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This research reports the results of an experimental and numerical analysis of the La 0.9 Ce 0.1 Ni 5 alloy's hydrogen absorption and desorption isotherms at three distinct temperatures (T = 313 K, 333 K, and 353 K). We first determined the morphological and structural properties, as well as the hydrogen storage isotherms, of the intermetallic La 0.9 Ce 0.1 Ni 5 experimentally. The experimental isotherms were then compared to a mathematical model based on statistical physical theory. Due to the good agreement between the experimental isotherms and the proposed model, the insertion and release of hydrogen atoms (n α , n β), geometric densities of receptor sites (N αm , N βm), and absorption-desorption energies (P α , P β) were determined. Moreover, thermodynamic functions like enthalpy, entropy, Gibbs free energy, and internal energy were calculated using these parameters. The findings demonstrated that the intermetallic compound's CaCu 5 structure promotes the formation of stable metal hydrides through attractive interactions, ensuring that hydrogen atoms are securely trapped in the metal lattice, thereby enhancing the material's hydrogen storage capacity. • The suggested alloy isotherms were determined experimentally at various temperatures. • A numerical model has been developed to adjust the experimental data of hydrogen storage by the La 0.9 Ce 0.1 Ni 5 alloy. • The numerical and experimental results demonstrate a good agreement. [ABSTRACT FROM AUTHOR]

In this paper, a metal hydride (MH) canister and a PEM fuel cell are coupled using heat pipes to study the minimum number of heat pipes required, the operating range of the fuel cell, and the temperature change patterns of the MH. We account for temperature difference limitations between the fuel cell and the MH (∆T = 35–55 K) on the heat pipe dynamics, which has been neglected in previous similar studies. Since the hydrogen absorption rate of the MH canisters exhibits an initial increase followed by a decrease with increasing temperature, an analysis was conducted to select the appropriate heat pipe under different hydrogen filling pressures. This analysis ensured that the MH canisters remained at the optimal charging temperature (326 K) and achieved the maximum charging rate (6.64 slpm). [ABSTRACT FROM AUTHOR]

We have been developing hydrogen utilization systems for buildings using fuel cell, electrolyzer, and metal hydride hydrogen storage. This paper describes the reduction of CO 2 emissions from buildings and assesses the hydrogen storage capacity required for using off-site hydrogen. We prepared a low- and a high-load-factor model to investigate the effects of off-site hydrogen deployment for different building uses. We confirmed that off-site hydrogen delivery contributes to reducing hydrogen storage capacity in the two models. We identified how hydrogen delivery planning can substantially reduce hydrogen storage capacity while achieving high CO 2 emission reductions. The study also confirmed that hydrogen transportation is effective, even when parameters such as photovoltaic (PV) generation capacity are considered. The entire off-site hydrogen utilization system costs, including the cost of operating off-site hydrogen in a building, were evaluated to identify lower-cost operation conditions. The findings show that the cost of operating an off-site hydrogen system in a building can be managed through a well-designed hydrogen delivery strategy that does not increase the capacity required for hydrogen storage facilities. • Utilization of off-site H 2 contributes to reduction of the H 2 storage capacity. • In >90% CO₂ reduction, off-site H 2 cuts storage capacity more in a HighF model. • Largest possible capacity of PV power generation leads to lower system costs. • Proper design of off-site H 2 storage capacity reduces system costs. [ABSTRACT FROM AUTHOR]

Metal hydrides have captured significant attention for hydrogen storage because of their high energy density and safety. However, the performance of these systems is largely influenced by the design of the storage reactor. In this perspective, a novel compact, lightweight, and effective multi tube MH reactor was designed, fabricated, and experimentally tested. The absorption and desorption behavior of the newly developed Ti 0.9 Zr 0.1 Mn 1.46 V 0.45 Fe 0.09 alloy using the proposed MH reactor for hydrogen storage applications was analysed. At 30 bar supply pressure, the MH reactor absorbed 164.3 g (1.58 wt.%) of hydrogen in 894 s and delivered specific energy at an average rate of 94.7 W/kg MH. Further, the reactor released 153.6 g (1.48 wt.%) of hydrogen in 2246 s, when the desorption temperature was set at 50 °C. Moreover, the parametric study revealed that by raising the supply pressure from 10 bar to 20 bar and 30 bar, the stored capacity was improved by 11 % and 18.9 %, respectively, whereas the absorption time was drastically reduced by 43 % and 61.5 %, respectively. Furthermore, the fabricated reactor achieved gravimetric and volumetric storage densities of 0.75 % and 20.6 kg/m3 of H 2. Also, the MH reactor achieved a maximum hydrogen storage efficiency of 82.3 %. Finally, the comparative results indicated that the MH reactor studied in this work demonstrated a faster hydrogen release rate compared to other medium to large capacity MH reactors reported in the literature. [Display omitted] • Absorption and desorption behavior novel MH reactor were analysed. • The multi tube reactor absorbed 1.56 wt% in 894 s at 30 bar supply pressure. • The reactor desorbed 1.46 wt% in 2246 s at desorption temperature of 50 °C. • The achieved volumetric storage density was 20.6 kg/m3 of H 2. • The MH reactor attained maximum energy storage efficiency of 82.3 %. [ABSTRACT FROM AUTHOR]

