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Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Long-term and large-scale H 2 storage is vital for a sustainable H 2 economy. Research in underground H 2 storage (UHS) in porous media is emerging, but the understanding of H 2 reconnection and recovery mechanisms under cyclic loading is not yet adequate. This paper reports a qualitative and quantitative investigation of H 2 reconnection and recovery mechanisms in repeated injection-withdrawal cycles. Here we use microfluidics to experimentally investigate up to 5 cycles of H 2 injection and withdrawal under a range of injection rates at shallow reservoir storage conditions. We find that H 2 storage capacities increase with increasing injection rate and range between ∼10% and 60%. The residual H 2 saturation is in the same range between cycles (30–40%), but its distribution in the pore space visually appears to be hysteretic. In most cases, the residually trapped H 2 reconnects in the subsequent injection cycle, predominantly in proximity to the large pore clusters. Our results provide valuable experimental data to advance the understanding of multiple H 2 injection cycles in UHS schemes. [Display omitted] • Microfluidics for examination of cyclic hydrogen injections. • Microscopic hydrogen storage capacities up to 60% of the pore space. • Reproducible residual hydrogen saturation between the injection cycles. • Efficient reconnection of residually trapped hydrogen in the next drainage cycle. [ABSTRACT FROM AUTHOR]

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. • A comparative study UGS vs UHS performance, using an inflow/outflow nodal analysis. • Hydrogen flows faster than methane yet provides less energy throughput. • At equal reservoir pressure a UHS can store 3–4 times less energy than a UGS. • Technical limitations can restrict flow rates and storage volumes of hydrogen. [ABSTRACT FROM AUTHOR]

The effects of a hybrid nanofluid (Cu‐Al layered double hydroxide (LDH)) on the CO2 hydrate formation kinetics was investigated at three different nanofluid concentrations (0.25–1.0 wt %). The Cu‐Al LDH nanofluid was prepared using a one‐step co‐precipitation technique. The addition of the LDH nanofluid reduces the induction time and enhances the hydrate formation kinetics. The maximum reduction in the induction time (by 91.08 %) was observed at the optimal nanofluid concentration of 0.5 wt %, compared to water. A chemical affinity model was implemented to predict the experimental data for CO2 hydrate formation in the presence of the different LDH nanofluid concentrations. An artificial neural network‐based Levenberg‐Marquardt model predicts the experimental data with higher accuracy than the scaled conjugate gradient model. The results indicate a strong dependency of the hydrate formation kinetics on the LDH nanofluid concentrations. [ABSTRACT FROM AUTHOR]

The multi-reservoir operation rules require accuracy in developing its technical parameters. This is done to prevent operational failure in one of the reservoirs. The water transfer concept is to manage the water resources distribution between the receiving watershed and the donor watershed. The availability of transferable water must be prioritized, meeting the water demand of the donor reservoir. Storage capacity in both reservoirs aims to meet water demand, especially in the recipient. The elevation of the interconnecting tunnel is the minimum limit for water use in simulation. The interconnected tunnels' location and capacity will determine the multi-reservoir's operation rule. The interconnected tunnel in the Rukoh Tiro reservoir transfers water in the operation of the two reservoirs. The simulation is carried out in three seasons, considering the inflow of each watershed, the reservoir's downstream water demand, and the reservoir's technical conditions. The simulation results of the Rukoh Tiro reservoir operated simultaneously in all three seasons show that the fulfillment of irrigation water demand can reach 100% as needed. The water transfer process through interconnected tunnels occurs throughout the year. The reservoir operating rule is expected to be a reference in the multi-reservoir operation to obtain an optimal reservoir operating rule. [ABSTRACT FROM AUTHOR]

Modern mining within ecologically fragile areas is under enormous pressure from the ecological and geological environment. Using abandoned coal mines as underground water reservoirs is an effective idea for reducing eco-geological risks in mining districts. Accurate estimation of reservoir capacity is conducive to guiding the construction of an underground water reservoir. In this paper, estimation models of underground water storage capacity were established, which were divided into two kinds: horizontal mining district and inclined mining district. Furthermore, the minimum porosity of broken rock mass was analyzed based on laboratory experiments, and the fitted equation of minimum porosity was developed. A modern coal mine in northwest China was taken as an example, and the feasibility of the proposed model was verified by in-situ measurement. Finally, the effects of porosity of broken rock mass, water storage height and coal seam dip angle on water storage capacity were presented. The coal seam dip angle should be the principal consideration in choosing the site of an underground water reservoir. HIGHLIGHTS Underground water reservoir can realize sustainable development in mining areas.; Prediction model of underground water storage capacity was established.; The minimum void ratio of broken rock mass with different gradations was studied.; The coal seam dip angle significantly affects underground water storage capacity.;

Global demand for underground gas storage (UGS) is steadily increasing, with the limestone-based UGS system situated in the Sichuan Basin of China gathering considerable interest in recent years. However, studies focusing on the fundamental mechanisms of the injection-production process in these systems are limited. Moreover, existing studies utilizing physical experimental methods frequently fall short in effectively visualizing micro-flow or incorporating real core samples from the reservoir. To address these gaps, we performed a coreflood experiment, integrating micro-Computed Tomography (CT) scanning to investigate mechanisms of fluid flow and storage capacity during the injection and production cycles in limestone reservoirs. Our approach involved utilizing core plugs with artificially engraved fracture-vuggy structures, which mimic the characteristics of the reservoir. Micro-CT scans were performed to visualize the microscopic changes in fractured-vuggy structures and the distribution of irreducible water during each cycle. This study reveals that increased cycles correspondingly affect gas storage capacity, particularly by expanding it in relative larger vuggy structures while reducing it in finer fissure network structures. The amount of irreducible water decreases after injection-production cycles, likely being expelled alongside the extracted dry gas. This plays a critical role in expanding the storage capacity in larger vuggy systems. Conversely, there is a decrease in storage capacity within fissure network systems, as the irreducible water is replaced by gas. This leads to a reduction in the opening force of the fine conduit. The dense matrix has a very limited effect on the flow mechanism and its influence on storage capacity. Overall, these findings offer practical insights for optimizing injection and production strategies in limestone UGS systems within the Sichuan Basin, contributing to a deeper understanding and efficient utilization of this vital infrastructure.

