Carbon dioxide capture technology is used to remove carbon dioxide from gas streams or separate it as a gaseous product. Capture is the first step in carbon capture and storage (CCS) technology. Carbon dioxide needs to be present in high purity during transportation and storage, but in most cases, the concentration of carbon dioxide in industrial exhaust gases does not meet this requirement. Therefore, carbon dioxide must be separated from the exhaust gas; this process is called carbon dioxide capture. Carbon dioxide capture technologies can be divided into several categories, including chemical absorption, physical absorption, physical adsorption, membrane separation, and cryogenic separation. The selection of capture methods and equipment depends on the actual characteristics and parameters of the carbon dioxide emission source.
Carbon capture processes have been used in the petroleum, chemical, and power industries for decades. Using current technology to capture all or three-quarters of the carbon dioxide in a typical power plant requires equipment many orders of magnitude larger than conventional equipment-a high-cost, high-energy-consuming option.