[nullc]

It's not all that energetically disfavorable to extract oxygen if you're already compressing the gas. There is a lot of demand for concentrated oxygen too, so one could manufacture it as a side product instead of storing it.

As far as 'closed loop' sadly that does break the economics, I think-- part of the reason why cryogenic nitrogen storage is interesting is because the nitrogen expands 800 fold at atmospheric pressure, so the container for the decompressed nitrogen would be gigantic.

[voakbasda]

I would wager that the regulations governing LO2 generation facilities preclude pursuing that as a side product. I imagine lots of red tape, either already in place or coming soon -- right after someone blows up their neighborhood trying.

[yetihehe]

Or you can use that liquid oxygen to precool your input, saving some energy over just venting it.