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A recent commentary by Santhosh and Ravindran on our paper (Int. J. Hydrogen Energy 2014, 39:10,606) demonstrated that the interaction between H 2 and MXene (Sc 2 C and Ti 2 C) phases are not Kubas-type and should be of weak physisorption, and thus made a conclusion that 2D Sc 2 C and Ti 2 C are not suitable for practical hydrogen storage applications. In this responses, we recalculated hydrogen adsorption on 2D Sc 2 C and Ti 2 C by using different exchange-correlation functionals. And based on the calculated results, bare MXenes (especially the Ti 2 C) are suitable as hydrogen storage materials at temperatures of several tens degrees lower than room temperature. And the hydrogen adsorptions on the MXenes terminated with oxygen group were also investigated. Among the Ti 2 C, Sc 2 C and their oxygen-functional counterparts, the binding energy of H 2 on Sc 2 CO 2 surface is the closest to the ideal range of 0.16–0.42 eV/H 2 at ambient conditions, and thus the Sc 2 C with oxygen group is expected to be more suitable as hydrogen storage materials. [ABSTRACT FROM AUTHOR]

In this work, a paper-based hydrogen fuel cell is developed without the need for hydrogen storage. Instead, an embedded aluminum foil inside the paper is utilized for in-situ hydrogen generation. The electrodes and current collectors are also deposited on the paper, leading to a lightweight, compact and flexible hydrogen fuel cell with an OCV reaching 0.93 V and a peak power density of 4 mW cm−2. Benefited from the impeded hydroxyl ion diffusion, the hydrogen generation rate is well controlled, leading to a high faradaic efficiency of 72%. In addition, the cell can be operated under different bending angles with negligible power loss. Furthermore, it can be conveniently stacked in the same piece of paper for higher voltage and power outputs. Such a novel fuel cell design is especially suitable for powering various flexible devices with small rated power. • A paper-based hydrogen fuel cell is developed with an OCV of 0.93 V. • The peak power density is 4 mW cm−2 and the maximum current density is 8 mA cm−2. • Faradaic efficiency and energy efficiency are as high as 72% and 18%, respectively. • 75–87.5% of the cell performance remains when bended by angles from 45° to 135°. • A 4-cell stack is developed with an OCV of 3.8 V and a stacking efficiency of 90.6%. [ABSTRACT FROM AUTHOR]

A recent commentary by Santhosh and Ravindran on our paper (Int. J. Hydrogen Energy 2014, 39:10606) demonstrated that the interaction between H 2 and MXene (Sc 2 C and Ti 2 C) phases are not Kubas-type and should be of weak physisorption, and thus made a conclusion that 2D Sc 2 C and Ti 2 C are not suitable for practical hydrogen storage applications. In this responses, we recalculated hydrogen adsorption on 2D Sc 2 C and Ti 2 C by using different exchange-correlation functionals. And based on the calculated results, bare MXenes (especially the Ti 2 C) are suitable as hydrogen storage materials at temperatures of several tens degrees lower than room temperature. And the hydrogen adsorptions on the MXenes terminated with oxygen group were also investigated. Among the Ti 2 C, Sc 2 C and their oxygen-functional counterparts, the binding energy of H 2 on Sc 2 CO 2 surface is the closest to the ideal range of 0.16–0.42 eV/H 2 at ambient conditions, and thus the Sc 2 C with oxygen group is expected to be more suitable as hydrogen storage materials. [ABSTRACT FROM AUTHOR]

Hu et al. reported the hydrogen storage properties of Sc 2 C and Ti 2 C based MXene phases utilizing density functional theory (DFT) as implemented in the CASTEP code [1, 2]. Based on such calculations, the authors suggest that the MXenes should be a new family of potential hydrogen storage media. Their results claim a maximum hydrogen storage capacity of 9.0 wt% with an average binding energy of 0.164 eV/H 2 in Sc 2 C MXene indicating Kubas-type interaction between H 2 and the MXene. These investigations are of prime importance since they provide insight about further applications of MXenes for hydrogen storage. In these calculations they have used local density approximation (LDA) to estimate the adsorption energies. However, binding energies for H 2 with the MXene phases mentioned above obtained from more accurate calculations based on Generalised Gradient Approximation (GGA) and calculation including dispersion correction (GGA + vdW) show very weak binding energy (∼ 0.064 e V / H 2 ) suggesting weak physical interactions between H 2 and the MXene phases. Our accurate DFT calculations predict that these MXene phases are not suitable for hydrogen storage at realistic conditions. So we conclude that appropriate exchange-correlation functional should be used to extract hydrogen adsorption energies in nano-phases to describe their hydrogen storage properties reliably. [ABSTRACT FROM AUTHOR]

To explore the factors affecting the hydrogen evolution performance of a new MgH 2 solid-state hydrogen storage heat exchanger, this paper designs the MgH 2 solid-state hydrogen storage device. The study numerically investigates the influence of operating parameters and structural parameters on the hydrogen release reaction. The results demonstrate that the hydrogen desorption rate increases as the pressure decreases from 0.3 MPa to 0.1 MPa. Moreover, the hydrogen evolution reaction rate significantly rises with an increase in the inlet temperature of the heat transfer fluid (HTF) from 600 K to 700 K. Similarly, the rate of hydrogen evolution reaction increases with an increase in the flow rate of the HTF from 0.5 m/s to 1.25 m/s. The hydrogen evolution reaction time can be notably reduced by increasing the thickness of the annular HTF layer. Compared to no annular fluid layer, the completion time of the hydrogen desorption reaction is shortened by 558 s with a 5 mm thickness. The arrangement of heat exchanger pipes plays a crucial role in the hydrogen evolution reaction, and thus a comprehensive index M is defined to evaluate its influence. A higher M value indicates slower hydrogen release efficiency of the device. By optimizing the operating conditions, the hydrogen desorption time can be shortened by 93.4 %. • A new type of solid-state hydrogen desorption system is designed. • The effect of working and structural parameters on hydrogen desorption performance is discussed in detail. • The paper defines a comprehensive performance index M to compare different bed designs. [ABSTRACT FROM AUTHOR]

This paper examines the problem of synthesizing a two-loop control system for a three-phase voltage source inverter designed for an autonomous power supply system. This type of DC/AC converters is an essential part of power supply systems with renewable energy sources as primary sources, and, accordingly, must corresponds to the requirements for the electric power quality. These requirements are met through circuit design solutions, as well as through the construction of high-precision automatic control systems. The system integrates: a hydrogen electrolyzer, a hydrogen storage system, and a hydrogen fuel cell. The paper proposes a method for calculating the parameters of PI controllers with resonant components, based on the time-scale separation method and allowing independent adjustment of the controller components. The introduction of a resonant component ensures high tracking accuracy for a desired main voltage harmonic and selective suppression of external harmonic influences. The proposed approach allows to synthesize an automatic control system that significantly improves the quality of the voltage inverter output parameters. [ABSTRACT FROM AUTHOR]

