After leakage from buried hydrogen-blended natural gas pipelines, gas may seep through the soil into quasi-closed enclosures and form buoyancy-driven non-uniform combustible clouds. The effect of ignition delay on such clouds remains insufficiently understood, particularly regarding the relationship between visible flame development and local thermal response. In this study, 44 soil-seepage combustion experiments were conducted in a 1.5 m × 1.5 m × 1.5 m enclosure. The methane and hydrogen concentrations at three heights, flame evolution, and transient temperatures were measured using gas sensors, high-speed imaging, and thermocouples. The ignition delay ranged from 27 s to 5429 s, with hydrogen blending ratios of 10–30 vol% and ignition positions at the floor, middle, and ceiling levels. The results show that longer ignition delays generally weakened the visible flame luminosity and propagation extent. However, the peak temperature measured by the central thermocouple did not decrease. For the long-delay subset with td > 307 s, the central peak temperature increased with the ignition delay, with R2 = 0.74. Concentration measurements indicated that preferential hydrogen migration and slower methane redistribution continuously reconfigured the local flammability state before ignition. These findings suggest that, in enclosed soil-seepage HBNG scenarios, prolonged ignition delay may weaken visible flame development but does not necessarily reduce local thermal exposure.

Hydrogen supply chains require coordinated planning from upstream production to downstream distribution and end-user delivery; however, significant logistical challenges remain under emerging hydrogen infrastructure constraints. In particular, the transportation sector faces difficulties in achieving efficient distribution while accounting for limited hydrogen refueling availability and vehicle range restrictions. This study evaluates key network design decisions involving distribution center location and fuel cell electric vehicle (FCEV) routing while incorporating hydrogen refueling stations within the transportation system. An integrated framework is proposed by combining K-means clustering for DC location planning with a hydrogen-powered FCEV routing model. Hydrogen refueling stations are incorporated as routing constraints to ensure feasible distribution operations. Next, a case study in Thailand is conducted to validate the proposed model under realistic logistical conditions. The results illustrate how clustering-based allocation improves network coordination, while the integrated FCEV routing approach ensures feasible and efficient delivery under refueling constraints. Comparative analysis further highlights improvements in system performance and provides practical insights for designing coordinated hydrogen logistics systems across integrated supply chain networks.

The reaction of aluminum with water is a promising method for producing hydrogen on demand for autonomous energy systems. However, its practical implementation faces the challenge of process control due to high exothermicity, leading to particle sintering and thermal instability, especially when using highly reactive nanopowders. The goal of this study is to implement an integrated approach to controlling this reaction, aimed at minimizing these risks. The approach is based on the principle of spatial and temporal distribution of reactants to ensure uniform heat release. Two process management methods were investigated: electrostatic application of aluminum powder to the reactor walls with its gradual release and pre-treatment of a nanopowder-ice mixture. Using a macrokinetic mathematical model, calculations of the conversion kinetics and heat release were performed and compared with experimental data. The results showed that both methods prevent slurry self-heating and achieve uniform hydrogen generation at a constant rate. In particular, the use of a pre-frozen mixture ensured stable hydrogen production over a long period of time without additional heating or stirring. The proposed approaches can be used in the design of safe and efficient hydrogen generators for autonomous power plants.

