[teknopaul]

I think OPs point is this tech is good only if you sink it after.

I. e. Collection is half the problem.

Collecting it in a way it's cheap to get it back again is potentially just less than minus half the problem.

[teknopaul]

Did a bit of searching: fizzy drinks companies sometimes go and get stored CO2 to put in drinks or make it.

Any atmospheric extraction has a net positive compared to that.