The sequestration of CO₂ in the deep geosphere is one potential method for reducing anthropogenic emissions to the atmosphere without necessarily incurring a significant change in our energy-producing technologies. Containment of CO₂ as a liquid and an associated hydrate phase, under cool conditions, offers an alternative underground storage approach compared with conventional supercritical CO₂ storage at higher temperatures. We briefly describe conventional approaches to underground storage, review possible approaches for using CO₂ hydrate in CO₂ storage generally, and comment on the important role CO₂ hydrate could play in underground storage. Cool underground storage appears to offer certain advantages in terms of physical, chemical and mineralogical processes, which may usefully enhance trapping of the stored CO₂. This approach also appears to be potentially applicable to large areas of sub-seabed sediments offshore Western Europe.