Hydrogen is a key element in the changing energy sector and presents an accessible alternative to conventional fossil fuel sources. In this work, a system of ten high-entropy alloys was prepared based on the Hume-Rothery rules. One of the biggest advantages of these alloys is their storage capacity, which reaches the highest value among all known alloys intended for hydrogen storage. Alloys based on Al-Ti-Nb-Zr elements with different atomic fractions show interesting accumulation capabilities with fast absorption kinetics and low specific gravity. Each alloy in this study underwent high-pressure gravimetric absorption and desorption tests. The main goals of this work were to prepare alloys with the lowest-possible specific gravity and the highest-possible storage capacity. One alloy from our system shows storage capacity values similar to commercial alloys, without any rare-earth elements.

As the need for energy storage systems (ESSs) capacity is increasing due to high accommodation of renewable resources, it is crucial to analyze in which location and for what purpose the ESSs are required to achieve the highest efficiency. Investors and system operators can place and operate the ESSs as expected based on this analysis. Therefore, this study assesses the specific roles of ESSs in a grid system based on their optimal capacity needs, locations, and operations. A long-term simulation model using mixed-integer programming is proposed to obtain these optimal solutions, such as ESS capacity and operational schedules for energy and reserves. Four-week operational simulations are performed for each month using data from the California Independent System Operator. ESSs are placed at sites with solar photovoltaic (PV) systems or wind farms, at baseload generator buses, and at load buses to verify the role of ESSs, depending on the locational differences. The detailed roles are analyzed from the aspects of flexible capacity supply, reserve deployments, time-shifting renewable and thermal energy generation, and costs. The results show that the ESSs on the baseload generation side provide flexibility by time-shifting baseload generation and turn on baseload generators, even when the net load is small. For instance, the required capacity of the flexible thermal generators, such as natural gas turbine generators, is about 3004 MW without the ESS operations in May. When 450 MW ESSs colocated with solar PVs are operated, the required flexible capacity of the thermal generators is lowered to 2404 MW. Moreover, ESSs are highly utilized as a downward reserve provider, although their costs for reserves are higher than thermal generators.

Suppliers often prefer to offer their retailers a delay period in payment to attract more sales and promote revenue in a supply chain. The retailers usually ask their customers to pay a portion of purchasing cost when receiving the product (i.e., a downstream partial trade credit) to reduce the default risk. On the other hand, the suppliers provide discounts for bulk purchases, and the retailer has enough capital to purchase more goods than can be stored in its warehouse. The retailer must store the excess quantities in a rented warehouse if the storage capacity is limited. A two-warehouse inventory system is needed to model this problem. In reality, the demand rate fluctuates with time, and the relevant cost is usually affected by the present value of time. This study focuses on the limited storage capacity inventory model for deteriorating items with fluctuating demand, downstream partial trade credit transactions, and discounted cash-flow considerations. The aim is to find the optimal replenishment cycle and order quantity and keep the present value of the total relevant cost per unit of time as low as possible. We further present numerical examples to demonstrate the applicability and develop managerial insights.

Post-Li batteries based on Na, K, Ca, and Mg offer compelling alternatives to Li ones, whose resources are scarce and unevenly distributed in the earth's crust. However, the development of these forthcoming batteries is currently thwarted by the lack of cost-effective, nontoxic, and highly efficient anode materials. To tackle this challenge, we employed a comprehensive structure search using the minima hopping method, followed by density functional theory (DFT) calculations. Our search led to an as-yet-unobserved metallic C7N monolayer with a Haeckelite structure. This unique structure features a network of sp2-nitrogen-containing heptagon and pentagon rings that are arranged in a way that enforces metallic characteristics. As such, C7N outperforms widely known 2D anode materials such as graphene, MoS2, and black phosphorus because of its superior storage capacity, lower diffusion barriers, and higher open-circuit voltages. It achieves a remarkable storage capacity of 1366 mA h g–1 for Na/K and an impressive 2730 mA h g–1 for Ca. Detailed analyses of charge, elastic constants, and molecular dynamics simulations demonstrate that the C7N possesses a strong yet flexible covalent network with a volume change of 2–4% during full charge and discharge cycles, ensuring long-term stability and reliability. The robust network of C7N also allows it to maintain a flat and thermally stable surface at full metal coverage and high temperatures. These findings open up avenues for exploring the Haeckelite carbon-nitride family as a promising candidate for next-generation battery technologies. [ABSTRACT FROM AUTHOR]

Geological storage has been proposed as a new technology to temporarily store significant amounts of hydrogen (H 2) gas in depleted gas reservoirs, underground salt caverns, or saline aquifers. Often, such subsurface reservoirs naturally contain trace amounts of organic acids, and these compounds can considerably alter the wettability of reservoir rocks, causing them to become less water-wet. We carried out Molecular Dynamics (MD) simulations of contact angles in a quartz-brine-H 2 system to evaluate wettability in realistic subsurface situations. MD simulations suggest that Humic acid makes quartz more hydrophobic, which can affect the overall behaviour of the storage reservoir. For the first time, this effect was experimentally investigated for a natural sandstone reservoir from the South West Hub Project, i.e., the Lesueur Sandstone (LS) formation. Multi-stage core flooding experiments were conducted on the same LS plug to investigate the impact of wettability alteration on initial and residual hydrogen saturation/trapping at depth. First, consecutive brine-H 2 drainage-imbibition cycles were carried out on the natural sample; the result indicated that the rock-brine-H 2 system was essentially water-wet. Then, the sample was aged in Humic acid with a molarity of 10−2 M for 42 days at 5 °C and 0.1 MPa. The wettability of the storage system shifted toward a less water-wet state, i.e., more hydrophobic. As a result of Humic acid ageing, the initial hydrogen saturation reduced from 29% to 15%, and the residual hydrogen trapping reduced from 23% to 11%. This is attributed to a change induced in the capillary force (i.e., snap-off) controlled by wettability and pore size. In addition, the wettability change induced by Humic acid increased the hydrogen recovery rate from 20.7% to 26.7%. [Display omitted] • Utilise Nuclear Magnetic Resonance (NMR) coreflooding cell to access hydrogen-rock interaction. • Impact of rock wettability on storage and mobility of hydrogen in subsurface reservoirs. • Laboratory assessment of Southwest Hub site of Western Australia for hydrogen storage. • Humic acid can positively impact the residual hydrogen saturation. • Molecular dynamics could be a good tool to study the H 2 -brine-silica interface. [ABSTRACT FROM AUTHOR]

