1 min video about a high altitude wind turbine from MIT startup http://www.altaerosenergies.com.
High altitude winds are one of the largest untapped renewable resources in the world. Professor Ken Caldeira of the Carnegie Institute for Science at Stanford University published research on the sector and concluded that “There is enough energy in high altitude winds to power civilization 100 times over.”
High altitude winds are more consistent and average around twice the velocity, with five to eight times the power density, than those found near ground-level
Founded by alumni Ben Glass '08, SM '10 and Adam Rein MBA '10, Altaeros has developed the world's first commercial airborne wind turbine, which uses a helium-filled shell to float as high as a skyscraper and capture the stronger, steadier winds available at that altitude.
Proven to produce double the energy of similarly sized tower-mounted turbines, the system, called Buoyant Air Turbine (or BAT), is now readying for commercial deployment in rural Alaska.
Surrounded by a circular, 35-foot-long inflatable shell made of the same heavy-duty fabric used in blimps and sails, the BAT hovers 1,000 to 2,000 feet above ground, where winds blow five to eight times stronger, as well as more consistently, than winds at tower level (roughly 100 to 300 feet).
Three tethers connect the BAT to a rotating ground station, automatically adjusting its altitude to obtain the strongest possible winds. Power generated by the turbine travels down one of the tethers to the ground station before being passed along to microgrids.