would apply to fossil-fuel power plants. CO2 is captured from flue gases at power stations or other point sources. The technology is well understood and is currently used in other industrial applications, although at smaller scale than required in a commercial scale station. Post combustion capture is most popular in research because fossil fuel power plants can be retrofitted to include CCS technology in this configuration. The technology for pre-combustion is widely applied in fertilizer, chemical, gaseous fuel (H2, CH4), and power production. In these cases, the fossil fuel is partially oxidized, for instance in a gasifier. The CO from the resulting syngas (CO and H2) reacts with added steam (H2O) and is shifted into CO2 and H2. The resulting CO2 can be captured from a relatively pure exhaust stream. The H2 can be used as fuel; the CO2 is removed before combustion. Several advantages and disadvantages apply versus post combustion capture. The CO2 is removed after combustion, but before the flue gas expands to atmospheric pressure. The capture before expansion, i.e. from pressurized gas, is standard in almost all industrial CO2 capture processes, at the same scale as required for power plants. In oxy-fuel combustion the fuel is burned in pure oxygen instead of air. To limit the resulting flame temperatures to levels common during conventional combustion, cooled flue gas is recirculated and injected into the combustion chamber. The flue gas consists of mainly CO2 and water vapour, the latter of which is condensed through cooling. The result is an almost pure CO2 stream. Power plant processes based on oxyfuel combustion are sometimes referred to as "zero emission" cycles, because the CO2 stored is not a fraction removed from the flue gas stream (as in the cases of pre- and post-combustion capture) but the flue gas stream itself. A certain fraction of the CO2 inevitably end up in the condensed water. To warrant the label "zero emission" the water would thus have to be treated or disposed of appropriately. Separation technologies The major technologies proposed for carbon capture are: Membrane Oxyfuel combustion Absorption Multiphase absorption Adsorption Chemical looping combustion Calcium looping Cryogenic Absorption, or carbon scrubbing with amines is the dominant capture technology. It is the only carbon capture technology so far that has been used industrially. Monoethanolamine (MEA) solutions, the leading amine for capturing CO2 , have a heat capacity between 3–4 J/g K since they are mostly