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This is a hugely flawed analysis. Noble gases are extracted from air through liquefaction, which requires dropping the temperature of air to the point where cer

This is a hugely flawed analysis. Noble gases are extracted from air through liquefaction, which requires dropping the temperature of air to the point where certain component gases are liquid, allowing them to be separated off. Krypton has a boiling point of 120 Kelvin, far higher than even Oxygen (90 K) or Nitrogen (77 K), making it trivial to extract Krypton at low cost from the atmosphere in any air liquefaction facility also set up to separate Oxygen and Nitrogen (which is basically all of them). Helium, however, boils at 4 Kelvin. It is not merely cryogenic, it is super cryogenic, and it can only be separated from air via liquefaction at extremely low temperatures. Instead, the method that is actually used to produce almost all Helium is to use natural gas (which contains as much as 7% Helium) and then separate out all of the stuff that isn't Helium (starting with the hydrocarbons, of course). This makes it possible to produce 99.995% pure "grade-A" Helium fairly cost effectively. Every cubic meter of natural gas processed could yield up to 70 liters of grade-A Helium. Compare that to processing air, where every cubic meter of air processed would yield just 5 milliliters of low grade Helium. And Helium isn't valuable enough to simply run those plants and throw away the other gases produced. By some estimates, if all of the Neon production facilities were modified to produce Helium as well then we might be able to meet 1/1000th of the world's Helium demand, so this is not a near-term solution to the problem, even if it might be able to produce the gas inexpensively.

Boxxed 8y ago
Naively, couldn't you extract helium by liquifying everything else and taking the leftover gas? So instead of cooling to 4 kelvin, cool to the boiling point of the element with the 2nd lowest boiling temperature. Or is that not helpful because that happens to be very low too?
- ant6n 8y ago
  Even further, shouldn't it only be necessary to liquefy down to Nitrogen, which should leave some gas that has a very high percentage of helium, and then use the same method that's used in separation of natural gas and Helium?
  - thaumasiotes 8y ago
    Further? That's the same idea.
    - ant6n 8y ago
      The difference is liquifying "to the boiling point of the element with the 2nd lowest boiling temperature" (likely Neon @ 27K) and "liquifying down to Nitrogen" (77K).
      - thaumasiotes 8y ago
        According to https://en.wikipedia.org/wiki/Natural-gas_processing https://en.wikipedia.org/wiki/Natural-gas_processing , the helium is recovered from natural gas during the phase in which nitrogen is removed. Natural gas has very different content compared to the atmosphere. Let's also note that even ignoring the specific details of the process, what you're proposing is to use a pipeline which produces helium as a side effect of its intended use of producing methane, and which is usually run on a mixture of gases that is 1% or more helium, and apply it to a mixture of gases which will produce no methane and is 0.0005% helium. The helium is nearly worthless and there's barely any to harvest in the first place; there is no possible way for this to be economical.
        ant6n 8y ago
        Well, the idea is to produce Helium as a by-product of producing liquid nitrogen. But indeed, the numbers may not work out: About 8 million tons of liquid nitrogen is produced per year, growing 5% every year [1], largely from Cryogenic distillation. By mass, the ratio of Nitrogen and Helium in air is about 1e6 [2]. So that means, about 8 tons would be produced, which is 3.5 orders of magnitude away from the current size of the market (like 30 thousand tons). But it may be possible to use non-cryogenic processes [3] to increase the ratio of Helium in the air before separating out the nitrogen. So between the increase of the nitrogen market, the decrease in demand if Helium gets more expensive when traditional sources run out, and better processes, this means that Helium will likely continue to be available for very valuable use cases almost indefinitely. [1] https://www.grandviewresearch.com/industry-analysis/liquid-nitrogen-market https://www.grandviewresearch.com/industry-analysis/liquid-n... [2] http://www.uigi.com/air.html http://www.uigi.com/air.html [3] https://en.wikipedia.org/wiki/Air_separation https://en.wikipedia.org/wiki/Air_separation
- mehrdadn 8y ago
  I'd guess you'd still have problem separating helium from hydrogen?
  - amluto 8y ago
    That seems relatively straightforward to solve chemically. Hydrogen can be adsorbed by many different materials. Or you could add just the right amount of oxygen to burn the hydrogen and then condense the water out.
    - zrm 8y ago
      Couldn't this also be done for the other reactive components (especially nitrogen and oxygen) before cooling the gas? Removing ~99% of the mass ahead of time would require that much less energy for cooling.
      - londons_explore 8y ago
        Liquid oxygen and nitrogen both have some commercial value. The tricky but is the liquidation process only liquifies some small fraction of the gas. The rest remains as a gas, so you now have "helium enriched" air, but it is still a very small percentage helium.
- InclinedPlane 8y ago
  Yes, that's how you could do it by modifying liquefaction plants that can produce Neon. In theory, you could take the leftovers after separating out Neon and you'd have a small amount of Helium. As I mentioned, at 5 ppm that doesn't give you much Helium, and you still need to purify it.

