> 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. Hmm.

> 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. Hmm. Actually. I don’t think this is quite “back of the napkin math,” which usually involves some figures, if just only very rough ones with lots of rounding. This seems more like an argument from basic principle in the style of “I’ll reject any proposal of a perpetual motion machine because, however clever, it fundamentally can’t produce power.” And I don’t think your fundamental principle here really is correct actually. Some ideas around carbon capture are basically to do a chemical process that releases some energy, and then make sure the byproducts don’t escape, and bury them underground, right? There’s no fundamental reason that this should be impossible. I mean it’s obviously possible to take a log, burn it in a very big airtight metal box (very big, so there’s enough oxygen in there to fully burn the thing), the box will heat up, and then the byproducts will all be in the box, so you just don’t open it. This is a silly contraption but there’s obviously no fundamental law of physics being violated, so it must not be physically impossible. I’m unhappy to write this because I agree with your conclusion. Carbon capture is mostly bullshit. But it is bullshit for complicated reasons, not simple or fundamental ones, I think.