Utility-scale subsurface hydrogen storage: UK perspectives and technology

To reduce effects from anthropogenically induced climate change renewable energy systems are being implemented at an accelerated rate, the UKs wind capacity alone is set to more than double by 2030. However, the intermittency associated with these systems presents a challenge to their effective implementation. This is estimated to lead to the curtailment of up to 7.72 TWh by 2030. Through electrolysis, this surplus can be stored chemically in the form of hydrogen to contribute to the 15 TWh required by 2050. The low density of hydrogen constrains above ground utility-scale storage systems and thus leads to exploration of the subsurface.This literature review describes the challenges and barriers, geological criteria and geographical availability of all utility-scale hydrogen storage technologies with a unique UK perspective. This is furthered by discussion of current research (primarily numerical models), with particular attention to porous storage as geographical constraints will necessitate its deployment within the UK. Finally, avenues of research which could further current understanding are discussed.     

Evaluating the hydrogen storage potential of shut down oil and gas fields along the Norwegian continental shelf

The underground hydrogen storage (UHS) capacities of shut down oil and gas (O&G) fields along the Norwegian continental shelf (NCS) are evaluated based on the publicly available geological and hydrocarbon production data. Thermodynamic equilibrium and geochemical models are used to describe contamination of hydrogen, loss of hydrogen and changes in the mineralogy. The contamination spectrum of black oil fields and retrograde gas fields are remarkably similar. Geochemical models suggest limited reactive mineral phases and meter-scale hydrogen diffusion into the caprock. However, geochemical reactions between residual oil, reservoir brine, host rock and hydrogen are not yet studied in detail. For 23 shut down O&G fields, a theoretical maximum UHS capacity of ca. 642 TWh is estimated. We conclude with Frigg, Nordost Frigg, and Odin as the best-suited shut down fields for UHS, having a maximum UHS capacity of ca. 414 TWh. The estimates require verification by site-specific dynamic reservoir models.     

A review on worldwide underground hydrogen storage operating and potential fields

Overreliance on fossil fuels for human energy needs, combined with the associated negative environmental consequences in terms of greenhouse gas emissions, has shifted our focus to renewable energy sources. Hydrogen has been identified by researchers as an energy source. Hydrogen is a non-carbon-based energy resource that has the potential to replace fossil fuels. This resource is seen as an alternative fuel since it may be produced using environmentally friendly methods.Hydrogen storage is a critical component of the hydrogen economy, particularly when hydrogen utilization on a large scale is required. This paper presents a review of worldwide underground operating and potential sites to provide a clear understanding of the current status of hydrogen storage in the world.The literature survey indicated that underground geological structures have been used to successfully store hydrogen. Some of the criteria used to select these sites for underground hydrogen storage include but are not limited to geological conditions, storage location, availability of brine, presence of insoluble impurities such as dolostone, limestone, or shale, and socio-economic characteristics.The key issues with the hydrogen storage in the subsurface geological structures include but are not limited to microbial, hydrogeological, hydrodynamics, geomechanics, and geochemical facilitated by injected hydrogen which significantly impact the success and operational efficiency of the projects.     

A novel hybrid energy system for hydrogen production and storage in a depleted oil reservoir

Renewable and carbon free energy relates to the sustainable development of human beings while hydrogen production by renewables and hydrogen underground storage ensure the stable and economic renewable energy supply. A hybrid energy system combining hydrogen production by offshore wind power with hydrogen storage in depleted oil reservoirs was constructed along with a mathematical model where the Weibull distribution, Wind turbine power function, Faraday's law, continuity equation, Darcy's law, state equation of real gas, Net Present Value (NPV) and the concept of leveling were adopted to clarify the system characteristics. For the case of a depleted oil field in the Bohai Bay, China, the annual hydrogen production, annual levelized cost of hydrogen and payback period are 2.62 × 10⁶ m³, CNY 34.6/kgH₂ and 7 years, respectively. Sensitivity analysis found that the wind speed impacted significantly on system NPV and LCOH, followed by hydrogen price and stratum pressure.     

