Hydrogen

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

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

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

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

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

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 La_1−xSr_xCo_1−yPd_yO₃ 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

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

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

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

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

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

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

Research on and the demand for hydrogen-powered vehicles have grown significantly over the past two decades as a solution for sustainable transportation. Bibliometric analysis helps to assess research trends, key contributions, and the impact of studies focused on the safety and reliability of hydrogen-powered vehicles. This study provides a novel methodology for bibliometric analysis that systematically evaluates the global research landscape on hydrogen-powered vehicle reliability using Scopus-indexed publication data (1965 to 2024). Eighteen key parameters were identified for this study that are often used by researchers for the bibliometric analysis of hydrogen-related studies. Data analytics, VOSviewer-based visualization, and research impact indicators were integrated to comprehensively assess publication trends, key contributors, and citation networks. The analysis revealed that hydrogen-powered vehicle reliability research has experienced significant growth over the past two decades, with leading contributions from high-impact journals, renowned institutions, and influential authors. The present study emphasizes the significance of greater funding as well as open-access distribution. Furthermore, while major worldwide institutions have significant institutional relationships, there are gaps in real-world hydrogen infrastructure evaluations, large-scale experimental validation, and policy-driven research. Full article

This article examines hydrogen production using Proton Exchange Membrane Electrolyzers (PEMELs) and photovoltaic (PV) panels using Maximum Power Point Tracking (MPPT). This method has great potential to maximize the production of pure hydrogen, making it possible to reduce and potentially eliminate the difficulties associated with sudden drops and interruptions in output power. The use of MPPT algorithms in conjunction with Direct Current to Direct Current (DC/DC) converters helps improve the energy efficiency of systems. This study aims to enhance green hydrogen production by optimizing PV-PEMEL performance using commercial power electronics, while improving energy storage and reducing costs for sustainable hydrogen generation. Full article

As the attention to using hydrogen as a potential energy storage medium for power generation and mobility increases, hydrogen production, storage, and transportation safety should be considered. For instance, hydrogen’s extreme physical and chemical properties and the wide range of flammable concentrations raise many concerns about the current safety measures in processing other flammable gases. Hydrogen cloud accumulation in the case of leakage in confined spaces can lead to reaching the hydrogen lower flammability limit (LFL) within seconds if the hydrogen is not properly evacuated from the space. At Jülich Research Centre, hydrogen mixed with natural gas is foreseen to be used as a fuel for the central heating system of the campus. In this work, the release, dispersion, formation, and spread of the hydrogen cloud in the case of hydrogen leakage inside the central utility building of the campus are numerically simulated using the OpenFOAM-based containmentFOAM CFD codes. Additionally, different ventilation scenarios are simulated to investigate the behavior of the hydrogen cloud. The results show that locating exhaust openings close to the ceiling and the potential leakage source can be the most effective way to safely evacuate hydrogen from the building. Additionally, locating the exhaust outlets near the ceiling can decrease the combustible cloud volume by more than 25% compared to side openings far below the ceiling. Also, hydrogen concentrations can reach the LFL in case of improper forced ventilation after only 8 s, while it does not exceed 0.15% in the case of natural ventilation under certain conditions. The results of this work show the significant effect of locating exhaust outlets near the ceiling and the importance of natural ventilation to mitigate the effects of hydrogen leakage. The approach illustrated in this study can be used to study hydrogen dispersion in closed buildings in case of leakage and the proper design of the ventilation outlets for closed spaces with hydrogen systems. Full article

Hydrogen atom transfer (HAT), a concerted charge transfer involving two elementary particles, a proton and an electron, plays a key role in many areas of chemistry and biochemistry. A molecular dynamics study based on density functional theory was performed to investigate the reaction mechanism of hydrogen atom transfer from quercetin anions to the hydroxyl radical in a neutral aqueous media. Intrinsic bond orbital (IBO) analysis of a series of structures obtained from trajectories was performed in simulations in which the reaction occurred, and the electron flow along the reaction coordinate was determined and applied to investigate the reaction mechanism. The reaction in the simulations proceeded rapidly as proton-coupled electron transfer (PCET) or electron transfer–proton transfer (ET-PT) depending on the initial position and solvation of the reactants. Full article

