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This is my third question in the series "Saturnian Cloud Cities", the previous question is "Ice Harvester Planes"

The Saturnian cloud city consists of a giant Titanium-Graphene zeppelin-like structure, which is filled with hot hydrogen I am not using blimps here, as they will be torn apart by the tremendous winds . The hydrogen gas is heated by long geothermal cables that dip down into the lower atmosphere to harvest Saturn's immense heat. The geothermal cables are attached with large copper blocks that act as an anchor to hold the ship in place. Since the wind speeds on Saturn are tremendous, about 1,700 mph, the colony uses massive titanium turbines that spin to produce electricity for the colony. Details come from my first question in the series. A diagram for reference. enter image description here

However, on my first question, I received an answer that said that wind turbines would be negated, as the city is moving with the wind, and thus the relative wind speed would be zero. Even after using the copper anchor, the city would be moving along with the wind, as there is no friction to slow it down.

How do I solve the problem of the negation of wind-turbine? If not, then what alternative electricity source must I use in place of it?

EDIT: I completely forgot that the copper chunks are there mainly for anchoring the ship by acting as heavyweights, and conducting heat is only a unintended byproduct.

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Objection could be valid, but it misses the important part that those layers have significantly different densities, and are separated by a good deal of km's and what will be harwested is the difference of speeds between those layers, and there will be a difference for many reasons(okay atleast few, same as jets in earth athmosohere).

But also it may be a good time to replace those placeholder things like copper chunks and grafene with something which may work.

First of all mass does nothing to anchor things on saturn, until you reach layers with metalic hydrogen which forms a surface, if there is one(or more regular stuff down the core, to which a mass do its regular doing - a friction)

But what does something is known as floating anchor/sea anchor which explotits exactly that difference in densities of layers water vs air and velocity differences of those layers.

So increase crossection(decrease density) for upper layer structures or down layer structures and your construction will be more in sync with an upper or lower layer flows.

Instead of useless(except anchoring properties) sail down there, your turbines can be there instead, so as they can be on top and regulating angle of their blades you can change (shift) to which layer movement you are sticking more, this way you can steer in a way, same as sail ships did.

Also a proper heat exchanger, to which more surface is better, and surface is what needed to stick more to movement of lower layer can serve as somewhat an anchor, but standstill (not achievable) are worse for heat exchanger, so it needs some balance.

Also you have to actively pump the heat up, via some heat carrier(water as an example), for it to be used for heating of you carrying construction so as used to extract energy from that heat temperature difference.

I mean no matter how good grafene, or a metal, are as heat conductors, when you talk about distances of 10's km it won't do it, and no matter how lovely copper is in radiators for cpu, when you have a 10m size chunk it surprising how poor of a conductor it becomes, one of the reasons why car radiators have those pass trough holes and why copper is relatively thin there.

I mean, you have to have proper saturnotermal heat/energy extraction sysytem, and what you choose will define how the whole structure behaves in relationship of mass flows(winds) of gas around it and layers it is "connected" to.

PS

Scale heigth of saturn is about 60km, so layers with 0.5 bar pressure and those water hot layers up to 20bar, 330K are separated by about 220km, so it about the length(heigth) of the whole structure, where 100 something km is the length of the cables on your picture.

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If not, then what alternative electricity source must I use in place of it?

/The hydrogen gas is heated by long geothermal cables that dip down into the lower atmosphere to harvest Saturn's immense heat./

Immense heat sounds like a good energy source. Use the heat to power a steam engine and generate electricity. You can also use the heat to heat your hydrogen, or you can have electrical heaters for the hydrogen.


As regards the copper blocks they are fine but I think better is if the city is anchored to an uncertain solid something. That is how anchors usually work. The builders of the city tried and tried for something solid that would hold an anchor and eventually they found something. They ran the geothermal cables and heat collection apparatus down the anchor line. It is still not known what exactly the city is anchored on. Whatever it is, it is a long way down.

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  • $\begingroup$ perhaps into the liquid hydrogen ocean? $\endgroup$
    – Alastor
    Commented Oct 7, 2022 at 4:57
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A) Deploy gliders, or lots of little drone or kite turbines, or B) piezoelectric 'cilia' or cables that hang below your city.

a) Rather than collecting energy from one large turbine, or a wall of turbines on your city, you could deploy swarms of energy collectors that use the potential energy of gravity and winds.

In a limited way this is already being done here on earth, with sea gliders using gravity to fall and drive water through a turbine, and buoyancy to float back up. This recharges the batters and makes them viable for long missions.

Another somewhat similar concept are kites or drones that are tethered and collect wind energy sending the generated electricity back (here on earth to the ground.) Being tethered they don't have to have large batteries to store the energy. They tend to fly in loops and that solves your relative motion problem. One concept was to have thousands of these low cost tethered drones out in the ocean rather than the larger much more expensive windmills.

So if you have some kind of super battery able to store a lot of energy, you could have the drones be energy collectors... then maybe you could have glider pilots that go out to collect energy, or maybe robot drones, and bring refilled batteries back.

b) You floating city starts to look more like a giant paramecium or microorganism with dangling piezoelectric cilia collect energy as they move around due to the turbulence, or by electromagnetic induction as the cables move through Saturns magnetic field (a little weaker than the Earth's). The induction method has been kind of tested for some satellites with mixed results. If the cillia or dangling cables are 'smart' somehow perhaps they have a airfoil shape and could also steer the city somehow.

The sea anchor concept, @MolbOrg, is a good one and it would be interesting to think of how much airflow you get, and since your structures have to be so big, if turbines would be able to use that airflow if on the outer structures, but if the pressure is 0.5 bar, it might be better to dangle them at some higher pressure for better efficiency.

BTW, your best heat engine will be between where you have the maximum temperature difference. Everywhere else you may want to just have an efficiently way to transport the energy. It seems like you copper blocks if more of an airfoil shape could also help control the altitude. That might keep your geothermal engine in the sweet spot. You have the buoyant force of the Zeppelin but you would also have aerodynamic flow forces that would depend on how the structure is moving through the atmosphere.

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