E.g. from 2000 - http://dge.stanford....Caldeira_Rau.html
Abstract
Various methods have been proposed for mitigating release of anthropogenic CO2 to the atmosphere, including deep-sea injection of CO2 captured from fossil-fuel fired power plants. Here, we use a schematic model of ocean chemistry and transport to analyze the geochemical consequences of a new method for separating carbon dioxide from a waste gas stream and sequestering it in the ocean. This method involves reacting CO2-rich power-plant gases with seawater to produce a carbonic acid solution which in turn is reacted on site with carbonate mineral (e.g., limestone) to form Ca2+ and bicarbonate in solution, which can then be released and diluted in the ocean. Such a process is similar to carbonate weathering and dissolution which would have otherwise occurred naturally, but over many millennia. Relative to atmospheric release or direct CO2 injection, this method would greatly expand the capacity of the ocean to store anthropogenic carbon while minimizing environmental impacts of this carbon on ocean biota. This carbonate-dissolution technique may be more cost-effective and less environmentally harmful than previously proposed CO2 capture and sequestration techniques.
(Emphasis added.)
It takes a lot of energy input to make it efficient. E.g. presumably the limestone would have to be trucked in, crushed to suitable dust; the power plant exhaust would have to be filtered to separate toxic things other than CO2 to control the pH, etc., etc.
On the Space Station, they have a nearly unlimited budget by comparison. About the only constraint is mass - mass is very expensive. But if some gizmo that filters/captures/transforms CO2 is very light costs a lot and needs a lot of power, that's not a big deal. One of the gizmo on the space station is the ISS CDRA - http://en.wikipedia....talisation_system . Photos are here - http://onorbit.com/node/1945 - it's not simple. It's had problems over the years.
Cheers,
Scott.