Investigations of AB5-type hydrogen storage materials with enhanced hydrogen storage capacity

The present study deals with investigations on synthesis, characterization and hydrogenation behavior of the MmNi₅-type hydrogen storage alloys Mm_0.9Ca_0.1Ni_4.9−xFe_xAl_0.1 (x = 0, 0.1, 0.2 and 0.3). All the alloys are synthesized by radio frequency induction melting following the composite pellet route. The X-ray diffraction pattern of dehydrogenated alloy without iron, detects peaks corresponding to calcium hydride, which are absent in the XRD pattern of the alloy with iron. The hydrogenation behavior is monitored by means of activation curves, absorption-desorption pressure-composition isotherms, hysteresis factors and desorption kinetic curves. The substitution of Iron at the place of nickel in the alloys Mm_0.9Ca_0.1Ni_4.9−xFe_xAl_0.1 (x = 0, 0.1, 0.2 and 0.3) gives an increase in the hydrogen storage capacity as 1.82, 1.90, 2.2 and 1.95 wt% corresponding to x = 0, 0.1, 0.2 and 0.3 respectively. The correlation between structural characteristics and hydrogenation behavior is described and discussed.     

Large-scale underground hydrogen storage: Integrated modeling of reservoir-wellbore system

Underground Hydrogen Storage (UHS) has received significant attention over the past few years as hydrogen seems well-suited for adjusting seasonal energy gaps.We present an integrated reservoir-well model for “Viking A″ the depleted gas field in the North Sea, as a potential site for UHS. Our findings show that utilizing the integrated model results in more reasonable predictions as the gas composition changes over time. Sensitivity analyses show that the lighter the cushion gas, the more production can be obtained. However, the purity of the produced hydrogen will be affected to some extent, which can be enhanced by increasing the fill-up period and the injection rate. The results also show that even though hydrogen diffuses into the reservoir and mixes up with the native fluids (mainly methane), the impact of hydrogen diffusion is marginal. All these factors will potentially influence the project's economics.     

氢能制取和储存技术研究发展综述

综述了氢能制取和储存技术研究的最新发展现状。生物质制氢、太阳能热化学循环制氢、太阳能半导体光催化制氢、核能制氢等技术具有资源丰富、使用可再生能源的优点,能克服传统电解水制氢能耗高和矿物原料有限的缺点,成为提高制氢效率、实现规模生产的研究重点。加压压缩储氢技术的研究进展主要体现在改进容器材料和研发吸氯物质方面;液化储氢技术研发重点是降低能耗和成本;金属氢化物储氢技术正努力突破储氢密度低的难题。氢能制取、储存技术正在走向实用阶段,重点技术方向是以水为原料,实现大规模、经济、高效和安全地制氢储氢,推动氢能可持续和洁净的利用,促进能源安全。     

Review on using the depleted gas reservoirs for the underground H2 storage: A case study in Niigata prefecture,Japan

Underground hydrogen storage (UHS) in depleted hydrocarbon reservoirs is a prospective choice to store enormous volumes of hydrogen (H₂). However, these subsurface formations must be able not only to store H₂ in an effective and secure manner, but also to produce the required volumes of H₂ upon demand. This paper first reviews the critical parameters to be considered for geological analysis and reservoir engineering evaluation of UHS. The formation depth, the interactions of rock-brine-H₂, the caprock (seal) and well integrity are the most prominent parameters as far as UHS is concerned. In respect of these critical parameters, tentative H₂ storage is screened from the existing gas storage fields in the Niigata prefecture of Japan, and it was revealed that the Sekihara gas field is a suitable candidate for UHS with a storage capacity of 2.06 × 10⁸ m³ and a depth of 1000 m. Then, a series of numerical simulations utilizing CMG software was conducted to find out the extent to which critical parameters alter H₂ storage capacity. The results demonstrated that this field, with a recovery factor of 82.7% in the sixth cycle of production is a prospective site for H₂ storage.     

Preliminary assessment of underground hydrogen storage sites in Ontario,Canada

The replacement of coal-fired power plants with increasing proportions of renewable and nuclear energies in the province of Ontario highlights the need to balance seasonal energy demands. This can be achieved through power-to-gas technology, where excess energy is used to generate hydrogen gas through electrolysis, and the generation is coupled with underground hydrogen storage. This article presents a preliminary assessment regarding the potential for underground hydrogen storage in geological formations including salt and hard rock caverns, depleted oil and gas fields, and saline aquifers in Ontario, highlighting potential locations where future storage could be feasible. Southern Ontario presents many potential storage options, including Silurian bedded salts, depleted Ordovician natural gas reservoirs, saline aquifers in Cambrian sandstone and hard rock caverns in argillaceous limestones. Hard rock caverns in Precambrian crystalline rocks of the Canadian Shield are also discussed, in addition to the potential for the use of lined rock caverns. This work aims to provide a basis for further research regarding the appropriate location of underground hydrogen gas storage facilities in Ontario.     

