Large-scale Hydrogen Storage Research Articles

Evaluation of the Dynamic Stability of Underground Structures Assuming a Hydrogen Gas Explosion Disaster in a Shallow Underground Hydrogen Storage Facility

Amid the ongoing global warming crisis, there has been growing interest in hydrogen energy as an environmentally friendly energy source to achieve carbon neutrality. A stable and large-scale hydrogen storage infrastructure is essential to satisfy the increasing demand for hydrogen energy. Particularly for hydrogen refueling stations located in urban areas, technological solutions are required to ensure the stability of adjacent civil structures in the event of hydrogen storage tank explosions. In this study, a numerical analysis using equivalent trinitrotoluene (TNT) and Concrete Damage Plasticity (CDP) models was employed to analyze the dynamic behavior of the ground in response to hydrogen gas explosions in shallow underground hydrogen storage facilities and to assess the stability of nearby structures against explosion effects. According to the simulation results, it was possible to ensure the structural stability of nearby buildings and tunnel structures by maintaining a minimum separation distance. In the case of nearby building structures, a distance of at least 6 to 7 m is needed to be maintained from the underground hydrogen storage facility to prevent explosion damage from a hydrogen gas explosion. For nearby tunnel structures, a distance of at least 10 m is required to ensure structural stability.

Concentration fluctuations and flammability of cryo-compressed hydrogen and methane jets

Compressed hydrogen stored at cryogenic temperatures has a much higher density than room-temperature storage, which enables large-scale hydrogen storage and transport. An understanding of the release of cryogenic hydrogen from pressurized vessels is needed to evaluate the risk and safety concerns with the use of this fuel. The present work extends the analysis of previous experimental studies that measured the gas concentrations of cryo-compressed hydrogen jets and methane jets using a laser Raman scattering diagnostic system. Since the Raman signals are very small, a denoising algorithm was applied to significantly reduce the noise to enable statistical analysis of the data. The transient features of the turbulent jets were characterized by their concentration intermittencies and probability density functions (PDFs). A two-part PDF was developed to predict the bimodal features of the jet concentration distributions. Then, the flammability factors of the cryogenic jets were calculated based on the intermittency and the PDF.

Highly efficient dehydrogenation of dodecahydro-N-ethylcarbazole over Al2O3 supported PdCo bimetallic nanocatalysts prepared by galvanic replacement

NEC is one of the most promising liquid organic hydrogen storage materials. The highly efficient and low cost dehydrogenation catalysts are crucial for large-scale hydrogen storage. In this paper, Co/Al2O3 precursors were prepared by chemical reduction, and then a series of Pd1Con/Al2O3 catalysts for 12H-NEC dehydrogenation was prepared by galvanic replacement of Pd2+ using Co as a template and reducing agent. The prepared catalysts were characterized by TEM, FT-IR, XPS, H2-TPR and H2-TPD. The results demonstrated that Pd1Con NPs were uniformly dispersed over the surface of Al2O3 in the form of Co@Pd core-shell structure, CoPd alloy and PdNPs, with an average particle size of 2.78 nm. The electron transfer occurred between Co and Pd. For the dehydrogenation of H12-NEC, the produced Pd1Co5/Al2O3 catalyst exhibited excellent catalytic activity. The dehydrogenation efficiency was 100% at 180 °C for 3 h and 98.5% at 150 °C for 6 h, and TOF reached 1.414 gH2/gPd min−1, which was significantly higher than that of monometallic Pd/Al2O3 catalysts and that reported in the literature. The kinetic studies of the catalytic 12H-NEC dehydrogenation showed that 4H-NEC→NEC is the rate-limiting step with the highest apparent activation energy of 68.72 kJ/mol. The hydrogen release efficiency remained essentially unchanged after four cycles.

