> 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.
No, we don't.
CO2 in the atmosphere is not the lowest-energy state in the system. If CO2 stopped being added to the atmosphere, it would eventually all be consumed out by chemical weathering of silicate rocks into carbonates, because that's an exothermic reaction that consumes CO2.
All the actually promising carbon capture proposals are essentially ways to speed up chemical weathering. The limiting factor here is surface area; the process is naturally very slow, and only occurs at an appreciable rate on the exposed surfaces of rocks in shallow water. None of them are cost-effective *yet* (and might never be), but there is not some one-sentence gotcha answer that prevents them from eventually being successful. They are not fighting against physics.
Um, no. The limiting factors are all still economic. If you want to try to rely on mineral weathering to reduce atmospheric CO2 any reasonable amount you now have to finance the quarrying, crushing to fine power, transport, and distribution of gigatons of stone or engineer a suitable replacement which replaces quarry and processing costs with input stock acquisition and synthesis leaving transportation and distribution untouched.
... Alternatively you do none of that and frack underwater basalt.
What makes these gotcha arguments so infuriating is that you have no clue what you are talking about, and refuse to spend even 15 minutes googling for what projects have been proposed and what is being studied. Instead you dream up an imaginary strawman to rail against. Literally no-one has ever proposed doing any of what you just talked about, because it would very clearly be economically unviable. There are many options that are not that which are being studied.
I'm going to go out on a limb and guess you haven't been paying any attention to ongoing pilot projects in europe studying seeding ag land with basalt fines as a possible mitigation strategy. Far from being uninformed I was merely trying to extend to you the benefit of the doubt inasmuch as I assumed nobody would credibly believe that fracking could produce meaningful amounts of surface area compared to powdered fines. Clearly I was mistaken, there are those among us that confuse make work for drill crews with actual progress. Carry on then.
No, we don't.
CO2 in the atmosphere is not the lowest-energy state in the system. If CO2 stopped being added to the atmosphere, it would eventually all be consumed out by chemical weathering of silicate rocks into carbonates, because that's an exothermic reaction that consumes CO2.
All the actually promising carbon capture proposals are essentially ways to speed up chemical weathering. The limiting factor here is surface area; the process is naturally very slow, and only occurs at an appreciable rate on the exposed surfaces of rocks in shallow water. None of them are cost-effective *yet* (and might never be), but there is not some one-sentence gotcha answer that prevents them from eventually being successful. They are not fighting against physics.