[eppp]

So CO2 is magical here or would a reservoir of highly pressurized atmosphere be just as valuable? I think you are missing where the value is in this situation.

[regularfry]

Strongly suspect you don't want pressurised oxygen-containing-atmosphere in that situation.

[mgiampapa]

Liquefying air and separating O2 and N2 isn't that hard to do, particularly if your end desired state is a high pressure gas.

[regularfry]

Yes, but if you don't have to do it, why bother?