Comment by to11mtm

> With compressed air, you just release the air back to the atmosphere.

The issue with compressed air is that you have to build more of the system to handle higher pressures and/or have a more robust regulator design, plus the pressures required to compress CO2 back to liquid are typically lower than what you'd need to store a useful final volume compressed air...

Also, As far as having an 'open loop' (i.e. venting to atmosphere), that's typically got it's own problems, mostly that when you need new air you have to make sure it's 'pure', not just things like dust but even whether there's water vapor.