[mixedbit]

Can't we just store C and let the O2 back in the air like plants do? We could store it right where it came from, in old coal mines.

[thinkcontext]

Chemical reduction of CO2 is a very hard problem since it takes a lot of energy. There's an enormous amount of research in this area. Storing it costs money, so most of the research focuses on turning the C into a useful product.

https://en.wikipedia.org/wiki/Electrochemical_reduction_of_c...