CCS involves three main stages:
CO2 is separated from other gases in an emission stream using a chemical process, and is thus "captured". The CO2 stream is compressed and sent on for transport.
When the CO2 gas is compressed to a liquid-like state, it is transported either via pipelines or in tankers and ships to a location suitable for permanent storage.
CO2 is injected into geological formations in the subsurface, at depths of one kilometre or more. Geological formations that are suitable for CO2 storage are composed of porous layers that CO2 can move and spread out within the formation, and one or more solid rocks that rest on the top like a cap, a barrier, thus preventing CO2 from leaking out.