CO2 capture/separation technologies
Cryogenic techniques use low temperatures to cool, condense and purify carbon dioxide from gas streams. They have been applied to moderately concentrated carbon-dioxide streams
Low temperature — cryogenics: flue gas under high pressure is cooled to sub-zero temperatures so only CO2 condenses. The other gases are released, leaving the carbon dioxide.
Low temperature — hydrates: chilled water is passed through cooling flue gas. Given the right temperature and pressure, CO2 and water freeze together to form ice-like crystals with the CO2 trapped inside (hydrates). The hydrates are removed and the CO2 released from the hydrates by heating.