Depleted low-permeability gas reservoirs are the primary storage media for underground hydrogen storage (UHS). An accurate assessment of the geomechanics and complex flow mechanisms in a depleted low-permeability gas reservoir is crucial for predicting the injection and production capabilities of UHS facilities. This paper proposes a novel hydromechanical multicomponent model that couples non-Darcy flow, relative permeability hysteresis (RPH), and geomechanics to evaluate the hydrogen storage capacity of UHS facilities in a depleted low-permeability gas reservoir. The coupled model was solved using a fully coupled strategy, employing the finite volume method to solve non-Darcy flow equations and the virtual element method to solve geomechanical problems. The results indicate that the high-velocity non-Darcy (hvnD) and geomechanical effects reduce the working gas volume by 12.82% and 10.56%, respectively. Additionally, the low-velocity non-Darcy (lvnD) effect causes the third stress/strain distribution to exhibit a "focusing" phenomenon, resulting in a 13.19% reduction in the working gas volume. This paper also describes a case where residual gas is captured by mechanisms such as "water lock" and "capillary capture" through the RPH effect. Considering the RPH effect, the gas-water transition zone expanded by 30%, and the peak volume of gas-containing pores in the water zone increased by 1.48 times. Ignoring the RPH effect led to a 19.73% overestimation of the utilization rate of the gas-containing pore space. Hence, this study achieves safe and successful seasonal hydrogen storage and provides theoretical support for designing multicycle operational plans. • A novel coupled hydro-mechanical multicomponent model was proposed. • Non-Darcy flow, hysteresis and geomechanical effects were evaluated thoroughly. • The underground hydrogen storage capacity could be evaluated accurately. [ABSTRACT FROM AUTHOR]

Metal hydride (MH) suffers from strong thermal effects during hydrogen absorption. To fully utilize the reaction heat during hydrogen absorption, phase change material (PCM) can be used to achieve efficient thermal management in the reactor. A novel MH-PCM reactor with the partition arrangement of MH and PCM was proposed in this paper. Then, the two-dimensional multiphysics coupled model of the reactor was developed, and the effects of the number of partitions n , the mass of PCM and the hydrogen absorption pressure P a on the hydrogen absorption performance were discussed detailedly. The results indicated that the novel MH-PCM reactor not only increases the heat transfer area and boots the hydrogen absorption rate, but also improves the uniformity of temperature distribution. As the n increases from 2 to 5, the hydrogen absorption time gradually shortens. Compared to the conventional MH-PCM reactor, the time for 90% hydrogen absorption shortens by 67.13%. Furthermore, the hydrogen absorption rate can be enhanced with the increasing mass of PCM and P a. However, the larger these values are, the weaker the enhancement effect becomes. The results of this paper may provide a new direction for the optimized design and engineering application of MH-PCM reactors. • A novel reactor with the partition arrangement of MH and PCM is proposed. • Effects of partition number, hydrogen storage pressure and PCM mass are examined. • Novel reactor boosts hydrogen absorption rate and improves temperature uniformity. • The hydrogen absorption time is shortened by 67.13% via a partition number of 5. • Absorption enhancement ratio reduces as hydrogen pressure and PCM mass increase. [ABSTRACT FROM AUTHOR]

With the wide application of hydrogen, the research related to 70 MPa pressure level hydrogen storage tank is very important. This paper takes the 70 MPa hydrogen storage tank in the hydrogen refueling station as the research object, and analyses the diffusion characteristics of hydrogen after leakage from the tank under different wind conditions by FLUENT. Studies find that after hydrogen ejects to the obstacle by the effect of high-pressure, it transforms to be dominated by the simple diffusion and the wind condition. The ambient wind helps to reduce the volume fraction of hydrogen. This paper proposes risk mitigation measures based on the distribution of the flammable clouds — installing nitrogen outlets and reducing the height of the enclosure. The volume of flammable clouds is reduced from about 2.72 m3 to less than 0.045 m3 after adding measures, which proves the feasibility of the measures. • A hydrogenation station model is established to simulate the leakage of a 70 MPa hydrogen storage tank. • The diffusion of hydrogen under different wind conditions is compared. • Risk mitigation measures based on the distribution of flammable clouds are proposed and validated. [ABSTRACT FROM AUTHOR]

The application of hydrogen energy is affected by the safety of hydrogen storage system. To grasp the current status of research and application in the research field of hydrogen storage safety and explore its research development trend, data analysis techniques, such as co-occurrence, co-citation, and burst detection, were adopted to conduct bibliometric analysis of the relevant literature. The study results show that the research hotspots of hydrogen storage safety mainly concentrate on six aspects: the stability of metal hydride hydrogen storage materials, the study of thermal management and stress relief in metal hydride reactors, the safety analysis of hydrogen fuel cells and hydrogen leakage monitoring, the analysis of leakage and explosion risks in hydrogen refueling stations, the study of filling pressure and temperature distribution in hydrogen storage tanks, and the study of safety issues in underground hydrogen storage. Mg-based hydride stability and underground hydrogen storage risk analyses are current research frontiers in hydrogen storage safety. • This paper presents the development of hydrogen storage in safety research. • 1552 papers are visualized and analyzed using bibliometrics. • Identifying research frontiers by combining timeline view with burst detection. • Knowledge bases, research hotspots, and frontiers are discussed. • The current challenges and perspectives for the future are proposed. [ABSTRACT FROM AUTHOR]

The uncertainty of renewable energy undermines the competitiveness of Renewable Energy Generation Companies (REGC) in market bidding. Hydrogen energy storage, as a novel high-energy-density energy storage technology, is considered an ideal solution to address the uncertainty of renewable energy and provide flexible ramping products (FRP) to the grid. Building upon this, this paper combines hydrogen energy storage and renewable energy to build a hydrogen-wind-photovoltaic (HWP) system, and introduces HWP into the flexible ramping market for the first time, while participating in the energy market. To capture the interactions between HWP and market players with different utility functions, this paper establishes a bi-level bidding strategy model for HWP participation in the integrated energy and flexible ramping markets, It enables HWP to optimize its internal unit output to increase revenue based on current market conditions. In addition to this, the uncertainty of renewable energy output is taken into account in the upper-level model. Finally, the effectiveness of the proposed two-stage stochastic bi-level optimization scheduling model was validated on IEEE 6-bus and 36-bus transmission-constrained networks. Tests demonstrated that the proposed model effectively assists HWP in formulating optimal bidding strategies in the joint market under uncertainty. Compared to solely participating in a single energy market, HWP's simultaneous participation in energy and flexible ramping markets increased total revenue by 12.22%. • Utilizing hydrogen energy storage to provide Flexible Ramping Product (FRP). • Hydrogen-Wind-Photovoltaic (HWP) participates in energy and flexible ramping market. • Establishing a bi-level strategic bidding model for HWP. • Considering the influence of renewable energy uncertainty on bidding strategies. • The introduction of the FRP increased HWP's total revenue by 12.22%. [ABSTRACT FROM AUTHOR]

