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Composite pressure vessels (CPVs) have become the main equipment for hydrogen storage; however, the effect of defect in the laminates of CPVs is difficult to detect. In this paper, composite specimens containing wrinkle defects were investigated, and a heterogeneity model of a wrinkle defect is proposed. A three-dimensional finite element code was developed to predict the behavior of carbon fiber-reinforced composite laminates with wrinkle defects. The effect of the geometric asymmetry of clamping was distinguished from the whole response. It was found that wrinkle defects are sensitive to tension but completely insensitive to torsion and that the distortion of out-of-plane displacement is strongly dependent upon wrinkle defects. An optical–mechanical method based on fringe projection was presented to measure the response of wrinkle defects, which shows an outstanding performance on wrinkle location and deformation visualization. [ABSTRACT FROM AUTHOR]

Applied to a hydrogen absorption-desorption cycle, the hydrogen storage bed will experience higher exchange temperatures and variety of mechanical load. Due to the complex structure of the double-layered annulus metal hydride bed and the importance of thermal stress on the failure of a metal hydride bed, the numerical modeling of its hot spot stress was carefully carried out. Moreover, in this paper, an analysis method considering the limit failure mode condition is proposed to deal with the stress analysis in the process of hydrogen absorption and desorption. According to the proposed analysis method, the maximum stress of thermal-structural coupling in the process of hydrogen absorption occurs at about 1/3 along the diameter direction and at the geometric mutation of the connection between the cooling pipe and the main body of the hydrogen storage bed in the process of hydrogen desorption. Apart from that, the hydrogen storage bed is also subjected to thermal-mechanical fatigue by the iterative process of absorption and desorption, and its operating temperature range is in the thermal creep temperature region. Based on the distribution of the stress and temperature, evaluation hot sites were selected and the ASME-NB and ASME-NH codes were used to evaluate fatigue and fatigue creep, respectively. The evaluation showed that the fatigue damage generated during its service life is small, while the creep damage is relatively large and the total damage generated during the service life of the hydrogen storage bed is within the safe range. Aiming at the structure and complex process of a double-layer hydrogen storage bed, creep and fatigue evaluation methods are proposed, various failure modes of hydrogen storage bed are highlighted, and the relationship between process parameters and life is established. [ABSTRACT FROM AUTHOR]

As the low-carbon economy continues to evolve, the energy structure adjustment of using renewable energies to replace fossil fuel energies has become an inevitable trend. To increase the ratio of renewable energies in the electric power system and improve the economic efficiency of power generation systems based on renewables with hydrogen production, in this paper, an operation optimization model of a wind–solar hybrid hydrogen energy storage system is established based on electrochemical energy storage and hydrogen energy storage technology. The adaptive simulated annealing particle swarm algorithm is used to obtain the solution, and the results are compared with the standard particle swarm algorithm. The results show that the day-ahead operation scheme solved by the improved algorithm can save about 28% of the system operating cost throughout the day. The analytical results of the calculation example revealed that the established model had fully considered the actual operational features of devices in the system and could reduce the waste of wind and solar energy by adjusting the electricity purchased from the power grid and the charge and discharge powers of the storage batteries under the mechanism of time-of-use electricity price. The optimization of the day-ahead scheduling of the system achieved the minimization of daily system operation costs while ensuring that the hydrogen-producing power could meet the hydrogen demand. [ABSTRACT FROM AUTHOR]

Green ammonia has potential as a zero-emissions energy vector in applications such as energy storage, transmission and distribution, and zero-emissions transportation. Renewable energy such as offshore wind energy has been proposed to power its production. This paper designed and analyzed an on-land small-scale power-to-ammonia (P2A) production system with a target nominal output of 15 tonnes of ammonia per day, which will use an 8 MW offshore turbine system off the coast of Nova Scotia, Canada as the main power source. The P2A system consists of a reverse osmosis system, a proton exchange membrane (PEM) electrolyser, a hydrogen storage tank, a nitrogen generator, a set of compressors and heat exchangers, an autothermal Haber-Bosch reactor, and an ammonia storage tank. The system uses an electrical grid as a back-up for when the wind energy is insufficient as the process assumes a steady state. Two scenarios were analyzed with Scenario 1 producing a steady state of 15 tonnes of ammonia per day, and Scenario 2 being one that switched production rates whenever wind speeds were low to 55% the nominal capacity. The results show that the grid connected P2A system has significant emissions for both scenarios, which is larger than the traditional fossil-fuel based ammonia production, when using the grid in provinces like Nova Scotia, even if it is just a back-up during low wind power generation. The levelized cost of ammonia (LCOA) was calculated to be at least 2323 CAD tonne−1 for both scenarios which is not cost competitive in this small production scale. Scaling up the whole system, reducing the reliance on the electricity grid, increasing service life, and decreasing windfarm costs could reduce the LCOA and make this P2A process more cost competitive. [ABSTRACT FROM AUTHOR]

To reduce pollution from ships in coastal and international navigation, shipping companies are turning to various technological solutions, mostly based on electrification and the use of alternative fuels with a lower carbon footprint. One of the alternatives to traditional diesel fuel is the use of hydrogen as a fuel or hydrogen fuel cells as a power source. Their application on ships is still in the experimental phase and is limited to smaller ships, which serve as a kind of platform for evaluating the applicability of different technological solutions. However, the use of hydrogen on a large scale as a primary energy source on coastal and ocean-going vessels also requires an infrastructure for the production and safe storage of hydrogen. This paper provides an overview of color-based hydrogen classification as one of the main methods for describing hydrogen types based on currently available production technologies, as well as the principles and safety aspects of hydrogen storage. The advantages and disadvantages of the production technologies with respect to their application in the maritime sector are discussed. Problems and obstacles that must be overcome for the successful use of hydrogen as a fuel on ships are also identified. The issues presented can be used to determine long-term indicators of the global warming potential of using hydrogen as a fuel in the shipping industry and to select an appropriate cost-effective and environmentally sustainable production and storage method in light of the technological capabilities and resources of a particular area. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the results of a hybrid air independent propulsion based on fuel cells for small submarines. The weight and volume of the investigated propulsion, and the major tactical and technical characteristics of the 540-tonne submarine equipped with this propulsion have been determined. Five onboard systems for the hydrogen storage or generation, and the oxygen storage are considered. Combining a micro-balloon hydrogen system with the cryogenic oxygen storage is the best solution for the propulsion. The submerged endurance and range improved 32.1-64.8 times, as compared to just battery. The indiscretion ratio equals zero at cruising speeds of less than 7.1 knots, while at higher speeds, this value has dramatically decreased, and submarine secrecy has increased significantly. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the addition of potassium chloride (KCl) by ball milling on the first hydrogenation kinetics of TiFe is reported. After milling, KCl was uniformly distributed on the TiFe's surface. As-synthesized TiFe does not absorb hydrogen. However, after ball milling with KCl, it absorbed 1.5 wt.% of hydrogen on the first hydrogenation without any thermal treatment. The storage capacity of TiFe with KCl addition is higher than that of the ball milled pure TiFe. The effects of the amount of KCl additive in TiFe and ball milling time on first hydrogenation kinetics are reported. It is noted that, with an increase in KCl amount and ball milling time, hydrogenation kinetics are improved. However, hydrogen storage capacity decreased for both cases. [ABSTRACT FROM AUTHOR]

