That's a bit of a weird idea. CO2 is not present in fairly high amounts in the air, using some quick math, I would estimate that for 1kg of CO2, one would need

That's a bit of a weird idea. CO2 is not present in fairly high amounts in the air, using some quick math, I would estimate that for 1kg of CO2, one would need to filter over 2.5 tons of air (Though if we keep pumping more CO2 into the air, this will become more efficient). The energy required to do this won't be trivial, so it would have to be from renewable resources. Why not use those directly? I would suggest it would be more efficient to draw the water from the air and produce hydrogen, which is a clean fuel unlike carbon (which just burns into CO2 again, under normal conditions). And if you run out of water to pull from the air, you can probably find a bit of water on this planet to use, it's not like we want a rising sea level (though it's unlike we will impact the sea level by pumping out the water and turning it into hydrogen fuel) And as I just mentioned, the CO2 you just pulled from the air will burn straight into CO2 again, in fact, it'll burn into the exact same amount of CO2 (assuming clean combustion), so it's just a very inefficient battery... [repost from dupe, original deleted]