“A process in which a relatively pure stream of carbon dioxide (CO2) from industrial and energy-related sources is separated (captured), conditioned, compressed and transported to a storage location for long-term isolation from the atmosphere” (IPCC AR6 WGIII). CCS can be applied to different emissions sources to achieve different climate outcomes. CCS can be applied to fossil power generation or to industrial processes like cement production. In these cases, CCS limits the release of fossil CO2 to the atmosphere and reduces the emissions of the process. On the other hand, CCS combined with biomass-based power generation can constitute a form of carbon removal (see Bioenergy with carbon capture and storage).
CCS is designed to target concentrated streams of CO2 emissions being released from point sources. Chemical processes for CCS include pre-combustion capture, post-combustion capture, and oxy-fuel combustion. While other methods are available to capture CO2, including direct air capture and photosynthesis, these involve different chemical processes compared with CCS, and involve the capture of CO2 from the atmosphere, rather than from a point source.