The geological storage of hydrogen is a seasonal energy storage solution, and the storage capacity of saline aquifers is most appropriately defined by quantifying the amount of hydrogen that can be injected and reproduced over a relevant time period. Cushion gas, stored in the reservoir to support the production of the working gas, is a CAPEX, which should be reduced to decrease implementation cost for gas storage. The cushion gas to working gas ratio provides a sufficiently accurate reflection of the storage efficiency, with higher ratios equating to larger initial investments. This paper investigates how technical measures, such as well configurations and adjustments to the operational size and schedule, can reduce this ratio, and the outcomes can inform optimisation strategies for hydrogen storage operations. Using a simplified open saline aquifer reservoir model, hydrogen storage is simulated with a single injection and production well. The results show that the injection process is more sensitive to technical measures than the production process; a shorter perforation and a smaller well diameter increases the required cushion gas for the injection process but has little impact on the production. If the storage operation capacity is expanded, and the working gas volume increased, the required cushion gas to working gas ratio increases for injection, reducing the efficiency of the injection process. When the reservoir pressure has more time to equilibrate, less cushion gas is required. It is shown that cushion gas plays an important role in storage operations and that the tested optimisation strategies impart only minor effects on the production process, however, there is significant need for careful optimisation of the injection process. It is suggested that the recoverable part of the cushion gas could be seen as a strategic gas reserve, which can be produced during an energy crisis. In this scenario, the recoverable cushion gas could be owned by the state, and the upfront costs for gas storage to the operator would be reduced, making the implementation of more gas storage and the onset of hydrogen storage more attractive to investors. [ABSTRACT FROM AUTHOR]

Hydrogen energy storage (HES) systems have recently received attention due to their potential to support real-time power balancing in a power grid. This paper proposes a data-driven model predictive control (MPC) strategy for HES systems in coordination with distributed generators (DGs) in an islanded microgrid (MG). In the proposed strategy, a data-driven model of the HES system is developed to reflect interactive operations of an electrolyzer, hydrogen tank, and fuel cell, and hence the optimal power sharing with DGs is achieved to support real-time grid frequency regulation (FR). The MG-level controller cooperates with a device-level controller of the HES system that overrides the FR support based on the level of hydrogen. Small-signal analysis is used to evaluate the contribution of FR support. Simulation case studies are also carried out to verify the accuracy of the data-driven model and the proposed strategy is effective for improving the real-time MG frequency regulation compared with the conventional PI-based strategy. [ABSTRACT FROM AUTHOR]

Depleted gas reservoirs represent a great opportunity for Hydrogen underground storage(UHS). Eni's portfolio contains several late-life assets that indeed may provide significant storage capacity. These fields, identified as potential storage sites, are producing for several decades, thus they are accompanied by deep reservoir knowledge and infrastructure availability. Moreover, the caprock, that was able to store hydrocarbon during the past centuries, represents a containment potentially effective also when the reservoir acts as H2 storage site. In the framework of the energy transition, Eni has adopted a robust workflow allowing for the identification of UHS opportunities among its depleted assets portfolio. Starting from a first selection of the sites based on multidisciplinary available data, the most promising opportunities are then deepened through lab analyses, 3D numerical modelling and special studies. The special studies are devoted to understanding interactions among injected H2 and the reservoir fluids/rock but also with the active communities of microorganisms. Accurate studies are also needed to evaluate the effects of H2 during interaction with wells materials. In this paper, we will show the steps that lead Eni to identify and mature UHS opportunities. [ABSTRACT FROM AUTHOR]

Hydrogen is acknowledged as a potential and appealing energy carrier for decarbonizing the sectors that contribute to global warming, such as power generation, industries, and transportation. Many people are interested in employing low-carbon sources of energy to produce hydrogen by using water electrolysis. Additionally, the intermittency of renewable energy supplies, such as wind and solar, makes electricity generation less predictable, potentially leading to power network incompatibilities. Hence, hydrogen generation and storage can offer a solution by enhancing system flexibility. Hydrogen saved as compressed gas could be turned back into energy or utilized as a feedstock for manufacturing, building heating, and automobile fuel. This work identified many hydrogen production strategies, storage methods, and energy management strategies in the hybrid microgrid (HMG). This paper discusses a case study of a HMG system that uses hydrogen as one of the main energy sources together with a solar panel and wind turbine (WT). The bidirectional AC-DC converter (BAC) is designed for HMGs to maintain power and voltage balance between the DC and AC grids. This study offers a control approach based on an analysis of the BAC's main circuit that not only accomplishes the function of bidirectional power conversion, but also facilitates smooth renewable energy integration. While implementing the hydrogen-based HMG, the developed control technique reduces the reactive power in linear and non-linear (NL) loads by 90.3% and 89.4%. [ABSTRACT FROM AUTHOR]

This paper proposes a novel configuration that combines wind turbines, an electrolyzer, and a gas turbine with the corresponding generator. A control strategy for this configuration is also proposed. The purpose of this configuration and its control strategy is to make the wind farm work like a conventional power plant from a grid's point of view. The final proposed configuration works properly with the proposed control strategy, the three times per revolution (3p) oscillation frequency is removed and the output power fluctuations caused by wind fluctuation are compensated. The final power output of the proposed configuration is constant like that of a conventional power plant, and it can change according to the different requirements of the transmission system operator. [ABSTRACT FROM AUTHOR]

