Wind Turbines Take to the Skies
Source: BBC News, Lakshmi Sandhana (6/3/10)
Kites can harvest the fast crosswinds found at high altitude.
His airborne wind turbines will take off and fly to around 2000 feet, where they will float, generating power that can be transferred to the ground via a tether.
"Global wind is a tremendous source of energy—carrying nearly 870 terrawatts in global tropospheric winds," says Mr Bevirt of Joby Energy, which is developing the wind turbine technology. "In comparison, the global demand is 17 terawatts. Harnessing a tiny fraction will transform the way we power our civilization."
The notion of tapping into high altitude winds was first posed in the 1970s, but was not technically possible. However, recent advances in materials, computing resources and unmanned aerial vehicles have now made the idea viable.
The autonomous structures are computer-controlled and can take off vertically before navigating to the desired altitude. Flight is controlled by an advanced computer system and the harnessed electricity is sent down the tether to a substation where it is converted from DC to AC power, which can then be routed to a power grid.
The technology's inventors say the devices are portable and relatively inexpensive to build when compared to conventional wind turbines and can generate twice the amount of power. "Operating at five times the height of a conventional turbine increases both wind speed and consistency resulting in more power, more often," said Mr Bevirt.
Eventually wind farms containing several airborne wind energy turbines could be constructed to deliver power consistently. However, issues of cost and safety need to be further demonstrated.