Hydrogen Storage System Research Articles

Simulation study on a novel solid–gas coupling hydrogen storage method for photovoltaic hydrogen production systems

Compressed hydrogen storage in photovoltaic hydrogen production systems faces several challenges, including limitations in storage volume, compression energy consumption and safety concerns. To improve the comprehensive hydrogen storage performance, this study develops a novel solid–gas coupling hydrogen storage method that combines metal hydride and phase change material (MH-PCM). Firstly, a vertical MH-PCM solid storage model considering the natural convection effect is proposed and investigated. Building upon this model, the solid–gas coupling hydrogen storage is constructed and integrated into the photovoltaic hydrogen production system to evaluate its comprehensive storage performance. Results reveal that considering natural convection leads to an approximately 12.7 % increase in the average storage rate, but is also accompanied by an uneven storage process. To address this unevenness and further enhance the storage rate, it's advisable to focus on structural optimization at the bottom of the tank. Additionally, improving the PCM thermal conductivity and hydrogen inlet pressure (to approximately 1 MPa) are also proven effective strategies. The proposed solid–gas coupling hydrogen storage demonstrates comprehensive advantages, particularly compact size and reduced energy consumption. Furthermore, appropriately increasing the coupling ratio between solid and gaseous capacities can achieve the even smaller storage volume. These findings can provide valuable theoretical and engineering guidance for implementing such hydrogen production and storage systems.

Enhanced system for hydrogen storage and conversion into green methanol in a geothermal environment

Variable Renewable Energy Sources are crucial for decarbonizing industries and efficient energy storage. Hydrogen storage technologies are limited in their large-scale capabilities. PtL technology can synthesize alternative fuels like methanol, which can be used in existing energy infrastructures to produce liquid fuel. The paper presents an innovative approach for utilizing in-situ thermal energy, using a hot reservoir rock (HRR) system for methanol synthesis at high temperature and pressure in an underground large-scale natural reservoir reactor. This approach aims to integrate renewable energy technologies into a single energy generation and fuel production system, including the direct utilization of renewable sources. Solutions from the oil and gas industry can be adapted to this action, such as continuous injection, alternate injection, separate injection, or chemical flooding. Conventional geothermal reservoirs, HDR systems, and depleted hydrocarbon reservoirs can be used as “underground reactors”. However, it was also noted that there are challenges, such as catalyst distribution and the complexity of reservoir pore space.

PdRu/SBA15 catalysts for hydrogen storage by reversible N-ethylcarbazole hydrogenation/dehydrogenation reactions

In this work, a stable double complex salt (DCS) on the surface of SBA-15 is constructed by phase transfer-assisted electrostatic adsorption method. DCS was then reduced by glow discharge plasma to obtain SBA-15 loaded PdRu bimetallic catalysts (PdRu/SBA15). The catalysts were characterized by nitrogen adsorption–desorption, TEM, FT-IR, XPS, H2-TPR and ICP-OES. The Pd anion dissolved by phase transfer is precisely adsorbed on the Ru cation, and this unique intimacy of two metals promotes the formation of stable structure. The synergistic effect of the DCS structure and the in-situ reduction of glow discharge plasma makes PdRu/SBA15 have highly dispersed and stable PdRu nanoparticles (NPs). PdRu/SBA15 is suitable for reversible hydrogen storage system. It not only catalyzed N-ethylcarbazole (NEC) hydrogenation efficiently, but also showed enhanced catalytic performance in the dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NEC). The hydrogenation efficiency reached 99.8% for 80 min at 100 °C, H2 pressure of 5 Mpa and the dehydrogenation efficiency reached 100% for 6 h at 180 °C under the action of the same PdRu/SBA15 catalyst. Moreover, the catalytic activity of PdRu/SBA15 catalyst did not decrease obviously after seven cycles in reversible hydrogen storage. The reversible hydrogen storage PdRu catalysts with excellent activity has a very bright prospect in the practical application of fuel cells.

