Calcium looping (CaL), or the regenerative calcium cycle (RCC), is a second-generation carbon capture technology. It is the most developed form of carbonate looping, where a metal (M) is reversibly reacted between its carbonate form (MCO) and its oxide form (MO) to separate carbon dioxide from other gases coming from either power generation or an industrial plant. In the calcium looping process, the two species are calcium carbonate (CaCO) and calcium oxide (CaO). The captured carbon dioxide can then be transported to a storage site, used in enhanced oil recovery or used as a chemical feedstock. Calcium oxide is often referred to as the sorbent.
Calcium looping is being developed as it is a more efficient, less toxic alternative to current post-combustion capture processes such as amine scrubbing. It also has interesting potential for integration with the cement industry.