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Green H 2 (GH) has emerged as a highly promising medium for the transportation of eco-friendly energy. The utilization of H 2 as the primary operational medium in H 2 -based energy storage systems and fuel cells has facilitated the integration of these systems with various other renewable energy sources, rendering such integration highly viable. This review presents an overview of the current advancements in the field of GH production techniques using water electrolyzers powered by renewable energy sources. The present paper starts with a concise overview of several production techniques and a detailed analysis of various types of water electrolyzer. It also offers a thorough examination of H 2 production methods utilizing solar, wind, and hybrid systems. An economic evaluation of GH production was analyzed by comparing the costs associated with different renewable sources. This study focuses on investigating the challenges and advantages of GH and the implementation of large-scale commercial operations. The proton exchange membrane water electrolyzer (PEMWE) technologies boast higher current densities (1-2Acm−2) than alkaline water electrolyzer (AWE); the PEMWE technologies also produce a higher purity of H 2 up to 99.9999 %. The wind energy-associated PEM LCOH ranges from 5.3 to 9.29 $/kg. AWE had levelized cost of H 2 (LCOH) of 7.49–7.59 $/kg. Other studies show that SOE-based LCOH ranges from 6 to 9.34 $/kg and should drop to 1.9 $/kg by 2050. The cost of GH was found to be significantly influenced by the rated wind speed compared to other wind turbine parameters, and it ranged from $1.7/kg to $40.00/kg. [Display omitted] • GH could help reduce global warming and transition to a more sustainable energy system. • Discussion on grand challenges, prospects, and key recommendations to the commercialization of water electrolysis systems. • The lack of global hydrogen standards hinders the growth of the global hydrogen market. [ABSTRACT FROM AUTHOR]

The focus of this study is to investigate the critical matter of voltage sags in power systems, which have a substantial adverse effect on both the functionality of equipment and the quality of power. Central to this investigation is the integration of hydrogen fuel cells and a D-STATCOM system, which is suggested as a substitute approach for mitigating voltage fluctuations. The hydrogen fuel cell serves as the pivotal component, renowned for its ability to significantly improve power quality through the efficient mitigation of voltage sag concerns. The paper provides a comprehensive analysis of the contribution that hydrogen fuel cell integration with D-STATCOM makes to the reliability of power systems. A systematic methodology is employed, supported by simulations and modeling, to emphasize the critical significance of hydrogen fuel cells in surmounting obstacles related to voltage injection and enhancing power quality. By utilizing a Type-3 Fuzzy system, the research evaluates the dependability of the control system and proposed model. The effectiveness of this method, which is focused on hydrogen fuel cells, is verified by means of MATLAB simulations, which demonstrate its superior performance in comparison to conventional PI and ANFIS controllers. • Integrates hydrogen fuel cells with D-STATCOM for improved power quality. • Achieves notable reduction in voltage sags in power systems. • Enhances power system reliability and stability. • Employs Type-3 Fuzzy system for advanced control. • Validated by MATLAB simulations, outperforming traditional controllers. [ABSTRACT FROM AUTHOR]

Energy and transport are the two largest contributors to carbon emissions. In recent years, the transport sector has made strides in reducing its carbon footprint by producing electric vehicles that emit zero carbon. This paper investigates the use of Fuel Cell Electric Vehicles (FCEVs) with a newly developed regenerative suspension module (RSM). The RSM uses an electromechanical mechanism to obtain regenerative electrical energy from the engine and is mounted to the passive suspension system. To determine the potential energy savings of the RSM module, a hydrogen fuel cell electric vehicle simulated under specific road geometries, speeds, and acceleration conditions. The simulation results indicate that the Regenerative Suspension Modules (RSM) mounted on each wheel of the FCEV generate 2.5 times more energy than the regenerative braking system. This result is evaluated as an increase in efficiency and range in electric vehicles. • This study aimed to investigate efficiency gains from adding an RSM to hydrogen fuel cell electric vehicles. • This is the first study in literature to integrate RSM into a Fuel Cell Electric Vehicle. • The charging efficiency of the FCEV is improved by the Regenerative Suspension Modules mounted on each wheel. • The FCEV's Regenerative Suspension Module mounted on each wheel generates 2.5 times more energy than regenerative braking. [ABSTRACT FROM AUTHOR]

