The concept of geothermal energy production from abandoned coal mine converted into CO₂ reservoir

Reducing CO₂ emissions results in decarbonisation and in consequence – mine closure. There is a need to find innovative solutions for economical managing of abandoned sites, while ensuring risks to public and the environmental safety. This new approach to repurposing mine sites, which was presented in the article may take advantage of existing mine infrastructure and contribute to the local community, environmental and economy after the mine has been closed down. The aim of this study is to present potential benefits of combining the integration of CO₂ storage with the production of heat and methane. The CO₂ storage in coal mines becomes more acceptable when integrated into a complete, overall energy development plan. The novelty of this concept is a comprehensive approach to the problem of abandoned mines management. This aim could be achieved by using CO₂ properties for enhanced coal bed methane recovery and geothermic energy extraction in abandoned coal mines. CO₂-geothermics aims at enhancing a density profile by cooling and condensing CO₂ using a heat exchanger at the top of the reservoir. A theoretical evaluation indicates some important benefits of CO₂-geothermics over other types of geothermal energy. The efficiency of the system is potentially very high, because the heat transport capacity per kg fluid in a dual-phase CO₂-system is almost 4 times higher than for a comparable hydrothermal project.