Airborne solar wind energy systems (ASWES) are evoked on
Airborne solar wind energy systems (ASWES) and on
The several kilometer long electrified tethers are a perhaps insurmountable problem: huge weight and drag, tensions on the balloon due to the taking of very powerful winds and requiring a solid and heavy construction, security in case of storms or too strong winds as the system is connected to the ground…
Free balloons flying in the stratosphere between about 15 km and 25 km has been realized or studied:
Stratobus’s power enables it to counter winds of this force, and remain stationary.
Loon deployed its high-altitude balloon network into the stratosphere, between altitudes of 18 km and 25 km. The company stated that the particular altitude and layer of the stratosphere is advantageous for the balloons because of its low wind speeds, which are usually recorded between 5 mph and 20 mph (10 km/h to 30 km/h). The layer is also an area of minimal turbulence.
Wind speed decreases in the stratosphere above jet-streams, and becomes low.
I think a large thermal and photovoltaic balloon could perhaps be used, not being subjected to the force of the wind and convection leading to the cooling of the contained air.
The black solar e-film of 60 g / m² and 2000 W / kg could be used for both thermal (for buoyancy) and photovoltaic (for electricity generation) uses:
Stratospheric solar (thermal) balloon are already in use:
Untethered airborne wind energy systems (untethered AWES) such as discussed on the current topic, cannot be mixed with untethered airborne solar energy systems (untethered ASES) where the relative wind speed is cancelled and not wanted.
It remains to store (batteries?) during the day and deliver at night, which is a thorny problem shared with untethered AWES. Another smaller balloon, this time inflated with hydrogen or helium, could make the round trips, discharging its charged batteries in the factory and taking back batteries not yet charged to repeat the cycle, its role being somewhat comparable to the tugs of ships.