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Hydrogen, Volume 6, Issue 3 (September 2025) – 13 articles

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14 pages, 5143 KiB  
Article
An Efficient Finite Element Model to Predict the Mechanical Response of Metallic-Reinforced Pressure Vessels
by Ana Lucía León Razo, Miguel Ernesto Gutierrez Rivera, Carlos Enrique Valencia Murillo, Elias Rigoberto Ledesma Orozco and Israel Martinez Ramirez
Hydrogen 2025, 6(3), 55; https://doi.org/10.3390/hydrogen6030055 - 6 Aug 2025
Abstract
In the design of pressure vessels for hydrogen storage, the durability and robustness of the designs are tested by using experimental methods, numerical simulations, or both. However, in the initial design phase, it is widely known that using numerical simulation tools reduces the [...] Read more.
In the design of pressure vessels for hydrogen storage, the durability and robustness of the designs are tested by using experimental methods, numerical simulations, or both. However, in the initial design phase, it is widely known that using numerical simulation tools reduces the cost of performing experiments; therefore, models that provide accurate and reliable results must be developed. This work presents an axisymmetric finite element model to predict the mechanical response of reinforced wire pressure vessels of type II. The main contribution of the present model is the use of equivalent properties and a minor number of contact elements to simulate the behavior of the wire reinforcement, which reduces the computational effort compared to a model with a solid-based mesh. The accuracy of the proposed model is tested against solid elements with very good agreement and experimental results with reasonable agreement. A parametric study was conducted to test the influence of the number of layers of reinforcement, and it was concluded that there is a limit to increasing the number of layers, which does not increase the vessel’s strength considerably, but it does with its mass. Full article
(This article belongs to the Special Issue Advances in Hydrogen Production, Storage, and Utilization)
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24 pages, 2539 KiB  
Article
Classification Framework for Hydrological Resources for Sustainable Hydrogen Production with a Predictive Algorithm for Optimization
by Mónica Álvarez-Manso, Gabriel Búrdalo-Salcedo and María Fernández-Raga
Hydrogen 2025, 6(3), 54; https://doi.org/10.3390/hydrogen6030054 - 6 Aug 2025
Abstract
Given the urgent need to decarbonize the global energy system, green hydrogen has emerged as a key alternative in the transition to renewables. However, its production via electrolysis demands high water quality and raises environmental concerns, particularly regarding reject water discharge. This study [...] Read more.
Given the urgent need to decarbonize the global energy system, green hydrogen has emerged as a key alternative in the transition to renewables. However, its production via electrolysis demands high water quality and raises environmental concerns, particularly regarding reject water discharge. This study employs an experimental and analytical approach to define optimal water characteristics for electrolysis, focusing on conductivity as a key parameter. A pilot water treatment plant with reverse osmosis and electrodeionization (EDI) was designed to simulate industrial-scale pretreatment. Twenty water samples from diverse natural sources (surface and groundwater) were tested, selected for geographical and geological variability. A predictive algorithm was developed and validated to estimate useful versus reject water based on input quality. Three conductivity-based categories were defined: optimal (0–410 µS/cm), moderate (411–900 µS/cm), and restricted (>900 µS/cm). Results show that water quality significantly affects process efficiency, energy use, waste generation, and operating costs. This work offers a technical and regulatory framework for assessing potential sites for green hydrogen plants, recommending avoidance of high-conductivity sources. It also underscores the current regulatory gap regarding reject water treatment, stressing the need for clear environmental guidelines to ensure project sustainability. Full article
(This article belongs to the Special Issue Advances in Hydrogen Production, Storage, and Utilization)
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20 pages, 2981 KiB  
Article
Data-Driven Modelling and Simulation of Fuel Cell Hybrid Electric Powertrain
by Mehroze Iqbal, Amel Benmouna and Mohamed Becherif
Hydrogen 2025, 6(3), 53; https://doi.org/10.3390/hydrogen6030053 - 1 Aug 2025
Viewed by 106
Abstract
Inspired by the Toyota Mirai, this study presents a high-fidelity data-driven approach for modelling and simulation of a fuel cell hybrid electric powertrain. This study utilises technical assessment data sourced from Argonne National Laboratory’s publicly available report, faithfully modelling most of the vehicle [...] Read more.