In recent years, global efforts towards a future with sustainable energy have intensified the development of renewable energy sources (RESs) such as offshore wind, solar photovoltaics (PVs), hydro, and geothermal. Concurrently, green hydrogen, produced via water electrolysis using these RESs, has been recognized as a promising solution to decarbonizing traditionally hard-to-abate sectors. Furthermore, hydrogen storage provides a long-duration energy storage approach to managing the intermittency of RESs, which ensures a reliable and stable electricity supply and supports electric grid operations with ancillary services like frequency and voltage regulation. Despite significant progress, the hydrogen economy remains nascent, with ongoing developments and persistent uncertainties in economic, technological, and regulatory aspects. This paper provides a comprehensive review of the green hydrogen value chain, encompassing production, transportation logistics, storage methodologies, and end-use applications, while identifying key research gaps. Particular emphasis is placed on the integration of green hydrogen into both grid-connected and islanded systems, with a focus on operational strategies to enhance grid resilience and efficiency over both the long and short terms. Moreover, this paper draws on global case studies from pioneering green hydrogen projects to inform strategies that can accelerate the adoption and large-scale deployment of green hydrogen technologies across diverse sectors and geographies.

To prevent climate change, Europe and the world must shift to low-carbon and renewable energies. Hydrogen, as an energy vector, provides viable solutions for replacing polluting and carbon-emitting fossil fuels. Gaseous hydrogen can be stored underground and coupled with existing natural gas pipe networks. Salt cavern storage is the best suited technology to meet the challenges of new energy systems. Hydrogen storage caverns are currently operated in the UK and Texas. A preliminary risk analysis dedicated to underground hydrogen salt caverns highlighted the importance of containment losses (leaks) and the formation of gas clouds following blowouts, whose ignition may generate dangerous phenomena such as jet fires, unconfined vapor cloud explosions (UVCEs), or flashfires. A blowout is not a frequent accident in gas storage caverns. A safety valve is often set at a 30 m depth below ground level; it is automatically triggered following a pressure drop at the wellhead. Nevertheless, a blowout remains to be one of the significant accidental scenarios likely to occur during hydrogen underground storage in salt caverns. In this paper, we present modelling the subterraneous and aerial parts of a blowout on an EZ53 salt cavern fully filled with hydrogen. [ABSTRACT FROM AUTHOR]

The magnesium-based hydrogen storage alloy has a very good prospect to be applied in the market of lightweight automobile due to its merits of light weight, excellent discharge performance, long cycle life, and large hydrogen storage capacity. However, existing studies on magnesium-based hydrogen storage alloy have a series of shortcomings such as the insufficient works in terms of model reasonability analysis, heat transfer behavior analysis, heat control scheme design, and comparative experiment analysis, etc. In view of these problems, this paper studied the thermal effect and heat control strategy of the Mgbased Hydrogen Storage Alloy (MHSA) system for lightweight automobile. At first, this paper constructed numerical models for the fluid-solid coupled heat exchange region and the heat conduction region in the system; then, based on the law of energy conservation, a heat transfer behavior model of the MHSA system was established and used to analyze the thermal effect of the system. After that, according to the driving process of hydrogen fuel cell electric vehicle, the working process of the MHSA system was further analyzed to study the heat control process. Next, this paper proposed a new idea for the heat control of the MHSA system, gave a few tips for the simulations, and presented the flow of the heat control scheme of the system. At last, the experimental results were given and analyzed. [ABSTRACT FROM AUTHOR]

A major issue in the renewable energy supply of buildings is to establish a simultaneity of the fluctuating renewable energy generation and the energy consumption in buildings. This work provides a new case for a better understanding of how to establish this simultaneity. Future solutions are being explored in practice on the campus of the FH Westküste University of Applied Sciences in the Lecturing and Exhibition Building (LEB). The motivation was to design and operate a case building for research in energy science for teaching the bachelor's program Green Building Systems as well as for demonstration purposes for the general public. With a floor space of 207 m, the LEB is supplied with renewable energy from the adjacent energy park consisting of a 10 kW wind turbine and photovoltaic modules with 10 kWp. The heat and cold generation system consists of two reversible heat pumps: one is an air–water heat pump with approx. 7 kW heating and 6 kW cooling power, and the second is a brine–water heat pump with approx. 8 kW heating power and a depth of the two boreholes of 80 m. To match the energy generation and the energy consumption, different kinds of storage units, i.e., batteries with 3 × 8 kWh and storage tanks with 1000 L heat storage and 600 L cold storage, were installed as well as a smart automation system with a database. This paper evaluates measurement data from 2021. It is demonstrated that a fully renewable energy supply of the building is possible for most of the time from spring to autumn. In winter, an additional long-term energy storage, e.g., hydrogen, is necessary for certain days. [ABSTRACT FROM AUTHOR]

Reversible polymer electrolyte membrane (PEM) fuel cells have attracted significant research attention in the last decade due to the associated benefits. However, flow-field design of the bipolar end plates, among various other parameters, largely affects its performance. Thus, the present paper focuses on determining hydrogen storage capacity of a typical activated carbon (aC) electrode employed in a reversible modified PEM fuel cell with varied designs of flow-field. Three flow-field orientations—pin-type, parallel, and interdigitated—are used and their performance is evaluated. The fabrication method of the electrode, reversible modified PEM fuel cell, and different orientations of micro flow channels is disclosed. The characterization of the employed aC electrode is done using scanning electron microscopy (SEM), x-ray diffraction analysis (XRD), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The fabricated cells are tested by linear voltage sweep and results are recorded. The result analysis revealed that the interdigitated flow-field design leads to better distribution of the reactants and encourages higher hydrogen adsorption in the carbon electrode compared to the other flow-field designs under consideration. The electrochemical hydrogen storage capacity of the carbon electrode with interdigitated flow-field design is found to be 1.47 weight percentage (wt. %), whereas for parallel and pin-type designs, it stands at 1.40 wt. % and 1.36 wt. %, respectively. The obtained energy storage density is comparable with the commercially available metal hydride based compressed hydrogen canisters. It is surely a step forward toward developing a reversible PEM fuel cell with enhanced performance capable of storing the charge, like a battery, with many potential applications. The presented work is a contribution toward the development of a commercially viable hydrogen fuel cell with potential applications in the automotive industry, farm machinery, defense industry, power sector, remote area power systems, etc. [ABSTRACT FROM AUTHOR]