The escalating demand for renewable energy solutions and the imperative for efficient energy storage mechanisms have catalyzed the evolution of Power-to-X (PtX) technologies. Germany has the most PtX projects, accounting for 44% of all projects that have been reported. PtX encompasses a spectrum of processes engineered to convert surplus renewable energy into versatile energy carriers or chemical commodities, such as hydrogen, methane, or synthetic fuels. The Paramount to this domain is to synergistically harness renewable energy sources and hydrogen carriers to curtail waste and bolster sustainability. Central to achieving this synergy is the effective control of PtX processes, ensuring optimal performance, cost efficiency, and seamless integration within existing energy frameworks. This paper delves into the control processes and environmental prerequisites within the PtX landscape, elucidating key challenges, and strategies within this dynamic realm. While providing an initial overview of fundamental PtX process chains, this paper accentuates the critical role of geographical considerations. Subsequently, it conducts a thorough analysis of equipment modeling challenges, addressing performance metrics, operational requisites, and capital investments, particularly focusing on methanol and hydrogen production and storage. Through holistic examination, this paper endeavors to delineate the evolving landscape of PtX control processes and conditions, advancing our understanding of this expanding field. [Display omitted] • Comprehensive overview of PtX control process, challenges, strategies, and advancements. • Overview of PtX process chains and geographical conditions. • Analysis of equipment modeling challenges for methanol and hydrogen. • Addressing crucial storage challenges in PtX system. • Exploration of diverse influences on PtX control processes. [ABSTRACT FROM AUTHOR]

Transitioning to a sustainable energy future necessitates innovative storage solutions for renewable energies, where hydrogen (H₂) emerges as a pivotal energy carrier for its low emission potential. This paper explores unlined rock caverns (URCs) as a promising alternative for underground hydrogen storage (UHS), overcoming the geographical and technical limitations of UHS methods like salt rock caverns and porous media. Drawing from the experiences of natural gas (NG) and compressed air energy storage (CAES) in URCs, we explore the viability of URCs for storing hydrogen at gigawatt-hour scales (>100 GWh). Despite challenges such as potential uplift failures (at a depth of approximately less than 1000 m) and hydrogen reactivity with storage materials at typical conditions (below temperatures of 100°C and pressures of 15 MPa), URCs present a flexible, scalable option closely allied with green hydrogen production from renewable sources. Our comprehensive review identifies critical design considerations, including hydraulic containment and the integrity of fracture sealing materials under UHS conditions. Addressing identified knowledge gaps, particularly around the design of hydraulic containment systems and the interaction of hydrogen with cavern materials, will be crucial for advancing URC technology. The paper underscores the need for further experimental and numerical studies to refine URC suitability for hydrogen storage, highlighting the role of URCs in enhancing the compatibility of renewable energy sources with the grid. • Detailed exploration of unlined rock cavern (URC) technology. • Analysis of URCs' potential for large-scale hydrogen storage. • Insights from historical use of URCs in compressed gas storage. • Examination of the opportunities and challenges in using URCs for hydrogen storage. [ABSTRACT FROM AUTHOR]

The paper is devoted to the development of a device for protecting facilities with turn-to-turn insulation, namely transformers and wind generators in order to increase the reliability of operation of electrical power systems, renewable energy installations and energy storage systems. The paper presents the results of experimental studies of the parameters of a prototype frequency-dependent device, as well as an assessment of the effectiveness of suppression of high-frequency surge voltages by the proposed device. The results of four groups of measurements are shown, which were compared with each other and with the results of previously showed computer simulations. The high efficiency of the proposed device when influencing the slope and amplitude of short high-frequency transients is shown. It is indicated that the parameters proposed earlier in the simulation allow the device to be used effectively. A brief analysis of alternative methods and means of protection is provided, and the prospects for using the device as protective equipment for wind power plants are also considered. [ABSTRACT FROM AUTHOR]

In order to meet the hydrogen refueling demand of fuel cell vehicles and reduce the cost of HRS operation process, it is necessary to study the hydrogen refueling process of cascade hydrogen storage system of hydrogen refueling station. In this paper, a thermodynamic model of the hydrogen refueling process for fuel cell vehicles is established, and the effect of the variation of these thermodynamic parameters on the specific energy consumption and utilization rate of the hydrogen refueling process is investigated in terms of the pressure ratio and capacity of the hydrogen storage tank, which is the core of the hydrogen refueling station, consisting of multiple hydrogen storage tanks. The results show that the specific energy consumption and hydrogen utilization of the hydrogen refueling station decreases as the ratio of the nominal pressure of the medium-pressure stage to the nominal pressure of the high-pressure stage increases over the course of the pressure ratio change. In addition, the capacity variation is only slightly changed as a result of the pressure ratio variation. Therefore, the lowest ratio of specific energy consumption can be found by fixing the utilization rate and by changing the pressure ratio. For example, in this paper, if the total mass of hydrogen in the station is 600 kg and the hydrogen utilization rate is required to be not less than 12 %, the optimal pressures for each level are 50.2 MPa, 65 MPa and 86.7 MPa. • A thermodynamic model of the hydrogen filling process for fuel cell vehicles is established. • The pressure ratio and capacity of cascade hydrogen storage systems were analyzed. • Specific energy consumption and hydrogen utilization are used as evaluation indicators. • The optimal pressures for each level are 50.2 MPa, 65 MPa and 86.7 MPa. [ABSTRACT FROM AUTHOR]

Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. [Display omitted] Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. • Stability of ZrXH 3 (X = Zn, Cd) hydride perovskites is confirmed by Enthalpy of formation. • ZrXH 3 (X = Zn, Cd) hydride perovskites have high value of decomposition temperature. • The gravimetric hydrogen storage capacities comes out to be 1.89 % and 1.46 % respectively. • Metallic behavior is reveled by electronic structure of these hydrides. [ABSTRACT FROM AUTHOR]

Due to the extra evaporation loss caused by the ortho-para hydrogen conversion (OPHC) during the storage and transportation of liquid hydrogen (LH 2), the initial concentration of ortho-hydrogen (o-H 2) plays an important role in the large-scale safe operation and utilization of LH 2. However, there are very limited studies focusing on clarifying the impact of the OPHC on thermal behaviors of LH 2 tanks. In light of this, this paper establishes and develops an extended thermal multi-zone model that couples the OPHC process with the mass and energy conservation equations of the ullage and liquid for an LH 2 tank. With the help of the model, a thermodynamic analysis of the pressurization rate is performed to obtain the dominant parameter that evaluates the effect of the initial o-H 2 concentration on the pressure build-up process. The results indicate that the interfacial mass transfer rate caused by the OPHC is the dominant parameter accounting for more than 90% of the effect of all parameters on the pressurization rate during a 10-day process with an initial liquid fill ratio of 90% and a heat leakage of 40 W. Additionally, the effect of the initial o-H 2 concentration on the optimal liquid fill ratio is discussed in this paper. The results indicate that when the initial o-H 2 concentration changes from 0.2% to 10%, the optimal liquid fill ratio decreases from 82.5% to 74%. The present work provides theoretical support and guidance for controlling the o-H 2 concentration to realize the long-term and high-efficiency storage of LH 2. • Modeling of transient ortho-para hydrogen conversion (OPHC) for LH 2 tanks. • Thermodynamic analysis coupled with OPHC on LH 2 storage is conducted. • Interfacial mass transfer by OPHC determines the pressure rise in LH 2 tanks. • Initial concentration of o-H 2 reduces the optimized liquid fill ratio of tanks. [ABSTRACT FROM AUTHOR]

