CCUS is a technology that involves the injection of industrial emissions of carbon dioxide into suitable geologic reservoirs for the purposes of either long-term storage or energy recovery. Various technologies exist and more are being developed to enable the capture of carbon dioxide (CO₂) from industrial facilities. Once the carbon dioxide has been captured, and depending upon the source, the gas is typically compressed then transported via pipeline to the injection well. The CO₂ enters the subsurface as a supercritical liquid where it is effectively entombed for thousands of years. If the CO₂ is used for enhanced oil recovery, the gas is recycled in a closed system, which likewise results in the carbon dioxide being stored in the reservoir.