To tackle the carbon emission problem, the exploitation of renewable energy resources (RESs) with zero emissions has gained much importance. In this context, hydrogen has become an important resource to involve itself in distributed energy resources (DERs) to generate electricity, energize vehicles, and heat our living areas. The utilization of hydrogen technologies is indispensable due to their procurement, environmental friendliness, and high efficiency for DERs. A challenging area in the field of hydrogen energy technologies is extracting efficient power and integration to DERs. This paper investigates how to model and operate a proton exchange membrane fuel cell (PEMFC) stack in a DER application to establish a living lab facility for educational and research purposes by covering Power-to-X (P2X). The PEMFC model of the studied system is designed in a MATLAB/Simulink environment and implemented in an experimental testbed. Thus, a fuel cell (FC) unit as a complementary source is preferred to be used near a photovoltaic (PV) array, a small-scale wind turbine (WT), and a lead acid battery energy storage system (BESS) by creating a P2X concept to form a living lab platform. Beyond the model, regarding the experimental part, a PV array, a WT, and a BESS are combined with a PEMFC module that is rated output of 1200 W. Expect for all systems, the FC part is emphasized in this study. Also, a dynamic model of the mentioned PEMFC is proposed and verified. • Importance of hydrogen energy is focused on its advantages, future role, potential, and challenges. • FC unit as a complementary source is evaluated by creating a P2X concept. • This platform is designed to meet the energy needs of research-education, diversify the supply, increase energy independence. • Energy procurement is supplied via green energy during a lesson, which is noteworthy and instructive. • Feasibility of combined PV/WT/BESS/PEMFC system is investigated. [ABSTRACT FROM AUTHOR]

Due to the widespread use of multi-generation systems utilizing renewable energy sources and the growing global demand for such systems from both economic and environmental considerations, numerous researchers have focused on the design and evaluation of their performance. To this end, this research presents a biomass-based multi-generation system with an innovative and practical design that can generate electricity, heat, and hydrogen. This system includes a modified gas turbine cycle, a supercritical CO 2 (SCO 2) cycle, a transcritical CO 2 (TCO 2) cycle, a proton exchange membrane (PEM) electrolyzer, and a PEM fuel cell unit. This study aims to evaluate the impact of various biomass sources (paper, wood, paddy husk, and municipal solid waste) on the system performance. The proposed system has been analyzed using the first and second laws of thermodynamics. This system uses the maximum capacity to produce power, heat and hydrogen. A fuel cell unit has been used to consume hydrogen and generate more electricity. In the basic mode, the system has energy and exergy efficiencies of 47.89% and 32.26%, respectively, and can produce 2.74 kg/h of hydrogen. The biomass fuel consumption rate within the system is 0.055 kg/s. The overall exergy destruction of the system amounts to 1240 kW, with the biomass boiler and the condenser being the components that experience the greatest exergy destruction, registering values of 535.5 kW and 432.3 kW, respectively. Notably, employing municipal waste as biomass increases the system's exergy efficiency to 33.16%. • To investigate a biomass-driven system for producing power, hydrogen, and heating. • To evaluate the impact of various biomass sources on the system performance. • To use PEME for hydrogen and PEMFC for power and heat production. [ABSTRACT FROM AUTHOR]

This paper presents a powerful performance optimization approach for load frequency control in the off-grid mode of a delayed fuel cell microgrid with PI controller. The new approach based on stability boundary locus is used. Thanks to this, the search is only carried out in PI control parameter space keeping stable the system in the proposed optimization. The superiority of the proposed approach in terms of iteration history, fitness values, and time responses of the system is presented by comparing the results obtained. According to the results obtained, the proposed approach reaches the global minimum in a very short number of iterations and achieves this by both guaranteeing the stability of the system and providing the desired time response performances compared to the other method. • The stability of a delayed fuel cell microgrid system is a very important issue, especially in off grid mode. • A delayed fuel cell microgrid system should provide the desired quality of energy to the load. • The optimization approach provides the desired quality of energy to the load ensuring the stability of the microgrid. • Proposed optimization approach has great advantages in terms of iteration history and fitness value. [ABSTRACT FROM AUTHOR]

Today, hydrogen fuel cells (HFCs) have become very popular in various applications because of their ability to be a clean energy source. One of the difficulties associated with HFCs is their sluggish response to variations in the load. This paper presents a nested control strategy based on a type-2 neuro-fuzzy controller (T2NFC) to improve the HFC's dynamic response in a hybrid stand-alone power network using HFC and battery. A system model is constructed using Matlab-Simulink. An interleaved converter is used to draw the maximal power from the HFC and reduce the ripple in the HFC's current. Two T2NFCs control DC voltage and battery charge/discharge current. The robustness of the T2NFC is evaluated for input disturbance, output disturbance, and both disturbances. The results show that the proposed control strategy is robust against input and output disturbances. Also, it provides improved dynamic response of the HFC, lower ripple in HFC current, and less overshoot or undershoot in DC voltage both in transient and steady-state. For step reference input, the proposed controller improves settling time of 24.06 % and overshoot of 59.55 % compared to the conventional PI controller. The results verify the effectiveness of the proposed controller under different operating conditions of hybrid stand-alone power network with fuel cell and battery. • The response of HFC is enhanced, leading to faster and more accurate power generation. • The hydrogen fuel cell's current is experienced a significant reduction in ripples. • The hydrogen fuel cell is now being operated at its maximum power point. • A Type-2 Neuro-Fuzzy Controller is developed to provide robust control of the hydrogen fuel cell's output voltage. [ABSTRACT FROM AUTHOR]