To explore more possibilities for hydrogen economy, Mg-based alloys containing long period stacking ordered (LPSO) phase for solid-state hydrogen storage deserve attention. In this paper, indium (In) element is adopted to alter the de/hydrogenation abilities of Mg–Y–Zn alloys. The relationship between microstructural features and hydrogen storage behaviors of Mg 95 Y 3 Zn 2- x In x (x = 0, 1 and 2 at.%) alloys are discussed in detail. Indium element can modify the morphology of LPSO phase and more Mg interfaces are obtained. LPSO phase cannot be generated when Zn is completely replaced by In element; instead α-Mg grains and eutectic phase (Mg + MgYIn) the constitute the In 2 alloy. Element In benefits the activation process of the alloys in this paper, which helps the alloy particles to be hydrogenated quickly in the first hydrogenation. Specifically, 1 at.% In substitution for Zn accelerates dehydrogenation and the dehydrogenation temperature reduces by 11 °C. The benefits of In element for dehydrogenation behaviors mainly come from increased Mg grain boundaries, larger MgH 2 lattice constants with weaker Mg–H bonds, uniformly distributed nanoscale YH 2 /YH 3 phase. • Indium can modify the morphology of LPSO phase with rough boundaries. • Indium substitution for Zn increases the MgH 2 cell volume, weakening Mg–H bonds. • Nanosized YH 2 and Indium alloying synergistically reinforce the hydrogen desorption. [ABSTRACT FROM AUTHOR]

This article estimates the potential of using depleted offshore gas fields in Brazil for hydrogen storage and the effects this may have in terms of energy security. Brazil is starting to invest in producing green hydrogen associated with offshore wind energy generation. This initiative has stimulated the search for suitable locations to store hydrogen, including in depleted offshore gas reservoirs. The methodology used in this paper allows for identifying which of the 85 assessed depleted offshore gas fields are the most suitable for hydrogen storage and evaluating the storage capacity of the selected fields. In addition, a wind speed analysis is made to investigate possible locations for prospective wind energy generation projects that can accommodate green hydrogen production. As our main result, we find that the selected depleted offshore gas fields have the potential to store around 5483 TWh worth of hydrogen. This amount is equivalent to about 10 times the total annual electricity consumption in Brazil. Hence, Brazil can comfortably leverage its offshore wind potential in connection with hydrogen production to enhance the energy security of its electricity supply. Considering that to date primarily natural gas has been used as the main source of energy security in Brazil and that its share in the electricity sector has significantly increased over the last decade, the combination of hydrogen storage and renewable energy such as offshore wind power has the potential to provide a resilient and decarbonised electricity system in the country. Furthermore, hydrogen stored in offshore reservoirs in Brazil can become an important resource in the international energy market and constitute a possible key to energy security for countries to which Brazil may export hydrogen. We end our paper by providing comments on the challenges, opportunities, and prospects of offshore hydrogen storage in Brazil. • Offshore natural gas fields in Brazil are suitable for hydrogen storage. • Depleted offshore gas fields can store around 5483 TWh worth of hydrogen. • Two main offshore storage clusters exist in the Southeast and Northeast of Brazil. • Fossil fuel dependence in Brazil can be reduced through hydrogen use and storage. • Large-scale hydrogen storage can contribute to Brazil's energy security. [ABSTRACT FROM AUTHOR]

Renewable energy systems (RESs) have played a vital role in meeting the continuously fast-rising energy demand. While RESs provide limitless and ecologically good possibilities, putting RESs in place has proven to be a challenging task due to their intermittent energy supply. Battery energy storage systems have widely been used in microgrids to manage the issue of intermittent energy supply caused by the RESs. The disadvantages of batteries include, large size, limited lifespan, and high cost. For this reasons, energy planners are looking into hydrogen-based storage systems as a potential solution. This paper aims to provide the recent advancements in the sizing and energy management of hybrid RES (HRES), as well as conventional methods. To achieve this, the authors have employed a review strategy that involves several specific tasks, such as preparing a database of articles related to Hybrid RESs with hydrogen storage, designing inclusion/exclusion criteria to filter out relevant articles, and analyzing each article from critical viewpoints. Thus, this paper elaborates on the general formulation framework for optimization, the classification and review of different optimization methods, and the literature on the application and research of Energy Management Systems (EMS). Additionally, the review presents an analysis and comparison of various system optimization methods and EMS through a study of several cases from the literature. It is hoped that the review will act as a basic framework for researchers looking to investigate HRES incorporated with hydrogen storage. • An efficient energy storage system is essential for managing intermittent energy supply. • A fuel cell generates electricity by combining hydrogen and oxygen to form water. • Soft computing techniques use both single and hybrid algorithms. • Deterministic rule-based controllers operate based on pre-defined rules. • Energy Management System coordinate the flow of power between different components. [ABSTRACT FROM AUTHOR]

This paper investigated the heat transfer phenomenon and enhancement mechanism in MgH 2 based hydrogen storage reactors, aiming to optimize the heat and mass transfer resistance and reaction kinetics issues encountered in practical applications of the hydrogen storage materials. The powdered MgH 2 hydrogen storage material and its compacted disks were prepared to study the thermophysical properties and hydrogen absorption/desorption characteristics. For the disk prepared by composite 5 wt% EG under a compression pressure of 100 MPa, its axial and radial thermal conductivity can be as high as 2.53 and 2.03 W/(m·K), respectively, and the average hydrogen absorption rate within 1000 s is 17.2% faster than that of the powder material when applied in reactors. To gain a better understanding of the influence of the material properties, and operating conditions on the heat transfer and reaction performance inside the reactor, mathematical models for the heat and mass transfer and reaction processes of the reactor were established. Simulation results revealed the coupling mechanism of heat transfer and reaction within the storage reactor, and showed that the increased thermal conductivity and hydrogen absorption pressure can further accelerate absorption process. When the thermal conductivity increases from 2 to 10 W/(m·K) and the absorption pressure increases from 1 to 1.8 MPa, the average hydrogen absorption rate can increase by 79.4% and 42.2%, respectively. • Ball milled magnesium hydride powder showed high reactivity. • Compacted disks showed high thermal conductivity and H 2 storage capacity. • An experimental device was built for testing H 2 ab/desorption of reactors. • Coupling mechanism between transfer and reaction inside reactors was revealed. • Higher H 2 pressure is profit to enhance heat transfer and absorption reaction. [ABSTRACT FROM AUTHOR]

The effectiveness of element doping in enhancing the hydrogen storage performance of ZrCo alloys has been well established. However, the impact of single element doping is limited, and research on the synergistic effect of multi-element alloying remains relatively scarce. In this paper, the hydrogen storage properties of Zr 0·75 Ti 0·125 Nb 0·125 Co 0·75 Ni 0.25 (ZTNCN) alloy were investigated using the first-principles method to explore the synergistic effect of Ti, Nb and Ni doping on ZrCo. The results indicate that the (−110) surface of ZTNCN undergoes significant reconstruction, leading to enhanced adsorption and dissociation of hydrogen on the surface. Moreover, there is no apparent dissociation barrier for H 2 , facilitating easier migration of H on the surface. The difference in atomic size leads to a variation in lattice interstices, resulting in a lower diffusion energy barrier for H compared to that of the ZrCoH x system. Through atomic substitution, the space within the 8e site becomes compressed, which makes the alloy exhibit improved resistance against disproportionation. Therefore, the synergistic effect of Ti, Nb, and Ni can greatly enhance hydrogen absorption and desorption kinetics in alloys and improve anti-disproportionation. [Display omitted] • The co-doping of Ti, Nb, and Ni promotes remodeling of the surface, enhancing hydrogen storage. • The co-doping of Ti, Nb, and Ni enhances H 2 dissociation and promotes H migration and diffusion. • The release of hydrogen from ZTNCN hydride is easier than from ZrCoH x system. • The co-doping of Ti, Nb, and Ni improves the ZrCo alloy's anti-disproportionation. [ABSTRACT FROM AUTHOR]

