. Altaeros' goal is to develop an AWT that reduces energy costs up to 65% by harnessing the stronger winds above 1,000ft. It could be deployed in just days to replace diesel generators at remote locations.
Altaeros is not alone in this field. Makani Power is developing a tethered unmanned aircraft that autonomously climbs to altitude to produce power at half the cost of a conventional wind turbine, and uses 90% less material. The automous flying wing can handle sudden shifts in wind speed and direction, the company says.
Photo: Makani Power
Once aloft between 800ft and 2,000ft, and controlled by an onboard computer, the tethered wing travels in a circle mimicking the tip path of conventional wind-turbine blade. Wing-mounted rotors generate the electricity, and can keep the wing aloft if the wind dies.
Makani is developing its AWT with funding from the Advanced Research Projects Agency - Energy under its Wing 7 program, and has flown an 8m-span, 30kW prototype. It's goal is to develop a 28m-span, 600kW commercial version capable of delivering energy at an unsubsidized cost competitive with coal, says ARPA-E.
In December, Altaeros says, the FAA released draft guidelines for siting airborne wind systems. Longer term, both companies have their sights set on the deep offshore wind-energy market.