Inspired by the Toyota Mirai, this study presents a high-fidelity data-driven approach for modelling and simulation of a fuel cell hybrid electric powertrain. This study utilises technical assessment data sourced from Argonne National Laboratory’s publicly available report, faithfully modelling most of the vehicle subsystems as data-driven entities. The simulation framework is developed in the MATLAB/Simulink environment and is based on a power dynamics approach, capturing nonlinear interactions and performance intricacies between different powertrain elements. This study investigates subsystem synergies and performance boundaries under a combined driving cycle composed of the NEDC, WLTP Class 3 and US06 profiles, representing urban, extra-urban and aggressive highway conditions. To emulate the real-world load-following strategy, a state transition power management and allocation method is synthesised. The proposed method dynamically governs the power flow between the fuel cell stack and the traction battery across three operational states, allowing the battery to stay within its allocated bounds. This simulation framework offers a near-accurate and computationally efficient digital counterpart to a commercial hybrid powertrain, serving as a valuable tool for educational and research purposes. Full article
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27 pages, 5196 KiB  
Article
Impact of Hydrogen Release on Accidental Consequences in Deep-Sea Floating Photovoltaic Hydrogen Production Platforms
by Kan Wang, Jiahui Mi, Hao Wang, Xiaolei Liu and Tingting Shi
Hydrogen 2025, 6(3), 52; https://doi.org/10.3390/hydrogen6030052 - 29 Jul 2025
Viewed by 252
Abstract
Hydrogen is a potential key component of a carbon-neutral energy carrier and an input to marine industrial processes. This study examines the consequences of coupled hydrogen release and marine environmental factors during floating photovoltaic hydrogen production (FPHP) system failures. A validated three-dimensional numerical [...] Read more.
Hydrogen is a potential key component of a carbon-neutral energy carrier and an input to marine industrial processes. This study examines the consequences of coupled hydrogen release and marine environmental factors during floating photovoltaic hydrogen production (FPHP) system failures. A validated three-dimensional numerical model of FPHP comprehensively characterizes hydrogen leakage dynamics under varied rupture diameters (25, 50, 100 mm), transient release duration, dispersion patterns, and wind intensity effects (0–20 m/s sea-level velocities) on hydrogen–air vapor clouds. FLACS-generated data establish the concentration–dispersion distance relationship, with numerical validation confirming predictive accuracy for hydrogen storage tank failures. The results indicate that the wind velocity and rupture size significantly influence the explosion risk; 100 mm ruptures elevate the explosion risk, producing vapor clouds that are 40–65% larger than 25 mm and 50 mm cases. Meanwhile, increased wind velocities (>10 m/s) accelerate hydrogen dilution, reducing the high-concentration cloud volume by 70–84%. Hydrogen jet orientation governs the spatial overpressure distribution in unconfined spaces, leading to considerable shockwave consequence variability. Photovoltaic modules and inverters of FPHP demonstrate maximum vulnerability to overpressure effects; these key findings can be used in the design of offshore platform safety. This study reveals fundamental accident characteristics for FPHP reliability assessment and provides critical insights for safety reinforcement strategies in maritime hydrogen applications. Full article
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19 pages, 2212 KiB  
Article
Impact of the Anode Serpentine Channel Depth on the Performance of a Methanol Electrolysis Cell
by Vladimir L. Meca, Elena Posada, Antonio Villalba-Herreros, Rafael d’Amore-Domenech, Teresa J. Leo and Óscar Santiago
Hydrogen 2025, 6(3), 51; https://doi.org/10.3390/hydrogen6030051 - 19 Jul 2025
Viewed by 350
Abstract
This work addresses for the first time the effect of anode serpentine channel depth on Methanol Electrolysis Cells (MECs) and Direct Methanol Fuel Cells (DMFCs) for improving performance of both devices. Anode plates with serpentine flow fields of 0.5 mm, 1.0 mm and [...] Read more.