Comprehensive study of the underground hydrogen storage potential in the depleted offshore Tapti-gas field

Hydrogen is becoming an alternative for conventional energy sources due to absence of any Greenhouse Gases (GHG) emissions during its usage. Geological storage of hydrogen will be potential solution for dealing with large volume requirement to manage uninterrupted Hydrogen supply-chain. Geological Storages such as depleted reservoirs, aquifers and salt caverns offer great potential option for underground hydrogen storage (UHS). There are several depleted gas fields in India. One of such field is located in Tapti-Daman formation. A comprehensive study is conducted to assess the possibility of hydrogen storage in this Indian field which is first of its kind. The geological characteristic of this site is assessed for its viability for storage. Additionally, several aspects including storage capacity, sealability, chemical and micro-biological stability, reservoir simulation, and production viability are assessed using various analytical and numerical models.The qualitative analysis of the Tapti-gas field suggests that the integrity of the storage site will be intact due to existing anticlinal four-way closed structure. The chemical and micro-biological losses are minimal and will not lead to major loss of hydrogen over time. The reservoir modeling results show that optimum gas production-injection scheme needs to be engineered to maintain the required reservoir pressure level in the Tapti-gas field. Also, the deliverability of the various seasonal storage time show that 80 days production scheme will be suitable for efficient operation in this field. Finally, a synergistic scheme to enable green energy production, storage, and transportation is proposed via implementation of UHS in the offshore Tapti-gas field.     

C7N6 monolayer as high capacity and reversible hydrogen storage media: A DFT study

Searching advanced materials with high capacity and efficient reversibility for hydrogen storage is a key issue for the development of hydrogen energy. In this work, we studied systematically the hydrogen storage properties of the pure C₇N₆ monolayer using density functional theory methods. Our results demonstrate that H₂ molecules are spontaneously adsorbed on the C₇N₆ monolayer with the average adsorption energy in the range of 0.187–0.202 eV. The interactions between H₂ molecules and C₇N₆ monolayer are of electrostatic nature. The gravimetric and volumetric hydrogen storage capacities of the C₇N₆ monolayer are found to be 11.1 wt% and 169 g/L, respectively. High hardness and low electrophilicity provides the stabilities of H₂–C₇N₆ systems. The hydrogenation/dehydrogenation (desorption) temperature is predicted to be 239 K. The desorption temperatures and desorption capacity of H₂ under practical conditions further reveal that the C₇N₆ monolayer could operate as reversible hydrogen storage media. Our results thus indicate that the C₇N₆ monolayer is a promising material with efficient, reversible, and high capacity for H₂ storage under realistic conditions.     

Toward underground hydrogen storage in porous media: Reservoir engineering insights

Subsurface hydrogen storage in depleted hydrocarbon reservoirs and saline formations is a potential option for storing hydrogen at large scales. These subsurface formations need to store sufficient hydrogen efficiently and securely, and the hydrogen must be withdrawn in adequate quantities on demand. In this study, we investigate the reservoir, geological, and operational controls that enable large-scale hydrogen storage and maximize hydrogen injection and withdrawal from depleted natural gas reservoirs. Hydrogen injection, storage, and withdrawal scenarios were computed using a reservoir simulator. Sensitivity analyses exposed the crucial parameters to achieve the goal of optimum storage and withdrawal of hydrogen. We determined that reservoirs with smaller pressures at the start of storage operations are suitable for hydrogen storage if wellhead pressure constraints permit. Steeply dipping reservoirs enable better hydrogen withdrawal if the reservoirs have good permeability (greater than 100 mD) and the injection/withdrawal well is placed updip within the reservoir. Permeable reservoirs and reservoirs with sufficient thickness increase hydrogen withdrawal rates. These findings and the results of the sensitivity analyses are used to propose site selection criteria for underground storage of hydrogen in depleted gas reservoirs.     