This paper presents Cr(III) removal from nickel sulfate waste solutions as a pretreatment step for the modification of hydrogen storage alloys. Adsorption with two cation exchange resins, Dowex G26 (strongly acidic) and MAC-3 (weakly acidic), and precipitation with various solutions were chosen as simple operations for Cr(III) removal from waste solutions. The adsorption of Cr(III) was investigated for both model and real waste nickel solutions. Dowex G26 appeared to be more efficient in Cr(III) removal (RCr(III) from 43 to 80%) than MAC-3 (RCr(III) from 40 to 53%). However, the adsorption from multi-component solutions (presence of Co(II), Ni(II) and Cr(III)) showed no selectivity in Cr(III) adsorption in comparison to those of Co(II) and Ni(II). Cr(III), Ni(II) and Co(II) were removed at a comparable level (30–36%) from a three-component solution of 10 g/dm3 of each metal ion, and a 56–72% removal of these ions was achieved from the real solution. Therefore, the precipitation of Cr(III) was carried out from a real waste nickel solution to compare its performance with adsorption. The best precipitation solution appeared to be 3 and 30% NaOH due to the quantitative precipitation of Cr(OH)3 at pH 5 and relatively small co-precipitation of Ni(II) and Co(II) hydroxides (PCo(II) = 20–52%, PNi(II) = 0–54%). Based on the results of the research, it can be concluded that precipitation with a NaOH solution is an efficient pretreatment operation of an electrolyte for further steps of the hydrometallurgical process of nickel electrodeposition and appears to be more selective in the elimination of Cr(III) than adsorption with Dowex G26 resin. [ABSTRACT FROM AUTHOR]

In this paper we report the effect of three different preparation methods on the first hydrogenation of the vanadium-rich BCC alloy Ti16V60Cr24: one-time cold rolling, 5 min ball milling and addition of 4 wt.% of Zr. All samples were synthesized by arc melting. Without Zr addition the alloy was single phase, but when 4 wt.% Zr was added, a secondary zirconium-rich phase was present. However, X-ray diffraction patterns only showed a single-body-centred cubic phase before hydrogenation for all samples. The crystal structure of the fully hydrogenated samples was body-centred tetragonal. The highest hydrogen capacity (3.8 wt.%) was measured for the Zr-doped alloy. The ball-milled alloy also exhibited a high storage capacity and fast kinetics. However, the maximum hydrogen storage capacity slightly decreased after cold rolling. It was found that air exposure increases incubation time for the first hydrogenation. The incubation time was shortened by cold rolling which, however, reduced the hydrogen storage capacity. The Pressure-Composition isotherms of Ti16V60Cr24 + 4 wt.% Zr at 297, 303 and 323 K were determined. The determined enthalpy and entropy of hydrides formation were −41 ± 5 kJ/mol and −134 ± 14 J/mol/K, respectively. [ABSTRACT FROM AUTHOR]

A significant contribution to the reduction of carbon emissions will be enabled through the transition from a centralised fossil fuel system to a decentralised, renewable electricity system. However, due to the intermittent nature of renewable energy, storage is required to provide a suitable response to dynamic loads and manage the excess generated electricity with utilisation during periods of low generation. This paper investigates the use of stationary hydrogen-based energy storage systems for microgrids and distributed energy resource systems. An exploratory study was conducted in Australia based on a mixed methodology. Ten Australian industry experts were interviewed to determine use cases for hydrogen-based energy storage systems' requirements, barriers, methods, and recommendations. This study suggests that the current cost of the electrolyser, fuel cell, and storage medium, and the current low round-trip efficiency, are the main elements inhibiting hydrogen-based energy storage systems. Limited industry and practical experience are barriers to the implementation of hydrogen storage systems. Government support could help scale hydrogen-based energy storage systems among early adopters and enablers. Furthermore, collaboration and knowledge sharing could reduce risks, allowing the involvement of more stakeholders. Competition and innovation could ultimately reduce the costs, increasing the uptake of hydrogen storage systems. [ABSTRACT FROM AUTHOR]

This paper reports for the first time the synthesis of polyhedral-like Zn(OH)2/ZnV3O8 nanostructures by a single-step sonochemical method. Particle formation and growth were controlled by using hydrazinium hydroxide and ethylenediamine under ultrasonic waves and then acidifying the medium. After synthesis and identification by XRD, EDS, and FESEM techniques, the mentioned nanostructures were used for electrochemical hydrogen storage, which showed a high potential of 3300 mAh/g storage. Metal hydroxides and multivalent ions such as vanadium are highly capable of electrochemical processes, so this paper focuses on their synthesis. [ABSTRACT FROM AUTHOR]

This document is an editorial for a special issue of the journal "Materials Reports: Energy" focused on hydrogen energy production, storage, and utilization. The editorial highlights the importance of hydrogen energy as a significant source for achieving energy transformation and carbon neutrality. It discusses various methods of hydrogen production, storage, and transportation, including mature technologies like fossil fuel reforming and water electrolysis, as well as newer methods like solar photolysis and biomass conversion. The special issue includes 10 selected papers that cover recent developments in hydrogen production and storage materials, catalyst design, structure characterization, and fuel cell systems. The goal of the special issue is to provide readers with a comprehensive understanding of the current research and advancements in hydrogen energy. [Extracted from the article]

The consumption of fossil fuel as the main energy sources results in the production of a large amount of greenhouse gases, such as carbon dioxide and methane, which are one of the main causes of climate change. Research and development as well as implementation of clean energy has been put as high priority in various countries to combat this issue. Hydrogen is one of the most promoted energy sources of clean energy due to its environmental benefits and high energy production. Major development can be seen in the field of hydrogen energy in the past few years from the stage of hydrogen production until the stage of hydrogen storage. This further enhanced the importance of hydrogen safety considerations. Safety considerations usually begins with hazard identification which can be done using various inherent safety assessment tools. Even though there a lot of inherent safety assessment methods that are available, the method that can be used to specifically assess the safety and health level of hydrogen storage is lacking. The aim of this paper is to introduce the development of an inherent safety and health assessment method specifically for hydrogen storage processes. This research begins with the identification of safety and health hazard parameters that existed in hydrogen storage process. Then, a hazard scoring index for safety and health parameters focusing on hydrogen storage is developed. At the current phase, this research will only focus on material-based chemisorption in stationary hydrogen storage technique. The scoring development for inherent safety and health assessment will be done quantitatively using logistic function. The inherent safety and health assessment methods developed will rank the chemicals involved according to their hazard level. [ABSTRACT FROM AUTHOR]