Community acceptance of hydrogen power plant projects: The case of South Korea

Hydrogen fuel cell power plants are emerging as a means of transition to a hydrogen economy paradigm to achieve carbon neutrality by 2050. Owing to its advantage of eliminating the need for high-voltage transmission grid installations and reducing related conflicts, the acceptance by the community is key to the successful construction of hydrogen fuel cell power plants near residential regions for a decentralized generation that provides heat as well as electricity. This study estimated residents’ willingness to accept the construction of a hydrogen fuel cell power plant construction and identified the marginal willingness to accept the attributes using a contingent valuation method and discrete choice experiment, respectively. Combining the results of the two methods, a simulation was conducted to determine the subsidy level. The results revealed that the annual WTA of residents for a 5 MW hydrogen fuel cell power plant at a distance of 1 km from the residential area was about KRW 7.8 million (USD 6037/year). However, the annual WTA decreases to KRW 5.41 million (USD 4185/year) if the plant does not have a large-scale hydrogen storage tank internally and increases to KRW 9.42 million (USD 7287/year) if the plant does not supply hot water. The results of this study can serve as empirical evidence for policymakers to secure their acceptance of expanding hydrogen fuel cell power plants and achieving a hydrogen economy.

Stability evaluation of salt cavern hydrogen storage and optimization of operating parameters under high frequency injection production

Hydrogen energy storage plays a crucial role in peak shaving of renewable energies, and underground salt caverns are ideal locations for large-scale hydrogen storage. The widespread utilization of hydrogen leads to wide-ranged injection production frequency (F) for salt cavern hydrogen storage (SCHS). To address the hydrogen demand under various scenarios, numerical simulation was employed to demonstrate the influence of F on the stability of SCHS at different buried depth (D), and the key operating parameters under high-frequency injection and production were optimized. A 3D geomechanical model was established for bedded salt formations, and evaluation criteria were proposed to quantitatively characterize the stability of SCHS. The stability of SCHS initially improves and then deteriorates with F at different D, and the optimal F is 6 times/year. The effect of F will be boosted as D increases. The recommended internal pressure (P) of SCHS at 900, 1700 and 2500 m under high-frequency injection and production is (0.25–0.85)σz, (0.35–0.85)σz, (0.5–0.85)σz MPa, respectively. And when P is reasonable, the pillar width (W) at different depths greater than 2 times the maximum diameter of salt cavern can meet the stability requirements. The stress difference and stress ratio of the surrounding rock increase with D, causing an increase in volume shrinkage and safety factor. The changes in volume shrinkage and plastic volume correspond well with the change of P when F is less than 6 times/year, while then it ceases to exist. The volume shrinkage growth model was established, and it quantitatively indicates that the small or large F is unfavorable to the stability of SCHS. The variation in the SCHS stability with F attributes to the different effects of creep and fatigue of salt rock.

Underground hydrogen storage: Integrated surface facilities and fluid flow modelling for depleted gas reservoirs

We report a new techno-economic model to assess performance and capital costs for large-scale underground hydrogen storage in depleted gas reservoirs. A simulation toolbox is developed to model surface facilities and to simulate the hydrogen flow in geological formations in an integrated fashion.Integrated modelling revealed the following key insights: 1) A buffer system is highly desirable to absorb inherent variability in upstream hydrogen production; 2) hydrogen mixing with existing gases in the reservoir, together with gravity segregation and diffusion, results in a decline in hydrogen purity at the wellhead over time and can require increased purification; 3) the capital cost is dominated by the cost of cushion gas (hydrogen) and the compression system where about 9% of the total energy content of the hydrogen is consumed for compression. The scenarios modelled in our study result in a levelized cost of storage in Australia ranging from 2.3 to 4.29 A$/(kg).

