Application of machine learning to thermal management of solid-state hydrogen storage: A comprehensive review

Safety in hydrogen storage is a key factor for its potential use in modern energy systems. Hydrogen is often referred to as the fuel of the future and therefore poses significant safety challenges due to its high flammability, low molecular density, and ability to easily penetrate various materials. Traditional methods of storing hydrogen include high-pressure storage under high pressures of 35–70 MPa in pressurized vessels and the storage of liquid hydrogen at temperatures as low as −253°C. Metal hydride hydrogen storage tanks are a safe alternative to these traditional storage systems. Hydrogen is a chemically bonded system to metal alloys at pressures under 10 bar(a) and room temperature, eliminating safety risks. During the absorption and desorption of hydrogen, endothermic and exothermic reactions occur, necessitating efficient thermal management. To ensure effective thermal management of the storage tank, various approaches can be applied. One highly innovative solution involves the use of a closed-loop heat pipe (LHP). This system requires no pumping work during operation; thus, it has low energy requirements for operation. The article presents the design of a thermal management system for heating and cooling a metal hydride hydrogen storage tank, along with the development of a physical model of the tank using loop heat pipes. It also discusses the experimental results obtained from measurements on the physical model. Results demonstrate that a well-designed thermal management system ensures optimal operation of the metal hydride storage tank.

Light-weight solid-state hydrogen storage materials characterized by neutron scattering

HyCARE project, supported by the Clean Hydrogen Partnership of the European Union, deals with a prototype hydrogen storage tank using a solid-state hydrogen carrier. Up to 40 kilograms of hydrogen are stored in 12 tanks at less than 50 barg and less than 100°C. The innovative design is based on a standard 20-foot container including 12 TiFe-based metal hydride (MH) hydrogen storage tanks, coupled with a thermal energy storage in phase change materials (PCM). This article aims at showing the main risks related to hydrogen storage in a MH system and the safety barriers considered, based on HyCARE’s specific risk analysis. Regarding the TiFe MH material used to store hydrogen, experimental tests showed that the exposure of the MH to air or water did not cause spontaneous ignition. Furthermore, an explosion within the solid MH cannot propagate due to internal pore size. Additionally, in case of leakage, the speed of hydrogen desorption from the MH is self-limited, which is an important safety characteristic since it reduces the potential consequences from the hydrogen release. Regarding the integrated system, the critical scenarios identified during the risk analysis were explosion due to release of hydrogen inside or outside the container, internal explosion inside MH tanks due to accidental mix of hydrogen and air and asphyxiation due to inert gas accumulation in the container. The identification phase of risk analysis identified the most relevant safety barriers already in place and recommended additional ones, if needed, which were later implemented to further reduce the risk. The main safety barriers identified were material and component selection (including the MH selected), safety interlocks, safety valves, ventilation, gas detection and safety distances. The risk management process, based on risk identification and assessment, contributed to coherently integrate inherently safe design features and safety barriers.

Solid-state hydrogen storage in various metal hydrides is among the most promising and clean way of storing energy, however, some problems, such as sluggish kinetics and high dehydrogenation temperature should be dealt with. In the present paper the advances of severe plastic deformation on the hydrogenation performance of metal hydrides will be reviewed. Techniques, like high-pressure torsion, equal-channel angular pressing, cold rolling, fast forging and surface modification have been widely applied to induce lattice defects, nanocrystallization and the formation of abundant grain boundaries in bulk samples and they have the potential to up-scale material production. These plastically deformed materials exhibit not only better H-sorption properties than their undeformed counterparts, but they possess better cycling performance, especially when catalysts are mixed with the host alloy promoting potential future applications.

