US Patent 10309374 Energy kite winching using buoyancy

Offshore airborne wind turbine systems with an aerial vehicle connected via a tether to an adjustably buoyant body. The tether may be coupled to an underwater mooring through which it may move, or it may be coupled to a floating platform through which it may move. The buoyancy of the buoyant body may be adjusted to change the tension in the tether or for other purposes.