Feasibility of hydrogen storage in depleted shale gas reservoir: A numerical investigation

Due to the low operation cost, high containment security, and large storage capacity, depleted shale gas reservoirs are considered as promising options for large-scale hydrogen storage. However, its feasibility has not been systematically examined yet. It is still unknown about whether the deliverability (injection/withdrawal) capacity could meet the energy supply/demand and how the depletion time, cushion gas selection, injection/withdrawal strategy will influence the performance of this scenario.Therefore, we present a numerical compositional modelling investigation on hydrogen storage in a partially depleted Fuling shale gas reservoir in China. The results demonstrated that: 1) a high injection/withdrawal capacity could be achieved through a single shale play pad in the area of interest as approximately 5.4 × 108 Sm3 hydrogen could be stored and 3 × 108 Sm3 could be recovered in each cycle (equal to 0.54 TWh of power output). 2) CH4 production is inhibited once hydrogen storage project is performed, an early depletion time could significantly reduce CH4 production but slightly improve H2 withdrawal. 3) Cushion gas injection is beneficial to reducing H2 loss and enhancing 2.8% H2 recovery, while the main drawback of this operational measure is an increase in capital cost in gas separation due to lower H2 purity in the produced gas.This work demonstrates that shale gas reservoir is a promising candidate for hydrogen storage, which is beneficial to the implementation of large-scale hydrogen economy and the operation of hydrogen supply chain.

Study on Hydrogen Flow and Heat Transfer in Underground Salt Cavern Hydrogen Storage

Hydrogen energy is a green, low-carbon, widely used secondary energy with abundant sources, and is gradually becoming one of the important carriers of energy transformation. The safe and efficient storage of hydrogen energy is particularly important. Underground hydrogen storage technology has received widespread attention due to its large scale and low comprehensive cost. Salt cavern hydrogen storage has good sealing performance, stable structure, and flexible operation, making it the most promising choice for large-scale underground hydrogen storage. According to the thermodynamic characteristics of hydrogen, a heat transfer model of hydrogen flow in salt cavern hydrogen storage is established. Three operating conditions, namely, hydrogen injection, static state, and hydrogen production, are simulated and calculated, and the flow field characteristics of hydrogen under different operating conditions are determined, providing technical support for the research on the design of hydrogen injection and production schemes for salt cavern hydrogen storage.

Power sector effects of green hydrogen production in Germany

The use of green hydrogen can support the decarbonization of sectors which are difficult to electrify, such as industry or heavy transport. Yet, the wider power sector effects of providing green hydrogen are not well understood so far. We use an open-source electricity sector model to investigate potential power sector interactions of three alternative supply chains for green hydrogen in Germany in the year 2030. We distinguish between model settings in which Germany is modeled as an electric island versus embedded in an interconnected system with its neighboring countries, as well as settings with and without technology-specific capacity bounds on wind energy. The findings suggest that large-scale hydrogen storage can provide valuable flexibility to the power system in settings with high renewable energy shares. These benefits are more pronounced in the absence of flexibility from geographical balancing. We further find that the effects of green hydrogen production on the optimal generation portfolio strongly depend on the model assumptions regarding capacity expansion potentials. We also identify a potential distributional effect of green hydrogen production at the expense of other electricity consumers, of which policy makers should be aware.

Intercomparison of numerical simulation models for hydrogen storage in porous media using different codes

Large-scale subsurface hydrogen storage in porous formations may play a crucial role in the future energy system. While numerical simulation has been used to assess hydrogen storage, simulators have not been proven to be reliable and accurate by a systematic and detailed code comparison. The hypothesis of this work is that codes will perform similarly with results within 5%. In this study, five numerical simulators were used to simulate a suite of test problems of increasing complexity applicable to subsurface hydrogen storage in porous formations. Intercomparison of results showed a good quantitative agreement of predicted molar fractions, saturations or phase pressures, with only subtle differences arising due to the details of fluid properties and numerical discretization approaches. This intercomparison analysis thereby builds confidence in numerical simulation for subsurface hydrogen storage and provides a basis for more complex scenarios including geomechanical or geochemical effects.