The increasing severity of global climate and energy problems has made renewable energy an inevitable choice for achieving a low-carbon society. Hydrogen is regarded as one of the most promising renewable energy due to its excellent characteristics, such as abundant and extensive resources, high calorific value, and non-pollution. How to achieve efficient hydrogen storage is one of the main hot spots of hydrogen energy research. For on-board hydrogen storage systems, which could be used for portable power sources and fuel cell vehicles, how to store hydrogen safely and effectively is one of the most urgent technological bottlenecks to overcome. The solid-state storage based on hydrogen storage materials has the advantages of low hydrogen storage pressure, high energy efficiency, safety and reliability, compared to conventional compressed hydrogen and cryogenic liquid hydrogen storage methods. It may be one of the most promising solutions to solve the above problems. Among the hydrogen storage materials, the lightweight composite hydrides Li–Mg–N–H system holds great promise for vehicular hydrogen storage applications owing to its moderate thermodynamic properties (∆Hdes ~ 44 kJ mol−1 H2 and ∆Sdes ~ 112 J mol−1 H2·K) and relatively high hydrogen capacity (~ 5.6 wt%). However, the Li–Mg–N–H material itself has poor cycling performance and a high energy barrier, resulting in a low dehydrogenation rate and high operating temperature. Apart from this, the multi-field coupling of mass and energy transfer also poses a challenge, hindering its on-board applications. In this paper, we present the modification methods and research status of the Li–Mg–N–H system's hydrogen storage materials. The effects of composition modification, nanocrystallization and catalyst addition on the thermal/kinetic properties of hydrogen storage materials in the Li–Mg–N–H system are expounded. The difficulties and directions for enhancing the hydrogen storage performance of Li–Mg–N–H system are discussed. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cell technology is securing a place in the future of advanced mobility and the energy revolution, as engineers explore multiple paths in the quest for decarbonization. The feasibility of hydrogen-based fuel cell vehicles particularly relies on the development of safe, lightweight and cost-competitive solutions for hydrogen storage. After the demonstration of hundreds of prototype vehicles, today, commercial hydrogen tanks are in the first stages of market introduction, adopting configurations that use composite materials. However, production rates remain low and costs high. This paper intends to provide an insight into the evolving scenario of solutions for hydrogen storage in the transportation sector. Current applications in different sectors of transport are covered, focusing on their individual requirements. Furthermore, this work addresses the efforts to produce economically attractive composite tanks, discussing the challenges surrounding material choices and manufacturing practices, as well as cutting-edge trends pursued by research and development teams. Key issues in the design and analysis of hydrogen tanks are also discussed. Finally, testing and certification requirements are debated once they play a vital role in industry acceptance. [ABSTRACT FROM AUTHOR]

Hydrogen-based technologies are among the most promising solutions to fulfill the zero-emission scenario and ensure the energy independence of many countries. Hydrogen is considered a green energy carrier, which can be utilized in the energy, transport, and chemical sectors. However, efficient and safe large-scale hydrogen storage is still challenging. The most frequently used hydrogen storage solutions in industry, i.e., compression and liquefaction, are highly energy-consuming. Underground hydrogen storage is considered the most economical and safe option for large-scale utilization at various time scales. Among underground geological formations, salt caverns are the most promising for hydrogen storage, due to their suitable physicochemical and mechanical properties that ensure safe and efficient storage even at high pressures. In this paper, recent advances in underground storage with a particular emphasis on salt cavern utilization in Europe are presented. The initial experience in hydrogen storage in underground reservoirs was discussed, and the potential for worldwide commercialization of this technology was analyzed. In Poland, salt deposits from the north-west and central regions (e.g., Rogóźno, Damasławek, Łeba) are considered possible formations for hydrogen storage. The Gubin area is also promising, where 25 salt caverns with a total capacity of 1600 million Nm3 can be constructed. [ABSTRACT FROM AUTHOR]

In this paper, Mg2Ni hydrogen storage alloy powder was prepared by high-energy ball milling mechanical alloying method, and the influence of stirring shaft rotation speed, ball milling time, and different sizes of ball mills on the formation time, powder morphology, and crystal structure of Mg2Ni alloy during ball milling was studied. The results show that the Mg2Ni alloy was obtained by high-energy ball milling in this work, and the efficiency was increased by about 76% compared with the traditional ball milling method. In the case of higher rotational speed or larger blades, the time to generate Mg2Ni alloy can be advanced, the alloying process can be shortened, and Mg2Ni alloy with a particle size of less than 10 um can be obtained. However, after the ball milling reaches a certain time, the cold welding and crushing of the alloy powder reach a balance, and the particle size is basically unchanged. The hydrogen storage alloy was activated, the hydrogen storage PCT curve was detected, and the hydrogen absorption kinetic curve and the PCT curve were analyzed. After ball milling at 900/1100 rpm for 13 hours, a Mg2Ni alloy with a single composition, extremely low impurity content, and partially amorphous and nanocrystalline coexistence was obtained. Its mass hydrogen storage density also reached the theoretical value of 3.6 wt%. [ABSTRACT FROM AUTHOR]

Reliable storage and transportation of hydrogen at scale is a challenge which needs to be tackled to allow a robust and on-demand hydrogen supply when moving towards a global low carbon hydrogen economy with the aim of meeting netzero climate goals. Numerous technologies and options are currently being explored for effective hydrogen storage and transportation to facilitate a smooth transition to the hydrogen economy. This paper provides an overview of different hydrogen storage and transportation technologies, focusing in more detail on liquid organic hydrogen carriers (LOHCs), its advantages and disadvantages and future considerations for the optimisation of the LOHC technology. [ABSTRACT FROM AUTHOR]

Multimicrogrid system is a novel notion in modern power systems as a result of developing renewable-based generation units and accordingly microgrids in distribution networks. Their energy management might be challenging due to presence of independent units. Thus, in this paper, a decentralized method for energy management of multimicrogrid systems has been proposed. Decentralized methods can enhance the privacy of users and reduce the burden of calculations. Alternating direction method of multipliers (ADMM) is selected as a decentralized approach which has the capability of breaking problems with complicating constraints in order to facilitate the solving process. Using decentralized approach not only reduces the burden of calculations, but also increases the privacy of entities. Wind turbines as renewable based generators are assumed to participate in this system. To model the uncertainties of these units, chance-constrained programming is employed. Also, due to clean output of hydrogen storage systems and fuel cells, the inclination for using these systems has expanded. Simulations on the test case study demonstrate the applicability and performance of the proposed methodology. Considering the reliability level as 0.9 results in 12, 989$ in the test case. By considering the reliability level as 0.8, the operational cost becomes 11, 712$ which shows a reduction of 1277$ which is achieved by jeopardizing the system reliability by 10%. [ABSTRACT FROM AUTHOR]