This work addresses for the first time the effect of anode serpentine channel depth on Methanol Electrolysis Cells (MECs) and Direct Methanol Fuel Cells (DMFCs) for improving performance of both devices. Anode plates with serpentine flow fields of 0.5 mm, 1.0 mm and 1.5 mm depths are designed and tested in single-cells to compare their behaviour. Performance was evaluated through methanol crossover, polarization and power density curves. Results suggest shallower channels enhance mass transfer efficiency reducing MEC energy consumption for hydrogen production at 40 mA∙cm−2 by 4.2%, but increasing methanol crossover by 30.3%. The findings of this study indicate 1.0 mm is the best depth among those studied for a MEC with 16 cm2 of active area, while 0.5 mm is the best for a DMFC with the same area with an increase in peak power density of 14.2%. The difference in results for both devices is attributed to higher CO2 production in the MEC due to its higher current density operation. This increased CO2 production alters anode two-phase flow, partially hindering the methanol oxidation reaction with shallower channels. These findings underscore the critical role of channel depth in the efficiency of both MEC and DMFC single-cells. Full article
(This article belongs to the Topic Hydrogen Energy Technologies, 3rd Edition)
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37 pages, 2077 KiB  
Review
Use of Hydrogen Energy and Fuel Cells in Marine and Industrial Applications—Current Status
by Sorin-Marcel Echim and Sanda Budea
Hydrogen 2025, 6(3), 50; https://doi.org/10.3390/hydrogen6030050 - 17 Jul 2025
Viewed by 665
Abstract
The promising development of hydrogen and fuel cell technologies has garnered increased attention in recent years, assuming a significant role in industrial applications and the decarbonisation of the shipping industry. Given that the shipping industry generates considerable greenhouse gas emissions, it is crucial [...] Read more.
The promising development of hydrogen and fuel cell technologies has garnered increased attention in recent years, assuming a significant role in industrial applications and the decarbonisation of the shipping industry. Given that the shipping industry generates considerable greenhouse gas emissions, it is crucial and imperative to implement integrated solutions based on clean energy sources, thereby meeting the proposed climate objectives. This study presents the standard hydrogen production, storage, and transport methods and analysis technologies that use hydrogen fuel cells in marine and industrial applications. Technologies based on hydrogen fuel cells and hybrid systems will have an increased perspective of application in industry and maritime transport under the conditions of optimising technological models, developing the hydrogen industrial chain, and updating standards and regulations in the field. However, there are still many shortcomings. The paper’s main contribution is analysing the hydrogen industrial chain, presenting the progress and obstacles associated with the technologies used in industrial and marine applications based on hydrogen energy. Full article
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16 pages, 2200 KiB  
Article
Effect of Partial Noble Metal (M = Pd, Rh, Ru, Pt) Substitution in La1−xSrxCo1−yMyO3 Perovskite-Derived Catalysts for Dry Reforming of Methane
by Pradeep Kumar Yadav, Ganesh Jabotra and Sudhanshu Sharma
Hydrogen 2025, 6(3), 49; https://doi.org/10.3390/hydrogen6030049 - 16 Jul 2025
Viewed by 538
Abstract
This study examines the surface chemistry of platinum, palladium, rhodium, and ruthenium-substituted lanthanum strontium cobaltate perovskite catalysts in the context of the dry reforming of methane (DRM). The catalysts were synthesized by the solution combustion method and characterized by using a series of [...] Read more.
