Renewables don't all have steady load, so it could be an alternative to batteries/hydro batteries. Use natural gas peakers when renewables don't produce enough, use excess renewable power to remove CO2 from the air when they are producing more than you need. Basically it's using the atmosphere as a reverse-battery
The alternative there is to do pre-combustion CO2 capture on the methane, storing hydrogen (or hydrogen + nitrogen) for use in the peaking turbines.
Another possibility is to store CO2 underground, and when "charging" use a solid oxide electrolyzer to turn it to carbon. When discharging, it would be run as a SOFC and produce CO2, which would be cooled and stored again. I believe Noon Energy is looking into schemes like this.
