Way, way above the ground, there's enough wind energy to power 50 globes, according to industry group Alternative Energy [source: Alternative Energy]. These high-altitude winds, historically beyond the reach of our technology and science, could be on the verge of feeding our grids.
Several companies are designing airborne turbines that would float thousands of feet in the air, converting high-altitude winds into electricity. Designs range from kite-type structures to blimps, essentially flying turbines that would capture wind, convert it to electrical power, and send it down to Earth by way of a tether.
Safety concerns abound, another reason why flying turbines have been a back-burner dream [source: Alternative Energy]. The Federal Aviation Administration has advised a limit of 2,000 feet (600 meters) for such structures, to avoid interference with air traffic, and designers have to prove that they can land their turbines safely should a tether fail or extreme weather cause other malfunctions.
High-altitude turbines are in various stages of development. They haven't yet been tested at the high altitudes for which they're intended [source: Alternative Energy].
Next, Tesla enters the picture.