This study examines the surface chemistry of platinum, palladium, rhodium, and ruthenium-substituted lanthanum strontium cobaltate perovskite catalysts in the context of the dry reforming of methane (DRM). The catalysts were synthesized by the solution combustion method and characterized by using a series of techniques. To explore the effect of noble metal ion substitution on the DRM, surface reaction was probed by CH4/CO2 TPSR using mass spectroscopy. It was recognized that La1−xSrxCo1−yPdyO3 show the best activities for the reaction in terms of the temperature but became deactivated over time. CH4/CO2 temperature-programmed surface reactions (TPSRs) were set up to unravel the details of the surface phenomena responsible for the deactivation of the DRM activity on the LSPdCO. The CH4/CO2 TPSR analysis conclusively demonstrated the importance of lattice oxygen in the removal of carbon, which is responsible for the stability of the catalysts on the synthesized perovskites upon noble metal ion substitution. Full article
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15 pages, 2643 KiB  
Article
Hot Mineral Water as a Medium for Molecular Hydrogen Reactions in the Primordial Hydrosphere for the Origin of Life
by Ignat Ignatov, Teodora P. Popova, Paunka Vassileva, Yordan G. Marinov and Mario T. Iliev
Hydrogen 2025, 6(3), 48; https://doi.org/10.3390/hydrogen6030048 - 15 Jul 2025
Viewed by 1423
Abstract
Studies have been conducted on the potential development of Hydrogenobacter thermophilus and Pseudomonas aeruginosa in an anaerobic environment, both in the presence and absence of molecular hydrogen (H2). H. thermophilus developed better at 70 °C and pH 7.0 in the presence [...] Read more.
Studies have been conducted on the potential development of Hydrogenobacter thermophilus and Pseudomonas aeruginosa in an anaerobic environment, both in the presence and absence of molecular hydrogen (H2). H. thermophilus developed better at 70 °C and pH 7.0 in the presence of molecular hydrogen. It also multiplied in its absence, but to a lesser extent. Dissolved hydrogen in an amount of 1 ppm is biologically active for this thermophilic chemolithotrophic species. The tested strains of P. aeruginosa also showed growth under anaerobic conditions in the presence of H2 concentrations of 1 ppm and 2 ppm, which was ensured by adding Mg. The results indicate that not only the oldest microorganisms on our planet, archaebacteria, but also current species such as H. thermophilus and P. aeruginosa are capable of development under conditions characteristic of the ancient hydrosphere. DFT analyses showed that hydrogen water forms stable water clusters, whose hydrogen bond network retains and stabilizes reducing agents such as molecular hydrogen and magnesium (Mg0). This creates a microenvironment in which key redox processes associated with autotrophic growth and chemical evolution can occur. This is a realistic model of the Earth’s primordial hydrosphere’s conditions. Full article
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22 pages, 2967 KiB  
Article
Techno-Economic Assessment of Pink Hydrogen Produced from Small Modular Reactors for Maritime Applications
by E. E. Pompodakis and T. Papadimitriou
Hydrogen 2025, 6(3), 47; https://doi.org/10.3390/hydrogen6030047 - 12 Jul 2025
Viewed by 430
Abstract
This paper presents a techno-economic assessment of liquid hydrogen produced from small modular reactors (SMRs) for maritime applications. Pink hydrogen is examined as a carbon-free alternative to conventional marine fuels, leveraging the zero-emission profile and dispatchable nature of nuclear energy. Using Greece as [...] Read more.
This paper presents a techno-economic assessment of liquid hydrogen produced from small modular reactors (SMRs) for maritime applications. Pink hydrogen is examined as a carbon-free alternative to conventional marine fuels, leveraging the zero-emission profile and dispatchable nature of nuclear energy. Using Greece as a case study, the analysis includes both production and transportation costs, along with a sensitivity analysis on key parameters influencing the levelized cost of hydrogen (LCOH), such as SMR and electrolyzer CAPEX, uranium cost, and SMR operational lifetime. Results show that with an SMR CAPEX of 10,000 EUR/kW, the LCOH reaches 6.64 EUR/kg, which is too high to compete with diesel under current market conditions. Economic viability is achieved only if carbon costs rise to 0.387 EUR/kg and diesel prices exceed 0.70 EUR/L. Under these conditions, a manageable deployment of fewer than 1000 units (equivalent to 77 GW) is sufficient to achieve economies of mass production. Conversely, lower carbon and fuel prices require over 10,000 units (770 GW), rendering their establishment impractical. Full article
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25 pages, 5958 KiB  
Article
Comparative Designs for Standalone Critical Loads Between PV/Battery and PV/Hydrogen Systems
by Ahmed Lotfy, Wagdy Refaat Anis, Fatma Newagy and Sameh Mostafa Mohamed
Hydrogen 2025, 6(3), 46; https://doi.org/10.3390/hydrogen6030046 - 5 Jul 2025
Viewed by 350
Abstract
This study presents the design and techno-economic comparison of two standalone photovoltaic (PV) systems, each supplying a 1 kW critical load with 100% reliability under Cairo’s climatic conditions. These systems are modeled for both the constant and the night load scenarios, accounting for [...] Read more.
