SkyLifters use sun and wind energy to fly.
The upper surface of the aerostat is the perfect place for solar collectors.
SkyLifters can drift with the wind, with thrust-off and using just a trickle of energy to power life-support, avionics and essential systems. Used when conditions permit, this is another major advantage of SkyLifters over their heavier-than-air, winged cousins.
SkyLifter’s are permanently floating so energy is used for propulsion, not for lifting. They will have a payload transport efficiency more similar to sea ships than to winged aircraft.