observe that where Helium becomes a significant percentage, there is also Hydrogen and (monoatomic) Oxygen.
if one were driven by purism or vanity for stoichiometric exactness, then at a height of 1000 km theres 2 Hydrogens per Oxygen atom, so this could be reacted to water, and the energy used to power compression of the Helium, the water would freeze.
without this vanity, helium becomes a significant fraction at much lower heights... and thus higher densities.
The energy to compress becomes nearly insignificant at low pressures.
if humanity ever builds space elevators, this will be one of many benefits of having space elevators.
The overall amount of helium in the atmosphere is still more than enough for the foreseeable future, and it could be extracted (albeit at high energy cost) by augmenting existing air separation units (ASU's). Of course natural gas wells currently provide an easier to extract source, seeing as the concentration there is way higher.
Helium is only 5ppm in the atmosphere. Extracting useful quantities of it that way will probably never be economically viable. In other words, if for some reason we can no longer get helium from natural gas wells then it will be cheaper to just let patients die instead of doing cryogenic distillation of helium from the atmosphere to run MRI machines.
Turns out -- no, it permanently escapes to space with the help of the solar wind
http://wordpress.mrreid.org/wp-content/uploads/2014/06/atmos...
the density is low though
observe that where Helium becomes a significant percentage, there is also Hydrogen and (monoatomic) Oxygen.
if one were driven by purism or vanity for stoichiometric exactness, then at a height of 1000 km theres 2 Hydrogens per Oxygen atom, so this could be reacted to water, and the energy used to power compression of the Helium, the water would freeze.
without this vanity, helium becomes a significant fraction at much lower heights... and thus higher densities.
The energy to compress becomes nearly insignificant at low pressures.
if humanity ever builds space elevators, this will be one of many benefits of having space elevators.
The overall amount of helium in the atmosphere is still more than enough for the foreseeable future, and it could be extracted (albeit at high energy cost) by augmenting existing air separation units (ASU's). Of course natural gas wells currently provide an easier to extract source, seeing as the concentration there is way higher.
Helium is only 5ppm in the atmosphere. Extracting useful quantities of it that way will probably never be economically viable. In other words, if for some reason we can no longer get helium from natural gas wells then it will be cheaper to just let patients die instead of doing cryogenic distillation of helium from the atmosphere to run MRI machines.
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Space is at the top of the atmosphere right? That place is full of stars producing helium by the teragram.
GP ain't wrong, but the phrasing implied we'd have it closer by than it actually is.
No, they're entirely incorrect because they used the word "near". There is no practically usable helium near the top of the atmosphere.
But, I'm also confident they were making a silly joke.
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Even if it didn't, collecting it seems wildly expensive.
Or free if we managed to run solar powered sails (or so) skirting the very top and autonomously sending the harvest down.
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Helium mines on the sun, pumping out millions of barrels of birthday-grade helium.
At night it’s called the moon