A new paper (1) published in the prestigious American Chemical Society journal, Environmental Science and Technology, has put the cat among the pigeons over carbon capture and storage (CCS). It argues that the colossal amount of money that CCS would entail globally would be better spent on "virtual CCS", meaning per se that instead of actual CCS, the emission of carbon be avoided in the first place by a wholesale implementation of non-fossil energy sources, specifically wind and nuclear power. As a statistic to prove the point, it is estimated that one wedge (billion tonnes) of carbon in the form of CO2 sequestered by CCS would cost $5.1 trillion over 50 years, while the same amount of money used to build wind-turbines would save 1.91 "wedges" worth of CO2 over the lifetime of the windmills. A strong rebuttal to this case is presented in the September Chemistry World (2), which calls for a parallel development of CCS and non-fossil energy rather than the exclusion of the former.
Since 100 million tonnes per DAY of CO2 would need to be so sequestered by CCS the engineering required to bring it to fruition is phenomenal. There are essentially two methods to remove carbon from fuel: post-combustion and pre-combustion. Post-combustion, CO2 is removed from flue gas by passing it through a liquid amine which dissolves the CO2. Pre-combustion, the fuel (coal, gas, biomass) is processed into a mixture of CO2 + H2 and the CO2 is removed. Either way, the CO2 must be put somewhere, for which strategies include pumping it into rocky formations (such as depleted oil and gas wells) at a pressure of 100 atmospheres, or even piping it in liquid form under pressure onto the sea-floor where it is cold enough and the pressure high enough that it is hoped the material will stay there, assisted by the formation of CO2-hydrate.
(1) C Tsouris, D S Aaron and K A Williams, 2010, Environ. Sci. Technol., 44, 4042