Hydrogen evolution through ammonia borane hydrolysis over iron tailored pig manure catalyst

Hydrogen storage systems have become of great interest particularly especially for those that conjugate a high storage capacity together with high safety standards. Chemical storage using amino borane has attracted a great interest and ammonia borane is playing a major role in the field due to the hydrogen storage capacity up to 19 wt%. Nevertheless, the hydrogen evolution from ammonia borane is a matter of great complexity and hydrolytic methods represent the simpler way to approach it. Actually, the ammonia borane hydrolysis is carried out by using complex catalysts not containing critical raw materials and/or noble metals. In the present work, we report the production of iron based heterogeneous catalyst support onto carbonized pig manure. The complexity of this waste stream was very helpfully to provide an active surface for the anchoring of iron nanoparticles and promoting the hydrogen evolution form hydrolysis of ammonia borane reaching a conversion of 98.3 % at 50 °C with an iron loading of 10 wt%. The catalytic system reduced the activation energy of the reaction up to 51 % increasing the kinetic constant of the reaction of one order of magnitude. Furthermore, the stability of the catalytic system was preserved after three cycles without appreciable changes.

Stochastic management of electric vehicles in an intelligent parking lot in the presence of hydrogen storage system and renewable resources

The paper emphasizes the significance of sustainable energy solutions centered around electric vehicles (EVs). This involves Electric Intelligent Parking Lots (IPLs) that are interconnected with Renewable Energy Sources (RES) and Hydrogen Storage Systems (HSS) to achieve both technical and environmental goals. The study introduces a probabilistic approach to managing HSS-based energy in IPLs, employing the Probabilistic Two-Point Estimate Method (TPEM) to consider variables like sun radiation, temperature, wind speed, and IPL load. The Honey Badger Algorithm (HBA) is employed for optimization, striving to minimize operational costs related to energy distribution while maximizing profits by exploring revenue opportunities within the IPL system. This strategy enhances energy management and intelligent EV charging in IPLs, improving efficiency and economic viability. The approach is tested in a standard IPL environment integrated with RES and load demand, showcasing its successful technical and financial outcomes. Results reveal a 7.8 % profit increase from renewable resources and an additional 4.89 % when uncertainties are factored in. Ultimately, the proposed energy management framework utilizing HSS and RES integration proves effective in achieving objectives, with the potential for greater profitability through renewable resource incorporation and uncertainty consideration.

Eco-Sustainable Energy Production in Healthcare: Trends and Challenges in Renewable Energy Systems

The shift from fossil fuels to renewable energy systems represents a pivotal step toward the realization of a sustainable society. This study aims to analyze representative scientific literature on eco-sustainable energy production in the healthcare sector, particularly in hospitals. Given hospitals’ substantial electricity consumption, the adoption of renewable energy offers a reliable, low-CO2 emission solution. The COVID-19 pandemic has underscored the urgency for energy-efficient and environmentally-responsible approaches. This brief review analyzes the development of experimental, simulation, and optimization projects for sustainable energy production in healthcare facilities. The analysis reveals trends and challenges in renewable energy systems, offering valuable insights into the potential of eco-sustainable solutions in the healthcare sector. The findings indicate that hydrogen storage systems are consistently coupled with photovoltaic panels or solar collectors, but only 14% of the analyzed studies explore this potential within hospital settings. Hybrid renewable energy systems (HRES) could be used to meet the energy demands of healthcare centers and hospitals. However, the integration of HRES in hospitals and medical buildings is understudied.