In this study, a techno-economic analysis tool for conducting detailed feasibility studies on the deployment of green hydrogen hubs for fuel cell bus fleets is developed. The study evaluates and compares five green hydrogen hub configurations' operational and economic performance under a typical metropolitan bus fleet refuelling schedule. Each configuration differs based on its electricity sourcing characteristics such as the mix of energy sources, capacity sizing, financial structure, and grid interaction. A detailed comparative analysis of distinct green hydrogen hub configurations for decarbonising a fleet of fuel-cell buses is conducted. Among the key findings is that a hybrid renewable electricity source and hydrogen storage are essential for cost-optimal operation across all configurations. Furthermore, bi-directional grid-interactive configurations are the most cost-efficient and can benefit the electricity grid by flattening the duck curve. Lastly, the paper highlights the potential for cost reduction when the fleet refuelling schedule is co-optimized with the green hydrogen hub electricity supply configuration. • Techno-economic analysis tool for a green hydrogen hub is developed. • Comparative analysis of five electricity supply configurations. • Comparison of green hydrogen economics across 5 cities in Europe. • Influence of Capex, wholesale electricity prices, and PPA price on LCOH. • A hybrid photovoltaic-wind-grid system with hydrogen storage is cost-optimal. [ABSTRACT FROM AUTHOR]

Liquid hydrogen (LH 2) is a promising and economical clean energy for achieving global carbon neutrality. Multi-layer insulation (MLI) with high performance is essential for the safe storage and operation of LH 2. To perform a better optimization of MLI, the second law of thermodynamics becomes a complement to the first law of thermodynamics. However, very few studies have carried out the optimization of MLI performance through the second law of thermodynamics. For the sake of achieving more efficient optimization of MLI as well as revealing the fundamental indicators limiting the performance of MLI, this paper analyzes the characteristics of entropy generation produced by the solid heat conduction, thermal radiation, and residual gas conduction distributed in the MLI schemes by a validated layer-by-layer model. For a 40-layer MLI arranged with a constant layer density of 20 layers/cm, the first 15 layers near the cold boundary occupy more than 98% of the total entropy generation, providing an effective range of layers for thermodynamic optimization. Besides, an optimization of variable-density MLI (VDMLI) separated into two segments based on the entropy generation minimization is conducted. The optimal VDMLI has substantially lowered the entropy generation from the solid heat conduction but at the cost of increasing the entropy generation from radiation and residual gas conduction. This study provides a reliable optimization method of MLI, which allows the safe storage of clean energy with a low boiling temperature. • A modified layer-by-layer model is built for entropy generation analysis. • Characteristics of entropy generation distributed in MLI are investigated. • Effect of layer density on components of entropy generation is detailed discussed. • Optimization of 2-segment VDMLI upon entropy generation minimization is conducted. [ABSTRACT FROM AUTHOR]

With the increasing depletion of fossil fuels, hydrogen has attracted much attention as one of the promising alternative energy sources. However, the large-scale application of hydrogen energy still has many challenges, such as insufficient storage, transportation, and demand. Among the various hydrogen storage media, methylcyclohexane (MCH) is regarded as a potential hydrogen storage technology, because of its unique and excellent safety performance, hydrogen storage capacity, physical and chemical properties, and other notable characteristics. Herein, the paper focuses on the current research progress of dehydrogenation technology, which is discussed in term of the reaction mechanism of MCH dehydrogenation, the research progress of catalysts, and the optimization of process conditions, respectively. Subsequently, a summary is provided to point out the possible reaction network diagrams. Additionally, based on the challenges associated with sourcing heat for applications, we propose a novel dual internal combustion engine drive method for hydrogen production from MCH, this innovative approach is expected to propel the advancement and application of hydrogen energy technology. Then, this work concludes with a brief overview of the current research progress in hydrogenation technology. Finally, it summarizes the present challenges of MCH dehydrogenation, and further research of MCH dehydrogenation have prospected in terms of optimal design theory, preparation of novel catalysts, reduction of energy consumption, reactor enhancement, and system coupling. [Display omitted] • The reaction mechanism of MCH dehydrogenation is explored and analyzed. • A network diagram of possible MCH dehydrogenation reactions is summarized. • Progress in the research of active centers, additives, and supports of the catalysts is discussed. • A novel dual internal combustion engine drive method for hydrogen production from MCH is proposed. • The developments, challenges, and prospects for MCH dehydrogenation are reviewed. [ABSTRACT FROM AUTHOR]

Underground hydrogen storage has emerged as a strategy to address the challenge of large-scale, long-term, and economically viable hydrogen preservation, fulfilling energy demands and balancing supply intermittency in renewable energy systems. This paper seeks to enrich the discourse on sensitivity analyses concerning underground hydrogen storage processes by reviewing the influence of wettability. In this work, we present our review of wettability in geological formation for hydrogen storage starting with sandstone formations, carbonates, shale, and finally basalt. Results show that published water/hydrogen contact angle measurements indicate strong water-wet to intermediate water-wet conditions at ambient conditions for most formations. • Sandstone and basalt show consistent water-wet state at various conditions, thus considered ideal for hydrogen storage. • Microbial activity alters wettability and increases contact angle, posing risks for certain lithologies like carbonate. • Increased organic matter in carbonate and shale increases contact angle measurements, especially at high pressure. [ABSTRACT FROM AUTHOR]

