In my previous questions, I discussed the possibility of cloud cities on Saturn
Saturn is a large planet, and if we were to settle on its moons, such as Titan, it would be easily overpulated in just a few millenia
And there were a few technologies which could be useful for the colony. The cloud-cities in question are giant airships, based on tensegrity spheres (not mentioned in the diagram as I am bad at making shapes in Paint), which use wind-energy to generate electricity. The city's oxygen supplies come from algae-bioreactors (electrolysers-too much energy and constant ice supply from Saturn's clouds) and the food is derived from plants that are grown on the airship, and from livestock (mainly cows, goats and sheep). The population varies from city to city, from meagre scientific outposts of 500 people, to a bustling city of 5-10 million people, with about as much as 3 times the number of pets. In order to prevent the supersonic Saturnian winds (~1700km/h) from making sonic booms constantly, a thick glass dome is installed over the colony, meaning that the people won't have to lose sleep due to continuous wind noises.
However, there is a major problem with the airships.... and that is lift.
In Saturn's mostly hydrogen atmosphere, a hydrogen balloon would provide really little lift. The only gas that could provide sufficient lift is heated hydrogen. The advantage is that the airships are based on the Cloud Nine tensegrity sphere model, which means that just a increase of 1 degree can lift the airship. But.... there is a paucity of heat sources on Saturn.
Saturn is more than 1 billion miles away from the Sun, and solar energy is pathetically weak at these distances. Nuclear energy requires a constant supply of fissile materials from Earth, or noisy fusion reactors which would result in lack of sleep for the colonists and other health issues. There isn't a heat source on Saturn which would be enough to heat up the hydrogen.... unless you counted on
geothermal Kronothermal heat.
Actually that's what my world uses as a heat source for making the hydrogen hot enough to provide sufficient lift. The concept revolves around the fact that Saturn's interior is really hot, and that heat can be utilized to heat up the hydrogen for lift.
Graphene cables, which are miles long and are about a quarter of a foot thick, are dangled from the cloud-city, deep into Saturn's atmosphere. The cables harvest this heat to heat the hydrogen to sufficient temperatures for proper lift. Sort of like this-
Ammonia, a powerful phase-driven refrigerant would simply suck the heat out of the cables, meaning that there would be little heat to heat the hydrogen. Also the temperature gradient on Saturn is pathetically low.
Dangling cables from the city to pull up heat is actually dangerous instead of beneficial as they provide a lot of weight to the tensegrity airship, raising dangers of sinking.
So, I came up with a alternate solution for the airship.
Stupendously Large Airships
No matter how light Saturn's atmosphere is, it would always be denser than hydrogen
In fact, Saturn's atmosphere at the 1-bar level is about 0.19 kg/m3, denser than Jupiter's 0.16 kg/3 at the 1-bar level. Really light, but still it's twice as dense as hydrogen which leads me to think of this possibility.
If you could get an airship to be large enough, you could possibly lift an entire city in Saturn's atmosphere. These airships are
extremely Stupendously large, to make up for the buoyancy required to keep a city to float in the light atmosphere. The interior of these airships consist of pure hydrogen. And since there is no massive cable dangling down and providing too much weight, theoretically, our cloud-city should float on Saturn. I call them Stupendously Large Airships due to their tremendous size.
However, there seem to be a few disadvantages in this design. The airship would be extremely voluminous, meaning that there is more surface area for strong winds to tear it apart. And if rockets carrying tourists/passengers made a mistake, they could end up hitting the airship, and release the gas, and causing it to sink.
What should I choose for the Saturnian Cloud-City :- Geothermal Cables or Stupendously Large Airships?