Chance constrained robust hydrogen storage management to service restoration in microgrids considering the methanation process model

After a natural disaster, electrical grids might go into a self-healing mode to restore service and reconnect any customers that lost power. In the self-heal system, the fast operation and restoring the critical loads (CLs) during a fault by available resources can increase the flexibility and resilience of the network. In addition to renewable energy sources and electric vehicles (EVs) storage devices, the hydrogen storage system and the process of converting hydrogen into electric energy by micro-gas turbine (MGT) have been modeled in order to assess the impact of this storage system in electrical loads restoration in critical conditions. Self-healing functionality is enhanced by using alternative and novel energy sources. In such a situation, how to interact with the stochastic nature of network components will be challenging. This paper formulates the optimal service restoration (SR) problem using chance-constrained Adaptive Distributionally Robust Optimization (ADRO) to address the ambiguities introduced by the uncertain parameters. A tri-level robust optimization model is developed such that the optimal switching in the network until clearing the fault is determined at the upper level, and the maximization of the SR based on the load demand values is determined at the lower level. The proposed method is demonstrated by simulation results on the modified Civanlar test system. In an equal operating condition and considering β = 3, it can be seen that the initial hydrogen State of the Tank (SoT) by 50 % can improve the load restoration by 7.5 % compared to the uncharged hydrogen tank. By increasing the initial SoT to the nominal value (10 Kg), the load restoration can increase to 13.2 %.

Optimizing Micro Gas Turbine Operation in a Microgrid System With Natural Gas and Hydrogen Fuel: An Artificial Intelligence-Based Approach

Abstract In the coming years, decentralized power generation systems with renewables are expected to take a leading role, and micro gas turbines will serve as backup sources to compensate for times of low inputs from other sources. In order to deal with the unpredictable energy inputs from renewables, the micro gas turbine must be capable of running under varying load conditions and making fast transitions between them. The operation of a micro gas turbine in an integrated microgrid (MG) has the potential to reduce operational costs and ensure the delivery of demanded heat and power to consumers. This paper investigates the operation of a micro gas turbine in a MG, serving as a supplementary power source for a municipal building. The building's required energy is initially provided by wind turbine power, and the micro gas turbine serves as a backup source during times of wind power deficiency. The micro gas turbine can operate using a natural gas/hydrogen fuel blend ranging from zero to 100% hydrogen. Furthermore, a water electrolyzer with a hydrogen tank is available to operate as a storage system within the MG. The study's results demonstrate the economic and environmental benefits of using hydrogen storage and optimizing operational planning in the MG. The primary objective of the paper is to highlight the feasibility and benefits of employing micro gas turbines and hydrogen storage systems within a MG as a renewable energy backup power source.

Isomeric Thiadiazole-xLi+(x = 1, 2) templates found to be efficient in search of potential H2 storage systems; a computational study

The hydrogen trapping possibility of isomeric thiadiazole-Li+ and thiadiazole-2Li+ building blocks has been evaluated by various functionals within density functional theory (DFT), and it is found that they can adsorb a maximum of five and ten H2 molecules respectively. Aromaticity is retained even after hydrogen adsorption. Average adsorption energy lies in the quasimolecular type adsorption range. The gravimetric wt% (9.7 ∼ 16.7) are found suitable as per norms. Topological analysis shows that the bond formation between Li and trapped H2 molecules is mostly non-covalent. At 200 K or below this temperature, the Gibbs free energy changes illustrate that the molecular hydrogen adsorption process is spontaneous for all isomeric thiadiazole-xLi+ [x = 1 and 2] building blocks. Higher temperatures are required for the desorption of H2 molecules. Thus, we believe that our studied system thiadiazole-xLi+ can be proposed as a practically viable system for hydrogen storage.

Experimental investigation on the development characteristics of explosive overpressure induced by high-pressure hydrogen jet flame

Accidental release of high-pressure hydrogen can induce the self-ignition, and the spontaneously combusting flame can eventually induce a non-premixed jet flame or even explosion. In this study, the explosion overpressure characteristic of hydrogen jet flame outside the pipeline was investigated. Experiments were conducted on high-pressure hydrogen release pipelines with a diameter of 10 mm and pipeline lengths of 750, 1450 and 2200 mm, respectively, under different hydrogen release pressure. The impact of different initial conditions on the peak value of high-pressure hydrogen jet explosion was systematically investigated. The external pressure signals and flame images were completely collected. The results show that the external explosion overpressure decreased with the increase of axial distance away from the nozzle. When the length of the pipeline increased, the peak value of the overpressure was also gradually decreased. Meanwhile, as the high-pressure hydrogen burst pressure increased, the overpressure rose first and then decreased. With the increase of release pressure, when the hydrogen pressure exceeded 8 MPa, the hydrogen flow in the tube formed a blocked flow, so the increase of external explosion overpressure became slow. This topic can provide a reference for the safety development of the high-pressure hydrogen storage system.

