Ke Li, Dejian Zhou, Huhao Gao, Leonhard Ganzer, Martin Sauter, Philip Jaeger, B. Hagemann, Alexandru Tatomir
This study presents a comparative evaluation of three subsurface energy storage technologies: methane storage, hydrogen storage, and high-temperature aquifer thermal energy storage (HT-ATES), within an identical geological and storage facility. The novelty lies in the application-oriented assessment of different energy storage carriers under unified porous media storage and long-term cyclic operation. Using a digital workflow based on a real geological model derived from a real gas field. The energy density, production performance, and energy efficiency of three storage types are analyzed over 20 years of cyclic operation. The results show: For energy density, methane storage exhibits the highest volumetric energy density and the greatest sensitivity to porosity, enabling substantially greater cumulative energy injection and recovery compared with hydrogen storage and HT-ATES. The energy density of HT-ATES shows limited sensitivity to porosity and demonstrates competitive performance in low-porosity formations. For production performance, all three storage types are capable of supplying energy continuously and stably during the winter season. The key difference is that methane and hydrogen storage can produce over 90% of their stored energy within two weeks, as they accumulate pressure during the energy injection season. HT-ATES is limited by material balance operation and higher working fluid density, it cannot withdraw large volume energy a short time. For energy efficiency, all three storage types exhibit high recovery performance. However, the requirement for cushion gas in gas storage systems reduces their competitiveness compared to HT-ATES. Methane storage has the largest CO₂ footprint due to combustion emissions. Hydrogen and HT-ATES, when charged with zero‑carbon sources, produce no direct emissions. HT-ATES incur higher system operational carbon emissions due to continuous pumping requirements.