A pair of companies in Arizona are about to build a system to pull CO2 out of the atmosphere, attempting to prove that the "wind-scrubber" concept works. The scrubber will employ sodium hydroxide, which reacts with carbon dioxide, to remove CO2 from air drawn through the system. In principle, such systems could help to reduce carbon dioxide levels already in the atmosphere, thereby complementing attempts to reduce the amount of additional carbon being emitted.
There are a few problems with the system under consideration: it may not work; sodium hydroxide is caustic and toxic; and, according to the article, "the stored CO2 could be supplied to the oil industry for use in the process of enhanced oil recovery" -- which seems rather self-defeating, in the long-run.
All that said, the notion of figuring out ways to actively reduce existing carbon levels alongside reducing the amount of new carbon added to the atmosphere is a good idea. If, as some recent reports suggest, we may be already too late to prevent massive problems even if we manage to cut our emissions dramatically, aggressive carbon sequestration may be critical. Let's hope that the proof-of-concept test works -- and that they can then come up with a better technology (and lose the "use the carbon to pump more oil" idea).
I always wonder about this.
Why doesn't anyone get bio-engineer plankton to be more efficient at scrubbing this stuff?
The key problem with this plan is that there's energy involved in getting that sodium hydroxide. It doesn't occur in nature and has to be electrolytically extracted from salt water.
Another plan I've heard of, is to compress the CO2 into a liquid (it would be dry ice at normal pressure) and pump it into the deep seabed. It would dissolve into the seawater, which can absorb more than the atmospher and take many centuries to get back to the surface.
But I think the most compelling idea is to provide micronutrients (iron mostly) to the empty seawater of the south Pacific. The resulting algal bloom would extract up to a third of our current CO2 emission level, according to one estimate.