[nullc]

I wonder if in the time since this was written if anyone has found a good source for small turbo expanders.

Liquefied air is a potentially interesting mode of energy storage for islanded solar because it doesn't require high pressure storage (which has safety concerns)-- for that application the round trip efficiency isn't critical as there is nothing else to do with the power... but it can't be a total joke. And the basic JT cycle is really poor. I understand that simply adding an expander and another heat exchange stage can improve it a lot.

[sandworm101]

If you are dealing with liquid nitrogen from air, then you are probably also dealing with liquid oxygen in the mix. I imaging that at power-storage scales the presence of such amounts of liquid oxygen might create safety issues. Separating it out might nullify any energy storage advantages.

[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.

[0cf8612b2e1e]

You could embed the chiller in a nitrogen only environment. I am imagining a closed loop system where you are cooling/using the nitrogen on a daily basis.