Storage is a challenging issue that cuts across distribution, delivery, and safe end-uses of hydrogen as fuel. All the fuel cell vehicles are equipped with inefficient and unsafe high-pressure hydrogen cylinders. It is well known that storing such a highly flammable gas at high pressure is not safe. Only hydrogen can be stored safely as a form of metal hydrides, and all the investigated metal hydrides are inefficient in one way or another. Four essential hydrogen parameters for solid-state storage for fuel cell applications are high volumetric storage capacity, excellent heat transfer, and recharge time and feasible charging discharging temperatures. The available metal tanks have good gravimetric storage capacity but did not satisfy the prescribed criterion for good volumetric capacity necessary for mobile applications. Recently, some promising reports are published on the hydrogen storage properties of newly discovered High Entropy Alloys (HEAs). HEAs provide vast composition selection freedom for the formation of favorable simple solid solution phase for hydrogen storage. The four core effects of these alloys may also play a vital role in hydrogen storage properties. Here we reviewed and summarized the published results on hydrogen storage properties of HEAs to date. We underlined different essential aspects for the future development of HEAs as hydrogen storage materials. This review article discusses and describes the perspectives of HEAs in regards to the hydrogen storage applications of these alloys and will provide insight into the future development of hydrogen storage HEAs. • Provide detailed, information on the different aspects of hydrogen storage properties of HEAs. • Discuss basic properties (definition and core effects) of HEAs regarding hydrogen storage properties. • Discuss benefits of HEAs over conventional alloys in regards to HS properties. • Underlined different aspects that have importance on the future development of hydrogen storage HEAs for applications. [ABSTRACT FROM AUTHOR]

The sodium (Na) storage behaviour of T4,4,4-graphyne of two-dimensional porous carbon sheet is explored using the density functional theory (DFT). The energy of adsorption and barrier, storage capacity, and open-circuit voltage are calculated. The calculations predict that Na atom is extraordinary mobile on T4,4,4-graphyne monolayer as a result of the relatively slight energy barrier. The Na storage capacity is as high as Na8C9, which exceeds the values reported for graphite and some other two-dimensional carbon-based materials. The high Na mobility and theoretical capacity make T4,4,4-graphyne monolayer suitable for implementation in rechargeable ion batteries. The electronic properties are also studied to ensure that T4,4,4-graphyne is suitable for Na-ion batteries as an anode material, and they revealed that semiconductor–metal transition is induced by Na adsorption. The favourable electronic conduction is another demand for promising Na-ion batteries. These results predict that the application of T4,4,4-graphyne sheet will increase efficiency of the Na-ion batteries. [ABSTRACT FROM AUTHOR]

Two-dimensional transition-metal carbides/nitrides (MXenes), as pseudocapacitor materials, have attracted extensive attention in the field of energy storage in recent years. However, the MXene surface is prone to oxidation and their layered structure is easy to stack, which limit their practical application. Here, we propose a facile and cost-effective strategy to fabricate a blend of poly-(o-phenylenediamine) (PoPD)-decorated vanadium carbide MXene (N–V4C3Tx) and PoPD as electrode materials to boost the storage capacity for supercapacitors and lithium-ion batteries. N–V4C3Tx nanosheets and PoPD nanoparticles were prepared by in situ oxidant-free polymerization and redox methods, respectively. The electrochemical performance of the blend shows that the introduction of PoPD nanoparticles can effectively improve the specific capacitance of N–V4C3Tx. The N–V4C3Tx/PoPD electrode exhibits excellent specific capacitance of up to 676.5 F g–1 at 1 A g–1 for supercapacitor application. Compared with the V4C3Tx-based device (276.3 F g–1), the capacitance reaches up to 2.48 times enhancement. In addition, the N–V4C3Tx/PoPD electrode also presents satisfactory cyclic stability, and the retention rate can remain unchanged after 10,000 cycles. As the electrode material for lithium-ion batteries, it also shows a high capacity of 561.2 mA h g–1 at 0.1 A g–1, excellent rate performance, and cyclic stability. Our work broadens the application of MXenes and conductive polymers as electrode materials in the field of energy storage and offers a simple and effective strategy to improve the capacity and stability of the pristine MXene. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the electrochemical characteristics of armchair silicon carbide nanoribbon (ASiCNR) for its potential deployment as 2D lithium-ion battery anode material. Density functional theory approach is used to calculate the adsorption energy, storage capacity, and open circuit voltage of ASiCNR for LIB. Adsorption of Li atoms introduces the new energy bands which cross the Fermi level; this results in semiconductor to metallic transition of ASiCNR. It indicates the strong interaction of Li atoms towards the ASiCNR. When adsorption of Li atoms increases one by one, the adsorption energy (E ads ) per Li atoms increases gradually. When all favourable sites are adsorbed by Li atoms E ads reached its maximum value and it results in maximum storage capacity of 818 mAhg - 1 and open circuit voltage of 1.15 V. Diffusion barrier of Li atoms for the substrate is 0.42 eV. Our computational results suggest that ASiCNR can be used as an anode material for Li-ion batteries, and it provides the theoretical background for the future study on ASiCNR and other Li storage structures. [ABSTRACT FROM AUTHOR]

