> All you need is napkin maths. We gain energy by turning carbon into carbon dioxide. Now, we need the same energy to reverse it, but with a loss factor. I thi

> All you need is napkin maths. We gain energy by turning carbon into carbon dioxide. Now, we need the same energy to reverse it, but with a loss factor. I think you're forgetting location and energy sources are a big factor here. Nobody is suggesting burning carbon to capture carbon. If you could somehow e.g. use nuclear power in the middle of the continent to capture carbon emitted across the world - that would be incredibly useful, even if you had to put in twice as much power as you had obtained originally. (I am not suggesting carbon capture is a particularly good idea, just pointing out that your napkin math ignores some key factors.)