After capture the CO2 is compressed into a dense, fluid-like state, before being injected under pressure to a depth of at least 800 metres. At this deep level the pressure and temperature is sufficient for the CO2 to remain in a supercritical state. It is known that CO2 in its supercritical state can be stored more efficiently in subsurface formations than in its gas or liquid state
To know about the details of carbon storage, and read about some of the disadvantages and risks involved: