Wind energy at altitude from kites

In a brief, excellent video on TED talks Saul Griffith demonstrates the harvesting of wind power from high altitude winds with kites. Kites offer two key advantages over ground-based wind turbines: they can access much faster wind speeds at higher altitudes, and they can sweep out much larger areas in the sky, thus capturing a lot more wind power (the power generated by a wind turbine is proportional to the area swept out by its blades).