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I'm in the need of some help here. I'm an artist and I want to paint digitally something that can have an use for the future of humanity. I would like to create an illustration about a futuristic hydroelectric that uses the vacuum of space to rise sea water into long hoses and then, before the water actually escapes, let the water come back, falling into generators.

So my question is, (I know it's a crazy idea but I'm allowing to dream technology will find the way to support structures with electric rockets), if we were capable to put a hose from the ocean to space, could it pump out water? Is that even possible?

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    $\begingroup$ The hose isn’t possible to engineer using today’s materials. It would have to be able to support its weight, and at miles in length, that would be an extremely large weight. It would also need to be vacuum-tight, and vacuum-tight materials that can also support miles of their own weight don’t really exist either :( $\endgroup$
    – TheEnvironmentalist
    Commented Aug 1, 2021 at 17:59
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    $\begingroup$ Does this answer your question? A water pipe from sea level to beyond the atmosphere $\endgroup$
    – PM 2Ring
    Commented Aug 1, 2021 at 22:05
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    $\begingroup$ Also related: physics.stackexchange.com/q/207076/123208 & physics.stackexchange.com/q/155371/123208 $\endgroup$
    – PM 2Ring
    Commented Aug 1, 2021 at 22:08
  • $\begingroup$ Thank you! Of course! gravity pull, sorry, I will start educating myself on physics, I know so little. Thank you again, this opens my eyes in a welcoming manner. $\endgroup$
    – Alenz
    Commented Aug 2, 2021 at 18:39

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No.

It's a little counter intuitive, but vacuum doesn't suck water up. Instead, air pressure pushed down everywhere.

If you had a vacuum hose from space down to the ocean, air pressure would not push down inside the hose. Since water is being pushed down everywhere else, it would rise in the hose until the weight of the lifted water pushed back hard enough to balance the upward push. This happens when the water has been pushed up 32 feet. See this Veritasium videos - World's Longest Straw

Trees play tricks to get it higher, but not above 300 feet. See these - How Can Trees Be Taller Than 10m? and How Trees Bend the Laws of Physics

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  • $\begingroup$ Thank you! The videos were great! I learned a lot. I have another question, is it possible to create a sintetic tree to suck up water in the same way? $\endgroup$
    – Alenz
    Commented Aug 2, 2021 at 19:00
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NO.

Sea water has to climb across the gravitational potential to reach space. Someone has to work against gravity. Don't be under the impression that vacuum would suck up liquid water like a suction pump. Supposing something similar to happen would lead to the creation of a perpetual energy source (wherein vaccum does work for you and you convert that energy to run turbines), which would violate Laws of Thermodynamics.

What will happen here is because the pressure above the water(inside the hose) is zero, now to maintain the vapor pressure above its surface (which is proportional to the temperature of water body) more water gets vaporized and rise up. Since the temperature at high altitude is low, this waster vapor is likely to condense onto themselves and fall back as droplets, unless you have a mechanism that maintains a warm temperature inside. Even if you manage to get this to the other end (vaccum end) you will only have water vapour and not liquid water

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  • $\begingroup$ Thank you very much for your kind answer! Does this means that If I put a real vacum pump at ten meters or so, I could get water vapor out of sea water due to cavitation? And if I were capable to create an structure, an advanced hose lets say, that get this vapor up to high altitude, I could condense it back to earth for turbine use? Is that theoretically possible? $\endgroup$
    – Alenz
    Commented Aug 2, 2021 at 19:27
  • $\begingroup$ In principle yes. But you have to realize that this vapour you get at the other end is very low in quantity unlike the vapour (steam) you get when you boil water. The vapour we are dealing with has to reach the top by diffusion (which depends on temperature) and also work against the gravity. Hence if you have a very long pipe upward the vapor you get would practically be unnoticeable, even after you thermally insulate the pipe and all that. A simple way out would be to boil the water and send the steam up, which is pretty dumb since we can have better steam engines working on the surface. $\endgroup$
    – TheImperfectCrazy
    Commented Aug 3, 2021 at 11:50
  • $\begingroup$ I love this web because it really proves me how much I don't know and I think I know. Thanks you! I get that a steam engine will get out more of the punch from vapor but isn't there a benefit of letting vapor get real high and then condense it down to a single and controled stream? My point is; if gravity accelerates objects going down, and we somehow get water very high and in a controled fashion, why we shouldn't obtain benefit from the pull of gravity on water down the road? Is it that difficult that vapor in a tube go real high? $\endgroup$
    – Alenz
    Commented Aug 4, 2021 at 13:54
  • $\begingroup$ Gravity does accelerate objects coming down, but gravity being impartial also does exactly the same thing for objects going up!! So had there being any benefit of objects falling under gravity, its already lost since you have to take the object up and against the gravity before it can fall down. That's the whole idea of conservation of energy. You really can't get anything more than you pay for! $\endgroup$
    – TheImperfectCrazy
    Commented Aug 5, 2021 at 8:06
  • $\begingroup$ hahahahahahaa I get it now! thank you, really thank you for having this much patience with me. $\endgroup$
    – Alenz
    Commented Aug 6, 2021 at 9:03
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Water pressure increases about 1.47 PSI per meter of depth due to the weight of the water (pressure may vary slightly with exact water temperature and purity). At a 10 meter depth water pressure is about 14.7 PSI which is about 1 atmospheric pressure. A complete vacuum in a pipe or tube could not lift water more than about 10 meters above sea level as atmospheric pressure could only push the water up about that high. And, as always, there is no free energy machine as it would violate thermodynamic laws.

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  • $\begingroup$ Thank you very much for your detailed answer! From all the other answers, what I can deduce is that the vacuum will rise water up to 10 meters but it will also make it boil due to cavitation. Is that right? If I would be able also to push vapor up through a gargantua hose, does circumstances change if I get the whole hose fill out with gas? Could it be that we were able to push gas through a looped hose that arrives and bends at cold high altitude region in the sky in order to make artificial waterfalls condensate over thounsands of turbines on they way back to earth? $\endgroup$
    – Alenz
    Commented Aug 2, 2021 at 19:50

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