Seasonal hydrogen storage in a depleted oil and gas field

Hydrogen storage is essential in hydrogen value chains and subsurface storage may be the most suitable large-scale option. This paper reports numerical simulations of seasonal hydrogen storage in the Norne hydrocarbon field, offshore Norway. Three different storage schemes are examined by injecting pure hydrogen into the gas-, oil-, and water zones. Implementation of four annual withdrawal-injection cycles followed by one prolonged withdrawal period show that the thin gas zone is a preferred target with a final hydrogen recovery factor of 87%. The hydrogen distribution in the subsurface follow the geological structures and is restricted by fluid saturation and displacement efficiencies. Case studies show that the pre-injection of formation gas as a cushion gas efficiently increases the ultimate hydrogen recovery, but at the cost of hydrogen purity. The injection of 30% hydrogen-formation gas mixture results in a varying hydrogen fraction in the withdrawn gas. An alternative well placement down the dipping structure shows lower storage efficiency.     

High capacity and reversible hydrogen storage on two dimensional C2N monolayer membrane

Searching advanced materials with high capacity and efficient reversibility for hydrogen storage is a key issue for the development of hydrogen as a clean energy. Here, we have explored the potential application of C₂N monolayer using as a promising material for hydrogen storage through a comprehensive density functional theory (DFT) investigation. Our calculational results indicate that hydrogen molecule can only form weak interaction on neutral C₂N monolayer with the adsorption energy of 0.06 eV. However, if extra charges (5 e^?) are introduced to the system, the adsorption energy of hydrogen molecule on C₂N will be dramatically enhanced to 0.27 eV. Moreover, once the extra charges are moved from the system, the adsorbed hydrogen molecule will be spontaneously released from C₂N monolayer without any barrier. Interestingly, the average adsorption energy for each of the 48 absorbed H₂ molecules is 0.28 eV with the charge injection (8 e^?). This adsorption energy meets the criterion of the Department of Energy (DOE) for hydrogen storage (0.2–0.6 eV). Moreover, C₂N has a high hydrogen storage capacity of 10.5 wt %. Overall, this investigation demonstrates that the new fabricated C₂N can be used as an efficient material for hydrogen storage with high capacity and reversibility by modifying the charges that it carried. The narrow band gap (1.70 eV) of C₂N also ensures the electrochemical methods can be easily realized in experiment.     

Safety investigation of hydrogen energy storage systems using quantitative risk assessment

Hydrogen energy storage systems are expected to play a key role in supporting the net zero energy transition. Although the storage and utilization of hydrogen poses critical risks, current hydrogen energy storage system designs are primarily driven by cost considerations to achieve economic benefits without safety considerations. This paper aims to study the safety of hydrogen storage systems by conducting a quantitative risk assessment to investigate the effect of hydrogen storage systems design parameters such as storage size, mass flow rate, storage pressure and storage temperature. To this end, the quantitative risk assessment procedure, which includes data collection and hazard identification, frequency analysis, consequence analysis and risk analysis, was carried out for the hydrogen storage system presented in a previous study [1]. In the consequence analysis, the Millers model and TNO multi-energy were used to model the jet fire and explosion hazards, respectively. The results show that the storage capacity and pressure have the greatest influence on the hydrogen storage system risk assessment. More significantly, the design parameters may affect the acceptance criteria based on the gaseous hydrogen standard. In certain cases of large storage volume or high storage pressure, risk mitigation measures must be implemented since the risk of the hydrogen storage system is unacceptable in accordance with ISO 19880-1. The study highlights the significance of risk analysis conduction and the importance of considering costs associated with risk mitigation in the design of hydrogen storage system.     

A detailed comparative performance study of underground storage of natural gas and hydrogen in the Netherlands

With the expected increase in the use of hydrogen as an energy carrier, large-scale underground storage sites will be needed. Unlike underground natural gas storage (UGS), many aspects on the performance of underground hydrogen storage (UHS) are not well understood, as there is currently no UHS in use for energy supply. Here we present the results of a detailed comparative performance study of UGS and UHS, based on an inflow/outflow nodal analysis. Three UGS sites in depleted gas fields and one in a salt cavern cluster in the Netherlands are used as case studies. The results show that although hydrogen can be withdrawn/injected at higher rates than natural gas, this can be limited by technical constraints. It also indicates that wider ranges of working pressures are required to increase the storage capacity and flow performance of an UHS site to compensate for the lower energy density of hydrogen.     