Practical mutual transformation of azobenzene and hydrazobenzene using porous BN supported Cu nanoparticles as a redox catalyst

Azobenzene and hydrazobenzene compounds are essential intermediates for synthesizing pharmaceuticals and dyes. Meanwhile, the hydrazobenzene/azobenzene couple is a potential hydrogen storage system when both the dehydrogenation of hydrazobenzene and the hydrogenation of azobenzenes can be achieved under mild reaction conditions. In this work, we report an entirely mutual transformation of azobenzene and hydrazobenzene under very mild conditions using porous BN supported Cu nanoparticles (Cu/PBN) as the catalyst for the first time. Direct oxidative dehydrogenation reaction proceeded in the open air with the removal of molecular hydrogen as the by-product and a wide range of hydrazobenzenes readily undergoes dehydrogenation, resulting in an excellent yield of the corresponding azobenzene.

A quasi-2D thermodynamic model for performance analysis and optimization of liquid hydrogen storage system with multilayer insulation and vapor-cooled shield

Liquid hydrogen (LH2) holds great potential in both aerospace and civil markets due to its high energy density. However, on account of the low boiling point and latent heat of vaporization of LH2, the high performance insulation storage system is the key to its efficient storage. One of the most efficient insulation methods for a LH2 storage system is considered to be Variable Density Multilayer Insulation (VDMLI) coupled with Vapor-Cooled Shield (VCS). This study establishes a quasi-two-dimensional (quasi-2D) thermodynamic model of liquid hydrogen storage system with VDMLI and VCS. The quasi-2D model incorporates the temperature gradient of VCS and its impact on VDMLI. The model can reveal the two-dimensional temperature and heat distribution in insulation systems, predict heat leakage and evaporation rate, and can be utilized for optimizing the design of the VCS structure. Using a NASA's tank as an example, the analysis conducted with the model indicates that the presence of VCS reduces the average temperature gradient of the inner VDMLI. The upper half of the tank exhibits a significantly smaller temperature gradient compared to the lower half, resulting in lower heat leakage. This effect becomes more pronounced as the VCS moves outward of the tank. Additionally, the VCS absorbs more heat in the inlet section than that in the outlet section, and this disparity becomes increasingly significant as the VCS moves outward of the tank. The model can also be employed to optimize the position of the VCS, resulting in a 69.73 % reduction in daily evaporation rate compared to NASA's original design. Lastly, a graphical method for the quick design of VCS structure is proposed which is based on calculated data for daily evaporation rate and apparent thermal conductivity. This method enables the retrieval of the corresponding apparent thermal conductivity based on the desired evaporation rate, facilitates the rapid determination of the range of VCS position, and allows for the quick prediction of the evaporation rate based on the VCS position. In conclusion, this research presents a new approach for the performance analysis and optimization design of liquid hydrogen storage system with VDMLI and VCS.

Hydrogen trapping and permeability in carbon fiber reinforced aluminum alloys

Carbon fibers and aluminum-based alloys are the most common choice for today's advanced hydrogen storage solutions due to their lightweight. They also combine exceptional mechanical performance and resistance to most chemicals. However, carbon fibers alone are the primary cost driver for hydrogen storage systems and high-strength aluminum alloys suffer from hydrogen embrittlement. Therefore, alternative carbon fiber-reinforced aluminum alloys can be considered to optimize storage tank costs. But, the effect of adding of carbon fibers on hydrogen trapping in an aluminum-based matrix has not yet been understood. To elucidate this, in this study, the interaction between hydrogen and a carbon fiber-reinforced aluminum alloy was investigated by correlating nano/microstructure characterization, hydrogen mapping techniques, and high-pressure hydrogen permeation tests. It is suggested that carbon fiber-reinforced aluminum alloy has three additional hydrogen trap sites compared to the reported traps for the aluminum alloy. The results showed that hydrogen trapping at these traps reduces the hydrogen permeability of composite material compared to a monolithic aluminum alloy.