The non-interconnected islands of Greece can benefit from the comprehensive use of RES to avoid water droughts and ensure energy autonomy. The present paper analyzes an HRES with two possible operating scenarios. Both of them include a wind park of 27.5 MW capacity, an 1175 m3/day desalination plant, and a 490,000 m3/day water tank in Lemnos, Greece. Regarding the wind power, 70% is used in the HRES, while the rest is channeled directly to the grid. The main difference comes down to how the wind energy is stored, either in the form of hydraulic energy or in the form of hydrogen. The lifespan of the system is 25 years, such as the produced stochastic series of rainfall, temperature, and wind of the area. Through the comparison of the operating scenarios, the following results arise: (i) the water needs of the island are fully covered and the irrigation needs have a reliability of 66%, in both scenarios. (ii) Considering the energy needs, the pumping storage seems to be the most reliable solution. (iii) However, depending on the amount of wind energy surplus, the use of hydrogen could produce more energy than the hydroelectric plant. [ABSTRACT FROM AUTHOR]

The European Union is aiming at reaching greenhouse gas (GHG) emission neutrality in 2050. Austria's current greenhouse gas emissions are 80 million t/year. Renewable Energy (REN) contributes 32% to Austria's total energy consumption. To decarbonize energy consumption, a substantial increase in energy generation from renewable energy is required. This increase will add to the seasonality of energy supply and amplifies the seasonality in energy demand. In this paper, the seasonality of energy supply and demand in a Net-Zero Scenario are analyzed for Austria and requirements for hydrogen storage derived. We looked into the potential usage of hydrogen in Austria and the economics of hydrogen generation and technology and market developments to assess the Levelized Cost of Hydrogen (LCOH). Then, we cover the energy consumption in Austria followed by the REN potential. The results show that incremental potential of up to 140 TWh for hydropower, photovoltaic (PV), and wind exists in Austria. Hydropower generation and PV is higher in summer- than in wintertime, while wind energy leads to higher energy generation in wintertime. The largest incremental potential is PV, with agrivoltaic systems significantly increasing the area amenable for PV compared with PV usage only. Battery Electric Vehicles (BEV) and Fuel Cell Vehicles (FCV) use energy more efficiently than Internal Combustion Engine (ICE) cars; however, the use of hydrogen for electricity generation significantly decreases the efficiency due to electricity–hydrogen–electricity conversion. The increase in REN use and the higher demand for energy in Austria in wintertime require seasonal storage of energy. We developed three scenarios, Externally Dependent Scenario (EDS), Balanced Energy Scenario (BES) or Self-Sustained Scenario (SSS), for Austria. The EDS scenario assumes significant REN import to Austria, whereas the SSS scenario relies on REN generation within Austria. The required hydrogen storage would be 10.82 bn m3 for EDS, 13.34 bn m3 for BES, and 18.69 bn m3 for SSS. Gas and oil production in Austria and the presence of aquifers indicates that sufficient storage capacity might be available. Significant technology development is required to be able to implement hydrogen as an energy carrier and to balance seasonal energy demand and supply. [ABSTRACT FROM AUTHOR]

In a fuel cell electric vehicle (FCEV) powered by a metal hydride tank, the performance of the tank is an indicator of the overall health status, which is used to predict its behaviour and make appropriate energy management decisions. The aim of this paper is to investigate how to evaluate the effects of charge/discharge cycles on the performance of a commercial automotive metal hydride hydrogen storage system applied to a real FCEV. For this purpose, a mathematical model is proposed based on uncertain physical parameters that are identified using the stochastic particle swarm optimisation (PSO) algorithm combined with experimental measurements. The variation of these parameters allows an assessment of the degradation level of the tank's performance on both the quantitative and qualitative aspects. Simulated results derived from the proposed model and experimental measurements were in good agreement, with a maximum relative error of less than 2 % . The validated model was used to establish the correlations between the observed degradations in a hydride tank recovered from a real FCEV. The results obtained show that it is possible to predict tank degradations by developing laws of variation of these parameters as a function of the real conditions of the use of the FCEV (number of charging/discharging cycles, pressures, mass flow rates, temperatures). [ABSTRACT FROM AUTHOR]

Converting CO2, a major component of greenhouse gas in the atmosphere, into value‐added fine chemicals is beneficial from environmental and economic aspects. Except for various methods for CO2 reduction such as thermal catalysis, photocatalysis, electrocatalysis and biological reduction, hydrothermal reduction of CO2 to organics is becoming a novel and promising strategy. The hydrogen formed in situ from high‐temperature water could avoid the serious issues of hydrogen storage and transportation. This paper summarizes the recent advances on CO2 conversion to formic acid with metal‐ and biomass‐based compounds under hydrothermal conditions mainly focusing on the role of high‐temperature water, autocatalysis mechanism of metal reductants, and interfacial catalysis mechanism of metal/metal oxides. The effects of several experimental variables including temperature, reaction time and pH of the solution on formic acid yield are systematically illustrated as well. Finally, future efforts for fundamental researches and industrial applications of hydrothermal CO2 reduction are discussed. [ABSTRACT FROM AUTHOR]

The fifth article in a series of five papers devoted to hydrogen energy digitalization. The article discusses the prospects for the introduction of digital technologies in the processes of industrial production, transportation and storage of hydrogen energy products. It is shown that the introduction of digitalization methods should be carried out within a single digital platform. The issues of digital security of hydrogen units, as well as the confidentiality of data transmission when using advanced information technologies, are considered. An increase in the pace of digitalization methods implementation can be achieved by training the personnel with competencies in interdisciplinary fields. A number of relevant problems that complicate the process of hydrogen industry digitalization are described. The requirements for the competencies of future experts in the interdisciplinary field are outlined. [ABSTRACT FROM AUTHOR]