The presented paper focuses on renewable energy-assisted electricity, hydrogen, and cold energy production. Solar energy is used as the energy source in the study. The organic Rankine cycle (ORC) is used for electricity generation, a proton exchange membrane electrolyzer (PEMe) for hydrogen production, and an ejector refrigeration system for cold energy production. The study is based on the exergy concept and examines thermo-economic and thermo-environmental analyses. The exergy efficiency of each equipment in the system is calculated from a holistic perspective. Considering the energy consumption values of the equipment in the whole system, the cost required for hydrogen production is calculated as 1.086 $/kg. Additionally, the exergy efficiency of the whole system is found to be 2.082 %. • Thermodynamic analysis of the solar-based hydrogen production system. • The exergy efficiency of the whole system is found as 2.082 %. • The cost of green hydrogen production is found as 1086 $/kg. [ABSTRACT FROM AUTHOR]

This paper introduces a confinement approach to enhance solid-state hydrogen storage by designing a nano-tubular and nano-fibrous structured boron-based storage medium. We detail the preparation of the confinement matrix, emphasizing its nanotubular and microfibrous structures provided by activated halloysite and sepiolite clays to achieve suitable confinement for ammonia borane (NH 3 BH 3 , AB). The thermolysis characteristics are thoroughly investigated in a lab-scale hydrogen reactor, elucidating the activation effects (thermal, acid, and both thermal-acid) on confinement and hydrogen generation performance. The resulting composite exhibits improved thermal stability and controlled hydrogen desorption characteristics, offering great promise for safe and efficient hydrogen storage applications. This research underscores the potential of tailored nanomaterials in advancing hydrogen storage technologies, with significant implications for clean energy solutions and the sustainable transportation sector. AB confined in acid-activated nano-tubular clay has shown improved hydrogen generation features at 120 °C, resulting in the highest improvement in H 2 equivalent per AB mole (98 %) and the initial hydrogen generation rate (233 %) while minimizing induction time up to 90 %. [Display omitted] • Tubular and fiber structured clays were used as ammonia borane scaffolds medium. • Halloysite and sepiolite clays were activated by thermal, acidic and combined method. • NH 3 BH 3 based nanocarriers were prepared via modified infiltration-confinement method. • Hydrogen production performance of composites were tested at 120 °C. • Acid activated composites showed the highest performance. [ABSTRACT FROM AUTHOR]

Biorenewable hydrogen is requisite to replace non-renewable hydrogen. Decarbonization is assured. Hydrogen demand is severely rising due to mitigating climate change and reducing fossil fuel dependency. Green Hydrogen from agro waste proposition makes bio-circular economy upcycling. The main objective of this study is to reinforce the hope of renewable, sustainable H 2 production from agro-waste. Initially, this paper shows the demand for green hydrogen, the sustainable availability of agro waste, and their capability to produce H 2. Insights into the gasification of agro waste about cellulose, hemicellulose, and lignin with conventional gasification. The effect of catalyst and supercritical gasification and their challenges is discussed. Most uniquely, other reviews highlight various aspirations behind agro-waste gasification to attain a strong business model, such as co-production, co-gasification, and CO 2 reforming with H2 yield. This review exhibits some main insight into various aspects of agro-waste gasification. H 2 from agrowaste gasification has high energy content (122 kJ/g) and high energy conversion efficiency in the range of 55–58 %, in addition to gaining the economic penalties of 2.2–2.5 net points for decarbonization. Agro waste is composed of lignocellulosic material that is relatively richer in hydrogen than fossil fuel resources. In SCWG, water is one of the natural solvents, which means feedstock effectively dissolves with water solvents. Intermittent density, low viscosity, and surface tension are nearly zero values due to SCW having no specific phase boundary, which enhances the gasification and substantially reduces tar formation during SCWG. Catalyst utilization enhances H 2 production. The present study comprehensively exhibits the role of catalyst and their supporter and promoter. Ni-based catalysts are mostly suggested for H2 production but fall into reusability issues. The main reason behind this is that Ni is inefficient in removing HCl, H 2 S, and total trace elements during gasification. Recently, low-cost and waste-to-wealth transformation aspects of biochar-based catalysts have gained attention. Renewable-assisted gasification significantly improves the energy and exergy of the system and suppresses the important concern of energy consumption during gasification. Renewable assisted and various aspiration incorporation into gasification is solidly recommended for future implementation based on energy, economic, and environmental benefits from them. Plastic and biomass are richer in hydrocarbon and oxygen, respectively; this synergistic effect has the potential to enhance the H 2 yield. From this study, PP plastic is mostly preferred for co-gasification with biomass. Compared to 100 wt% of biomass, the introduction of plastic slightly increased the coke formation, but the H 2 yield was improved. When the plastic mixture of 10 wt% increases coke deposition, however, significant coke deposition is not reported when 20 wt% of plastic concentration is not reported. Carbon capture via CO 2 inert gas supply enhances the H 2 yield, provides a route to carbon trade, and substantially contributes to GHG pollution mitigation. Agro-waste gasification is produced by a product that has the potential to be used in a wide range of applications due to its unique properties, such as large specific surface area, porosity, functional groups, high reliability, and minimum cost. Hopefully, this review will be an optic to the most appropriate green hydrogen production path for sustainable clean energy production and effective agro-waste management. • This review acts as an optic to the most appropriate green hydrogen production path. • Hydrogen separation, purification, and storage need more care. • Carbon dioxide reformation aids a carbon trading system and reduces environmental effect. • These research provide direction for energy nexuses that may be derived from agricultural waste. [ABSTRACT FROM AUTHOR]

