Exergy Analysis of Coupled CO2 Sequestration with Geothermal Energy Production

The case analysed in this study is the direct injection of captured CO2 into aquifer water that has been pumped to the surface by the geothermal plant, thereby being stored in solution. An exergy analysis of the process as a whole, utilising recently produced data on the exergy inputs and outputs of coupled CCS and geothermal technology. The system has been divided into core systems each characterised in a MATLAB exergy model, comprising of two parts, i) a case study model taking previous exergy studies of power plants and geothermal plants and integrating them allowing for validation of the model based on current systems; ii) is a theoretical model allowing for a continuous analysis of each component, this is based on utilising emission factors of power plants and then looking at identifying the optimum geothermal plant size for the dissolution of the associated CO2. The construction of the models has further looked to develop on the current state of exergy analysis by increasing the level of physics by departing from utilising ideal gas states to an improved equation of state better able to capture the fluid properties in particular of Carbon dioxide.