The evolution of the phase contents and kinetic characteristics of hydrogen desorption processes by composites based on the eutectic alloy Mg89Ni11, including those with additives of graphene-like material (GLM), obtained by reactive ball-milling in hydrogen, were studied using the in situ high-temperature X-ray diffraction technique, volumetric measurements on a Sieverts setup, and approximation of the registered kinetic curves by Avrami−Erofeev equation. It was shown that at the initial stage of desorption processes at 300–360°C and 0–1 atm. H2, the decomposition of the magnesium dihydride phase makes the main contribution to the amount of hydrogen released from the composites. The addition of GLM has a positive effect on the kinetics of hydrogen desorption processes, concurring with that of the heat-conducting phase Mg2NiH≤0.3, which is also present in the composite. It was found that the apparent activation energy for the hydrogen desorption by composites is within a range of 125–140 kJ/mol H2. The correlation of the obtained values with the results of both experimental studies and quantum-chemical calculations obtained in the study of other magnesium systems is discussed. [ABSTRACT FROM AUTHOR]

The modular photoelectrochemical (PEC) reactor accommodating eight photoelectrodes with a total active area of up to 46 cm2 has been designed and manufactured using the fused deposition modeling method. The device was equipped with an electrolyte flow system, a relay module for the photoelectrode connection, and a feedback-loop module for switching between counter electrodes. The performance and durability of the system were tested within three case study experiments. The water splitting process was successfully combined with an in situ hydrogen storage in the form of metal hydride phases (confirmed by powder X-ray diffraction) using Fe2O3- or WO3-based photoanodes and LaNi5-based cathodes. The PEC water oxidation at the anodes was realized either in a strongly alkaline electrolyte (pH > 13.5) or in acidified synthetic seawater (pH < 2) for Fe2O3 and WO3 electrodes, respectively. In the latter case, the photoresponse of the anodes decreased the cell charging voltage by 1.7 V at the current density of 60 mA∙g−1. When the seawater was used as an anolyte, the oxygen evolution reaction was accompanied by the chlorine evolution reaction. The manufactured PEC-metal hydride reactor revealed mechanical and chemical stability during a prolonged operation over 300 h and in the broad range of pH values. [ABSTRACT FROM AUTHOR]

Recently, the role of hydrogen technology has become more important in decarbonizing society and achieving carbon neutrality goals. The most important sector where it is possible to implement hydrogen technologies to achieve carbon neutrality is the automotive industry. For hydrogen technologies in the field of transport to be able to compete with conventional motor vehicles, research in several areas is necessary. One of the most important areas is the issue of hydrogen storage. The article in question discusses the issue of low-pressure hydrogen storage by means of metal hydride storage tanks for mobile applications and solves the design of a double-shell metal hydride storage tank using an active and passive cooling module and the subsequent implementation of the metal hydride storage tank in the real operation of a bus on which test runs were carried out and evaluated. From the test runs, it was found that research and development in the field of initial preheating of the metal hydride storage tanks in the bus is necessary for the efficient removal of hydrogen into the fuel cell. [ABSTRACT FROM AUTHOR]

Metal hydride is a type of solid hydrogen storage material that offers excellent hydrogen absorption and desorption reaction properties. However, there is a strong thermal effect during the reaction process when the materials are applied in reactors. Thus, effective thermal management techniques are crucial for promoting efficient reactions. Prior studies on the subject have shown that phase change materials can be coupled with metal hydride reactors to transfer the reaction heat. To further enhance the transfer of heat and reaction efficiency of the metal hydride reactors based on phase change materials, this study explored heat transfer enhancement methods on the phase change materials side, including adding heat transfer fins and discussing the fin parameters and composite foam metal. The findings of the study showed that in comparison to the reactor without fins, the absorption rate of adding 10 sets of fins can increase by 28%, and as the number of fins increased to 14, this value could increase to 39.4%. The use of Y-shaped fins did not substantially improve the reaction rate, mainly due to the sufficient number of straight fins, and the heat transfer area reaching the limit of the fin enhanced the process of heat transport. Thus, the improved method of using copper foam is further considered. Compared with the reactor with and without fins, the absorption rate of the copper foam coupled reactor is increased by 23.4% and 61.3%, respectively. • The fins on the PCM side can enhance the performance of MH reactors. • The shape and quantity of fins have limited performance enhancement effect. • Foam metal can significantly break the upper performance limit of fins. • MH reactor based on PCM composite copper foam shows excellent performance. [ABSTRACT FROM AUTHOR]

Metal hydrides are serious contenders for materials‐based hydrogen storage to overcome constraints associated with compressed or liquefied H2. Their ultimate performance is usually evaluated using intrinsic material properties without considering a systems design perspective. An illustrative case with startling implications is (LiNH2+2LiH). Using models that simulate the storage system and associated fuel cell of a light‐duty vehicle (LDV), the performance of the bulk hydrides is compared with a nanoscaled version in porous carbon (PC), (LiNH2+2LiH)@(6‐nm PC). Using experimental material properties, the simulations show that (LiNH2+2LiH)@(6‐nm PC) counterintuitively has higher usable gravimetric and volumetric capacities than the bulk counterpart on a system basis despite having lower capacities on a materials‐only basis. Nanoscaling increases the thermal conductivity and lowers the desorption enthalpy, which consequently increases heat management efficiency. In a simulated drive cycle for fuel cell‐powered LDV, the fuel cell is inoperable using bulk (LiNH2+2LiH) as the storage material but completes the drive cycle using the nanoscale material. These results challenge the notion that nanoscaling incurs mass and volume penalties. Instead, the synergistic nanoporous host‐hydride interaction can favorably modulate chemical and heat transfer properties. Moreover, a co‐design approach considering application‐specific tradeoffs is essential to accurately assess a material's potential for real‐world hydrogen storage. [ABSTRACT FROM AUTHOR]

Researchers are investigating the integration of metal hydride reactors (MHR) with phase change materials (PCMs) to enhance hydrogen storage and thermal energy management. This approach, first proposed in 2013, combines two technologies for improved thermal management and energy efficiency. Despite numerous numerical studies, experimental investigations on MHR-PCM integration remain limited. This study experimentally evaluates an MHR filled with TiMn2-type hydride and coconut oil PCM, achieving a maximum hydrogen storage efficiency of 40% at specific ab/desorption pressures of 16/0.05 bar. Adding 1 wt% of additives like graphite, Al 2 O 3 and MgO, significantly reduces absorption time and boosts hydrogen storage capacity by 11%. Additionally, two-dimensional numerical modeling was developed, validating experimental results with less than ±8% error, thus demonstrating the effectiveness of MHR-PCM systems in hydrogen storage applications. [Display omitted] • Experimental study of H 2 storage performance of an MH reactor equipped with PCM. • The hydrogen storage efficiency is limited to 40 % during H 2 ab/desorption cycle. • The insertion of 1 wt% additives into PCM reduced the H 2 absorption time by 50 %. • Gaussian and sigmoid functions fit well the experimental PCM melting fraction. [ABSTRACT FROM AUTHOR]

An electron beam may be used to generate bremsstrahlung photons that go on to create photoneutrons within metals. This serves as a low-energy neutron source for irradiation experiments. In this article, we present simulation results for optimizing photoneutron yield for a 10-MeV electron beam on tantalum foil and erbium deuteride (ErD3). The thickness of the metal layers was varied. A tantalum foil thickness of 1.5 mm resulted in the most photons reaching the second metal layer. When a second metal layer of ErD3 was included, the photoneutron yield increased with the thickness of the secondary layer. When the electron beam was directly incident upon a layer of ErD3, the photoneutron yield did not differ significantly from the yield when a layer of tantalum was included. The directional photoneutron yield reached a maximum level when the thickness of the ErD3 layer was around 12 cm. About 1 neutron was generated per 104 source electrons. When using a 2-mA beam current, it is possible to generate up to 1012 neutrons per second, making this combination a relatively-inexpensive neutron generator.

Metal hydride hydrogen storage is a hydrogen storage method based on the principle of chemical absorption. Featuring high volumetric hydrogen storage density and high safety, its potential applications in the field of hydrogen storage on ships have attracted significant attention. Against this background, there is a series of issues to be studied, such as material properties, reactor performance, thermal management systems, cost, etc. This paper categorizes metal hydride hydrogen storage technology, summarizes its working principle and research progress on its material properties, and introduces its applications on ships. Next, combined with the application environment and demands of hydrogen ships, the paper analyzes the technological and economic feasibility of the application of metal hydride hydrogen storage technology on ships. To meet the requirements of hydrogen ships for hydrogen storage capacity and release rate, research on marine metal hydride hydrogen storage systems is introduced, including hydrogen storage system performance research, hydrogen storage reactor structure, reactor structure optimization and design ideas for thermal management systems coupled with marine fuel cell and hydrogen storage systems. Finally, the research direction of marine metal hydride hydrogen storage systems is predicted and summarized.

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The first hydrogenation of most metal hydrides is a lengthy process that usually requires high pressure and temperature. This, in turn, significantly increases the production cost of metal hydrides. In this paper, the low temperature hydride-forming LaNi5 was selected to investigate the mechanism of first hydrogenation. For the first time, the effect of particle size, temperature and pressure on the incubation time were studied. We found that the first hydrogenation of LaNi5 follows an Arrhenius process, with an activation energy of EA = 78 ± 4 kJ/mol H2. We also found that the pre-exponential factor depends on the applied pressure. [ABSTRACT FROM AUTHOR]

The burgeoning potential of hydrogen as a future clean energy source has spurred intense research into hydrogen storage solutions. Novel hydride perovskite materials aside metal hydride are at the forefront of this effort, engaging researchers worldwide. This study utilizes Ab-initio calculations based on density functional theory (DFT) implemented in VASP to compare the electrical, elastic, thermodynamic, and optical properties of cubic KXH 3 (X = Mg, Be) compounds. Generalized gradient approximation (GGA) with the Perdew-Burke-Ernzrhof (PBE) scheme is employed for optimization. Our calculations agree well with previously reported results. However, the tolerance factor suggests KBeH 3 may not be stable in the cubic form. The electronic structure reveals KMgH 3 to be semiconductive, while KBeH 3 exhibits metallic behavior. Both compounds exhibit mechanical stability within the study. Optical properties are also investigated, showing suitability for hydrogen storage in the low energy range. Additionally, the mechanical parameters satisfy the Born stability criterion, indicating good mechanical stability for both compounds. Finally, the gravimetric ratios for hydrogen storage are calculated as 5.86 wt% and 4.52 wt% for KMgH 3 and KBeH 3 , respectively. These high values suggest both compounds hold significant promise for diverse renewable energy applications and long-term hydrogen fuel storage. • The booming potential of hydrogen as a clean energy source drives research into novel hydrogen storage solutions. • This study explores KXH 3 (X = Mg, Be) perovskite materials as promising candidates for hydrogen storage using advanced computational methods. • Electrical, elastic, thermodynamic, and optical properties of both compounds are examined, revealing key characteristics for hydrogen storage applications. • KMgH 3 shows good stability and semiconductive behavior, while KBeH 3 might require further investigation due to potential cubic instability. Both exhibit optical properties and mechanical stability suitable for low-energy hydrogen storage. • KMgH 3 and KBeH 3 boast impressive gravimetric hydrogen storage ratios of 5.86 wt% and 4.52 wt%, respectively, making them potential game-changers for renewable energy and long-term hydrogen fuel storage. [ABSTRACT FROM AUTHOR]

Metal hydride based thermally driven systems have attracted significant attention for storing and transporting hydrogen due to their higher energy density. However, their utility can extend to other diverse applications, such as space heating and fuel cell integration, due to their inherent MH formation or decomposition processes. In this perspective, the objective of the present study is to analyse the hydrogen storage or release behavior and thermal characteristics of a newly developed La 0.7 Ce 0.3 Fe 0.75 Ni 4.25 using an annular finned MH reactor under various operating conditions. The absorption outcomes revealed that La 0.7 Ce 0.3 Fe 0.75 Ni 4.25 stored a maximum hydrogen storage capacity of 1.35 wt.% in 1237 s while releasing heat with an average heat output rate of 104.4 W/kg MH at a supply inlet pressure of 25 bar. Also, the achieved peak temperature gain of 14.6 K under similar conditions indicates its utilization in space heating applications, especially in cold countries. The outcomes of desorption at constant pressure indicate that La 0.7 Ce 0.3 Fe 0.75 Ni 4.25 demonstrated 96 % reversibility by releasing 1.31 wt.% of hydrogen in 4509 s with an average heat input rate of 36.4 W/kg MH when operating at a HTF temperature of 303 K. Further, the MH reactor was capable of supplying hydrogen at a discharge rate of 13 lpm for 123.5 min at 323 K HTF temperature, ensuring its possible integration with a 1-kW PEM fuel cell. Further, the La 0.7 Ce 0.3 Fe 0.75 Ni 4.25 achieved gravimetric and volumetric storage densities of 0.76 % and 24.6 kg/m3 of H 2. Moreover, La 0.7 Ce 0.3 Fe 0.75 Ni 4.25 showed excellent reversibility and exhibited superior desorption characteristics compared to La 0.7 Ce 0.1 Ca 0.3 Ni 5. • Hydrogen storage and thermal characteristics of La 0.7 Ce 0.3 Fe 0.75 Ni 4.25 were analysed. • The La 0.7 Ce 0.3 Fe 0.75 Ni 4.25 stored 1.36 wt% in 1237 s at 25 bar feed pressure. • The La 0.7 Ce 0.3 Fe 0.75 Ni 4.25 released 1.34 wt% in 2324 s at HTF temperature of 323 K. • At 13 lpm discharge rate and 303 K, the reactor released 94 % of hydrogen. • The reactor achieved a heat discharge effectiveness of 0.88 at 25 bar supply pressure. [ABSTRACT FROM AUTHOR]

Loose powder in metal hydride reactors poses challenges, such as poor thermal conductivity and tube deformation. To address these issues, the metal powder can be encapsulated in a polymer-based matrix to form pellets. This encapsulation helps make the pellets oxygen-impermeable, capable of accommodating the volumetric expansion of metal hydrides, and increases system processability. This study investigates the use of polymer-based pellets containing AB5-based compounds for ambient hydrogen storage. Polymers were selected using ANSYS Granta software, and polyethylene and polymethylmethacrylate were chosen. The AB5 alloy activation in the pellet occurs efficiently after 3 min at 20 °C and 30 bar of hydrogen, facilitated by ball milling-induced reactive surfaces and increased grain boundaries. The optimized pellet, comprising 90 wt% AB5 powder in a PE matrix, exhibits stable hydrogen storage properties, with good mechanical resistance and minimal powder loss (below 3%) over 20 hydrogen sorption cycles in an in-house fabricated single-tube metal hydride reactor. [Display omitted] • Loose metal hydride powder bound in a polymer matrix formed pellets without solvents, simplifying handling and processing. • PE and PMMA were selected via ANSYS Granta as suitable matrix materials for hydride pellets, ensuring effective binding. • 90 wt.% AB5 in a PE matrix demonstrated stable H₂ storage, strong mechanical properties, and less than 3% powder loss. • AB5 alloy in the pellets activated within 3 min at 20°C and 30 bar H₂, enabling rapid and efficient hydrogen storage. • Pellets maintained consistent performance through 20 hydrogen sorption cycles in a custom single-tube reactor. [ABSTRACT FROM AUTHOR]

Exploring superconducting materials stands as a pivotal pursuit in condensed matter physics, particularly, the investigation of superconductivity in two-dimensional metal hydrides is of paramount importance due to its intriguing nature. Our study focuses on elucidating the metallic state of van der Waals layered TM-H (TM = Ti, Zr, Hf) compounds, a key factor in predicting their superconducting (SC) characteristics. Leveraging an evolutionary algorithm rooted in density functional theory, we predicted the structures of hydrides, including Ti 2 H 2 , Ti 2 H 4 , Zr 2 H 2 , Zr 2 H 4 , Zr 2 H 5 , Hf 2 H 2 , Hf 2 H 4 , Hf 2 H 5 , and determined their energetically stable structures. Along with exploring the potential for SC, we conducted a comprehensive examination of relevant electronic properties. A significant aspect addressed was the influence of anharmonic phonon properties in determining the stochastic self-consistent harmonic approximation. These findings underscore the pivotal role of anharmonicity in determining the SC of two-dimensional metal hydrides. [Display omitted] • A variety of atomic configurations of hydrogen are unveiled in the discovery of novel two-dimensional monolayers featuring transition metals. • Enhancing T c relies significantly on the impact of quantum fluctuations and anharmonic corrections. • The SSCHA method renormalizes an analytical expression for lattice dynamics, ensuring stabilization at finite temperatures. • Hf 2 H 5 exhibits superconductivity with a notable T c of 10.3 K. [ABSTRACT FROM AUTHOR]

This study investigates the optimal configuration of a Metal Hydride-based Solar Thermal Collector (MH-STC) by developing a transient 3D mathematical model to simulate three distinct configurations: C1, C2, and C3. These configurations differ in the placement of water pipes within the metal hydride bed C1 features pipes in the top region, C2 in the core zone, and C3 at the bottom. The performance of these configurations was rigorously compared based on hydrogen charge state, outlet water temperature, useful energy output, and thermal efficiency across varying water flow rates. Results reveal that configuration C1 achieves superior thermal performance during daytime operation, producing outlet temperatures up to 10 °C higher than the other configurations. Conversely, configuration C3 excels at nighttime heating, delivering water temperatures approximately 11.5 °C higher than C1. Furthermore, the analysis indicates that hydrogen desorption pressure significantly impacts outlet water temperature; for instance, increasing the pressure from 2.41 bar to 6 bar enhances the average outlet temperature of the C3 design by about 20 °C during the day and reduces it by approximately 15 °C at night. These findings highlight the critical need for optimizing solar collector designs to effectively meet the thermal demands of both daytime and nighttime applications.

While there are some hydrogen refueling stations (HRS) functioning in different parts of the world, their use is not widespread enough, primarily due to their expensive cost. Hydrogen compression is a main contributor to the capital and operation costs of the HRS. By improving H2 compression technology, it is possible to optimize the infrastructure for refueling with hydrogen in terms of cost and performance. The use of metal hydride hydrogen compressors (MHHCs), which have the potential to be inexpensive and have the ability to use waste heat and renewable energy sources for the H2 compression, is a promising solution to overcome this issue. The duration of the H2 compression cycle is nevertheless a serious challenge due to the metal hydride (MH) bed's low heat conductivity. As a heating technique to improve the performance of MHHCs, electromagnetic induction (EMI) is examined numerically for the first time in this work. The dynamic behavior of a two-stage MHHC with each MH reactor having an external heat exchanger and being ringed by a copper coil traversed by an alternating current is described by a two-dimensional mathematical model, which was established and successfully verified by the reference data. Numerical simulations were performed with the help of this model, and the findings showed that the EMI heating method is faster than the heat transfer fluid (HTF) heating technique. For instance, at a delivery temperature of 373 K and a supply pressure of 20 bar, it is possible to produce 106 NL H2 per kilogram of HPMH at a pressure of 97 bar with a 74 % shorter compression time than with the HTF heating technique.

The first hydrogenation of most metal hydrides is a lengthy process that usually requires high pressure and temperature. This, in turn, significantly increases the production cost of metal hydrides. In this paper, the low temperature hydride-forming LaNi5 was selected to investigate the mechanism of first hydrogenation. For the first time, the effect of particle size, temperature and pressure on the incubation time were studied. We found that the first hydrogenation of LaNi5 follows an Arrhenius process, with an activation energy of EA = 78 ± 4 kJ/mol H2. We also found that the pre-exponential factor depends on the applied pressure.

The present study reports the feasibility of a metal hydride (MH) purification technology employed for hydrogen produced via SRM using Cu/ZnO/Al 2 O 3 catalysts. The catalysts were synthesized by using the coprecipitation method and characterized by various techniques such as XRD, BET, FESEM, FETEM, EDX, XPS, TGA, FTIR, TPR and N 2 O chemiosorption. SRM was carried out under varying operating conditions viz., temperature 200–320 °C, water to methanol molar ratio (W/M) 1–1.7, and a feed flow rate (F M /W) 2.78–27.78 mmol·min−1g−1. Increasing the reaction temperature raised the methanol conversion rate, reaching 100 % at 300 °C, but it simultaneously promoted the formation of CO via rWGS. The increase in W/M ratio increases the methanol conversion rate while reducing the CO selectivity. The impact of feed flow rate (F CH3OH /W cat) on conversion and selectivity revealed that both methanol conversion and CO selectivity decreased at higher feed flow rates, but the rate of hydrogen production increased significantly. Specifically, raising F CH3OH /W cat from 2.78 to 27.8 mmol·min−1g−1 led to a decline of methanol conversion from 97% to 30% and CO selectivity from 0.8 % to 0 %, but the hydrogen production rate was increased from 180 to 570 mL min−1g−1 at 280 °C. The integration of MH based purification system to the production line resulted in the production of highly pure hydrogen (nearly 99% purity) using low-grade heat input (50–60 °C), for an impurity range of up to 40%. [Display omitted] • The Cu/ZnO/Al 2 O 3 catalyst was synthesized by using the coprecipitation method. • Catalyst was characterized using XRD, BET, FESEM, FETEM, EDX, XPS, TGA, and FTIR. • Cu/ZnO/Al 2 O 3 was tested for SRM reaction under various operating conditions. • Metal hydride-based hydrogen purification was employed for H 2 purification. • TCD was employed to analyize the gas composition during H 2 production and purification. [ABSTRACT FROM AUTHOR]

While there are some hydrogen refueling stations (HRS) functioning in different parts of the world, their use is not widespread enough, primarily due to their expensive cost. Hydrogen compression is a main contributor to the capital and operation costs of the HRS. By improving H 2 compression technology, it is possible to optimize the infrastructure for refueling with hydrogen in terms of cost and performance. The use of metal hydride hydrogen compressors (MHHCs), which have the potential to be inexpensive and have the ability to use waste heat and renewable energy sources for the H 2 compression, is a promising solution to overcome this issue. The duration of the H 2 compression cycle is nevertheless a serious challenge due to the metal hydride (MH) bed's low heat conductivity. As a heating technique to improve the performance of MHHCs, electromagnetic induction (EMI) is examined numerically for the first time in this work. The dynamic behavior of a two-stage MHHC with each MH reactor having an external heat exchanger and being ringed by a copper coil traversed by an alternating current is described by a two-dimensional mathematical model, which was established and successfully verified by the reference data. Numerical simulations were performed with the help of this model, and the findings showed that the EMI heating method is faster than the heat transfer fluid (HTF) heating technique. For instance, at a delivery temperature of 373 K and a supply pressure of 20 bar, it is possible to produce 106 NL H 2 per kilogram of HPMH at a pressure of 97 bar with a 74 % shorter compression time than with the HTF heating technique. [ABSTRACT FROM AUTHOR]

Hydrogen storage is concerned with the process of storing hydrogen safely and efficiently. This is crucial because hydrogen may hold the potential as a green clean energy source to better exploit the energy obtained via renewable sources, although it is also highly flammable and can be difficult to store. In order to enrich the literature and further enhance the current understanding of hydrogen storage details, this review paper shortly discusses use of compression of hydrogen to high pressures, hydrogen liquefaction and metal hydride(s) for the purpose of storage of hydrogen. Results of the reviewed work have indicated that each process has its own advantages and disadvantages in terms of storage density, safety and energy requirements, etc., although; in general, the advantages defeat disadvantage. Proper hydrogen storage is a significant component in hydrogen utilization for different applications to help decarbonize related sectors [ABSTRACT FROM AUTHOR]

Hydrogen is a promising energy carrier to decarbonise aviation. However, many challenges regarding its storage or handling still have to be solved to successfully utilise hydrogen in aircraft and at airport infrastructures. The increasing use of hydrogen also generates opportunities for disruptive improvements, like the possibility to integrate metal hydrides (MHs) into the hydrogen powertrain and its infrastructure. Besides their ability to store hydrogen, MHs enable a wide range of potential secondary functions such as high-power thermal applications or compression. This way, MHs may contribute to achieve the goal of sustainable hydrogen-powered aviation. Hence, potential MH application options and their current state-of-the-art are presented. Based on that overview, the following seven use cases for aviation are selected for evaluation: 'hydrogen emergency storage', 'cabin air-conditioning', 'thermal management of fuel cells', 'gas gap heat switches', 'hydrogen boil-off recovery', 'onboard hydrogen compression' and 'hydrogen safety sensors'. Four of these use cases are investigated to achieve comparable degrees of detail to avoid misevaluations in the subsequent weighted point rating. The results reveal the high potential of MHs for 'hydrogen boil-off recovery', 'hydrogen safety sensors' and 'cabin air-conditioning'. For the three most promising use cases, outlooks to their potential future implementation are provided in order to outline the ability of MHs to empower sustainable aviation. These investigations highlight the huge potential of MHs for boil-off treatment. [ABSTRACT FROM AUTHOR]

Hydrogen absorption in transition metals has received enormous attention for applications such as the hydrogen storage, sensing and corrosion. In particular, the Pd‐H system is a simple and classical metal hydride system that serves as a platform for a deeper understanding of hydrogen behavior. In the past few years, Pd‐H has been reported as electrocatalyst in multiple reactions, whereas the impact of hydrogen absorption/desorption in electrocatalytic applications remains unclear. Therefore, in this concept, factors influencing the hydrogen adsorption/desorption of palladium in the gas phase, such as facet engineering, ligand effects, and alloying effects, are summarized. Subsequently, in the context of electrocatalysis, factors affecting electrochemical hydrogen adsorption/desorption are outlined. Particularly, prospects for the further investigation of electrochemical hydrogen adsorption/desorption in catalysis are discussed. [ABSTRACT FROM AUTHOR]

The importance of the energy transition and the role of green hydrogen in facilitating this transition cannot be denied. Therefore, it is crucial to pay close attention to and thoroughly understand hydrogen storage, which is a critical aspect of the hydrogen supply chain. In this comprehensive review paper, we have undertaken the task of categorising and evaluating various hydrogen storage technologies across three different scales. These scales include small-scale and laboratory-based methods such as metal-based hydrides, physical adsorbents, and liquid organic hydrogen carriers. Also, we explore medium and large-scale approaches like compressed gaseous hydrogen, liquid cryogenic hydrogen, and cryocompressed hydrogen. Lastly, we delve into very large-scale options such as salt caverns, aquifers, depleted gas/oil reservoirs, abandoned mines, and hard rock caverns. We have thoroughly examined each storage technology from technical and maturity perspectives, as well as considering its techno-economic viability. It is worth noting that development has been ongoing for each storage mechanism; however, numerous technical and economic challenges persist in most areas. Particularly, the cost per kilogramme of hydrogen for most current technologies demands careful consideration. It is recommended that small-scale hydrogen storage technologies such as metal hydrides (e.g., MgH 2 , LiBH 4) need ongoing research to enhance their performance. Physical adsorbents have limited capacity except for activated carbon. Some liquid organic hydrogen carriers (LCOHs) are suitable for medium-scale storage in the near term. Ammonia-borane (AB), with its high gravimetric and volumetric properties, is a promising choice for medium-scale storage, pending effective dehydrogenation. It shows potential as a hydrogen carrier due to its high storage capacity, stability, and solubility, surpassing DOE targets for storage capabilities. Medium-scale storage, utilising compressed gas cylinders and advancements in liquefied and cryocompressed hydrogen storage, requires cost reduction measures, and a strategic supply chain. Large-scale storage options include salt caverns, aquifers, and depleted gas/oil reservoirs, with salt caverns offering pure hydrogen, need further techno-economic analysis and deployment projects to mature, but storage costs are reasonable, ranging mostly from €0.25/kg to €1.5/kg for location specific large-scale options. • Comprehensive review of hydrogen storage technologies from small to very large scale. • Metal hydride MgH 2 shown to be economically viable with storage at €2.8 per kg. • Ammonia-borane (AB) offers promising medium-scale hydrogen storage potential. • Technological advancements are enhancing compressed gas hydrogen storage systems. • Large-scale hydrogen storage costs vary between €0.25 and €1.58 per kg. [ABSTRACT FROM AUTHOR]

This paper presents an innovative thermally coupled system architecture with a parallel coolant-heated metal hydride tank (MHT) designed to satisfy the hydrogen supply requirements of proton exchange membrane fuel cell s(PEMFCs). This design solves a problem by revolutionising the cold start capability of PEMFCs at low temperatures. During the design process, LaNi5 was selected as the hydrogen storage material, with thermodynamic and kinetic properties matching the PEMFC operating conditions. Afterwards, the MHT and thermal management subsystem were customised to integrate with the 70 kW PEMFC system to ensure optimal performance. Given the limitations of conventional high-pressure gaseous hydrogen storage for cold starting, this paper provides insights into the challenges faced by the PEMFC-MH system and proposes an innovative cold start methodology that combines internal self-heating and externally assisted preheating techniques, aiming to optimise cold start time, energy consumption, and hydrogen utilisation. The results show that the PEMFC-MH system utilises the heat generated during hydrogen absorption by the MHT to preheat the PEMFC stack, and the cold start time is only 101 s, which is 59.3% shorter compared to that of the conventional method. Meanwhile, the cold start energy consumption is reduced by 62.4%, achieving a significant improvement in energy efficiency. In conclusion, this paper presents a PEMFC-MH system design that achieves significant progress in terms of time saving, energy consumption, and hydrogen utilisation. [ABSTRACT FROM AUTHOR]

Efficient heat transfer is important for metal hydride hydrogen storage tank to charge or discharge rapidly. In this work, three heat transfer fin structures were built and they are "Inner-Fin", "Outer-Fin", and "Inter-Fin", respectively. The impacts of fin structures on temperature evolution and hydrogen absorption performance of metal hydride hydrogen storage tank were studied and then optimized by establishing mathematic models and using finite element method for numerical simulation. Compared with the traditional Inner-Fin structure, the Inter-Fin and the Outer-Fin structures can increase the heat transfer efficiency by 16.9% and 38.5%, respectively and increase the hydrogen absorption efficiency by 20% and 40%, respectively. The novel fin structures proposed in this work is efficient to improve the heat transfer performances of the hydrogen storage tank and is relatively simple and easy to manufacture, which is suitable for practical application. This work provides a reference for the structure design of metal hydride hydrogen storage tanks. [Display omitted] • Inner-Fin, Inter-Fin, and Outer-Fin were built and installed in the tank. • Fins greatly enhances the heat transfer and hydrogen absorption of tank. • Tank with Outer-Fin exhibits the best hydrogen storage performances. • Larger fin length and denser fin distribution are beneficial to the heat transfer. • Fin structures proposed in this work is efficient and easy to manufacture. [ABSTRACT FROM AUTHOR]

The present study aims to assess the technical feasibility of a novel Metal Hydride-based Solar Thermal Collector (MH-STC) system. This system includes a flat-plate solar collector integrated with a metal hydride bed, a hydrogen compressor, a photovoltaic panel, a hydrogen tank, and a water storage tank. This system combines the principles of a conventional solar thermal collector with the energy storage capabilities of metal hydrides, enabling the storage of surplus thermal energy. The LaNi5 alloy was used as heat storage material. A 3D-mathematical model is established and a numerical code written in Fortran-90 is developed to simulate the dynamic behavior of the proposed solar thermal collector. It was shown that the developed 3D-model produces computational results that are consistent with experimental data. In addition, to check the accuracy of the mathematical model and numerical approach, the relative errors in the mass balance and energy balance were calculated and values of 0.054 % and 0.18 %, respectively, were obtained.The simulation results offer insights into the system's technical feasibility, revealing an overall efficiency of 90.6 %, the water temperature at the collector outlet can reach 357.3 K, and a water volume heated of 230.4 L under the considered operating conditions. Moreover, the results indicate that the proposed MH-STC system exhibits significant potential as a viable alternative for thermal storage in domestic hot water systems.

Mg shows great potential as a metal hydride for switchable optical response and hydrogen detection due to its ability to stably incorporate significant amounts of hydrogen into its lattice. However, this thermodynamic stability makes hydrogen removal difficult. By alloying Mg with secondary elements, the hydrogenation kinetics can be increased. Here, we report the dynamic optical, loading, and stress properties of three Mg alloy systems (Mg-Al, Mg-Ti, and Mg-Ni) and present several novel phenomena and three distinct device designs that can be achieved with them. We find that these materials all have large deviations in refractive index when exposed to H2 gas, with a wide range of potential properties in the hydride state. The magnitude and sign of the optical property change for each of the alloys are similar, but the differences have dramatic effects on device design. We show that Mg-Ti alloys perform well as both switchable windows and broadband switchable light absorbers, where Mg0.87Ti0.13 and Mg0.85Ti0.15 can achieve a 40% transmission change as a switchable window and a 55% absorption change as a switchable solar absorber. We also show how different alloys can be used for dynamically tunable color filters, where both the reflected and transmitted colors depend on the hydrogenation state. We demonstrate how small changes in the alloy composition (e.g., with Mg-Ni) can lead to dramatically different color responses upon hydrogenation (red-shifting vs blue-shifting of the resonance). Our results establish the potential for these Mg alloys in a variety of applications relating to hydrogen storage, detection, and optical devices, which are necessary for a future hydrogen economy.

Degradation of performance over lifetime is a challenge for interstitial metal-hydride hydrogen storage systems, especially those employed in thermodynamic machines such as compressors and heat pumps, since these must execute many thousands of cycles of absorption and desorption with minimal loss of throughput. Degradation manifests typically as diminished reversible hydrogen capacity, sometimes accompanied by undesirable changes in the shape of the absorption/desorption isotherm or slower kinetics. Understanding the origin and evolution of degradation during absorption/desorption cycling is crucial to designing for long service life with minimal maintenance and replacement costs. This review examines the degradation mechanisms observed in interstitial metal hydrides, focussing on those relevant to thermodynamic machines. Based on the reviewed literature, identifying standard measures for evaluating the degradation of metal hydrides in thermodynamic machines proves challenging. This challenge stems from the variety of reported alloy compositions, and from the widely differing operational configurations employed in published research studies. Furthermore, the degradation mechanisms that manifest during extended absorption/desorption cycling (decrepitation, sintering, hydrogen trapping, loss of crystallinity, disproportionation) are intertwined, sometimes acting sequentially and sometimes concurrently. Time spent in the hydride phase at elevated temperature is a key controlling factor. This review offers insights to aid the selection of alloys for service in hydrogen storage generally and thermodynamic machines in particular. Additionally, an in-depth exploration of the degradation of LaNi 5 , by far the most studied hydrogen storage alloy, is presented, highlighting the intertwined nature of the acting degradation mechanisms. [Display omitted] • In-depth review presented of atomistic mechanisms that degrade metal hydrides during cycling. • Focus on thermodynamic machines, distinguishing compressors and heat pumps. • Decrepitation, sintering, hydrogen trapping, loss of crystallinity and disproportionation examined. • Drivers of degradation – elevated temperature, impure hydrogen, prolonged cycling – considered. • Detailed case study on LaNi 5 presented. [ABSTRACT FROM AUTHOR]

Metal hydride (MH) based hydrogen storage is one of the potential methods for achieving higher volumetric storage densities. However, its poor thermal conductivity limits heat transfer during exothermic hydriding and endothermic dehydriding processes. Hence, heat transfer augmentation is essential in MH reactors to speed up the charging and discharging of hydrogen. The present study proposes a novel flat coil tube heat exchanger with a spiral fin for heat transfer augmentation. It offered superior performance than conventional single and double helical tube heat exchangers, taking 35.3 and 16.7% less time for 90% storage time. Further, optimization of design parameters (pitch and fin thickness) is carried out considering several key parameters such as weight ratio (WR), gravimetric exergy output rate (GEOR), and energy efficiency (EE). A pitch of 30 mm with a fin thickness of 0.25 mm is optimum according to a novel performance index. The influence of the operating parameters (H 2 supply pressure and heat transfer fluid inlet temperature) on the absorption performance is investigated for the optimized design. Finally, a single desorption case is presented at 1 bar and 333 K to gain insights about desorption behavior. • Novel flat coil tube heat exchanger (FCTH) is proposed for a metal hydride reactor. • FCTH offered superior performance than conventional designs. • Performance index (PI) is proposed to optimize the reactor. • Optimum pitch and fin thickness are 30 and 0.25 mm. [ABSTRACT FROM AUTHOR]