Toward Low-Temperature Heterogeneous Hydrogenation of Carbonyl Compounds: Molecular Systems for Reversible Hydrogen Storage

Toward Low-Temperature Heterogeneous Hydrogenation of Carbonyl Compounds: Molecular Systems for Reversible Hydrogen Storage

Transport kinetics of protium and deuterium in titanium: Experiments and modeling

We conducted absorption experiments on Ti using hydrogen isotopes, protium and deuterium, to gain insights into the kinetics of hydrogen atoms, particularly across the Ti surface. Rather than relying on various surface pretreatments, we identified the initial temperature of Ti in vacuum as the determining factor in achieving a high absorption rate and content. Specifically, we found that the initial Ti temperatures of approximately 900 and 980 °C are optimal for protium and deuterium, respectively, likely due to sufficient removal of the native surface oxide on Ti. The dependence of the absorption rate and amount of hydrogen isotopes on the temperature during absorption was partially explained by the phase transformation and exothermicity of the hydrogenation reaction. Moreover, this dependence strongly indicated the existence of a tunneling transport process. Additionally, we developed a kinetic model for hydrogen isotope transport in Ti to conduct numerical simulations. The absorption curves, calculated using the developed model, closely matched a series of experimental curves obtained at different temperatures. These curves were from an identical set of equations and kinetic parameters for both protium and deuterium. Our numerical kinetic model has the potential to serve as a valuable simulation tool for various applications, such as the design of high-performance hydrogen storage systems and maintenance strategies against hydrogen embrittlement of structural materials.

Operation of the stand-alone electrical system based on optimal energy management

This paper focuses on optimizing the energy of a stand-alone energy grid by incorporating energy storages and demand side participation. The increasing popularity of energy storage systems and demand side participation is mainly attributed to their advantages, such as the ease of distribution in electrical networks and operational flexibility during critical periods. The main objective functions of the model involve optimizing the stand-alone electrical grid by maximizing efficiency and minimizing energy costs. The efficiency is modelled by energy not supplied. The costs of energy consumption are represented by the fuel costs consumed by resources. To encourage consumers to reduce their demand during peak times, an incentive approach is suggested for their participation. Additionally, a hydrogen storage system is operated in the stand-alone energy grid to enhance the primary objectives. The particle swarm optimization (PSO) algorithm is utilized to optimize energy usage and solve objective functions. Numerical simulations are conducted in two case studies to validate and demonstrate the effectiveness of energy optimization when incorporating storage system and consumers. The case studies based on non-participation and participation of the storage system and consumers in the energy management are implemented. With participation of the storage system and consumers, efficiency and energy costs are improved by 3% and 29.8% than non-participation of them.

Liquid hydrogen storage design trades for a short-range aircraft concept

Preliminary design trades for the liquid hydrogen storage system of a short-range aircraft are presented. Two promising insulation methods, namely rigid foam and multilayer insulation, are identified as main design drivers. In addition, the maximal pressure and the shape of the hydrogen storage tank influence the aircraft performance and the insulation efficiency. In this study, the hydrogen storage tanks are integrated in wing pods. The main effects driven by the design parameters are addressed using conceptual and preliminary methods: models are carried out for the storage mass, additional drag, propeller efficiency loss and the dynamical thermodynamic behavior of the liquid hydrogen storage. These effects are coupled making an integrated design method necessary. For the sizing of the liquid hydrogen storage, a multidisciplinary workflow is set up including the aircraft sensitivities on the design mission block fuel. The trade-off study reveals the opposing trend between insulation efficiency and aircraft performance. For the insulation architecture based on rigid foam, the penalties implied by the storage tank on aircraft level and the penalties due to vented hydrogen can be balanced and result in minimal block fuel for the design mission. The application of multilayer insulation avoids venting during the design mission, but has an increased penalty on the aircraft performance compared to rigid foam insulation. Besides the criterion of minimal block fuel, the dormancy time is compared, indicating the thermal efficiency. Applying multilayer insulation, the dormancy time can be increased significantly calling for a discussion of operational requirements for hydrogen-powered aircraft.