Boxxed 8y ago

Naively, couldn't you extract helium by liquifying everything else and taking the leftover gas? So instead of cooling to 4 kelvin, cool to the boiling point of the element with the 2nd lowest boiling temperature. Or is that not helpful because that happens to be very low too?

ant6n 8y ago
Even further, shouldn't it only be necessary to liquefy down to Nitrogen, which should leave some gas that has a very high percentage of helium, and then use the same method that's used in separation of natural gas and Helium?
- thaumasiotes 8y ago
  Further? That's the same idea.
  - ant6n 8y ago
    The difference is liquifying "to the boiling point of the element with the 2nd lowest boiling temperature" (likely Neon @ 27K) and "liquifying down to Nitrogen" (77K).
    - thaumasiotes 8y ago
      According to https://en.wikipedia.org/wiki/Natural-gas_processing https://en.wikipedia.org/wiki/Natural-gas_processing , the helium is recovered from natural gas during the phase in which nitrogen is removed. Natural gas has very different content compared to the atmosphere. Let's also note that even ignoring the specific details of the process, what you're proposing is to use a pipeline which produces helium as a side effect of its intended use of producing methane, and which is usually run on a mixture of gases that is 1% or more helium, and apply it to a mixture of gases which will produce no methane and is 0.0005% helium. The helium is nearly worthless and there's barely any to harvest in the first place; there is no possible way for this to be economical.
      - ant6n 8y ago
        Well, the idea is to produce Helium as a by-product of producing liquid nitrogen. But indeed, the numbers may not work out: About 8 million tons of liquid nitrogen is produced per year, growing 5% every year [1], largely from Cryogenic distillation. By mass, the ratio of Nitrogen and Helium in air is about 1e6 [2]. So that means, about 8 tons would be produced, which is 3.5 orders of magnitude away from the current size of the market (like 30 thousand tons). But it may be possible to use non-cryogenic processes [3] to increase the ratio of Helium in the air before separating out the nitrogen. So between the increase of the nitrogen market, the decrease in demand if Helium gets more expensive when traditional sources run out, and better processes, this means that Helium will likely continue to be available for very valuable use cases almost indefinitely. [1] https://www.grandviewresearch.com/industry-analysis/liquid-nitrogen-market https://www.grandviewresearch.com/industry-analysis/liquid-n... [2] http://www.uigi.com/air.html http://www.uigi.com/air.html [3] https://en.wikipedia.org/wiki/Air_separation https://en.wikipedia.org/wiki/Air_separation
mehrdadn 8y ago
I'd guess you'd still have problem separating helium from hydrogen?
- amluto 8y ago
  That seems relatively straightforward to solve chemically. Hydrogen can be adsorbed by many different materials. Or you could add just the right amount of oxygen to burn the hydrogen and then condense the water out.
  - zrm 8y ago
    Couldn't this also be done for the other reactive components (especially nitrogen and oxygen) before cooling the gas? Removing ~99% of the mass ahead of time would require that much less energy for cooling.
    - londons_explore 8y ago
      Liquid oxygen and nitrogen both have some commercial value. The tricky but is the liquidation process only liquifies some small fraction of the gas. The rest remains as a gas, so you now have "helium enriched" air, but it is still a very small percentage helium.
InclinedPlane 8y ago
Yes, that's how you could do it by modifying liquefaction plants that can produce Neon. In theory, you could take the leftovers after separating out Neon and you'd have a small amount of Helium. As I mentioned, at 5 ppm that doesn't give you much Helium, and you still need to purify it.