Comprehensive Approach for Modeling Underground Hydrogen Storage in Depleted Gas Reservoirs

Renewable energy is becoming an integral part of our energy supply; however, seasonality and weather dependence are some of their major limitations. Therefore, grid integration with reliable storage systems is crucial. One promising energy storage technology is green hydrogen generation and storage. Some research has been ongoing into hydrogen storage in underground porous media, but it mostly lacks comprehensive dynamic modelling of the storage operation and the associated potential losses. In this work. a holistic hydrogen storage operation in a heterogenous depleted gas reservoir and its likely associated underground losses was modelled. Fluid model verification was performed to assess the suitability of a typical equation of state to represent hydrogen behavior at reservoir conditions. The study aimed to assess the feasibility of storing 15% of the renewably generated power in Malaysia for grid-scale equilibration purposes. A total of 12 storage cycles with potential diffusion and biochemical losses were simulated. The storage operation performed effectively in all the key performance indicators. 68.1% of the injected storage volume was recovered by the 12th cycle. It was observed that the purity of the produced hydrogen is influenced by reservoir heterogeneity. Lastly, it was found that storing 15% of Malaysian renewable energy in a depleted gas reservoir was technically feasible.