The fourth article in a series of five papers devoted to hydrogen energy digitalization. The article discusses the methods for ensuring digitalization in the field of hydrogen storage and transportation at hydrogen energy enterprises using the example of organizing a storage structure in databases built according to relational and non-relational models. The process of processing and using large data arrays for training neural networks in order to correlate the characteristics of digital twins of power plants are described. The arguments in favor of the introduction of human-machine interfaces such as SCADA are given. Information on the trends and prospects for the development of the proposed technologies for the digitalization of hydrogen energy as a cryogenic sector is provided. [ABSTRACT FROM AUTHOR]

Seaports are responsible for consuming a large amount of energy and producing a sizeable amount of environmental emissions. However, optimal coordination and cooperation present an opportunity to transform this challenge into an opportunity by enabling flexibility in their generation and load units. This paper introduces a coordination framework for exploiting flexibility across multiple ports. The proposed method fosters cooperation between ports in achieving lower environmental emissions while leveraging flexibility to increase their revenue. This platform allows ports to participate in providing flexibility for the energy grid through the introduction of a green port-to-grid concept while optimising their cooperation. Furthermore, the proximity to offshore wind farms is considered an opportunity for the ports to investigate their role in harnessing green hydrogen. The proposed method explores the hydrogen storage capability of ports as an opportunity for increasing the techno-economic benefits, particularly through coupling them with offshore wind farms. Compared to existing literature, the proposed method enjoys a comprehensive logistics-electric model for the ports, a novel coordination framework for multi-port flexibility, and the potentials of hydrogen storage for the ports. These unique features position this paper a valuable reference for research and industry by demonstrating realistic cooperation among ports in the energy network. The simulation results confirm the effectiveness of the proposed port flexibility coordination from both environmental and economic perspectives. • A comprehensive logistics-electric model for optimising port operation. • A multi-port coordination framework for investigating port cooperation. • Integrating multi-port flexibility into the whole energy system. • Highlighting the potentials of harnessing hydrogen. • Introducing the green port to grid concept. [ABSTRACT FROM AUTHOR]

Hydrogen Direct Reduction of Iron (HDRI) combined with renewable electricity is an attractive option for low-carbon steel production. In this paper, we present a novel and computationally efficient techno-economic power-to-x-plant optimization model which is then applied to an HDRI plant located in Finland. Plant dimensioning was carried out in several current and future power market and regulatory scenarios. We predict a production cost of 373 €/t for hot briquetted iron, and 351 €/t for a future scenario of 2025–2030. When the recently introduced EU rules for renewable fuels of non-biological origin are applied, the production costs increased by 30–46 €/t. The rules also have a significant increasing effect on the required hydrogen storage. The flexibility of the direct reduction shaft emerged as an important parameter affecting the required hydrogen storage as well as total production cost. The results of this paper hold significance for the optimal design of future low-carbon steel plants. • Computationally efficient optimization model for Power-to-X operations and dimensions. • Hydrogen Direct Reduction Ironmaking (HDRI) plant using wholesales and wind power. • Significant amounts of intermittent wind power can be absorbed by the HDRI plant. • HDRI/HBI production costs analyzed for EU regulatory scenarios on green hydrogen. • Emission reductions over 96% compared to CO 2 emissions of fossil steelmaking. [ABSTRACT FROM AUTHOR]

The aim of this paper is the multiscale investigation of composite pressure vessel structures wound with varying fibre tension. The paper explores the potential of "programming" the fibre tension force during the winding process of a high pressure hydrogen storage vessel. Two series of vessels were wound with two different tensions: Two series of vessels wound with forces of 3 N and 80 N respectively were experimentally investigated. Other technological factors, such as the type and weight of carbon fibre used, were kept constant throughout the study. Quasi-static burst tests were used to measure the elastic deformation of the vessel surface. Microscopic studies were also carried out to analyse the structure of the composite at different length scales. The fibre content, the geometric parameters of the voids and the distribution of the three main components of the composite – carbon fibre, technological defects and resin – were also determined. Representative RVE elementary cells were generated for both materials using statistical modelling. The composite was then homogenised and elasticity matrices were obtained for the fibre tensile forces in both materials. [ABSTRACT FROM AUTHOR]

This concept study extends the power-to-gas approach to small combined heat and power devices in buildings that alternately operate fuel cells and electrolysis. While the heat is used to replace existing fossil heaters on-site, the power is either fed into the grid or consumed via heat-coupled electrolysis to balance the grid power at the nearest grid node. In detail, the power demand of Germany is simulated as a snapshot for 2030 with 100% renewable sourcing. The standard load profile is supplemented with additional loads from 100% electric heat pumps, 100% electric cars, and a fully electrified industry. The renewable power is then scaled up to match this demand with historic hourly yield data from 2018/2019. An optimal mix of photovoltaics, wind, biomass and hydropower is calculated in respect to estimated costs in 2030. Hydrogen has recently entered a large number of national energy roadmaps worldwide. However, most of them address the demands of heavy industry and heavy transport, which are more difficult to electrify. Hydrogen is understood to be a substitute for fossil fuels, which would be continuously imported from non-industrialized countries. This paper focuses on hydrogen as a storage technology in an all-electric system. The target is to model the most cost-effective end-to-end use of local renewable energies, including excess hydrogen for the industry. The on-site heat coupling will be the principal argument for decentralisation. Essentially, it flattens the future peak from massive usage of electric heat pumps during cold periods. However, transition speed will either push the industry or the prosumer approach in front. Batteries are tried out as supplementary components for short-term storage, due to their higher round trip efficiencies. Switching the gas net to hydrogen is considered as an alternative to overcome the slow power grid expansions. Further decentral measures are examined in respect to system costs. [ABSTRACT FROM AUTHOR]

Zr2Fe alloys have been widely used in fusion energy and hydrogen energy for hydrogen storage. However, disproportionation reactions occur easily in Zr-based alloys at medium and high temperatures, which greatly reduces the storage capacity of the alloys, and is not conducive to repeated cycle applications. The doping of Zr-based alloys with appropriate transition metal elements has been found to significantly improve their H storage properties and prevent hydrogen disproportionation. A convenient approach is required to efficiently predict the desirable doped structures that are physically stable with optimal properties. In this paper, based on the MatCloud High-Throughput Material Integrated Computing Platform (MatCloud), an automated process algorithm was established to solve the disproportionation reaction of Zr2Fe. Rather than testing the doping materials one by one, such high-throughput material screening is effective in reducing the computational time. The structural stability of modified Zr2Fe alloys, with different doping elements and doping concentrations, is systematically studied. The results indicate that the maximum doping concentration of Ni-doped Zr2Fe is 33 at%, and beyond this doping concentration, Zr2(Fe1−xNix) phases become unstable. While Ti doping Zr2Fe will form a new phase, the overall hydrogen absorption capacity may have been affected by the decrease in the phase content of Zr2Fe in the main phase. The present study can shed valuable light on the design of high-performance Zr-based alloys for fusion energy and hydrogen storage. [ABSTRACT FROM AUTHOR]

