Numerical simulation of a supercritical CO2 geothermosiphon

The thermo-hydraulic performance of a CO2 geothermosiphon has been numerically investigated using the commercially available software CFX. A simple Engineered (or Enhanced) Geothermal System, EGS, consisting of an injection and a production well as well as a reservoir is numerically simulated. Both water and carbon dioxide have been examined as the working fluid. While the former fluid has been very popular for its availability, the latter offers advantages such as favorable thermodynamic properties as well as the inherent possibility of geosequestration. However, detailed analysis of such CO2 geothermosiphon systems is not available in the open literature. Higher heat extraction rate from the reservoir at lower pressure drops for a CO2 geothermosiphon, compared to water-based systems, can be achieved and general criteria for that are presented.