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Published online 29 April 2009 | Nature | doi:10.1038/4581094a
Climate crunch: Sucking it up
It's simple to mop carbon dioxide out of the air, but it could cost a lot of money. In the second of three features on the carbon challenge, Nicola Jones talks with the scientists pursuing this strategy.
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Am I missing something here? It is claimed to be "only" twice as expensive to collect CO2 from the air than from flue gases. Are we short of flue gases to extract CO2 from, then? ...and the cost is orders of magnitude higher than sequestration in soils, oceans etc.
This all assumes that carbon capture and storage (CCS) proves to be cheap and effective. If we end up finding that it is not a viable way to keep CO2 out of the atmosphere, there will be nowhere for air-captured gasses to go. Also, if it proves to be expensive per tonne, the cost estimates here might be considerably increased. One other possibility worth mentioning is that we might be able to run thermal plants on biofuels, then use CCS for the emissions. In theory, that could play the same concentration reducing role as chemical air capture.
We are in the Wright Brothers era of CCS technology, and it is far too soon to project whether it will be an important stabilization wedge or an expensive flop. It is definitely too early to be estimating the specific quantities of emissions that will be averted by as-yet-nonexistent technologies at unknown future dates. It emissions are going to peak and descend to safe levels, we are going to need a lot of stabilization wedges: efficiency, protected and enhanced forests, zero-carbon electricity and fuels, and more. If we want to have a strategy that can survive the failure of a few major initiatives, that means we need extra wedges for contingency. As such, we probably can?t reject technologies like air capture, CCS, and the increased use of nuclear fission out of hand.
The article doesn't mention current projects to turn CO2 to fuel (redox cycling, for example). A trivial point: what do % and ppm mean when referring to gases?