Feasibility study of hydrogen storage in underground reservoirs in Oman

Hydrogen (H2) has been recognized worldwide as the energy carrier in transition from the current fossil-energy to the decarbonized economy. Large-scale green H2 produced by renewable energy is the key driving force of this energy system transition. Oman has been positioned as one of the regional hubs for green H2 production via water electrolysis in the next decades. Solar and wind are the two renewables to power water electrolysis in Oman, but both are intermittent and the associated variations on the supply have trouble matching a stable demand. To address this issue, excess solar or wind power can be used to produce H2 as a form of energy storage, and then distributed to the consumers during the low production season. This balancing method, however, requires large-scale H2 storage, which is beyond storage capacity of surface storage tanks. Depleted hydrocarbon reservoirs, which are widely available in Oman, provide potential solutions for both seasonal and long-term H2 storage. These reservoirs prove their geological seal integrity as oil/gas reserves. The existing onsite infrastructures can be retrofitted for H2 storage. Hydrogeological properties have also been well characterized during the decades of oil/gas recovery. The proposed study aims to investigate the feasibility of using these underground reservoirs for large-scale H2 storage by numerical model simulations. A hydrogeological model will be constructed to simulate injected H2 and native brine flow in a reservoir of the Fahud Field in Oman. Key properties of the reservoir will be estimated from rock samples in the laboratory. Seasonal injection, extraction, storage, and recovery efficiency of H2 will be evaluated for various operational scenarios. In addition to technical metrics, levelized cost of the H2 storage system will also be calculated based on the model results and market economic parameters to evaluate financial feasibility of the system development and operations. Optimal solutions for design and operation of the H2 storage system will be found to minimize the levelized cost. This techno-economic feasibility assessment will lay a foundation for potential pilot H2 storage projects using depleted hydrocarbon reservoirs in Oman.