Phase change material (PCM)-based thermal energy storage (TES) can provide energy and cost savings and peak demand reduction benefits for grid-interactive residential buildings. Researchers established that these benefits vary greatly depending on the PCM phase change temperature (PCT), total TES storage capacity, system configuration and location and climate of the building. In this study, preliminary techno-economic performance is reported for a novel heat pump (HP)-integrated TES system using an idealized approach. A simplified HP-TES was modeled for 1 year of space heating and cooling loads for a residential building in three different climates in the United States. The vapor compression system of the HP was modified to integrate with TES, and all heat transfer to and from the TES was mediated by the HP. A single PCM was used for heating and cooling, and the PCT and TES capacity were varied to observe their effects on the building's energy consumption, peak load shifting and cost savings. The maximum reduction in electric consumption, utility cost and peak electric demand were achieved at a PCT of 30 °C for New York City and 20 °C for Houston and Birmingham. Peak energy consumption in Houston, New York City, and Birmingham was reduced by 47%, 53%, and 70%, respectively, by shifting peak load using a time-of-use utility schedule. TES with 170 MJ storage capacity allowed for maximum demand shift from on-peak to off-peak hours, with diminishing returns once the TES capacity equaled the daily building thermal loads experienced during the most extreme ambient conditions. [ABSTRACT FROM AUTHOR]

The rapid development of wind power has imposed many challenges on the operation of the power system. Energy storage system has broad application prospects in promoting wind power to the grid. However, the high price of the energy storage restricts the development of the combined wind energy-storage system. In order to deal with the power fluctuation of the large-scale wind power grid connection, we propose an allocation strategy of energy storage capacity for combined wind-storage system considering the wind power output volatility and battery storage system’s own operational constraints. The model aims to maximize the annual avenue of the cogeneration system, which allows for the investment fee, operation and maintenance fee and penalty cost of the combined system. The calculation results validate the effectiveness of the optimal allocation strategy.

The estimation of storage capacity is crucial for underground hydrogen storage. Shale gas reservoirs have low permeability and porosity, so it is the potential site for hydrogen storage. The study is based on the depleted shale gas reservoirs with multiple flow mechanisms (diffusion, desorption and seepage). Firstly, this paper, using Laplace transformation, point source function and Stehfest inversion, presents a semi-analytical solution for bottom-hole pressure response with hydrogen duration injection. Then we, considering the multiple flow mechanisms, deduce a material balance equation specifically for shale gas reservoirs and plot modified type curves based on the Blasingame decline analysis theory. Furthermore, we discuss the effects of different critical parameters related to hydrogen storage capacity on type curves. In the final part, we describe in detail the method of obtaining hydrogen reserves using type curves. The proposed one can estimate the hydrogen volume in fractures and matrix systems, and get the actual underground storage volume through pressure response, compared with the hydrogen storage capacity calculated by the volumetric method. This study is helpful for the hydrogen capacity estimation of shale gas underground storage on-site. • Theoretical derivation addresses the bottom-hole pressure during the hydrogen injection for shale reservoirs. • Building the modified Blasingame type curves estimates the hydrogen storage capacity. • Fractures' parameters and adsorption index affect the capacity estimation result and reflect in typical curves. [ABSTRACT FROM AUTHOR]

The repercussions of the burning of fossil fuels on the global air quality index need to be countered with implementable green alternatives such as the hydrogen economy. High energy density, abundance, and the eco-friendly oxidation product of hydrogen make it an ideal fossil fuel replacement. However, the quest for safe, inexpensive, and compact storage material for hydrogen remains the prime concern. The scientific community is mainly looking for two major characteristics, i.e., high hydrogen storage capacity and the onboard reversibility of the host at operable thermodynamic conditions. Since the past decade, a tremendous amount of research has been undertaken toward such material development and exploring their stable hydrogen storage characteristics. In this extensive review, we report the significant material advancements made in this decade toward the methodical and sustainable hydrogen economy. Hydrogen weight percentage (wt%), reversibility, stability, onboard feasibility, and the heat-pressure response of these prospective hydrogen storage hosts have been thoroughly discussed. • Hydrogen is a green-energy source and the best replacement for fossil fuels. • Reversible hydrogen storage materials with high sorption is highlighted. • Newly developed porous and low-dimensional materials store hydrogen reversibly. • Metal functionalization enhances the hydrogen storage capacity of materials. • Scope of advancement in the thermodynamic stability of hosts is discussed. [ABSTRACT FROM AUTHOR]

Off-grid hybrid renewable energy systems represent the most modern and flexible solutions that can cover a wide range of energy efficiency needs for household consumers. In the current context, these systems must be taken into account by most household consumers, given the fact that the price of energy has increased. This paper proposes an experimental analysis of the behavior of such a system, in real operating conditions, considering two renewable energy sources, wind and photovoltaic sources, using an experimental stand. It can be considered a testing platform for hybrid energy production systems, in that the power installed in the two sources can be scaled up. The platform has the advantage of allowing the implementation of different load and wind curves through a programmable logic controller; in this way, it is possible to evaluate the degree of coverage of the energy consumption produced from renewable sources, in the north-east of Romania, in the Suceava County region. The experimental study also involves an analysis of the storage capacity in relation to the consumption and the electricity produced by the two renewable sources. In this regard, three scenarios differentiated by the state of charge (30%, 50% and 70%) have been established. The results indicate that, for each of the imposed scenarios, the energy required to cover consumption is produced by renewable energy sources (42%, 47% and 53%), to which the energy stored in batteries (39%, 28% and 18%) is added. [ABSTRACT FROM AUTHOR]