The main goal of this study was to develop and validate a laboratory-scale prototype of a rechargeable metal hydride (MH)–air battery integrating gas diffusion electrodes (GDEs) and MH electrodes with stable performance over extended operation (>500 h) and repeated charge–discharge cycling (>100 cycles). This work addresses the critical transition from optimized electrode materials to a functioning system by investigating its operation under deep-discharge conditions, a key but still insufficiently explored regime in the context of stationary renewable energy storage. In this respect, this study explicitly targets the practical applicability of the developed system rather than focusing solely on material-level performance. The most efficient electrode materials, previously optimized, were successfully integrated into a single-cell configuration and systematically evaluated under various operating conditions. By determining the limiting current density for stable GDE operation, an appropriate operating window was defined, enabling maximum capacity utilization without compromising electrode integrity. At a current density of 10 mA, the maximum depth of discharge was achieved at a cell voltage of 575 mV, ensuring operation in a regime that limits GDE degradation while maintaining high energy efficiency. In addition, the electrode retains its mechanical stability after operation is interrupted, indicating good structural robustness. Furthermore, the performance of two identical cells connected in series was investigated to assess system scalability. The cells were operated under near-limit conditions and exhibited stable behavior. Overall, the present results confirm that the developed MH–air battery system extends beyond laboratory-scale validation and shows strong potential for implementation in stationary energy storage applications.

Hydrogen (H2) was produced from recycled aluminum microparticles (180–250, 300–425, and 425–500 μm) via alkaline hydrolysis using a 1.0 M NaOH solution to enhance oxide layer removal and aluminum dissolution. Maximum hydrogen flow rates of approximately 13, 15, and 19 mL·min−1 were obtained, confirming that smaller particle sizes promote faster reaction rates due to increased specific surface area. The hydrogen evolution exhibited two-stage kinetic behavior: an initial stage characterized by rapid aluminum dissolution and increasing H2 production, followed by a gradual decline associated with the formation of a passivating Al(OH)3 layer. Despite the higher reaction rates observed for smaller particles, the maximum cumulative hydrogen production was obtained for the intermediate particle size (363 µm, 132 mL), compared to 106 mL and 102 mL for 215 µm and 463 µm, respectively, indicating a trade-off between surface area and passivation effects. Kinetic analysis based on the shrinking core model showed excellent agreement (R2 = 99.94–99.97%), with rate constants of 0.137, 0.064, and 0.050 min−1. The relationship k ∝ d−n (n ≈ 1.4) suggests a mixed kinetic regime involving both surface reaction and diffusion through the Al(OH)3 layer. These findings indicate that hydrogen generation can be modulated by particle size; however, the relatively low flow rates and yields limit its immediate practical applicability.

Hydrogen is a clean energy carrier with broad application potential. This study focuses on improving hydrogen production efficiency in a proton exchange membrane (PEM) electrolyzer system that integrates a photovoltaic (PV) array, a battery energy storage system, and the electrolyzer. The PV array is interfaced with the electrolyzer through a buck converter using a maximum power point tracking (MPPT) algorithm to ensure maximum energy harvesting. A key contribution of this work is the integration of a battery system through a dual-active-bridge (DAB) converter. The DAB converter employs a multilayer perceptron (MLP) model to dynamically regulate the electrolyzer current and maintain optimal operating efficiency. An adaptive energy management strategy is further proposed to address solar irradiance fluctuations and enhance long-term operational stability. The MLP model is developed in Python and embedded into a PLECS simulation environment. The simulation results verify the effectiveness of the proposed control approach and efficiency optimization scheme. Throughout the simulation period, the PEM electrolyzer sustains an optimal efficiency of 69.9% under maximum PV power output. A limitation of this study is that the efficiency model is derived from the literature and does not yet consider all operational factors, indicating the need for refinement in future work.

The development of a green hydrogen industry is a strategic priority for Russia’s energy transition, yet the dynamics of scaling up this nascent sector remain poorly understood. This study uses agent-based modeling (ABM) to simulate the co-evolution of Russia’s electricity, hydrogen, and electrolyzer sectors over 2024–2050. The model incorporates three types of heterogeneous agents (power producers, hydrogen producers, and electrolyzer manufacturers) operating under bounded rationality. Four scenarios are examined across 50 Monte Carlo runs each, varying the electrolyzer learning rate (10–25%), willingness to pay for green hydrogen (2–6 $/kg), and government support intensity. The results reveal an endogenous three-phase development pattern: Phase I (2024–2028) dominated by renewable capacity build-up reaching ~30 GW; Phase II (2029–2040) characterized by rapid electrolyzer deployment scaling to 14.5 GW; and Phase III (2041–2050) marked by stabilization at approximately 30 GW producing 1.12 Mt/year at 3.1 $/kg. Two critical thresholds are identified: renewable capacity exceeding 30–38 GW and low-cost electricity above 4–7 TWh/year. The electrolyzer learning rate emerges as the most influential parameter, while the pessimistic scenario confirms market failure without a green premium (WTP < 2 $/kg). Strategic investment losses of 2–6 billion USD are necessary catalysts for industry emergence. Russia’s 2030 production target (0.55 Mt) is found structurally infeasible under all scenarios.