A one- and three-dimensional coupled model and simulation investigation for the large-scale oil-heating type Mg-based hydrogen storage tank

A large-scale oil-heating type Mg-based hydrogen storage tank is the key device for the high-efficiency and high-safety Mg-based solid hydrogen storage and transportation. However, the complicated heat and mass transfer in the Mg alloy bed and oil tube during the hydrogen desorption process impede the design of high-performance hydrogen storage tanks. In this work, a one- and three-dimensional coupled model considering the impact of oil velocity and temperature on the internal heat and mass transfer was developed to simulate the hydrogen desorption process of large-scale oil-heating type Mg-based hydrogen storage tanks. This model was then solved by the finite element method, and the simulation results agreed well with the experimental data obtained from an Mg-based hydrogen storage tank. Moreover, simulation results indicate that the oil velocity has a considerable impact on the hydrogen desorption performance of the Mg-based hydrogen storage tank, and a recommended oil velocity of 4 m s−1 was identified. In addition, high oil temperature and low hydrogen desorption pressure benefit the hydrogen desorption performance, thus should be determined by the application scenarios. Besides, the complete hydrogen desorption time was barely affected by the initial bed temperature, which is suggested as ≥ 573 K to meet the high rate requirement of hydrogen supply, otherwise as room temperature to reduce energy costs. The model and simulation results presented in this work provided a foundation for the design of high performance large-scale oil-heating type Mg-based hydrogen storage tanks that can be applied practically in the field of hydrogen energy.

Geochemical modelling on the role of redox reactions during hydrogen underground storage in porous media

Underground Hydrogen Storage (UHS) in porous media appears to be a promising means for large-scale hydrogen storage, underpinning the full-scale of hydrogen supply chain development. Hydrogen-brine-rock interactions play an important role in hydrogen conversion and contamination during hydrogen cycling process. While the redox reaction triggered by injected H2 and pre-existing O2 is unique in UHS compared to other types of gas subsurface storage, few research have been done to understand the role of redox reactions in hydrogen solubility, pH, and fewer works have looked beyond its process on hydrogen conversion and contamination, which may affect the stored H2 purity and storage efficiency. In this context, we examined the redox reactions on hydrogen-brine-minerals (e.g., calcite, siderite, quartz and pyrite) reactions as a function of dissolved oxygen concentration (from 5.5 to 5500 ppm), temperature, and pressure through geochemical modelling using geochemical solver PHREEQC.Our results showed that increasing dissolved oxygen concentration from 5.5 to 5500 ppm resulted in negligible impact on hydrogen solubility and pH for all tested minerals. As the sensitive minerals, siderite and calcite can react with H2 through the redox process, leading up to a certain hydrogen loss at the pressure of 20 MPa, respectively. Meanwhile, quartz and pyrite are insensitive minerals to hydrogen, causing less than 0.2% hydrogen loss at the same pressure condition. Our results indicate that the mineral oxidation due to the pre-existing O2 dissolved in formation brine played a negligible role in H2-brine-rock interactions. The results also showed that carbonate minerals such as siderite and calcite may act as electron acceptors, which triggered hydrogen dissociation and thus formed a strong reduction environment based on PHREEQC geochemical database. This process likely causes measurable hydrogen loss associated with abiotic geochemical reactions for the lifetime of the underground hydrogen storage operation. Taken together, we suggest that clean standstone reservoirs will signifcantly reduce the hydrogen conversion and contamination during underground hydrogen storage from abiotic geochemical perspective.