Transient flow dynamics behaviors during quick shut-off of ball valves in liquid hydrogen pipelines and storage systems

The cryogenic nature of liquid hydrogen can lead to brittleness in materials, posing a significant risk of severe safety incidents due to liquid shock. In this study, the compressibility of liquid hydrogen and the rapid closing of the valve are described by user defined function (UDF) using Fluent software, and the reliability of the calculation simulation is verified based on the water hammer experiment and theoretical model. The results show that the rapid closure of a valve causes liquid hydrogen to generate a significant pressure change, leading to a swift drop of flow velocity in the liquid hydrogen pipeline. The pressure fluctuation amplitude near the valve is greater than the pressure fluctuation amplitude away from the valve, and the pattern for velocity is reversed. For valve closing time of tvalve is 0.84, 1.68, and 3.36 times of Tp, the maximum transient flow pressure in the pipe is 60.96 kPa, 48.49 kPa, and 39.06 kPa, respectively. The transient flow pressure is 2.4, 1.9, and 1.5 times for the inlet pressure at valve closing times of 0.01, 0.02, and 0.04 s, suggesting that the quicker the valve closes, the higher the maximum transient pressure in tubes. Furthermore, a new pressure fluctuation coefficient is introduced to describe the transient flow characteristics of the liquid hydrogen in the pipelines. The valve closing time is halved, and the pressure fluctuation coefficient doubles. The research results are expected to provide a technical basis for liquid hydrogen pipelines' design and vibration reduction.

A comparative analysis of the regulations, codes and standards for on-board high-pressure hydrogen storage cylinders

Hydrogen storage cylinder is an important component in high-pressure gaseous hydrogen (HPGH2) storage system, and plays a key role in hydrogen-powered transportation including land vehicles, ships and aircrafts. Over the past decade, the number of hydrogen fuel cell vehicles (HFCVs) has rapidly increased worldwide. In order to promote the application of hydrogen storage cylinder, guide its design, manufacture, inspection and testing, a series of regulations, codes and standards have been issued. The Chinese national standard, GB/T 42612, for type IV hydrogen storage cylinders has also been issued. This paper first gives a brief overview to these regulations, codes and standards. Furthermore, the specifications including scope, category, filling cycles, service life, materials, design, manufacture, qualification tests and periodic inspections are analyzed and compared. Issues about evaluation method for hydrogen compatibility of non-metallic materials, welded joints of plastic liner, joint between boss and liner are also discussed. Notably, the performance requirements in GB/T 42612 are generally in accordance with the international ones, but the requirements of materials, design and manufacture are more detailed.

Two layer control strategy of an island DC microgrid with hydrogen storage system

In this paper, a two-layer hierarchical control strategy for an isolated DC microgrid with a hybrid energy storage system is considered. The DC microgrid studied is composed of a short-term battery energy storage system, long-term hydrogen-based energy storage system and renewable energy resources. The proposed control strategy, combines concepts of Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC) as a primary level and Model Predictive Control (MPC) as a supervisory level. The IDA-PBC layer guarantees a correct power balance and ensures global stability according to Lyapunov theory, considering the non-linear behavior of the physical system. On the other hand, the MPC layer calculates the reference signals for the primary level, ensuring null stationary error in the desired variables. As known, it is important to keep the electrolyzer, the fuel cell and the batteries in a safe operating mode to increase their useful life and guarantee the quality of the hydrogen produced. In this sense, the benefits of MPC are exploited by considering system constraints in the controller design. The main objective of the two-layer control strategy is to ensure the supply of electrical energy to the loads and quality in the electrical variables of the network. Representative simulation results under demanding conditions verify the effectiveness of combining IDA-PBC and MPC for this class of problems.