This study presents the design and techno-economic comparison of two standalone photovoltaic (PV) systems, each supplying a 1 kW critical load with 100% reliability under Cairo’s climatic conditions. These systems are modeled for both the constant and the night load scenarios, accounting for the worst-case weather conditions involving 3.5 consecutive cloudy days. The primary comparison focuses on traditional lead-acid battery storage versus green hydrogen storage via electrolysis, compression, and fuel cell reconversion. Both the configurations are simulated using a Python-based tool that calculates hourly energy balance, component sizing, and economic performance over a 21-year project lifetime. The results show that the PV/H2 system significantly outperforms the PV/lead-acid battery system in both the cost and the reliability. For the constant load, the Levelized Cost of Electricity (LCOE) drops from 0.52 USD/kWh to 0.23 USD/kWh (a 56% reduction), and the payback period is shortened from 16 to 7 years. For the night load, the LCOE improves from 0.67 to 0.36 USD/kWh (a 46% reduction). A supplementary cost analysis using lithium-ion batteries was also conducted. While Li-ion improves the economics compared to lead-acid (LCOE of 0.41 USD/kWh for the constant load and 0.49 USD/kWh for the night load), this represents a 21% and a 27% reduction, respectively. However, the green hydrogen system remains the most cost-effective and scalable storage solution for achieving 100% reliability in critical off-grid applications. These findings highlight the potential of green hydrogen as a sustainable and economically viable energy storage pathway, capable of reducing energy costs while ensuring long-term resilience. Full article
(This article belongs to the Special Issue Advances in Hydrogen Production, Storage, and Utilization)
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15 pages, 4230 KiB  
Article
Synergistic Cs/P Co-Doping in Tubular g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution
by Juanfeng Gao, Xiao Lin, Bowen Jiang, Haiyan Zhang and Youji Li
Hydrogen 2025, 6(3), 45; https://doi.org/10.3390/hydrogen6030045 - 3 Jul 2025
Viewed by 330
Abstract
Developing high-performance photocatalysts for solar hydrogen production requires the synergistic modulation of chemical composition, nanostructure, and charge carrier transport pathways. Herein, we report a Cs and P co-doped tubular graphitic carbon nitride (Cs/PTCN-x) photocatalyst synthesized via a strategy that integrates elemental doping with [...] Read more.