In this work, a model of an energy system based on photovoltaics as the main energy source and a hybrid energy storage consisting of a short-term lithium-ion battery and hydrogen as the long-term storage facility is presented. The electrical and the heat energy circuits and resulting flows have been modelled. Therefore, the waste heat produced by the electrolyser and the fuel cell have been considered and a heat pump was considered to cover the residual heat demand. The model is designed for the analysis of a whole year energy flow by using a time series of loads, weather and heat profile as input. This paper provides the main set of equations to derive the component properties and describes the implementation into MATLAB/Simulink. The novel model was created for an energy flow simulation over one year. The results of the simulation have been verified by comparing them with well-established simulation results from HOMER Energy. It turns out that the novel model is well suited for the analysis of the dynamic system behaviour. Moreover, different characteristics to achieve an energy balance, an ideal dimensioning for the particular use case and further research possibilities of hydrogen use in the residential sector are covered by the novel model. [ABSTRACT FROM AUTHOR]

In this paper, we have performed systematic theoretical surveys of C20 and its C20−2nTinNn nanocages with n = 1–8 at DFT. Full optimization indicates none of the structures collapse to open deformed as segregated heterofullerene. Also, in order to avoid the resulted strain of fused five-pentagon configuration, some of them deform their cage at the Ti–N bonds and appear cubic-like. Binding energy (Eb) increases, and the absolute heat of atomization │ΔHat│ of the designed C20−2nTinNn structures decreases, respectively, as the number of substituting Ti–N units increases. The calculated Eb of 57.05 eV/atom and │ΔHat│ of 2437.40 kcal/mol display C4Ti8N8 as the most thermodynamic stable heterofullerene where including eight separated Ti–N units through two double C═C bonds. In contrast, the calculated band gap of 2.06 eV shows C18Ti1N1 as the best-insulated heterofullerene. Here isolable or extractable open-shell C18Ti1N1 heterofullerene must be kinetic stable species, and closed-shell C4Ti8N8 should be thermodynamic stable species. Compared to the suggested Ti-decorated B38 fullerene as a high capacity hydrogen storage material with large Eb (5.67 eV/atom), our studied C20−2nTinNn heterofullerenes show the higher Eb with a range of 13.78 to 57.05 eV/atom, the higher stability, and the higher capacity hydrogen storage. Each Ti–N unit can bind up to two hydrogen molecules with an average adsorption energy of 0.073 eV/H2. While the C4Ti8N8 fullerene substituted with 8 Ti–N units can store 16 H2 molecules, the hydrogen gravimetric density (the hydrogen storage capacity) reaches up to 5.61 wt% with an average adsorption energy of 0.587 eV/H2. Based on these results, we infer that C4Ti8N8 fullerene is a potential material for hydrogen storage with high capacity and might motivate active experimental efforts in designing hydrogen storage media. [ABSTRACT FROM AUTHOR]

Accelerating the transition to a cleaner global energy system is essential for tackling the climate crisis, and green hydrogen energy systems hold significant promise for integrating renewable energy sources. This paper offers a thorough evaluation of green hydrogen’s potential as a groundbreaking alternative to achieve near-zero greenhouse gas (GHG) emissions within a renewable energy framework. The paper explores current technological options and assesses the industry’s present status alongside future challenges. It also includes an economic analysis to gauge the feasibility of integrating green hydrogen, providing a critical review of the current and future expectations for the levelized cost of hydrogen (LCOH). Depending on the geographic location and the technology employed, the LCOH for green hydrogen can range from as low as EUR 1.12/kg to as high as EUR 16.06/kg. Nonetheless, the findings suggest that green hydrogen could play a crucial role in reducing GHG emissions, particularly in hard-to-decarbonize sectors. A target LCOH of approximately EUR 1/kg by 2050 seems attainable, in some geographies. However, there are still significant hurdles to overcome before green hydrogen can become a cost-competitive alternative. Key challenges include the need for further technological advancements and the establishment of hydrogen policies to achieve cost reductions in electrolyzers, which are vital for green hydrogen production.

With the increasing use of renewable energy sources and decentralized power systems, certain challenges have emerged in meeting consumers’ electrical energy demands. The intermittent nature of renewable energy generation means that it cannot always align with consumers’ needs, resulting in periods of excess energy production when it is not required. To bridge this gap between production and consumption, energy storage systems are necessary. This paper defines the work of an isolated microgrid, which consists of renewable sources (wind and PV) for energy production, households with electric vehicles as consumers, and a combined storage system. This storage system is made from batteries, hydrogen storage, and a control system that defines the best use of the storage. Stored energy is utilized through fuel cells to generate electricity for consumption when renewable sources cannot meet the demand. This paper presents the principles of electrolysis and models of individual elements within such a system, as well as the definition and principle of control of the system functionality based on rules and conditions. The proposed control system aims to increase the energy storage lifecycle by deciding when and how to utilize which type of storage and define a self-sufficient microgrid based on renewable sources of production. An economic analysis of the storage part of the system was carried out in which the levelized cost of energy stored and the NPC of the storage systems are calculated. A simulation of the system’s operation is conducted using one-hour measurements of wind turbines, solar panels, and household consumption in Serbia. To analyze the system’s behavior, a one-week time horizon is considered.

This paper delivers an examination of relative permeability hysteresis in porous media in the field of petroleum engineering, encompassing mathematical modeling, experimental studies, and their practical implications. It explores two-phase and three-phase models, elucidating the generation of scanning curves and their applications in various porous materials. Building on the research of traditional relative permeability hysteresis models, we have incorporated literature on forward calculations of relative permeability based on digital rock core models. This offers a new perspective for studying the hysteresis effect in relative permeability. Additionally, it compiles insights from direct relative permeability and flow-through experiments, accentuating the methodologies and key findings. With a focus on enhanced oil recovery (EOR), carbon capture, utilization and sequestration (CCUS), and hydrogen storage applications, the paper identifies existing research voids and proposes avenues for future inquiry, laying the groundwork for advancing recovery techniques in oil and gas sectors.