The current world is increasingly focusing on renewable energy sources with strong emphasis on the economically viable use of renewable energy to reduce carbon emissions and safeguard human health. Solid-state hydrogen (H2) storage materials offer a higher density compared to traditional gaseous and liquid storage methods. In this context, this review evaluates recent advancements in binary, ternary, and complex metal hydrides integrated with 2D Ti3C2 MXene for enhancing H2 storage performance. This perspective highlights the progress made in H2 storage through the development of active sites, created by interactions between multilayers, few-layers, and internal edge sites of Ti3C2 MXene with metal hydrides. Specifically, the selective incorporation of Ti3C2 MXene content has significantly contributed to improvements in the H2 storage performance of various metal hydrides. Key benefits include low operating temperatures and enhanced H2 storage capacity observed in Ti3C2 MXene/metal hydride composites. The versatility of titanium multiple valence states (Ti0, Ti2+, Ti3+, and Ti4+) and Ti-C bonding in Ti3C2 plays a crucial role in optimizing the H2 absorption and desorption processes. Based on these promising developments, we emphasize the potential of solid-state Ti3C2 MXene interfaces with various metal hydrides for fuel cell applications. Overall, 2D Ti3C2 MXenes represent a significant advancement in realizing efficient H2 storage. Finally, we discuss the challenges and future directions for advancing 2D Ti3C2 MXenes toward commercial-scale H2 storage solutions.

The world is moving toward sustainable and low-carbon energy systems, which means we need hydrogen storage solutions that are safe, scalable, and cost-effective. Among several methods, solid-state hydrogen storage has become a promising alternative to traditional gaseous and liquid storage methods because it has a higher gravimetric capacity, is more stable, and is safer. This chapter delineates a computational analysis of perovskite hydrides XYH3 (X = Li, Na, K) employing first-principles density functional theory (DFT). The study thoroughly investigates their structural, electrical, optical, and mechanical properties to assess their viability for hydrogen storage applications. LiYH3, NaYH3, and KYH3 have lattice constants of 4.42 Å, 4.30 Å, and 4.41 Å, and their gravimetric hydrogen storage capacities are 3.06 wt%, 2.64 wt%, and 2.31 wt%, respectively. Thermodynamic study showed that the formation enthalpies were negative (−16.19 eV, −13.54 eV, and − 9.13 eV), which confirmed their stability. The Gibbs free energy values at 1000 K were also still good (−0.51 eV, −0.69 eV, and − 1.48 eV). The mechanical investigation showed that Young’s moduli were 27.59 GPa, 52.19 GPa, and 49.29 GPa, and all of the compounds were brittle (B/G < 1.75). Optical tests revealed significant absorption peaks between 26 and 29 eV, underscoring their suitability for optoelectronic applications. These findings underscore that perovskite hydrides are promising candidates for next-generation hydrogen storage devices, providing computationally informed design principles that enhance experimental initiatives. This combination of simulation and materials engineering helps create solid-state hydrogen storage solutions that are efficient, long-lasting, and cheap, which is important for the growth of the hydrogen economy.

Unraveling the Potential of Solid-State Hydrogen Storage Materials: Insights from First Principle Calculations

Metal hydrides are a class of materials that can absorb and release large amounts of hydrogen. They have a wide range of potential applications, including their use as a hydrogen storage medium for fuel cells or as a hydrogen release agent for chemical processing. While being a technology that can supersede existing energy storage systems in manifold ways, the use of metal hydrides also faces some challenges that currently hinder their widespread applicability. As the effectiveness of heat transfer across metal hydride systems can have a major impact on their overall efficiency, an affluent description of more efficient heat transfer systems is needed. The literature on the subject has proposed various methods that have been used to improve heat transfer in metal hydride systems over the years, such as optimization of the shape of the reactor vessel, the use of heat exchangers, phase change materials (PCM), nano oxide additives, adding cooling tubes and water jackets, and adding high thermal conductivity additives. This review article provides a comprehensive overview of the latest, state-of-the-art techniques in metal hydride reactor design and heat transfer enhancement methodologies and identifies key areas for future researchers to target. A comprehensive analysis of thermal management techniques is documented, including performance comparisons among various approaches and guidance on selecting appropriate thermal management techniques. For the comparisons, the hydrogen adsorption time relative to the reactor size and to the amount of hydrogen absorbed is studied. This review wishes to examine the various methods that have been used to improve heat transfer in metal hydride systems and thus aims to provide researchers and engineers working in the field of hydrogen storage with valuable insights and a roadmap to guide them to further explore the development of effective thermal management techniques for metal hydrides.