Potential of Salt Caverns for Hydrogen Storage in Southern Ontario, Canada

Salt caverns produced by solution mining in Southern Ontario provide ideal spaces for gas storage due to their low permeability. Underground hydrogen storage (UHS) is an important part of the future renewable energy market in Ontario in order to achieve global carbon neutrality and to fill the gap left by retiring nuclear power plants. However, large-scale hydrogen storage is still restricted by limited storage space on the ground’s surface. In this study, hydrogen’s physical and chemical properties are first introduced and characterized by low molecular weight, high diffusivity, low solubility, and low density. Then, the geological conditions of the underground reservoirs are analyzed, especially salt caverns. Salt caverns, with their inert cavity environments and stable physical properties, offer the most promising options for future hydrogen storage. The scales, heights, and thicknesses of the roof and floor salt layers and the internal temperatures and pressures conditions of salt caverns can affect stabilities and storage capacities. Finally, several potential problems that may affect the safe storage of hydrogen in salt caverns are discussed. Through the comprehensive analysis of the influencing factors of hydrogen storage in salt caverns, this study puts forward the most appropriate development strategy for salt caverns, which provides theoretical guidance for UHS in the future and helps to reduce the risk of large-scale storage design.

Hydrogen storage in depleted gas reservoirs using nitrogen cushion gas: A contact angle and surface tension study

The utilization of depleted natural gas reservoirs is a significant consideration for large-scale hydrogen (H2) storage and production. However, accurate knowledge of cushion gas compositions such as nitrogen (N2), methane (CH4), and carbon dioxide (CO2) is crucial, as they are critical components that affect the rock-fluid interfacial phenomenon, thereby impacting deployment feasibility. Moreover, there are limited reported studies on rock/brine/gas-mixture wettability and gas-mixture/brine surface tension for this type of reservoir. To address this gap, we explore the possibility of using N2 as a cushion gas (in the presence of CH4 and CO2) on a pristine quartz for H2 storage across various pressure (500–3000) psi, temperature (30–70) °C, and salinity (2–20) wt.%. We conducted extensive contact angle (CA) and surface tension (ST) experiments for different gas mixtures (H2–N2–CH4–CO2) to generate relevant data for H2 storage in depleted natural gas reservoirs using drop shape analyzer (DSA 100) equipment. Our findings suggest that the wettability behavior of the gas-mixture compositions studied is likely to remain consistent unless the rock's initial wetting state is altered. The CAs were observed to range between 28 and 46°, regardless of reservoir pressure, temperature, and salinity. It also increased with increasing pressure but decreased with increasing temperature. In addition, CA was lower at a lower N2 fraction (Mix 1–80% H2 – 10% N2 – 5% CH4 –5% CO2) compared to a higher N2 fraction (Mix 4–20% H2 – 70% N2 – 5% CH4 –5% CO2). The ST of the gas-mixture/brine systems declined with increasing (i) pressure, (ii) temperature, and (iii) N2 fraction but increased with increasing salinity for every gas mixture. Based on our investigation, mixtures 2 and 3 with H2 (40–60%) and N2 (30–50%) fractions (at constant 5% CH4 and 5% CO2) were identified as the optimal cushion gas for H2 storage and withdrawal under the studied conditions. The results of this study provide accurate and valuable input parameters and data for reservoir-scale simulations utilized in optimizing geo-storage in depleted natural gas reservoirs.

Geochemical Integrity of Wellbore Cements during Geological Hydrogen Storage.

Increasing greenhouse gas emissions have put pressure on global economies to adopt strategies for climate-change mitigation. Large-scale geological hydrogen storage in salt caverns and porous rocks has the potential to achieve sustainable energy storage, contributing to the development of a low-carbon economy. During geological storage, hydrogen is injected and extracted through cemented and cased wells. In this context, well integrity and leakage risk must be assessed through in-depth investigations of the hydrogen-cement-rock physical and geochemical processes. There are significant scientific knowledge gaps pertaining to hydrogen-cement interactions, where chemical reactions among hydrogen, in situ reservoir fluids, and cement could degrade the well cement and put the integrity of the storage system at risk. Results from laboratory batch reaction experiments concerning the influence of hydrogen on cement samples under simulated reservoir conditions of North Sea fields, including temperature, pressure, and salinity, provided valuable insights into the integrity of cement for geological hydrogen storage. This work shows that, under the experimental conditions, hydrogen does not induce geochemical or structural alterations to the tested wellbore cements, a promising finding for secure hydrogen subsurface storage.