With the increasing popularity of hydrogen fuel cell vehicles (HFCV), the risk of hydrogen leakage is becoming increasingly prominent. The closed nature in the vehicle structure may lead to rapid accumulation of hydrogen in the cabin when a leak occurs, creating a high concentration that can threaten passengers' respiratory safety and even their lives, as well as potentially triggering an explosion accident. Therefore, this study focuses on hydrogen fuel cell vehicles (HFCVs) with a hydrogen storage pressure of 70 MPa, applying computational fluid dynamics (CFD) methods to simulate the diffusion of hydrogen leakage at different locations, and discusses the impact of leakage rates, leakage hole shapes, and ventilation conditions. This study reveals how hydrogen concentration and distribution change with time in the vehicle under different leakage scenarios, providing important theoretical support for improving the safety of HFCVs. The results indicate that hydrogen leaks at different positions lead to different concentration distributions. Specifically, leaks at position one can accumulate hydrogen between the driver and co-driver, increasing the flammable risks for the front seats. Leaks at position two gather around the seats and spread outward, with the area around the vehicle's roof edge prone to hydrogen accumulation. Leaks at position three, due to the confined space of the trunk, lead to a rapid increase in hydrogen concentration. Further analysis indicates that the higher the leakage rate, the faster the hydrogen diffuses, and the broader the range of concentration distribution becomes; the irregular rectangular shape of the leakage hole accelerates the diffusion speed of hydrogen in both horizontal and vertical directions, expanding the diffusion range. The location of the vent plays a significant role in controlling hydrogen diffusion under different leakage positions. At position one, the vent at the front of the car can effectively reduce the hydrogen concentration on the hood and driving position. At position two, the vents at the front and rear of the car can more rapidly decrease the hydrogen concentration inside the vehicle, reducing the time personnel are in danger. At position three, the vent at the rear can effectively promote the quick exhaust of hydrogen, lowering the concentration inside the car and reducing the risk of ignition. • Focusing on the hydrogen leakage at different positions in the car, the state of hydrogen leakage on the concentration distribution inside the car is analyzed. • The shape of the leak hole has a significant effect on hydrogen diffusion in the vehicle. The irregular rectangular shape of the leak hole spreads the fastest and most widely in both horizontal and vertical directions, increasing the risk of hydrogen explosion in the car. • The location of the vents is critical to controlling the spread of hydrogen leaks，and the position of the vent determines the path of hydrogen control and diffusion. • This paper analyzes the impact of different leakage rates on the speed and range of hydrogen diffusion. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cell vehicles (HFCVs) may cause fires in the event of an accident. When the high-pressure hydrogen storage cylinders are exposed to fire for a long time, there will be a risk of catastrophic consequences such as leakage, jet fire and explosion. Fire test is the main method to study the safety performance of hydrogen storage cylinders. During the firing process, the wall and internal temperature of the hydrogen storage cylinder rise gradually, and the thermally activated pressure relief device (TPRD) of the cylinder reaches a certain temperature and then releases high-pressure hydrogen to prevent the cylinder from bursting. As the hydrogen storage cylinder is in the fire environment, the release of high-pressure hydrogen will be ignited to form a jet fire and cause damage to personnel and equipment. In this paper, CFD software Fluent was used to numerically simulate the local fire test of the hydrogen storage cylinder with high-temperature air as the fire source. The variation law of cylinder wall temperature, gas temperature and pressure inside the cylinder, and the activation of TPRD were analyzed. At the same time, on the basis of the fire test simulation, a high-pressure hydrogen jet fire simulation numerical model caused by the TPRD action was established. The velocity field, temperature field and hydrogen concentration distribution of the jet fire were obtained, and the overpressure generated by the jet fire and the flame length size were analyzed. The results show that the high-pressure hydrogen released by TPRD was ignited under the fire condition to produce a jet flame and generated an overpressure in the jet direction, and the influence range of the overpressure was smaller than the influence range of the jet flame. • The internal temperature, pressure and wall temperature variation laws of cylinders were analyzed. • Hydrogen jet fire flow field changes after TPRD activation were simulated. • The influence range of overpressure in the direction of the jet is smaller than that of the jet flame. • The length of the jet flame is affected by the initial injection pressure and the TPRD discharge diameter. [ABSTRACT FROM AUTHOR]

Triazine-based graphitic C 3 N 4 (g-C 3 N 4) sheet is considered a promising material for hydrogen storage due to its porous structure and light mass. Decoration with the superalkali cluster for it not only avoids the gathering of metal atoms but also provides more adsorption sites for hydrogen. In this paper, the performance of (NLi 4) n @g-C 3 N 4 (n = 1,2) as a hydrogen storage material is investigated based on first principles calculations. The results indicate that two NLi 4 clusters can be anchored on the 2 × 2 supercell of g-C 3 N 4 with a large binding energy of −4.39eV. Each NLi 4 can adsorb nine hydrogen molecules with an average adsorption energy of −0.20eV. The hydrogen storage capacity of (NLi 4) 2 @g-C 3 N 4 coated by NLi 4 on both sides is approximately 7.4 wt%. The AIMD simulations for (NLi 4) 2 @g–C 3 N 4 –18H 2 show that when the temperature is higher than 254K at ambient pressure, hydrogen molecules are released partially from the system, and 83.3% of hydrogen is released from the adsorption system at 300K. As a result, we predict that g-C 3 N 4 modified by NLi 4 can be used as a potential material for the storage of hydrogen at ambient temperature. [Display omitted] • Superalkali NLi 4 decorated nanomaterials are proposed for hydrogen storage. • NLi 4 clusters can be stably anchored on g-C 3 N 4 monolayer. • Superalkalis effectively solve the aggregation of metal atoms on substrate. • High reversible storage capacities can be achieved at ambient temperature. [ABSTRACT FROM AUTHOR]

This paper proposes a molecular model of covalent grafting of azobenzene derivatives with graphite-like carbon nitride based on hydrogen bond regulation to improve the azobenzene photothermal energy storage density. The enthalpy of isomerization (Δ H) of azobenzene molecular cis - trans isomers is calculated using density functional theory, and the magnitude of Δ H is used to evaluate the photothermal storage performance of the azobenzene graphite-like carbon nitride model. The results showed that the molecular Δ H value increased by 0.105–0.243 eV after the azobenzene derivatives were covalently grafted to the graphitic carbon nitride template. In addition, when the donator group replaced the active benzene ring ortho-site of azobenzene, its value was 0.069–0.295 eV higher than that of the electron-withdrawing groups. Moreover, intramolecular hydrogen bonds can stabilize cis - trans isomers and increase the energy of azobenzene. Compared with unsubstituted azobenzene, the energy of azobenzene Δ H containing one intramolecular hydrogen bond increased by 0.295 eV, while the energy of azobenzene Δ H containing multiple intramolecular hydrogen bonds increased by 0.775 eV. [Display omitted] • A molecular model for covalent grafting of azobenzene onto g-C 3 N 4 with hydrogen bond was developed. • The energy conversion density of azobenzene synthetic was determined using density functional theory. • The grafting effect was evaluated by considering intramolecular hydrogen bond, substitution location, and electron group. [ABSTRACT FROM AUTHOR]

Cryo-adsorption is an attractive method for hydrogen storage. However, the non-uniformity of temperature during the charging process affects its performance. To improve the uniformity of the temperature field inside the hydrogen storage tank, and thus improve the hydrogen storage performance and hydrogen storage efficiency of the tank, this paper proposed a thermal management method that combines the central and spiral cooling tubes with vacuum adiabatic heat management. Accordingly, a numerical model was built to investigate the hydrogen adsorption performance of the installation. The results reveal that satisfactory temperature-uniformity was shown in charging and dormant stages. Suitable operating conditions also can improve hydrogen storage performance by reducing the impact of thermal effects. Moreover, the hydrogen storage capacity of activated-carbon cryo-adsorption is roughly 2.5 times that of cryo-compressed storage and 10 times that of ambient-compressed storage. [Display omitted] • A new cooling structure enhancing temperature uniformity was proposed. • The charge cycle of cryogenic activated carbon hydrogen storage is simulated. • Hydrogen storage capacity is significantly improved with new cooling structure. • Proper operating condition leads to satisfactory hydrogen storage amount. [ABSTRACT FROM AUTHOR]

