System Design and Economic Feasibility Study of Large-Scale Hydrogen Storage in Aquifers

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 220044, “Technoeconomic Optimization of Underground Hydrogen Storage in Aquifers,” by Behzad Amiri, SPE, Mojtaba Ghaedi, and Pål Østebø Andersen, SPE, University of Stavanger, et al. The paper has not been peer reviewed. _ Serious concerns exist about the economic feasibility of underground hydrogen (H2) storage (UHS) in aquifers. The authors’ objective is to investigate the use of an optimization workflow to maximize both H2 storage and net present value (NPV), consequently obtaining an optimal reservoir development strategy. Introduction An aquifer storage system for H2 typically consists of a brine-saturated formation layer, injection and withdrawal wells, and surface pipelines. The injected gas is divided into cushion gas (usually H2 or another gas) and working gas (H2). The main purpose of the cushion gas is to maintain sufficient minimum pressure, while the working gas is aimed at temporary storage and later production and sale. During UHS, the working gas is injected into the subsurface and then mixed with the formation fluid and extracted in a cyclical manner. Compressed H2 is injected into the target formation through a well. Fluid flow primarily is driven by pressure gradients and controlled by H2/brine mobility and density contrasts. However, the high mobility contrast between gas and water can lead to bypassing. Gravity segregation enhances the recovery of H2 during production but increases the risk of uncontrolled horizontal migration and leakage through the caprock. NPV analysis is used in UHS projects to assess if anticipated returns over time are sufficient to justify investment. By carefully formulating and optimizing the NPV, the profit of the storage process will be maximized. The complete paper details several works in the literature devoted to the economic potential and feasibility of hydrogen storage. To determine the profitability of the whole project, it is necessary to calculate the NPV. Furthermore, it is necessary to examine the interplay between H2-storage technical issues and NPV to determine the most effective development strategy. This research focuses on optimizing the development strategy of UHS in a deep aquifer. Methodology Aquifer Model. An open-source version of the Norne field model is used. The Norne field is on a raised block in the southern part of the Norwegian Sea. The Horst block has an estimated length of 9 km and a width of 3 km. The porosity of the material falls within the range of 25–30%, while the permeability varies from 20 to 2500 md. The original model consists of 22 vertical layers, which are further split into 46 and 112 grids in the x and y directions, respectively. The model consists of three separate zones: gas, oil, and water. An impermeable barrier, known as Not, separates the oil and water zones from the gas zone. The current research specifically examines the oil and water zones while excluding the gas zone from the model. The revised model is fully saturated with water by positioning the oil/water contact over the least-deep section of the reservoir. The eastern half of the model has been deactivated to improve computational efficiency. In its place, a pore volume multiplier of 30 is applied to the final vertical segment.

Numerical simulation of large-scale seasonal hydrogen storage in an anticline aquifer: A case study capturing hydrogen interactions and cushion gas injection

Key aspects of underground hydrogen storage in depleted hydrocarbon reservoirs and saline aquifers: A review and understanding

The development of large-scale, flexible, and safe hydrogen storage is critical for enabling a low-carbon energy system. Deep saline aquifers (DSAs) offer substantial theoretical capacity and broad geographic distribution, making them attractive options for underground hydrogen storage. However, hydrogen storage in DSAs presents complex technical, geochemical, microbial, geomechanical, and economic challenges that must be addressed to ensure efficiency, safety, and recoverability. This study synthesizes current knowledge on hydrogen behavior in DSAs, focusing on multiphase flow dynamics, capillary trapping, fingering phenomena, geochemical reactions, microbial consumption, cushion gas requirements, and operational constraints. Advanced numerical simulations and experimental observations highlight the role of reservoir heterogeneity, relative permeability hysteresis, buoyancy-driven migration, and redox-driven hydrogen loss in shaping storage performance. Economic analysis emphasizes the significant influence of cushion gas volumes and hydrogen recovery efficiency on the levelized cost of storage, while pilot studies reveal strategies for mitigating operational and geochemical risks. The findings underscore the importance of integrated, coupled-process modeling and comprehensive site characterization to optimize hydrogen storage design and operation. This work provides a roadmap for developing scalable, safe, and economically viable hydrogen storage in DSAs, bridging the gap between laboratory research, pilot demonstration, and commercial deployment.

