The idea is to have something that is tethered to the ground and held aloft by the winds at high altitude and that has wind turbines to generate power, which is sent back to the ground by cable.
There are pretty much always strong winds over much of the US at 5k-6k meters, so such a wind power generator would provide 24 hour a day power most of the time.
Here's a site showing the wind over the at around the height [1]. Click where it says "earth" in the lower left to change the height. The height is given in pressure. My link is for 500 hPa pressure which is somewhere around 5500 m. The 700 hPa option would be around 3000 m, and the 250 hPa option would be around 9000 m. Here's a site with a graph of pressure vs height if you want to know the heights for the other pressure options [2]. That graph uses kPa. 0.1 kPa = 1 hPa.
The proposals I've seen I've proposed a few different things to fly. One is basically just a kite carrying turbines. Another is a parasail. Another is some sort of rotor aircraft similar to a quad drone. I believe I've also seen some that use fixed wing aircraft with propellors.
The ones with the rotors or propellers would have electric motors powered from the ground that can be used to get the thing up to operating altitude, and then they switch the motors from taking electricity to drive the rotors/props to letting the wind drive the rotors/props to generate electricity.
[1] https://earth.nullschool.net/#current/wind/isobaric/500hPa/o...
[2] https://www.engineeringtoolbox.com/air-altitude-pressure-d_4...