This article examines the use of hydrogen as fuel for transport applications and the problems encountered in its storage. Firstly it outlines the current compressed hydrogen and liquid hydrogen schemes and their drawbacks. It then focusses on the use of solid state and porous storage materials such as metal hydrides and the ongoing research in this area. The goal is to develop a solid-state hydrogen storage tank that will not only store more hydrogen on board a fuel cell vehicle, compared to compressed and liquid hydrogen, but could be adaptable to any type of solid-state hydrogen storage. The article also discusses the use of this technology in consumer and portable power electronics.

The hydrogen storage in metal hydrides is an imminent, innovative, and environmentally beneficial approach that offers benefits for example, an ample amount of storage and elasticity in terms of thermodynamics necessary for hydrogen absorption and release. By successfully integrating temperature management with hydrogen storage procedures, thermal energy storage (TES) systems offer a way to improve the energy efficiency and economic viability of metal hydride‐based storage. This review presents an overview of metal hydride materials utilized for storing hydrogen, emphasizing their thermodynamic and kinetic characteristics. This study examines TES materials, focusing on sensible, latent, and thermochemical energy storage options, particularly those functioning at temperatures suitable for extensively researched hydride systems. An analysis of lanthanum and magnesium‐based metal hydride is presented. Additionally, the study presents a comprehensive review that yields additional combinations of magnesium‐based and lanthanum‐based metal hydrides, elucidating their properties, which encompass the ranges of absorption and desorption temperatures, as well as gravimetric storage capacity. The study concludes that the kinetics of both absorption and desorption are enhanced; in the case of magnesium‐based metal hydrides at elevated temperatures (MgH 2 –7 wt% Fe−7 wt% HCS and MgH 2 @Ni‐MOF) exhibit the highest absorption and desorption temperatures. This study provides a greater understanding to researchers in developing efficient materials for hydrogen storage and can identify patterns in various alloys, including the influence of alloy composition on thermodynamic properties and can screen alloys with desirable properties for various applications.

Expanded graphite as heat transfer matrix in metal hydride beds

The emergence of a Hydrogen Economy will require the development of new media capable of safely storing hydrogen with high gravimetric and volumetric densities. Metal hydrides and complex metal hydrides, where hydrogen is chemically bonded to the metal atoms in the bulk, offer some hope of overcoming the challenges associated with hydrogen storage. Many of the more promising hydrogen materials are tailored to meet the unique demands of a low temperature automotive fuel cell and are therefore either entirely new (e.g. in structural or chemical composition) or in some new form (e.g. morphology, crystallite size, catalysts). This proceeding presents an overview of some of the challenges associated with metal hydride hydrogen storage and a few new approaches being investigated to address these challenges.

Carbon-based materials for Mg-based solid-state hydrogen storage strategies

Metal hydride hydrogen compressors have been explored as an alternative to mechanical hydrogen compressors since the first patents were filed in the 1970s. As heat engines, their productivity significantly depends on the achievable heat transfer rate, which is inherently limited by the pressure-bearing walls separating the heat transfer fluid from the reactive metal hydride beds and their effective thermal conductivity. This work presents and analyzes a new metal hydride compressor system that uses hydrogen as heat transfer fluid in direct convective contact with the metal hydride material. Following this principle, we show how an integrated compressor can be designed and behaves on a system and metal hydride bed level. The achievable productivity surpasses what has been reported for experimental metal hydride compressors while showing good prospects for low electrical energy consumption.

Coiled-tube heat exchanger for high-pressure metal hydride hydrogen storage systems – Part 2. Computational model