Sediment deposition in water reservoirs has major implications for storage capacity, reservoir lifetime, and water quality. Changes in rainfall patterns and land use will consequently alter the rate of erosion and therefore have a direct effect on sedimentation rates. This literature review employed a systematic mapping approach to collate and describe evidence of contemporary sedimentation trends for impounded reservoirs and natural lakes with emphasis on studies which analysed impacts on water storage capacity. Fourteen studies determined an overall increase in sedimentation rate, 13 identified a recent decline and another 5 reported mixed results. Interestingly, 83.3% of the articles that studied natural lakes found an increase in recent contemporary sedimentation, while 54.5% of the articles on impounded reservoirs indicated recent declines in sediment deposition. Land use change was the main causative factor responsible for sedimentation rate increase followed by the combined effects of land activities and climate change. Soil and sediment management strategies, implemented in and upstream of some impounded reservoirs, have proved to be effective in mitigating and remediating reservoir sedimentation. From the 147 papers preselected, only 33 contain sufficient sedimentation data to infer recent rate trends with only about 45% of these articles reporting quantities of storage capacity loss caused by sedimentation. Across these 33 studies, assessments of sedimentation and associated storage capacity loss are compromised by the limited spatiotemporal resolution of current measurement methods, reinforcing the requirement to develop new, more robust techniques to monitor sedimentation and storage capacity changes. [ABSTRACT FROM AUTHOR]

In the present work, we have analyzed the suitability of two‐dimensional (2D) h‐AlC as a high‐capacity anode material for Mg‐ion batteries (MIBs) by employing first principles‐based density functional theory (DFT). The structural parameters, electronic band structure, partial density of states (PDOS), theoretical storage capacity (TSC), diffusion energy barrier (DEB), open‐circuit voltage (OCV), and room temperature stability (from ab initio molecular dynamic (AIMD) simulations) are calculated and discussed. The band structure of h‐AlC monolayer remains metallic for all considered adsorption concentrations of Mg‐atoms which indicates its good electrical conductivity. A significant quantity of charge is transferred from Mg atom to h‐AlC during adsorption of the Mg atom due to its lower electronegativity compared with the Al and C atoms. The calculated TSC is 1221.75 mAh g−1 which is higher than many anode materials. For MIBs, calculated DEB and OCV are 1.21 and 0.73 V, respectively. However, transition from planar structure to buckled structure takes place during the adsorption of more than 9 Mg‐atoms over h‐AlC. The lattice change is negligible during adsorption of Mg atoms. The AIMD calculations revels that the 9 and 18 Mg atoms adsorbed h‐AlC is stable at T = 300 K. The aforementioned findings suggest that h‐AlC can be anode material for MIBs. [ABSTRACT FROM AUTHOR]

Copyright of Geominas is the property of FUNDA-GEOMINAS. (Fundacion de Egresados d Amigos de la Escuela de Ingenieria Geologica y de Minas) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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 H 2 , respectively. This work provides essential guidance for the geologic hydrogen storage in the I-WEST region. [Display omitted] • Techno-economic analysis of hydrogen geologic storage in the Intermountain-West, US. • Promising sites for geologic hydrogen storage are identified. • The hydrogen storage capacity and energy demand are estimated. • H 2 storage costs in different geologic formations are estimated and optimized. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) storage in underwater reservoirs is a valuable method of reducing carbon emissions. Saline aquifers such as those in the South Yellow Sea Basin (SYSB), China, have great potential for geological CO2 storage. Thus, we use the recommended calculation method of USDOE and a formation volume model to determine the geological conditions for CO2 storage and estimate the CO2 storage capacity of the Cenozoic saline aquifers in the SYSB (depth: 800–3200 m). Overall, the SYSB exhibits weak fault activity and seismicity, medium and low geothermal fields, four types of source sandstone reservoir, and four sets of carbon reservoir–caprock assemblages developed from the Cenozoic strata, providing relatively good geological conditions for CO2 storage. The estimated capacity of the Cenozoic strata ranges from 39.59 Gt to 426.94 Gt (average: 155.25 Gt), indicating an extensive storage capacity that can meet the carbon sequestration needs of Shandong and Jiangsu Provinces for approximately 89 years. The Yantai Depression has a lower geothermal gradient and terrestrial heat, weaker seismic activity, and double the storage capacity of the Qingdao Depression, indicating that it is the most suitable area for Cenozoic CO2 storage in the SYSB, whereas the Laoshan Uplift is not suitable for storage. This study provides a scientific basis for the selection of offshore CO2 storage sites. [ABSTRACT FROM AUTHOR]

Geological CO2 storage is an emerging topic in energy and environmental community, which is, as a commonly accepted sense, considered as the most promising and powerful approach to mitigate the global carbon emissions during the transition to net‐zero. Of the geological media which initially considered cover the saline aquifers, oil and gas reservoirs, coal beds, and potentially basalts, up to now only the first two choices have been proven to be the most capable storage sites and successfully implemented at pilot/commercial scales. Here, two tandem papers propose novel strategies for the first time, by synthesizing and utilizing new high‐dryness CO2 foam, to enhance geological CO2 storage capacity in saline aquifer and oil and gas reservoirs. In this paper, a new high‐dryness CO2 foam is synthesized and injected into the saline aquifers to explore the storage capacity enhancement, with the unique foam‐induced advantages of sweep area expansion and storage efficiency improvement. Such a new idea is specifically evaluated and validated through a series of static analytical and dynamic performance experiments. With the optimum surfactant concentration of 0.5 wt%, the foaming volume and quality are determined to be 521 mL and 80.81%, respectively, which also shows excellent salt tolerance with 45,000 ppm Na+, 25,000 ppm Ca2+, and 25,000 ppm Mg2+. Moreover, the water consumption for CO2 storage decreases from 464.31 g/mol at 25% foam quality to 67.38 g/mol at 85% foam quality by using the new CO2 foam. Overall, the newly synthesized CO2 foam could effectively enhance geological CO2 storage capacity and concurrently diminish water consumption, therefore realizing the win‐win environment and economic benefits. Plain Language Summary: Geological CO2 storage is an emerging topic in energy and environmental community, which is, as a commonly accepted sense, considered as the most promising and powerful approach to mitigate global carbon emissions amid the transition to net‐zero. The geological CO2 storage options initially included ocean storage, surface mineral carbonation, and geological storage, but currently only refer to the storage in geological media. Of the geological media which initially considered cover the saline aquifers, oil and gas reservoirs, coal beds, and potentially basalts, up to now only the first two choices have been proven to be the most capable storage sites and successfully implemented at pilot/commercial scales. Here, a paper proposes novel strategies for the first time, by synthesizing and utilizing new high‐dryness CO2 foam, to enhance geological CO2 storage capacity in saline aquifer and oil and gas reservoirs. Novel strategies, which effectively enhance geological CO2 storage capacity, are specifically evaluated and validated through a series of static analytical and dynamic performance experiments. Qualitative and quantitative analyses fill the knowledge gap or enhancing geological CO2 storage in saline aquifer and oil and gas reservoirs. Also, solid scientific analyses/supports are provided for future academic research and practical geological CO2 utilization and storage. Key Points: Novel strategies for the first time, by synthesizing and utilizing new high‐dryness CO2 foam, to enhance geological CO2 storage capacity in saline aquiferQualitative and quantitative analyses fill the knowledge gap of enhancing the geological CO2 storage in saline aquiferSolid scientific analyses/supports are provided for future academic research and practical geological CO2 utilization and storage [ABSTRACT FROM AUTHOR]

