Storing excess wind or photovoltaic energy

There are batteries and pumped hydro for storing excess green energy - even that wacky idea of raising and lowering weights (gravity battery):

But this is a really interesting idea:

Sardinia - doesn't seem real

https://spectrum.ieee.org/co2-battery-energy-storage

They use a big bubble to store carbon dioxide gas.  When the sun is out or the wind is blowing they pump the gas out, compress it to a liquid and store it in tanks.  Then at night or during calm periods they release the compressed CO2 through a turbine to generate electricity, the uncompressed CO2 from the turbine output is stored in the bubble.  

This seems like a much easier concept (and more scalable) than gravity batteries:

https://www.cnet.com/home/energy-and-utilities/how-these-24-ton-bricks-could-fix-a-huge-renewable-energy-problem/

All that concrete and steel and mechanical pulleys/motors and generators make the gravity battery really complicated (something like 625 cement blocks - what does it sound like, probably smells OK :).

Hopefully Wile E. Coyote (genius) won't trash every green energy harvester like solar or wind.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm