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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]

The low thermal conductivity of hydrogen storage materials significantly limits the reaction rate of hydrogen storage and release in metal hydrides reactors. In present paper, a heat transfer fluid channel was designed by topology optimization method to enhance the heat transfer performance and increase the hydrogen storage and release rates. Firstly, a series of channel structures were obtained through two-dimensional topology optimization, then they were embedded into metal hydride reaction beds by three-dimensional reconstruction. The hydrogen storage and release performance of different reaction beds were analyzed, the most effective bed structure was derived and compared with the finned bed. The results show that the hydrogen storage and release time of the designed fluid channel reaction bed is 31.5% and 24.4% less than the finned bed. Lastly, the hydrogen storage and release performance of the designed reaction bed under different operating conditions were examined. The appropriate operation conditions were derived: for hydrogen storage, hydrogen pressure of 1.0 MPa, HTF inlet velocity of 0.25 m s−1 and inlet temperature of 293 K; for hydrogen release, hydrogen pressure of 0.1 MPa, HTF inlet velocity of 0.25 m s−1 and inlet temperature of 363 K. Moreover, the reaction bed designed by topology optimization has obvious advantages and shows better hydrogen storage and release performance compared to finned reactors under various operating conditions. • A reactor structure for hydrogen storage is obtained by topology optimization. • The absorption and desorption time of optimized reactor is 31.5% and 24.4% less than the finned reactor. • The appropriate operation conditions for hydrogen storage and release are obtained. • The optimized reactor has better performance than finned reactors under various conditions. [ABSTRACT FROM AUTHOR]

The first principle of calculation is a computational technique based on quantum mechanics that may precisely determine the ground-state electronic structure and associated mechanical and thermodynamic characteristics of solid materials. This study explains the history of first-principles development, calculation techniques, and the use of ultra-soft pseudopotential in hydrogen storage materials based on an inquiry and analysis of the findings of previous research. This paper primarily reviews the research progress of first principles in improving two-dimensional hydrogen storage materials, metal-organic framework materials, alkali metal-base composite hydrides, and metal-base hydrogen storage materials in order to speculate on the hydrogen storage mechanisms of materials. It is possible to estimate the location of hydrogen adsorption in a material by computing its electronic structure, band structure, electron density, and lattice vibration. This information is then used to compute the hypothetical new hydrogen storage material. Finally, the direction of first-principles computing in hydrogen storage materials is anticipated. • The research progress of DFT in predicting and simulating new hydrogen storage materials is introduced. • The merits and demerits of the application of DFT in solid hydrogen storage and its future development direction are pointed out. [ABSTRACT FROM AUTHOR]

This paper investigates an innovative study on the performance of a hybrid condensing boiler-fuel cell micro-cogeneration system for single residential applications. It combines experimental and dynamic numerical investigations including renewable energy for green hydrogen production and solid storage. Basing on the hourly measurements for a typical winter day, a dynamic model was developed and validated against different home heating need. Highlighting the influence home energy needs on fuel cell operating mode, it shows that single homes with low energy demand led to reduce the fuel cell's yearly operation below 50 %. In low-energy homes, a reduction in fuel cell size led to an increase in yearly operation to 60-70 % and achieved a 55 % electrical coverage rate. The integration of metal hydride hydrogen solid storage, powered by renewable sources, is emphasized. This setup increases heat demand, influencing fuel cell operation. In winter season, fuel cell operated for an average of 611 h, compared to 61 h in summer. System efficiency averaged 91 % annually, peaked at 95 % in summer, and sustained 93 % when both FC and condensing boiler were switched on. [Display omitted] • Modeling of a hybrid Boiler-Fuel Cell MCHP system for residential energy management. • Calibration of the FC-MCHP model using experimental data from a real MCHP unit. • Electrical and thermal coverage of the FC-MCHP unit with green hydrogen production and storage under different scenarios. • Strategies for optimal hydrogen consumption in in residential application. • Impact of solid-state hydrogen storage on FC-MCHP consumption and thermal management. [ABSTRACT FROM AUTHOR]

Hydrogen, known for its renewable nature, high energy utilization efficiency, and clean combustion, holds significant importance as a component in future energy systems. However, the development of an economical, safe, and efficient method for hydrogen storage remains a formidable challenge. In recent decades, researchers have made significant progress in achieving reversible hydrogen absorption and release using various metal hydrides. Among them, magnesium hydride (MgH 2) has attracted considerable attention for its high energy density, low cost, and good reversibility. Nevertheless, the high hydrogen absorption and desorption temperature, sluggish kinetic properties, and poor cycling performance of MgH 2 remain as the bottlenecks for its practical application. To mitigate these deficiencies, significant research efforts have been focused on the development of carbon-based materials as a means of preparing multifunctional materials. Carbon-based materials have demonstrated great potential in facilitating synergistic modification strategies, such as nanosizing, catalytic effects, and spatial confinement, which have been proven effective in enhancing the hydrogen storage performance of MgH 2. In this paper, we present a comprehensive overview of various carbon-based materials, highlighting their unique properties and their contribution to improving hydrogen storage within MgH 2 matrices. To be specific, we have been systematically reviewed the synergistic impacts of carbon materials, metal-organic frameworks, transition metal carbides (MXenes), and their respective composites on enhancing the hydrogen storage performance of MgH 2. Additionally, this study underscores the benefits of utilizing multifunctional carbon-based materials as modifiers for MgH 2 and proposes potential avenues for academic research. [Display omitted] • The properties and benefits of various carbon-based materials has been comprehensively reviewed. • Carbon-based materials and their roles in improving the hydrogen storage of MgH 2 have been thoroughly investigated. • The promise of multifunctional carbon-based materials as modifiers for MgH 2 is highlighted. • The future directions of carbon-based materials in hydrogen storage are discussed. [ABSTRACT FROM AUTHOR]

The cost of hydrogen production from environmentally friendly energy resources is a primary barrier to fully realizing a hydrogen economy. Therefore, a detailed analysis of hydrogen production costs from various sustainable routes is required. This paper presents a comparative economic study of hydrogen production using several nuclear reactors integrated with electrolysis hydrogen production methods. The Hydrogen Economic Evaluation Program (HEEP) software is used for comparing hydrogen production using different technologies. The HEEP tool was developed by International Atomic Energy Agency (IAEA) and offers comprehensive data for the different nuclear power plants, hydrogen production processes, and various storage and transportation options. The current study utilizes HEEP capabilities to evaluate the cost of nuclear hydrogen production and compare it with non-nuclear sources. Furthermore, it considers the cost of hydrogen storage and transportation options. The reactors considered are Advanced Pressurized Water Reactor (APWR) and High Temperature Gas-cooled Reactor (HTGR) to power low- and high-temperature electrolyzers. In addition, the costs of hydrogen produced using electricity from grid, solar, and wind are evaluated and compared with that of nuclear plants. It is found that the cost of hydrogen production and storage using Compressed Gas (CG) from an APWR plant is 8.2 $/kg for a plant capacity of 360 MWe; the cost is reduced to 6.06 $/kg when the capacity increased to 1117 MWe. It is also found that HTGR integrated with HTSE can produce hydrogen at 3.51 $/kg, which is slightly lower than the case of using the grid electricity, which costs 3.55 $/kg. • Studied costs of electrolysis hydrogen production using APWR and HTGR at different scales. • Compared costs of hydrogen production using nuclear, solar, wind, and grid electricity. • Considered additional costs for compression, liquefaction, and metal hydride storage options. • Evaluated and compared vehicle and pipeline transportation costs for 500 km. [ABSTRACT FROM AUTHOR]

The world is still largely dependent on oil and natural gas for its energy requirements which are harmful to the environment; therefore, it is high time that we look for alternative technologies for our growing energy needs. One such emerging area is fuel cell technology which produces clean energy in the form of electrical power. Integrating a Metal Hydride Hydrogen Storage (MHHS) system with a fuel cell can help increase energy efficiency. The heat dissipated during hydrogen absorption in MHHS can be used in other applications. In this paper, energy and exergy analysis of a fuel cell-based integrated system is performed. The system presents a Reversible Proton Exchange Membrane Fuel Cell capable of working in dual modes, i.e., as an Electrolyser as well as a fuel cell. The MHHS and Vapour Absorption Refrigeration System (VARS) are coupled with a reversible fuel cell for hydrogen storage and cooling applications, respectively. While working in the fuel cell mode, maximum efficiency of 47.84% is evaluated at 80 °C. The system efficiency with and without the VARS system at 80 °C was 73.29% and 47.84%, respectively. On the contrary, in the electrolyzer mode, the maximum efficiency comes out to be 85.65%. The use of the MHHS system for hydrogen storage results in excess heat release, and as a result, the overall efficiency of the electrolyzer was increased to 94.05%. • Thermodynamic integration of PEMFC with MHHS and VARS is performed. • Effect of key parameters on fuel cell system performance is investigated. • System energy and exergy efficiency of 73.3% and 59.5% respectively are reported. • The proposed system can achieve maximum electrolyzer efficiency of 85.65%. • Maximum cooling output from vapour absorption system is found to be 60.56 kW. [ABSTRACT FROM AUTHOR]

To design and optimize the thermal management of metal hydride (MH) tank, high-fidelity model (HFM) composed of numerous partial differential equations, is often adopted to capture the spatial evolution of key parameters accurately. However, computational difficulties raise in dealing with such nonlinear interconnections for system-level simulation. Therefore, the model reduction of MH system has drawn much attention aiming at the trade-off between accuracy and computational cost. In this paper, a hybrid modeling method which integrates advantages of the state-space model (SSM) and HFM, is proposed and applied for the model reduction of MH tank. In particular, four data-driven matrices are introduced to improve the model accuracy. The results show that the root mean square errors of the average temperature between hybrid reduced model (HRM) and HFM are 0.0399 K and 0.1989 K respectively for the cases without and with thermal management. In addition, the HRM is able to capture dynamic characteristic under perturbed input variables with a relative error of temperature within 0.4%, indicating great potential for system-level simulation. What's more, the analysis of predominant pole derived from the state matrices of different thermal managements, reveals that the expanded graphite has superior effect on the adjustment time extension compared with fins, while the fins have distinct advantages in heat transfer enhancement at the cost of volumetric hydrogen storage density. • A hybrid modeling method combining state-space model and data-driven correction is proposed. • The reduced model of MH tank shows great agreement with HFM under various operation parameters. • The accuracy of reduced model has also been verified for the MH tank with thermal management and perturbed variables. • The effect of thermal management on the dynamic characteristic of MH tank is summarized. [ABSTRACT FROM AUTHOR]

In this paper, three optimisation methods are used to determine the parameters of a commercial metal hydride hydrogen tank, considered as a grey box in which the thermophysical parameters are unknown. These parameters are essential for the development of energy management strategies and the study of tank ageing. A model of the hydride tank containing an AB 5 intermetallic was developed and experimentally validated. An absorption test campaign of the studied tank was carried out to collect data necessary for the optimisation algorithms. A comparative study was carried out in accordance with the speed of convergence and precision between the three stochastic optimisation methods: Particle Swarm Optimisation (PSO), Genetic Algorithm (GA) and Differential Evolution (DE). The results of the simulation of the storage system using the parameters determined by the algorithms show a remarkably close agreement with the experimental data, with a maximum error of 2.1%. • Innovative proposal for the determination of parameters of a metal hydride hydrogen tank. • Experimental test for the static characterization of a metal hydride tank for hydrogen storage. • An experimentally verified mathematical model for the hydrogen storage system is put forth. • Validation with experimental data and three stochastic optimisation methods: PSO, GA and DE. [ABSTRACT FROM AUTHOR]

The perovskite-type hydride compounds are potential candidate materials in the field of hydrogen storage. This paper presents a systematical study of XTiH 3 (X = K, Rb, Cs) using density functional theory. The analysis of formation energy, elastic properties and phonon dispersion curves indicate that all the studied materials are thermodynamically, mechanically and dynamically stable. By analyzing the B/G ratio, it is determined that these compounds are brittle materials. The electronic properties reveal that the XTiH 3 compounds exhibit semi-metallic characteristics. The charge transfer characteristics of these compounds were analyzed using Bader partial charges. Moreover, the thermodynamic characteristics of these compounds were investigated and the dependence of their free energy, entropy and heat capacity on the temperature were analyzed. Finally, the gravimetric hydrogen storage capacities of KTiH 3 , RbTiH 3 and CsTiH 3 were calculated to be 3.36, 2.22 and 1.65 wt%, respectively. The hydrogen desorption temperatures of KTiH 3 , RbTiH 3 and CsTiH 3 were found to be 209 K, 161 K and 107 K, respectively. To our knowledge, this study represents the very first investigation of XTiH 3 compounds and offers valuable references to this hydrogen storage material. [Display omitted] • XTiH 3 (X = K, Rb, Cs) perovskite have been investigated using first-principles. • XTiH 3 perovskite exhibit thermodynamic, mechanical and dynamical stability. • The gravimetric hydrogen storage capacity is found to be 3.36 wt% for KTiH 3. [ABSTRACT FROM AUTHOR]