You can use the NaOH/CaO cycle to scrub carbon dioxide at atmospheric conditions and even regenerate the calcium carbonate with a (fairly cheap) methane + pure

You can use the NaOH/CaO cycle to scrub carbon dioxide at atmospheric conditions and even regenerate the calcium carbonate with a (fairly cheap) methane + pure oxygen lime kiln (electric lime kilns are currently in testing). I'm fact, as long as we still use mined limestone to feed kilns, one can just switch them over to burn with pure oxygen (possibly diluted with it's own exhaust to reduce flame temperatures) and get a pure CO₂/H₂O exhaust. Usage in construction partially reacts back to limestone using atmospheric CO₂. The issue with plants is just that they are really inefficient compared to solar panels, to the point where scientists have some success feeding solar-industrial synthetic acetate to plants [0] and ending up substantially more efficient per solar-capturing area than outdoor plants. [0]: https://news.ycombinator.com/item?id=31957068 https://news.ycombinator.com/item?id=31957068