Developing high-performance photocatalysts for solar hydrogen production requires the synergistic modulation of chemical composition, nanostructure, and charge carrier transport pathways. Herein, we report a Cs and P co-doped tubular graphitic carbon nitride (Cs/PTCN-x) photocatalyst synthesized via a strategy that integrates elemental doping with morphological engineering. Structural characterizations reveal that phosphorus atoms substitute lattice carbon to form P-N bonds, while Cs+ ions intercalate between g-C3N4 layers, collectively modulating surface electronic states and enhancing charge transport. Under visible-light irradiation (λ ≥ 400 nm), the optimized Cs/PTCN-3 catalyst achieves an impressive hydrogen evolution rate of 8.085 mmol·g−1·h−1—over 33 times higher than that of pristine g-C3N4. This remarkable performance is attributed to the multidimensional synergy between band structure tailoring and hierarchical porous tubular architecture, which together enhance light absorption, charge separation, and surface reaction kinetics. This work offers a versatile approach for the rational design of g-C3N4-based photocatalysts toward efficient solar-to-hydrogen energy conversion. Full article
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20 pages, 3503 KiB  
Article
Finite Element Analysis Framework for Structural Safety Evaluation of Type IV Hydrogen Storage Vessel
by Gunwoo Kim, Hyewon Kim, Hanmin Park, Kyuhwan Park, Sujin Yoon, Hansu Lee, Seokjin Lee, Jonglyul Kim, Gyehyoung Yoo, Younggil Youn and Hansang Kim
Hydrogen 2025, 6(3), 44; https://doi.org/10.3390/hydrogen6030044 - 2 Jul 2025
Viewed by 306
Abstract
Type IV composite overwrapped pressure vessels (COPVs) store hydrogen at pressures up to 70 MPa and must meet stringent safety standards through physical testing. However, full-scale burst, plug torque, axial compression, impact, and drop tests are time-consuming and costly. This study proposes a [...] Read more.
Type IV composite overwrapped pressure vessels (COPVs) store hydrogen at pressures up to 70 MPa and must meet stringent safety standards through physical testing. However, full-scale burst, plug torque, axial compression, impact, and drop tests are time-consuming and costly. This study proposes a unified finite element analysis (FEA) workflow that replicates these mandatory tests and predicts failure behavior without physical prototypes. Axisymmetric and three-dimensional solid models with reduced-integration elements were constructed for the polyamide liner, aluminum boss, and carbon/epoxy composite. Burst simulations showed that increasing the hoop-to-axial stiffness ratio shifts peak stress to the cylindrical region, promoting a longitudinal rupture—considered structurally safer. Plug torque and axial load simulations revealed critical stresses at the boss–composite interface, which can be reduced through neck boss shaping and layup optimization. A localized impact with a 25 mm sphere generated significantly higher stress than a larger 180 mm impactor under equal energy. Drop tests confirmed that 45° oblique drops cause the most severe dome stresses due to thin walls and the lack of hoop support. The proposed workflow enables early-stage structural validation, supports cost-effective design optimization, and accelerates the development of safe hydrogen storage systems for automotive and aerospace applications. Full article
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29 pages, 1717 KiB  
Review
Development of the Hydrogen Market and Local Green Hydrogen Offtake in Africa
by Chidiebele E. J. Uzoagba, Princewill M. Ikpeka, Somtochukwu Godfrey Nnabuife, Peter Azikiwe Onwualu, Fayen Odette Ngasoh and Boyu Kuang
Hydrogen 2025, 6(3), 43; https://doi.org/10.3390/hydrogen6030043 - 24 Jun 2025
Viewed by 1058
Abstract
Creating a hydrogen market in Africa is a great opportunity to assist in the promotion of sustainable energy solutions and economic growth. This article addresses the legislation and regulations that need to be developed to facilitate growth in the hydrogen market and allow [...] Read more.
Creating a hydrogen market in Africa is a great opportunity to assist in the promotion of sustainable energy solutions and economic growth. This article addresses the legislation and regulations that need to be developed to facilitate growth in the hydrogen market and allow local green hydrogen offtake across the continent. By reviewing current policy and strategy within particular African countries and best practices globally from key hydrogen economies, the review establishes compelling issues, challenges, and opportunities unique to Africa. The study identifies the immense potential in Africa for renewable energy, and, in particular, for solar and wind, as the foundation for the production of green hydrogen. It examines how effective policy frameworks can establish a vibrant hydrogen economy by bridging infrastructural gaps, cost hurdles, and regulatory barriers. The paper also addresses how local offtake contracts for green hydrogen can be used to stimulate economic diversification, energy security, and sustainable development. Policy advice is provided to assist African authorities and stakeholders in the deployment of enabling regulatory frameworks and the mobilization of funds. The paper contributes to global hydrogen energy discussions by introducing Africa as an eligible stakeholder in the emerging hydrogen economy and outlining prospects for its inclusion into regional and global energy supply chains. Full article
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