Density functional theory simulations were performed to investigate the structural, electronic, and electrochemical properties of the two-dimensional α-SiX (X = N, P) monolayers as anode material in Li-ion batteries (LIBs). Our result indicates that α-SiX monolayers have excellent mechanical, dynamical, and thermal stability. The obtained adsorption energy values suggest that the Li atom adsorption over α-SiX is a favorable process. According to the Löwdin charge transfer and partial density of states analysis, charge transfer takes place from Li atom to α-SiX monolayers. From the band structure plots, we observed that after the adsorption of a single Li atom, the α-SiX monolayers are converted into a metallic state from the semiconductor state and remain in the metallic state for the different adsorption concentrations of Li atoms, which is essential to facilitate the diffusion of stored electrons. The calculated specific storage capacity is 956.16 and 733.66 mA h g–1 for α-SiN and α-SiP monolayers, respectively, which is remarkably higher than that of the conventional anode materials (such as graphite and TiO2). Ab initio molecular dynamics simulations confirm the room-temperature stability of the α-SiX monolayers at the maximum loading of Li atoms. The lower diffusion energy barriers of 0.30 eV (for α-SiN monolayers) and 0.16 eV (for α-SiP monolayers) ensure good diffusivity of ions over monolayers. The calculated open-circuit voltage is also favorable for battery applications. The aforementioned findings suggest that the α-SiX monolayers could be beneficial and compelling host anode material for high-performance LIBs. [ABSTRACT FROM AUTHOR]

Water in rivers is delivered via the critical zone (CZ)—the living skin of the Earth, extending from the top of the vegetation canopy through the soil and down to fresh bedrock and the bottom of significantly active groundwater. Consequently, the success of stream‐rearing salmonids depends on the structure and resulting water storage and release processes of this zone. Physical processes below the land surface (the subsurface component of the CZ) ultimately determine how landscapes "filter" climate to manifest ecologically significant streamflow and temperature regimes. Subsurface water storage capacity of the CZ has emerged as a key hydrologic variable that integrates many of these subsurface processes, helping to explain flow regimes and terrestrial plant community composition. Here, we investigate how subsurface storage controls flow, temperature, and energetic regimes that matter for salmonids. We illustrate the explanatory power of broadly applicable, storage‐based frameworks across a lithological gradient that spans the Eel River watershed of California. Study sites are climatically similar but differ in their geologies and consequent subsurface CZ structure that dictates water storage dynamics, leading to dramatically different hydrographs, temperature, and riparian regimes—with consequences for every aspect of salmonid life history. Lithological controls on the development of key subsurface CZ properties like storage capacity suggest a heretofore unexplored link between salmonids and geology, adding to a rich literature that highlights various fluvial and geomorphic influences on salmonid diversity and distribution. Rapidly advancing methods for estimating and observing subsurface water storage dynamics at large scales present new opportunities for more clearly identifying landscape features that constrain the distributions and abundances of organisms, including salmonids, at watershed scales. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) storage capacity is the main criterion for assessing CO2 geological storage. Based on actual data from the Shiqianfeng formation in the Ordos Basin, three-dimensional (3D) models were built using the TOUGHVISUAL visualization software and simulated using the TOUGH2 integral finite difference modeling code with the ECO2N fluid property module to explore the impact of formation attributes (formation slope) and controllable factors (injection temperature) on CO2 storage capacity. A total of 16 schemes were designed, with four injection temperatures (24 ℃, 31 ℃, 38 ℃, and 45 ℃) and four formation slopes (0°, 5°, 10°, and 15°). Simulation results showed that the injection temperature and formation slope both had a significant influence on CO2 storage capacity. The impact of injection temperature on the total storage amount was more obvious than that of the impact of formation slope. A higher injection temperature resulted in a greater total storage amount. Increasing the formation slope and injection temperature increased the gas-phase, dissolved-phase, and total CO2 storage amounts in the upper left section of the injection well, but decreased them in the lower right part of the injection well. The impact of formation slope on the conversion rate from gas-phase CO2 to dissolved-phase CO2 was more obvious than the impact of injection temperature. A steeper formation slope resulted in a higher conversion rate. A smaller formation slope and a higher injection temperature should be selected to store CO2. [ABSTRACT FROM AUTHOR]

