[klunger]

At first, I thought this was an elaborate joke because fossil fuels are effectively "CO2 batteries."

Instead, it's compressed gas. Which is fine and possibly the best solution in certain contexts. But, it isn't exactly revolutionary or necessarily preferable to Li-ion most of the time.

[adrian_b]

Energy is extracted like from compressed gas, but the advantage of CO2 is that it can be liquefied at a relatively low pressure, so it can be stored at a relatively low volume in vessels that have to resist only to modest pressures.

So it is much easier to store a high amount of energy than it would be to store that energy in compressed air.