Underground hydrogen storage in aquifers is a promising solution to address the imbalance between energy supply and demand, yet its practical implementation requires optimized strategies to ensure high efficiency and economic viability. To improve the storage and production efficiency of hydrogen, it is essential to select the appropriate cushion gas and to study the influence of reservoir and process parameters. Based on the conceptual model of aquifer with single-well injection and production, three potential cushion gas (carbon dioxide, nitrogen and methane) were studied, and the changes in hydrogen recovery for each cushion gas were compared. The effects of temperature, initial pressure, porosity, horizontal permeability, vertical to horizontal permeability ratio, permeability gradient, hydrogen injection rate and hydrogen production rate on the purity of recovered hydrogen were investigated. Additionally, the impact of different well pattern on the purity of recovered hydrogen was studied. The results indicate that methane is the most effective cushion gas for improving hydrogen recovery in UHS. Different well patterns have significant impacts on the purity of recovered hydrogen. The mole fractions of methane in the produced gas for the single-well, line-drive pattern and five-spot pattern were 16.8%, 5%, and 3.05%, respectively. Considering the economic constraints, the five-spot well pattern is most suitable for hydrogen storage in aquifers. Reverse rhythm reservoirs with smaller permeability differences should be chosen to achieve relatively high hydrogen recovery and purity of recovered hydrogen. An increase in hydrogen production rate leads to a significant decrease in the purity of the recovered hydrogen. In contrast, hydrogen injection rate has only a minor effect. These findings provide actionable guidance for the selection of cushion gas, site selection, and operational design of aquifer-based hydrogen storage systems, contributing to the large-scale seasonal storage of hydrogen and the balance of energy supply and demand.

Hydrogen storage in saline aquifers: Opportunities and challenges

Pore-scale modelling on hydrogen transport in porous media: Implications for hydrogen storage in saline aquifers

Hydrogen-brine mixture PVT data for reservoir simulation of hydrogen storage in deep saline aquifers

Assessing the potential of large-scale geological hydrogen storage in North Dakota's Bakken Formation: A case study integrating wind-powered hydrogen production

This paper proposes the characteristics a techno-economic model for 5G should\nhave considering both mobile network operators perspective and end users needs.\nIt also presents a review and classification of models in the literature based\non the characteristics of such theoretical techno-economic reference model. The\nperformed analysis identifies current gaps in the techno-economic modeling\nliterature for 5G architectures and shows it can be enhanced using agile\ntechno-economic models like the Universal Techno-Economic Model (UTEM) created\nand developed by the author to industrialize assessment of different\ntechnological solutions, considering all market players perspectives and\napplicable to decision-making in multiple domains. This model can be used for\nan effective and agile 5G techno-economic assessment, including not only\nnetwork deployment perspective but also customers and end users requirements as\nwell as other stakeholders to select the most adequate 5G architectural\nsolution considering both technical and economic feasibility. UTEM model is\ncurrently available for all industry stakeholders under specific license of\nuse.\n

Underground hydrogen storage in aquifers is a novel approach to address the regional dispersion and volatility of renewable energy, enabling large-scale H2 storage. The selection of injection and production schemes determines the safe operation and operational efficiency of underground hydrogen storage. Given the limited research on factors influencing the hydrogen storage capacity of underground aquifers and the inadequate analysis of hydrogen migration during injection and production, this study developed an underground aquifer model using numerical simulation methods to investigate these issues. To ensure injection safety, the capillary pressure of the model caprock was calculated prior to numerical simulation. The maximum initial injection flow rate was then determined using a trial-and-error method, ensuring that the capillary pressure threshold was not exceeded. Through simulation, it is observed that peak pressure in the top well area of the reservoir typically occurs at two critical moments: first, when H2 from the bottom of the well initially reaches the cap rock, and second, when the increasing plume thickness causes the top pressure of the reservoir to approach its critical value. Through the implementation of a segmentation injection strategy and adjustment of the injection rate, the maximum storage capacity of the model over a fixed 24-month period is determined to be 0.270 Mt.

To solve the fluctuation and instability of renewable energy, a large-scale energy storage technology is considered to be an effective way. Due to the merits of large energy storage scale and long storage period, compressed air energy storage has attracted extensive attention and research. The working principle and advantages as well as research status of compressed air energy storage in aquifers are discussed. The key problems of economic cost, reservoir property, wellbore structure design, caprock safety and injection-production scheme design of compressed air energy storage in aquifers are also analyzed. Furthermore, the shortcomings in the current research of compressed air energy storage in aquifers at the present stage are summarized. Finally, proposed more indoor experiments and pilot tests of actual sites are needed in future research.

Review on large-scale hydrogen storage systems for better sustainability

This study investigated the impact of cushion gas type and presence on the performance of underground hydrogen storage (UHS) in an offshore North Sea aquifer. Using numerical simulation, the relationship between cushion gas type and UHS performance was comprehensively evaluated, providing valuable insights for designing an efficient UHS project delivery.Results indicated that cushion gas type can significantly impact the process's recovery efficiency and hydrogen purity. CO2 was found to have the highest storage capacity, while lighter gases like N2 and CH4 exhibited better recovery efficiency. Utilising CH4 as a cushion gas can lead to a higher recovery efficiency of 80%. It was also determined that utilising either of these cushion gases was always more beneficial than hydrogen storage alone, leading to an incremental hydrogen recovery up to 7%. Additionally, hydrogen purity degraded as each cycle progressed, but improved over time. This study contributes to a better understanding of factors affecting UHS performance and can inform the selection of cushion gas type and optimal operational strategies.

The role of underground salt caverns for large-scale energy storage: A review and prospects