Surface Modifications of Magnesium-Based Materials for Hydrogen Storage and Nickel–Metal Hydride Batteries: A Review

Whether it is fossil energy or renewable energy, the storage, efficient use, and multi-application of energy largely depend on the research and preparation of high-performance materials. The research and development of energy storage materials with a high capacity, long cycle life, high safety, and high cleanability will improve the properties of energy storage systems and promote their wide application. In recent years, Mg-based materials, from a comprehensive consideration of energy storage performance, raw material reserves, and prices, have demonstrated potential industrial applications as large-scale hydrogen storage materials. Nevertheless, Mg-based materials also have obvious disadvantages: as a hydrogen storage material, the hydrogen absorption/desorption rate is insufficient, as well as the high hydrogen absorption/desorption temperatures; as the electrode material of Ni-MH batteries, the reactions of Mg with alkaline electrolyte and corrosion are the main problems for applications. This article reviews different surface treatment methods and mechanisms for surface modifications of Mg-based materials for hydrogen storage and Ni-MH battery applications, as well as the performance of the materials after surface modifications. Multiple experimental studies have shown that the surface layer or state of Mg-based materials has a strong impact on their performance. Surface modification treatment can greatly improve the energy storage performance of magnesium-based materials for hydrogen storage and Ni-MH battery applications. Specifically, Mg-based materials can have a lower hydrogen absorption/desorption temperature and a faster hydrogen absorption/desorption rate when used as hydrogen storage materials and can improve the corrosion resistance, initial discharge capacity, and cycling stability in alkaline solutions when used as negative electrode materials for Ni-MH batteries. By offering an overview of the surface modification methods for Mg-based materials in two energy storage fields, this article can improve researchers’ understanding of the surface modification mechanism of Mg-based materials and contribute to improving material properties in a more targeted manner. While improving the material properties, the material’s preparation and surface modification treatment process are considered comprehensively to promote the development, production, and application of high-performance Mg-based materials.

Techno-economic analysis of large-scale green hydrogen production and storage

Producing clean energy and minimising energy waste are essential to achieve the United Nations sustainable development goals such as Sustainable Development Goal 7 and 13. This research analyses the techno-economic potential of waste heat recovery from multi-MW scale green hydrogen production. A 10 MW proton exchange membrane electrolysis process is modelled with a heat recovery system coupled with an organic Rankine cycle (ORC) to drive the mechanical compression of hydrogen. The technical results demonstrate that when implementing waste heat recovery coupled with an ORC, the first-law efficiency of electrolyser increases from 71.4% to 98%. The ORC can generate sufficient power to drive the hydrogen's compression from the outlet pressure at the electrolyser 30 bar, up to 200 bar. An economic analysis is conducted to calculate the levelised cost of hydrogen (LCOH) of system and assess the feasibility of implementing waste heat recovery coupled with ORC. The results reveal that electricity prices dominate the LCOH. When electricity prices are low (e.g., dedicated offshore wind electricity), the LCOH is higher when implementing heat recovery. The additional capital expenditure and operating expenditure associated with the ORC increases the LCOH and these additional costs outweigh the savings generated by not purchasing electricity for compression. On the other hand, heat recovery and ORC become attractive and feasible when grid electricity prices are higher.