We investigated experimentally the influence of flow conditions and electrode position on a diffusion H₂–air flame subjected to an external electric field. We determined the minimum impurity level required to observe changes in flame properties with applied voltage. Flame OH chemiluminescence signals were recorded using a UV-sensitive CCD array as a function of voltage (+10 to −10 kV) applied to a stainless-steel ring electrode placed around the burner nozzle. Changes in chemiluminescence signals are reported as a function of electrode height above the burner, airflow, and fuel composition. Significant changes in OH* distributions were observed for voltages below −5 kV. Under optimum conditions, the height of the chemiluminescence flame decreased by up to 67% at the maximum applied voltage. The flame transitioned from a teardrop shape to a flat, open-tip flame at a voltage corresponding to an inflection point in the flame height–voltage profiles. Increasing the airflow rate shifted the inflection point to more negative values until almost suppressing the effect of the electric field on the flame structure. This study reveals that carbon impurities in hydrogen fuel as low as 10 ppm are sufficient to observe significant effects from external electric fields without changing the underlying neutral chemistry. We also determine the set of parameters that control the amplitude of the structural change. Full article

To pursue the total decarbonization goal set at 2050, the introduction of hydrogen to replace the usage of fossil fuel in hard-to-abate industrial sectors is crucial. Hydrogen will replace natural gas in hard-to-abate sectors where natural gas is required to make heat necessary for the industrial process. Naturally, all this is worthwhile if hydrogen is produced following a green pathway, meaning that it is connected with renewable sources. In this manuscript, a techno-economic analysis related to a real case scenario is carried out. The real system addressed involves continuous high-temperature industrial furnace operation with a seasonally variable but stable thermal energy demand, representing typical conditions of hard-to-abate industrial processes. Solar photovoltaic panels combined with batteries are used to generate and store electricity that in turn is used to generate green hydrogen. Different scenarios are considered, including mixed natural gas/hydrogen, the seasonal variability of industrial needs, and the variability of solar production. The economic aspects considered include the usage of anion exchange membrane water electrolyzers (AEMWEs) to produce green hydrogen, the improvement in efficiency during operations (operational costs, OPEX), and the decrease in the AEMWE cost (Capital expenditures, CAPEX) that occur over time. The study shows that the hydrogen production cost could decrease from 12.6 EUR kg⁻¹ in 2024 to 9.7 EUR kg⁻¹ in 2030, with further reduction to 8.7 EUR kg⁻¹ achievable through seasonal blending strategies. CO₂ emissions are significantly reduced through partial displacement of natural gas with green hydrogen, highlighting the environmental potential of the system. Full article

The gasification of cellulose typically requires high temperatures (>600 °C) due to the thermal stability of levoglucosan, a major intermediate formed during pyrolysis. In this study, we investigated the gasification behavior of cellulose by combining infrared (IR) heating with low-power dielectric barrier discharge (DBD) plasma treatment. Cellulose filter paper was first pyrolyzed using localized IR irradiation (2 kW for 30 s), generating mist-like volatile products including levoglucosan. These volatiles were then exposed to DBD plasma (16–64 W for 1 or 3 min) under Ar flow. Despite the relatively low estimated gas temperatures below 240 °C in the plasma region, gas yields, including H₂ and CO, increased markedly with discharge power, reaching up to 72.6 wt% at 64 W for 3 min—more than four times that obtained with IR heating alone. These results indicate that DBD plasma facilitates the gasification of pyrolysis volatiles under significantly lower temperature conditions than those required in conventional thermal gasification. This approach may offer a route toward low-temperature biomass gasification with reduced tar, coke, and clinker formation. Full article