CO2 high-temperature aquifer thermal energy storage (CO2 HT-ATES) feasible study: Combing the heating storage and CCUS

Carbon dioxide (CO2) capture, utilization, storage (CCUS), and High-temperature aquifer thermal energy storage (HT-ATES) have been considered as effective advanced techniques that could remarkably contribute to renewable energy and mitigating global warming. Thus, this study tries to combine these two concepts. We investigate the potential for storing & extracting the heating from deep aquifers by utilizing CO2 as a working fluid. To compare the performance of CO2 and traditional HT -ATES working fluid water (H2O), two parallel HT-ATES cycling simulations are employed in DuMux based on a real geology model, identical well doublet design, and pump performance to test the behavior of H2O HT-ATES and CO2 HT-ATES. The 30 years cycling simulation shows CO2 HT-ATES have similar reliable performance to H2O HT-ATES, but there is some difference worth noting: The traditional H2O HT-ATES (76-90 C) have a higher and more stable extract temperature than CO2 HT-ATES (73-90 C-degrees) because of water heat capacity is larger. The CO2 HT-ATES (27.3-28.3 kg/s) have higher flow rates than H2O HT-ATES (20.8-24.3 kg/s) since the viscosity difference. The CO2 HT-ATES could form the CO2 gas cap, thermal conduction and convection to the caprock less than H2O HT-ATES, which leads to less heating loss during the heating store stage. H2O HT-ATES (4000 TJ) have more total energy input/output volume than CO2 HT-ATES (3000 TJ), but the energy efficiency of CO2 HT-ATES (92 %) is superior to H2O HT-ATES (85 %). Besides, CO2 HT-ATES can sequester a certain amount of CO2 yearly, over 1.6 Mt CO2 will be sequestered in the aquifer after 30 years of operation.