One of the main challenges in hydrogen production via electrolysis is the reliable measurement of the electrical work supplied. In this work, a robust electronic data acquisition system was developed to obtain precise and accurate data to evaluate the electrical work. The electrolytic concentration and electrical work were the main variables in this study. The supplied electrical energy was analyzed under both constant and pulsed voltage conditions. The results reveal that hydrogen production depends on voltage amplitude, PWM, and electrolyte concentration. The applied voltage shows a slight positive correlation with hydrogen production. PWM influences hydrogen production in the range of 0 to 1 Hz, while no significant effect is observed at higher frequencies. Electrolyte concentration has a stronger influence on hydrogen production in the range of 0.125 to 0.25 M. The optimal operating conditions were identified at 0.375 M, 1 Hz and 6 VDC, and under these conditions the hydrogen production is 0.145 mL/s and the specific energy is 165 kWh/kg.

The rally to mitigate growing carbon emissions and climate change necessitates decarbonization strategies, with hydrogen emerging as a key candidate option across multiple sectors. This review examines the current state of the hydrogen economy, including production, implementation, and associated risks. Hydrogen’s versatility in industry, transportation, and energy storage is highlighted, alongside the challenges of transitioning from fossil fuel-based production. It explores the current state of hydrogen technologies, differentiating between green, blue, and gray hydrogen production methods, and highlights advancements in production techniques like thermochemical water splitting. Key findings show that while green hydrogen offers the cleanest pathway, high production costs and infrastructure limitations remain significant barriers to widespread adoption. This study also addresses safety concerns and public perception, emphasizing the need for robust risk assessment methodologies and management approaches. Furthermore, this paper underscores the importance of technological innovations, such as high-temperature electrolysis and synergies with renewable energy sources, to enhance efficiency and sustainability. Policy recommendations include financial incentives, regulatory frameworks, and international cooperation to accelerate hydrogen adoption and balance its development with other low-carbon solutions.

The decarbonization of hard-to-abate sectors remains a significant challenge in achieving net-zero emissions targets. These industries depend on energy-dense fuels, making direct electrification and the direct use of hydrogen technically and economically challenging. Electrofuels present a promising pathway to reducing emissions while leveraging surplus renewable energy. This review evaluates the feasibility of electrofuels for deep decarbonization, focusing on production processes, energy demands, and economic viability. Environmental performance is discussed in terms of lifecycle greenhouse gas (GHG) emissions, carbon circularity considerations, and energy conversion efficiencies, while techno-economic feasibility is evaluated using metrics such as levelized cost of hydrogen (LCOH), CO2 capture costs, and projected fuel production costs. The review indicates that while electrofuels can achieve substantial lifecycle emission reductions up to 40–90%, depending on pathway and electricity source, their deployment remains constrained by high energy demand, conversion losses, and capital costs. Projected reductions in LCOH to below $2.1/kg by 2030 and declining renewable electricity costs could significantly improve competitiveness, particularly in regions with abundant solar and wind resources. However, substantial trade-offs exist between efficiency, infrastructure compatibility, scalability, and carbon neutrality across different electrofuel routes. The review identifies key technological bottlenecks, cost drivers, and research priorities necessary to position electrofuels as a strategic solution for deep decarbonization in sectors where direct electrification is not feasible.