The objectives of this study were to predict the inflow and optimal operation of the Koka reservoir under the impact of climate change for the 2020s (2011–2040), 2050s (2041–2070), and 2080s (2071–2100) with respect to the reference period (1981–2010). The optimal elevation, storage, and hydropower capacity were modeled using the HEC-ResPRM, whereas the inflow to Koka reservoir was simulated using the calibrated SWAT model. Based on the result, the average annual inflow of the reference period was 139.675 Million Cubic Meter (MCM). However, from 2011 to 2100 an increase of +4.179% to +11.694 is expected. The inflow analysis at different flow regimes shows that the high flow may decline by (−28.528%) to (−22.856%) due to climate change. On the other hand, the low flow is projected to increase by (+78.407%) to (+90.401%) as compared to the low flow of the reference period. Therefore, the impact of climate change on the inflow to the Koka reservoir is positive. The study also indicates that the optimum values of elevation and storage capacity of the Koka reservoir during the reference period were 1590.771 m above mean sea level (a.m.s.l) and 1860.818 MCM, respectively. However, the optimum level and storage capacity are expected to change by (−0.016%) to (−0.039%) and (−2.677%) to (+6.164%), respectively from 2020s to 2080s as compared with their corresponding values during the reference period. On the other hand, the optimum power capacity during the reference period was 16.489 MCM, while it will likely fluctuates between (−0.948%) - (+0.386%) in the face of climate change. The study shows that the optimum elevation, storage, and power capacity were all higher than the corresponding observed values. However, the occurrence month of their peak value will likely shift due to climate change. The study can be used as a first-hand information for the development of reservoir operation guidelines that can account for the uncertainty caused by the impacts of climate change.

In the future, the development of a zero-carbon economy will require large-scale hydrogen storage. This article addresses hydrogen storage capacities, a critical issue for large-scale hydrogen storage in geological structures. The aim of this paper is to present a methodology to evaluate the potential for hydrogen storage in depleted natural gas reservoirs and estimate the capacity and energy of stored hydrogen. The estimates took into account the recoverable reserves of the reservoirs, hydrogen parameters under reservoir conditions, and reservoir parameters of selected natural gas reservoirs. The theoretical and practical storage capacities were assessed in the depleted natural gas fields of N and NW Poland. Estimates based on the proposed methodology indicate that the average hydrogen storage potential for the studied natural gas fields ranges from 0.01 to 42.4 TWh of the hydrogen energy equivalent. Four groups of reservoirs were distinguished, which differed in recovery factor and technical hydrogen storage capacity. The issues presented in the article are of interest to countries considering large-scale hydrogen storage, geological research organizations, and companies generating electricity from renewable energy sources.

Solar energy is accessible freely and can be utilized for many household and industrial applications. The consumption of solar energy for cooking applications has found significant success. Various innovations have been employed in facilitating cooking during off-sunshine hours. Thermal energy storage helps in overcoming the fluctuations in the supply of energy required for cooking during different time periods of the day. This study focuses on the different types of thermal energy storage mediums that are currently utilized in solar cooking. Primarily, oils and pebbles are most commonly used as sensible heat storage (SHS) while organic phase change materials (PCMs) are used as latent heat thermal energy storage materials (LHTES). The properties and performances of various SHS and latent heat storage (LHS) mediums have been compared for their suitable utilization. SHS materials are cost-effective but have lower thermal gradient compared to LHTES materials. The energy storage capability of LHTES is high while degradation with the increasing number of charging and discharging cycles is also considerable. The melting point should be close to the utilization temperature for being used as LHTES as thermal diffusivity of the materials greatly influences the performance of solar cookers. The cooking time is lower for solar cooking systems equipped with energy storage compared to non-equipped cooking systems. It is recognized that the use of energy storage has been proved as a huge advantage to solar cooking systems, however, the design, and heat transfer characteristics of the cooking vessel along with the storage material type and volume must be optimized in order to make this technology more influential.

Biochar materials have attracted people’s attention because of their environmental friendliness, abundant resources, and the use of waste resources for reuse. As a potassium-ion anode material, biomass char materials synthesized by different methods have broad application prospects. However, due to the problems of low initial magnification and limited potassium-storage capacity, it is necessary to improve the electrochemical performance through modifications, such as atomic doping. Atomic doping is an effective way to improve battery conductivity and potassium storage. In this paper, the synthesis method of biochar as an anode material for potassium-ion batteries and the influence of atomic doping on its modification in recent years are reviewed.

For lithium-ion batteries (LIBs), the dilemma of low-capacity commercial graphite electrode has forced researchers to keep developing high-capacity electrodes. While two-dimensional (2-D) carbon materials are widely used in the field of energy storage due to their excellent physical and chemical properties. Here, based on density functional theory, we systematically investigate Li adsorption and diffusion on graphene with vacancy defects of different sizes, namely GVn (n = 2, 4, 6, 10, and 13). Our results show that, unlike pristine graphene, these defective structures can adsorb Li atoms stably and dispersedly. The adsorption energy of Li gradually enhances as it approaches the vacancy defects. Furthermore, the diffusion of Li on the surfaces of the GVn (n = 6, 10, and 13) is more difficult due to the presence of large vacancy defects. Fortunately, when their vacancy defects are filled with Li atoms, the corresponding diffusion barriers would decrease dramatically. What is most interesting is that as the size of vacancy defect increases, its corresponding Li storage capacity also increases considerably. The calculated storage capacities of GV10 and GV13 are 614 mA h g−1 and 637 mA h g−1, respectively, which exceed that of conventional graphite electrode and many other 2-D graphene-like electrodes. Thus, we believed that is an interesting and competitive example for developing high-capacity electrodes.

Abstract Geological CO2 storage is an emerging topic in energy and environmental community, which is, as a commonly accepted sense, considered as the most promising and powerful approach to mitigate the global carbon emissions during the transition to net‐zero. Of the geological media which initially considered cover the saline aquifers, oil and gas reservoirs, coal beds, and potentially basalts, up to now only the first two choices have been proven to be the most capable storage sites and successfully implemented at pilot/commercial scales. Here, two tandem papers propose novel strategies for the first time, by synthesizing and utilizing new high‐dryness CO2 foam, to enhance geological CO2 storage capacity in saline aquifer and oil and gas reservoirs. In this paper, a new high‐dryness CO2 foam is synthesized and injected into the saline aquifers to explore the storage capacity enhancement, with the unique foam‐induced advantages of sweep area expansion and storage efficiency improvement. Such a new idea is specifically evaluated and validated through a series of static analytical and dynamic performance experiments. With the optimum surfactant concentration of 0.5 wt%, the foaming volume and quality are determined to be 521 mL and 80.81%, respectively, which also shows excellent salt tolerance with 45,000 ppm Na+, 25,000 ppm Ca2+, and 25,000 ppm Mg2+. Moreover, the water consumption for CO2 storage decreases from 464.31 g/mol at 25% foam quality to 67.38 g/mol at 85% foam quality by using the new CO2 foam. Overall, the newly synthesized CO2 foam could effectively enhance geological CO2 storage capacity and concurrently diminish water consumption, therefore realizing the win‐win environment and economic benefits.

