But it turns into CaCO3 after absorbing CO2 from the air, no?

The input substrate to produce CaO is CaCO3. This requires a lot of energy, often obtained by burning coal and the reaction releases CO2. Absorbing CaO/Ca(OH)2 makes sense only in systems like submarines/bunkers with no external air supply. As a CO2 capture method on a large scale is makes no sense. Even if we think about using CaO as some "CO2 capture and release" material with who knows, storing pure CO2 underground, I think even theoretical no CO2 emitting energy needed for baking CaCO3 has a better use.

What? Did you respond to the wrong comment? Can you tell me what you think my comment is trying to say?

Yeah, but making lime is very energy intensive.

If the lifetime energy savings are greater than this energy cost then it's still a good idea. You only need a thin coating so it sounds plausible to me.

Wrong thread? (because there's no paper being discussed in this one…)

Scroll up. Find the reference to the paper. Click on it. Read it.

Bad bot