The storage phase involves the compression of CO2 followed by transport, often via pipelines, to suitable geological formations where it is securely injected and stored in deep subterranean reservoirs.

The Danish underground has the potential to store up to 22 billion tonnes (GT) of CO2, which is equivalent to 500 to 1,000 years of Denmark’s current total emissions. Pilot CO2 injections have been conducted in Denmark, but the scale-up of the technology requires further research and understanding of the subsurface behavior of CO2.