Abstract Water in rivers is delivered via the critical zone (CZ)—the living skin of the Earth, extending from the top of the vegetation canopy through the soil and down to fresh bedrock and the bottom of significantly active groundwater. Consequently, the success of stream‐rearing salmonids depends on the structure and resulting water storage and release processes of this zone. Physical processes below the land surface (the subsurface component of the CZ) ultimately determine how landscapes “filter” climate to manifest ecologically significant streamflow and temperature regimes. Subsurface water storage capacity of the CZ has emerged as a key hydrologic variable that integrates many of these subsurface processes, helping to explain flow regimes and terrestrial plant community composition. Here, we investigate how subsurface storage controls flow, temperature, and energetic regimes that matter for salmonids. We illustrate the explanatory power of broadly applicable, storage‐based frameworks across a lithological gradient that spans the Eel River watershed of California. Study sites are climatically similar but differ in their geologies and consequent subsurface CZ structure that dictates water storage dynamics, leading to dramatically different hydrographs, temperature, and riparian regimes—with consequences for every aspect of salmonid life history. Lithological controls on the development of key subsurface CZ properties like storage capacity suggest a heretofore unexplored link between salmonids and geology, adding to a rich literature that highlights various fluvial and geomorphic influences on salmonid diversity and distribution. Rapidly advancing methods for estimating and observing subsurface water storage dynamics at large scales present new opportunities for more clearly identifying landscape features that constrain the distributions and abundances of organisms, including salmonids, at watershed scales.

Lithium-ion batteries (LIBs) have emerged as a technological game-changer. Due to the rising price of lithium and the environmental concerns LIBs pose, their use is no longer viable. Sodium (Na) may be the best contender among the alternatives for replacing lithium. Conventional graphite has a limited capacity for Na storage. Hence, α -graphyne, an allotrope of carbon, was studied here as a potential anode material for Na-ion batteries (NIBs), employing density functional theory. In-plane Na atom adsorption results in a semi-metallic to metallic transition of α -graphyne. Electronic transport calculations show an increase in current after Na adsorption in graphyne. The successive adsorption of Na atoms on the surface of graphyne leads to a theoretical capacity of 1395.89 mA h gâˆ'1, which is much greater than graphite. The average open circuit voltage is 0.81 V, which is an ideal operating voltage for NIBs. Intra- and inter-hexagon Na diffusions have very low energy barriers of 0.18 eV and 0.96 eV, respectively, which ensure smooth operation during charge/discharge cycles. According to this study, the α -graphyne monolayer thus has the potential to be employed as an anode in NIBs. [ABSTRACT FROM AUTHOR]

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 quantitative risk assessment of the hydrogen energy storage system was conducted. • The effects of system parameters (storage capacity, pressure) are thoroughly investigated. • The storage capacity and pressure have the greatest influence on system safety. • A system with a large storage capacity or high pressure poses an unacceptable risk in accordance with standard requirements. [ABSTRACT FROM AUTHOR]

An off-grid hybrid PV-wind-diesel-battery system with the best hybrid combination of system's components is designed to fulfill the electricity demand an off-grid village. For this purpose, five scenarios of system's renewable energy fractions (namely 0% renewable energy, 25% renewable energy, 50% renewable energy, 75% renewable energy and 100% renewable energy) were modeled, simulated, optimized and analyzed. The results obtained using the Hybrid Optimization of Multiple Energy Resources (HOMER) software of the National Renewable Energy Laboratory (NREL)/USA showed that the hybrid system with 50% renewable energy fraction is the optimal one in terms of both its technical performance and the cost of generated electricity which was found to be $0.202/kWh. It was also proved that deploying this system for electricity generation reduces the emissions by 49% compared to the conventional system comprising only diesel generator sets. Moreover, a sensitivity analysis was conducted to reveal the impact of diesel prices, solar radiation and wind speed on the cost of generated – by this optimal system – electricity. The obtained results indicated that diesel price is the most influential factor in the cost of generated electricity. It changes from $0.168/kWh to $0.0.237/kWh for a variation in diesel prices from −30% to +30% of its current prices. The effect of battery bank's storage capacity on the performance and cost of electricity, generated by the optimal system was investigated as well. The results showed that varying the storage capacity from −30% to +30% (from the base case value of 2971 kWh) increases the hybrid system's capital cost, but reduces each of the excess electricity, diesel generators operation hours, the annual diesel consumption and consequently the CO2 emissions. However, increasing the storage capacity from −30% till 0% (the base case), reduces the cost of electricity, while increasing the storage capacity from the base case of 0% to +30% does not affect the cost of generated electricity. [ABSTRACT FROM AUTHOR]

Underground storage is a method of storing large amounts of renewable energy that can be converted into hydrogen. One of the fundamental problems associated with this process concerns determining the timing and amount of injected gas in the first filling period for the operation of an underground storage facility. Ascertaining the hydrogen flow rate is essential to ensure that the capillary and fracturing pressures are not exceeded. The value of the flow rate was assessed by modelling the injection of hydrogen into a deep aquifer. The best initial H 2 injection period was found to be five months. The volume of the cushion gas and the total storage capacity expanded with the extension of the first filling period length. The working capacity grew as the depth increased, reaching maximum values at depths of approximately 1200–1400 m. This depth was considered optimal for storing hydrogen in the analysed structure. [Display omitted] • Capillary and fracture pressures are essential for underground hydrogen storage. • The storage capacity depends on the possible hydrogen flow rate. • The capacity can be increased by dividing the initial storage process into stages. • The optimal depth for UHS is 1200–1400 m. [ABSTRACT FROM AUTHOR]

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