"High-altitude winds between 1,640 and 3,281 feet (500 and 10,000 meters) above the ground are stronger and steadier than surface winds. These winds are abundant, widely available, and carbon-free.
"The physics of wind power makes this resource extremely valuable. “When wind speed doubles, the energy it carries increases eightfold, triple the speed, and you have 27 times the energy,” explained Gong Zeqi "
Could you use hot air? It might require some of the energy being generated be consumed, but its much more sustainable.
So it’s a 100kW generator and you would need around 60kW to float the weight of a hot air balloon basket with a couple of people. My math is probably way off though.