Technical assessment of cryo-compressed hydrogen storage tank systems for automotive applications

On-board and off-board performance and cost of cryo-compressed hydrogen storage are assessed and compared to the targets for automotive applications. The on-board performance of the system and high-volume manufacturing cost were determined for liquid hydrogen refueling with a single-flow nozzle and a pump that delivers liquid H₂ to the insulated cryogenic tank capable of being pressurized to 272 atm. The off-board performance and cost of delivering liquid hydrogen were determined for two scenarios in which hydrogen is produced by central steam methane reforming (SMR) or by central electrolysis. The main conclusions are that the cryo-compressed storage system has the potential of meeting the ultimate target for system gravimetric capacity, mid-term target for system volumetric capacity, and the target for hydrogen loss during dormancy under certain conditions of minimum daily driving. However, the high-volume manufacturing cost and the fuel cost for the SMR hydrogen production scenario are, respectively, 2–4 and 1.6–2.4 times the current targets, and the well-to-tank efficiency is well short of the 60% target specified for off-board regenerable materials.     

Theoretical discovery of high capacity hydrogen storage metal tetrahydrides

Hydrogen energy is attractive energy carrier due to its high energy density, abundant, environmentally friendly and renewable etc. However, the search for the high capacity hydrogen storage material is still a great challenge. In addition, the hydrogen storage materials should have excellent catalytic activity and superior mechanical properties to meet dehydrogenation and transportation. Here, we report on a novel metal tetrahydride that can effectively improve the hydrogen storage capacity. We obtain two novel metal tetrahydrides: TiH₄ and VH₄ based on the phonon dispersion and thermodynamically, respectively. In particular, those metal tetrahydrides not only exhibit good dehydrogenation behavior but also show superior mechanical properties. We demonstrate that the high hydrogen storage capacity of those tetrahydrides derives from the alternative stacking of metal layer and hydrogen layer. However, the excellent dehydrogenation process is attributed to the van der Waals interaction between hydrogen layers. Finally, the thermodynamic properties of TiH₄ and VH₄ are discussed.     

Capacity assessment and cost analysis of geologic storage of hydrogen: A case study in Intermountain-West Region USA

Hydrogen is an integral component of the current energy transition roadmap to decarbonize the economy and create an environmentally-sustainable future. However, surface storage options (e.g., tanks) do not provide the required capacity or durability to deploy a regional or nationwide hydrogen economy. In this study, we have analyzed the techno-economic feasibility of the geologic storage of hydrogen in depleted gas reservoirs, salt caverns, and saline aquifers in the Intermountain-West (I-WEST) region. We have identified the most favorable candidate sites for hydrogen storage and estimated the volumetric storage capacity. Our results show that the geologic storage of hydrogen can provide at least 72% of total energy consumption of the I-WEST region in 2020. We also calculated the capital and levelized costs of each storage option. We found that a depleted gas reservoir is the most cost-effective candidate among the three geologic storage options. Interestingly, the cushion gas type plays a significant role in the storage cost when we consider hydrogen storage in saline aquifers. The levelized costs of hydrogen storage in depleted gas reservoirs, salt caverns, and saline aquifers with large-scale storage capacity are approximately $1.15, $2.50, and $3.27 per kg of H₂, respectively. This work provides essential guidance for the geologic hydrogen storage in the I-WEST region.     

Assessment of the potential for underground hydrogen storage in bedded salt formation

Salt formations of an appropriate thickness and structure, common over the globe, are potential sites for leaching underground caverns in them for storage of various substances, including hydrogen. Underground hydrogen storage, considered as underground energy storage, requires, in first order, an assessment of the potential for underground storage of this gas at various scales: region, country, specific place.The article presents the results of the assessment of the underground hydrogen storage potential for a sample bedded salt formation in SW Poland. Geological structural and thickness maps provided the basis for the development of hydrogen storage capacity maps and maps of energy value and heating value. A detailed assessment of the hydrogen storage capacity was presented for the selected area, for a single cavern and for the cavern field; a map of the energy value of stored hydrogen has also been presented. The hydrogen storage potential of the salt caverns was related to the demand for electricity and heat. The results show the huge potential for hydrogen storage in salt caverns.