Using salt caverns for the Underground Hydrogen Storage (UHS) is a promising means to address climate change and the energy crisis. However, the complex Thermal-Hydro-Mechanical (THM) coupling problems existing in the UHS salt caverns pose a challenge to the safe and efficient storage of hydrogen. In this paper, a coupled THM model which considers the thermodynamic properties of hydrogen, the thermal expansion and creep of the surrounding rock, and the hydrogen seepage was proposed. The model was validated by the results of a field test and a numerical simulation. A numerical model was established to analyze the stability and tightness of the UHS cavern in bedded salt rock under different Frequencies of Hydrogen Injection and Withdrawal (FHIW). The results show that with the increase of the FHIW, there is an increase in the variation ranges of pressure and temperature. The distributions of the von Mises stress, the first principal stress and the effective creep strain suggest that the risk of failure induced by creep and tensile is more significant at the interface of the salt rock and interlayer on the cavern wall. Additionally, the displacements, Volume Loss Rate (VLR), and hydrogen loss ratio of the cavern all increase with the increase of FHIW, and the maximum displacement of the cavern is found at the roof. The interlayer is the main channel for hydrogen leakage, and the existence of the "seepage step" and "seepage peak" indicates that frequent injections and withdrawals primarily impacts the region close to the cavern. [Display omitted] • A novel coupled thermal-hydro-mechanical model for hydrogen storage in salt cavern was proposed. • The stability and tightness of the cavern under different frequencies of hydrogen injection and withdrawal were analyzed. • The risk of failure induced by creep and tensile is more significant at the interface of the salt rock and interlayer. • The injection and withdrawal of hydrogen will produce the "seepage step" and "seepage peak", respectively. [ABSTRACT FROM AUTHOR]

Hydrogen is an efficient and environmentally friendly energy source, and the research of hydrogen storage technology is of extreme importance. Solid-state hydrogen storage technology using metal hydrides as carriers has good application prospects. This paper aims to optimize the heat transfer resistance and hydrogen absorption kinetics encountered in practical applications of reactors with LaNi 5 hydrogen storage materials. A novel fin structure is proposed to optimize the performance of a U-tube heat exchanger type reactor. The numerical simulation models of hydrogen absorption reaction in a single U-tube heat exchanger reactor and a reactor with fins installed in a straight section of the U-tube are established. The comparison results showed that the auxiliary heat dissipation of heat transfer fins accelerated the speed of hydrogen absorption reaction to a certain extent, but did not achieve the expected effect. Based on this situation, an additional curved fin was added to the U-tube bend section. The results showed that the addition of curved fins can overcome the inherent defects of the U-tube heat exchanger, significantly improve the heat dissipation capacity of the reactor, and the reaction rate approximately doubled. To further enhance the performance of the reactor, the operating conditions of the heat exchanger and reactor were discussed, including HTF flow rate, inlet temperature, as well as hydrogen absorption pressure. The results indicate that there is an optimal inlet flow rate of 2 m/s for HTF. The increase in hydrogen absorption pressure and the decrease in HTF's inlet temperature can effectively enhance the heat transfer and H 2 absorption rate of the reactor. • The new fin structure can effectively improve the performance of the reactor. • There is an optimal HTF inlet velocity for better heat transfer and absorption rate. • The decreased HTF inlet temperature accelerated heat transfer and H 2 absorption. • The increased absorption pressure can effectively enhanced reaction heat transfer. [ABSTRACT FROM AUTHOR]

Magnesium-based hydrogen storage has garnered significant attention in the field of hydrogen storage due to its notable advantages, including high hydrogen storage capacity and low material cost. However, the relatively high thermodynamic stability of magnesium-based hydrogen storage materials necessitates heating the material to a specific temperature during the hydrogen charging and discharging processes, severely limiting the practical application and further development of this technology.Therefore, this paper aims to design a temperature control system for a magnesium-based solid-state hydrogen storage bottle. The system employs an optimized particle swarm optimization (PSO) algorithm to determine PID parameters, enabling rapid preheating of the hydrogen storage bottle and maintaining a stable operating temperature. Furthermore, by incorporating an appropriate penalty function, the system effectively suppresses temperature overshoot, preventing adverse effects on hydrogen storage performance caused by transient high temperatures, thereby ensuring the safety and stability of the hydrogen storage process. [Display omitted] • Enhanced PSO algorithm improves PID control for dynamic temperature environments. • New method significantly reduces temperature overshoot from 29.2% to 2%. • Improved hydrogen storage system performance and reliability with PSO algorithm. • Reduced need for thermal buffers and increased system efficiency. [ABSTRACT FROM AUTHOR]

The viability of hydrogen storage in bedded salt caverns hinges on understanding the geomechanical challenges posed by the anisotropic stress states and complex geology of such environments. This study presents a comprehensive geomechanical analysis focusing on a proposed cavern within the Carribuddy Formation in Western Australia, characterized by its interbedded salt layers. This paper introduces a new geomechanical workflow, encompassing 1D and 3D modeling techniques to provide detailed changes of mechanical properties and stress state in interbedded salt formation allowing to identify the initial optimal operational pressures for underground hydrogen storage. Initial 1D models evaluated mechanical properties and in-situ stresses, while subsequent 3D simulations, enriched by data from neighboring wells, detailed the stress, strain, and displacement responses of the cavern walls to internal pressure changes. The analysis pinpointed an initial safe gas pressure range between 3000 and 4000 psi, attributing this margin to the robust characterization of the mechanical and in-situ stress of the formation. Our findings underscore the significance of high-resolution geomechanical modeling in identifying initial optimal operational pressures for hydrogen storage in salt caverns, ensuring both safety and structural integrity. • Integrated 1D and 3D models assess hydrogen storage in salt caverns. • Cavern within Carribuddy Formation exhibits initial safe pressure of 3000–4000 psi. • High-resolution models are crucial for understanding geomechanical behavior. • Study emphasizes the formation's robustness and stress resilience. • Findings guide optimal operational pressures for safety and integrity. [ABSTRACT FROM AUTHOR]

Fuel cell electric vehicles (FCEVs) hold great promise for achieving sustainable and environmentally friendly transportation. However, their widespread adoption depends on the efficient development of the hydrogen supply chain (HSC) required for refueling these vehicles. Given the interdependence between the HSC and power distribution networks (PDNs), this paper presents an innovative model to jointly plan the HSC and reinforce PDNs. In this new model, the inherent uncertainties related to wind energy generation, load demand, and FCEV consumption are modeled. Furthermore, coordinating the planning of hydrogen storage and battery energy storage systems is incorporated. The results underscore the critical importance of simultaneous planning for the HSC and PDN reinforcement. Moreover, the findings reveal that hydrogen storage alone can provide sufficient energy arbitrage, leading to a 9.6% reduction in total costs compared to the scenario where storage is disregarded. [Display omitted] • A novel planning model for hydrogen supply chains and power distribution networks. • Both hydrogen storage and battery energy storage are included. • Uncertainties related to wind generation and loads are modeled. • Model results show that simultaneous planning cuts costs by 25.9%. • Hydrogen storage alone reduces costs by 9.6%. [ABSTRACT FROM AUTHOR]

