So my Cloud-cities, were practically Rigid-Hull Airships made of titanium and graphene to withstand severe wind-speeds and turbulent weather on Saturn. The Cloud-cities in question, are floating in the altitude of Saturn's atmosphere, where the pressure is about 1-bar, temperatures are about -180$^\circ$C, and the air density is about 0.30 kg/m3, according to this wonderful answer from BMF on my previous question. The average area of one "Cloud-City" is about 100,000 km2. Electricity comes from titanium wind turbines, that harvest the intense winds of Saturn, and produce energy for generating light for Algae-O2 generators and food crops.

In my old questions, I used to feature a common feature in my cloud-city- Kronothermal Cables.

The concept was really, really simple- They were graphene cables with extremely high tensile strength, which were plunged deep into Saturn's atmosphere, attached with a bunch of copper weights to serve as ballast. The graphene cables would then absorb this heat and conduct them upwards, to the airship-hull, which contained pure hydrogen. This hydrogen envelope would get heated up and get less denser than the surrounding Saturnian atmosphere, and buoy up the balloon.

However, I am no longer optimistic about that idea, due to the following reasons:

  • Since these cables are too long, they will not be able to efficiently conduct up heat to the cloud-city, and hence not work.
  • These cables along with the copper blocks, won't act like a ballast for the ship to stay anchored in place.

So, I came up with a new idea.

Kronothermal Hydrogen Pumps

So this idea is very similar to the "cables" idea, but with a twist: There is no conduction of heat being used here.

The basic principle here is:

  • First, a extremely long hose is lowered/dipped deep into the Saturnian Atmosphere, till it reaches the depth, where the temperature is 400$^\circ$C. The hose in question is made up of an composite titanium alloy that is flexible and strong.
  • Then, a large pressure difference is created, via starting a vacuum chamber connected to the hose. This creates a pressure difference that lowers the pressure inside the hose.
  • The hot Saturnian gas at the bottom of the hose is sucked up due to the low pressure inside the pipe. This gas rises up till it reaches the cloud-city, where it is made to contact the cloud-city's supporting gas-envelope, heating up the gas inside it. This heated hydrogen then buoys up the cloud-city.

What are the problems with my design? If so, what should I do to fix them?


1 Answer 1


There is already a large difference in temperature and pressure between the depth of Saturn and the height where you want to place your city, but it's not sufficient to raise the atmosphere up to there.

The additional vacuum that you can make, which is at most 1 bar, won't change the landscape too much: raising the mass of gas against the gravitational field will dissipate the energy content of the gas, giving you nothing at the end.

If you want to harvest heat from the depth, you should probably use a carrier fluid, which absorbs the heat in the depth and releases it in the city: a very large scale heating system.

  • 1
    $\begingroup$ Yeah, this won't work for the same reason that a 100 km long straw from sea level doesn't suck the ocean/atmosphere out to space. The force between vacuum "sucking" on the atmosphere and gravity is evenly balanced. $\endgroup$
    – BMF
    Commented Dec 9, 2022 at 16:20
  • $\begingroup$ You might be able to manage some kind of OTEC-style system, basically using the pipe to constrain an artificial convection current, but in reality the thermal losses would be essentially total. There are far better alternatives, like the fusion reactors that previous questions indicate are available. $\endgroup$ Commented Dec 11, 2022 at 15:33

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