The techno-economic potential of large-scale hydrogen storage in Germany for a climate-neutral energy system

The seasonal storage of natural gas is a recognized and reliable technology in the energy industry. Salt caverns are particularly suitable for storing alternative gaseous fuels such as hydrogen. Germany has a great technical potential for expanding its cavern storage capacity, which exceeds the expected demand for hydrogen many times. Regarding the projected long-term decline in natural gas use, the question arises as to whether existing caverns can meet future storage requirements. To this end, a techno-economic model is presented to meet electricity and hydrogen demand in a cost-optimal solution. This analysis focused on the utilization of hydrogen storage in terms of energy throughput and maximum storage capacity. To link the outcome of economic dispatch to the literature, the fundamental assumptions are based on comprehensive capacity expansion models. This study advances the state of the art by evaluating key input parameters of the future energy system. By conducting 192 model runs, the analysis revealed the range of uncertainty in terms of storage use. This indicates a strong dependence of the systemic and economic value of hydrogen storage on boundary conditions such as a consideration of dark doldrums, a flexible hydrogen demand profile, hydrogen import restrictions and a larger electrolyzer capacity. The uncertainty ranged from 0 to 67 TWhH2 for the storage capacity, with an average of 36.6 TWhH2 across all scenarios, and from 0 to 190 TWhH2 for the annual energy throughput. These results are significant for gas storage operators who derive transformation strategies and policymakers evaluating financial funding requirements.

A Mini-Review on Underground Hydrogen Storage: Production to Field Studies

Hydrogen has become increasingly popular as one of the alternative fuels to reduce greenhouse gas emissions. Storing hydrogen in geological structures is a technology that shows great potential in storing large amounts of hydrogen efficiently. However, this technology is relatively new and requires a clear understanding. Therefore, a quick review of underground hydrogen storage is needed to understand its fundamental concepts. This review article presents important components relevant to underground hydrogen storage. First, some currently available hydrogen production methods are discussed followed by hydrogen storage methods. Both small-scale and large-scale hydrogen storage methods are presented. Next, some important factors (fluid properties, rock properties, solid–fluid interactions, and chemical interactions) influencing underground hydrogen storage are summarized. This is followed by presenting various interesting field studies for underground hydrogen storage. Lastly, some challenges and future outlooks pertinent to underground hydrogen storage are reviewed. This article will serve as a useful resource that provides a quick overview of underground hydrogen storage for both researchers and industrialists.

Linking geological and infrastructural requirements for large-scale underground hydrogen storage in Germany

Hydrogen storage might be key to the success of the hydrogen economy, and hence the energy transition in Germany. One option for cost-effective storage of large quantities of hydrogen is the geological subsurface. However, previous experience with underground hydrogen storage is restricted to salt caverns, which are limited in size and space. In contrast, pore storage facilities in aquifers -and/or depleted hydrocarbon reservoirs- could play a vital role in meeting base load needs due to their wide availability and large storage capacity, but experiences are limited to past operations with hydrogen-bearing town gas. To overcome this barrier, here we investigate hydrogen storage in porous storage systems in a two-step process: 1) First, we investigate positive and cautionary indicators for safe operations of hydrogen storage in pore storage systems. 2) Second, we estimate hydrogen storage capacities of pore storage systems in (current and decommissioned) underground natural gas storage systems and saline aquifers. Our systematic review highlights that optimal storage conditions in terms of energy content and hydrogen quality are found in sandstone reservoirs in absence of carbonate and iron bearing accessory minerals at a depth of approx. 1,100 m and a temperature of at least 40°C. Porosity and permeability of the reservoir formation should be at least 20% and 5 × 10−13 m2 (∼500 mD), respectively. In addition, the pH of the brine should fall below 6 and the salinity should exceed 100 mg/L. Based on these estimates, the total hydrogen storage capacity in underground natural gas storages is estimated to be up to 8 billion cubic meters or (0.72 Mt at STP) corresponding to 29 TWh of energy equivalent of hydrogen. Saline aquifers may offer additional storage capacities of 81.6–691.8 Mt of hydrogen, which amounts to 3.2 to 27.3 PWh of energy equivalent of hydrogen, the majority of which is located in the North German basin. Pore storage systems could therefore become a crucial element of the future German hydrogen infrastructure, especially in regions with large industrial hydrogen (storage) demand and likely hydrogen imports via pipelines and ships.