This paper proposes a novel risk-averse approach for scheduling of an active electrical distribution network (AEDN). The network is connected to an electric vehicle parking lot (PL) and gas and hydrogen fueling stations (GHFSs). In addition, the AEDN operator is able to participate in both day-ahead and real-time markets to supply energy demands. In order to address the uncertainties of the studied network, a two-stage stochastic programming incorporating conditional value-at-risk (CVaR) is employed to model uncertainties of wind turbine and photovoltaic output, electric vehicles behavior in PL, and GHFSs energy consumption, while a robust optimization method is used to handle the uncertainty of real-time market price. According to the numerical results, the AEDN operator can decrease the risk level by up to 1.2% while the operational cost rises by 7.5%. Furthermore, the optimal use of multiple energy storage technologies and price-sensitive shiftable electric loads (PSELs) reduces the operational cost by 7.4%. [Display omitted] • The role of P2G and P2H along with power and hydrogen storage systems is examined. • A CVaR-stochastic/robust optimization model is proposed for uncertainties modeling. • An energy supply scheme for EVs, HVs and GVs is proposed in power markets. • A comprehensive study is presented by implementing hydrogen storage systems. [ABSTRACT FROM AUTHOR]

Maritime propulsion is recognized as a hard-to-abate sector and its decarbonization will therefore require transversal efforts, including the introduction of alternative fuels to reduce CO 2 emissions. Both ammonia and hydrogen could provide clean power; however, forecasts hint that ammonia will be especially useful for longer routes, while hydrogen suffers from low volumetric energy density. This paper evaluates the feasibility of a cargo ship with a SOFC powertrain equipped with LOHC-based hydrogen storage and compares the sizing and heat management requirements of four LOHC systems, namely N-ethylcarbazole (NEC), dibenzyltoluene (DBT), methylcyclohexane (MCH), decaline (DEC), with an ammonia-based one. The size of the 8.4 MW SOFC system is similar for the five carriers as expected. The dynamic performance of the LOHC system shows that the hydrogen flow rate can be effectively controlled by acting on the LOHC flow rate, reactor temperature, and pressure. However, LOHC systems are heavier (by a factor of 1.6 to 2.1) and larger (by 1.6 to 2.3 times) than ammonia systems. The decalin system results in the lowest mass and volume, while NEC is the heavier, and MCH is the least dense of the evaluated LOHCs. Similarly, the utilization of SOFC waste heat to cover dehydrogenation heat ranges from 45.6 % (NEC) to 27.9 % (ammonia). Overall, even considering the lower reaction temperature, LOHCs do not appear to be competitive with ammonia as hydrogen storage systems in the maritime sector. • Liquid organic hydrogen carrier (LOHC) systems discussed for maritime applications. • Different LOHC systems are sized, and the heat demand is evaluated. • Control strategies are devised to meet instantaneous hydrogen demand. • The dynamic response of LOHC-based systems is more than satisfactory. • Comparison with ammonia is unfavorable in terms of mass, volume and heat demand. [ABSTRACT FROM AUTHOR]

Green hydrogen production from renewable energy sources has emerged as a promising solution towards achieving the global target of net-zero emissions by 2050. The sultanate of Oman is among the countries that have a significant green hydrogen potential, as evident by the national target of producing one million tons of green hydrogen by 2030. This paper aims to study the techno-economic viability of integrating a floating solar photovoltaic (FPV) system with hydrogen energy storage for electricity generation in Oman. The integration of this system is modelled and simulated using HOMER Pro software to determine the optimum component sizes with the minimum cost of energy (COE). While the FPV system is designed and simulated using PVsyst software. The simulated system incorporates a 26.57 MWp FPV system, 22 MW PEM electrolyser, 13 MW PEM fuel cell, 60,000 kg hydrogen tank and 12.4 MW converter and generates 65.5 GWh of clean electricity annually. The system produces 826,624 kg of green hydrogen annually, significantly contributing to Oman's green hydrogen economy. The simulation results reveal a levelized cost of energy (LCOE) of $0.97/kWh and a levelized cost of hydrogen (LCOH) of $29.7/kg. The relatively high LCOH is attributed to the utilisation of large-scale hydrogen energy storage components, which results in a higher initial cost of the system. However, the system demonstrated its ability to meet the electrical demands of 422 households near Wadi Dayqah dam area in Qurayat with minimal capacity shortage, emphasising its technical viability. The economic viability may be improved in the future with advancements in hydrogen energy storage technology and rising fossil fuel prices. • Techno-economic analysis of large-scale hydrogen storage with FPV application. • LCOE is determined to be at $0.970/kWh. • The system is capable of fulfilling 100% of the electrical demands of 422 households. [ABSTRACT FROM AUTHOR]

Hydrogen has become a popular alternative energy to traditional fossil fuels due to its potential to contribute to a more sustainable future. It is recognized that the safety, efficiency, and economic aspects of hydrogen storage and transportation play an important role in the hydrogen energy industry. The development and commercialization of hydrogen energy are currently hindered by the structural integrity issue associated with hydrogen storage tanks. To tackle this structural integrity issue, a tangible structural health monitoring (SHM) technology is entailed for the health management of hydrogen storage tanks. Currently, flexible transducers are increasingly used to construct sensing systems and facilitate the deployment of SHM methods due to their superior properties such as conformality, low profile, and lightweight. This paper provides an overview of the SHM methods based on flexible sensing technology for hydrogen storage tanks. The most common damage modes caused by diverse factors during the service life for four types of hydrogen storage tanks are first summarized. The burgeoning flexible sensing technologies with corresponding damage characterization methods (including strain-based and elastic wave-based methods) are reviewed, and their applications in storage tanks are also discussed. On this basis, potential advancements and research topics regarding SHM systems based on flexible sensing technology for hydrogen storage tanks are discussed, and it is expected that flexible sensing technology will play a game-changing role in the future construction of SHM systems for hydrogen storage tanks. [Display omitted] • Flexible sensors are suitable for the SHM application of hydrogen storage tanks. • The sensor array and composite sensor-structure approaches are introduced. • Flexible piezoelectric transducers can provide guided waves with mode tuning. • Applying ultrasonic guided wave method to composite pressure vessels is limited. [ABSTRACT FROM AUTHOR]

The radial displacement of hydrogen storage composite overwrapped pressure vessel (COPV) is a key factor related to the collapse failure and burst pressure. However, there is still lack of effective method to monitor the radial displacement during the hydrostatic test and service process of the vessels. This paper proposed a method to measure the radial displacement based on fringe projection profilometry (FPP). Hydrostatic test with a composite overwrapped pressure vessel verifies the proposed method. The variation of displacement changing with inner pressures observed in the experiments is in agreement with that obtained from finite element analysis. Also Computed Tomography (CT) scanning is conducted and a widely spread micro defects is found in the composite layer of the cylinder. 78.9% of the total observed defects are small (<1000 mm2). In regions where large-sized defects (>1000 mm2) are concentrated, the total area of defects reaches 16,200 mm2. According to the statistical analysis, the strong correlation is found between the defects area and radial displacement. • Presented a novel method based on fringe projection profilometry (FPP) for monitoring the deformation of composite overwrapped pressure vessels (COPVs) during hydrostatic testing. • Employing 3D point clouds from FPP to reconstruct the cylinder and measure radial displacement. • The variation trend of radial displacement with pressure obtained by experiments is consistent with the finite element results. • Utilized Computed Tomography (CT) to detect and quantify micro delamination defects in the cylinders. • A significant correlation was found between the area of defects and radial displacement, while the relationship between the number of defects and radial displacement was less pronounced. [ABSTRACT FROM AUTHOR]