I am not sure if this is a unique idea, but it is interesting
In a fixed location like that, why use an expensive and dangerous Lithium battery when you can used compressed CO2.?
Maybe the conversion efficiency is lower, but that hardly matters if the power being stored is solar.
How many of these would we need to significantly reduce atmospheric CO2?
Iām not sure this would reduce significantly because we keep producing more and more (low cost air-travel???) but if CO2 can be used for storing energy it beats mining for Lithium (or anything that needs to be extracted) any day!
Yes. Lithium is good for tiny portable batteries, like in your phone. There are alternatives when if comes to massive energy storage in a fixed location. Other examples are pumping water uphill, using abandoned mineshafts to raise and lower heavy weights, storing compressed air in abandoned underground mine tunnels, and sand batteries storing heat.