The necessity of employing renewable energy sources within microgrid-based Power-to-X (P2X) systems has been emphasized by the imperatives of reducing global warming and fossil fuel consumption. Due to their numerous advantages, solar and wind energy have acquired prominence in contemporary power systems. However, their intermittent nature presents challenges. To overcome these challenges, energy storage devices are utilized. Batteries, however, are plagued by issues such as high maintenance needs, self-discharge, and diminishing storage capacity with age. Consequently, investigating alternatives such as hydrogen storage has become a financially viable option, especially for high-power applications. However, the intrinsically slow dynamics of hydrogen production from electricity contrast with the rapid responses of contemporary power electronic devices. This paper presents a versatile technique for optimizing hydrogen production in the presence of stochastic fluctuations in solar irradiance and wind speed. The proposed method combines a modified version of the Symbiotic Differential Whale Optimization Algorithm (m-SDWOA) with power converters to maximize production from renewable sources and electrolyzers. Using extensive simulations to demonstrate the efficacy of the proposed method by comparing its performance to that of the Whale Optimization Algorithm (WOA) and Particle Swarm Optimization (PSO). The results demonstrate the superior performance of the m-SDWOA-integrated method and pave the way for improved hydrogen generation in microgrid-based P2X systems. • Innovative control framework coordinates WT, PV, BESS, and HESS. • Maximizes hydrogen production while maintaining power quality. • Efficient controllers stabilize DC-bus voltage amidst WT/PV variability. • Ensures consistent, reliable power supply in microgrid. • Efficient energy management via m-SDWOA for resource optimization. [ABSTRACT FROM AUTHOR]

In recent years, Electric Vehicles (EVs) powered by a Proton Exchange Membrane Fuel Cell (PEMFC) which has high energy density and efficiency have become an attractive solution for the automotive industry. However, since the power density of the PEMFC is not high enough for different road conditions such as accelerating and going uphill, a supercapacitor (SC) is preferred as the auxiliary energy source for high power density in EVs. Thus, in this paper, a hybrid power system consisting of the Fuel Cell (FC) and SC for a Four-Wheel Drive Electric Vehicle (4WDEV) is proposed. Since energy requirement of the EV depends on the travel route, an effective Energy Management System can be designed by using a Geographic Information System (GIS). According to the road trajectory, the power requirement of the EV is estimated and thus, energy consumption is reduced. The proposed system is validated by using the Matlab Simscape Toolbox. • A hybrid power system consisting of a PEM Fuel Cell and SC for a 4WDEV is proposed. • An effective energy management system is designed using a GIS based on road route. • The high power demand of the EV is met from the SC in the sloping roads. • The energy consumption and the stresses of the power converters are reduced. [ABSTRACT FROM AUTHOR]

The current study examines a novel multigeneration plant that uses geothermal energy to produce clean and sustainable products. The process includes a re-compression supercritical Brayton power plant (re-sBC), an ejector cooling unit (EJCS), a humidifier dehumidifier desalination (HDH) unit, a Proton-Exchange Membrane (PEM) process, and a hot water preparation unit. The designed plant is able to generate hot water, cooling, power, hydrogen, and freshwater using the geothermal source. In the current paper, the thermodynamic analysis, CO 2 emission assessment, and exergoenvironmental index evaluation are executed to determine the system efficiency and the association between the system and the environment. A thorough parametric examination is fulfilled, to show how the system indicators impact efficiency and generated products. According to analysis data, the proposed multigeneration plant is able to generate 1278 kW of heating load, 229.6 kW of refrigeration capacity, and 109.5 kW of net power rate. Additionally, the capacity of the freshwater is 0.1188 kgs − 1 and the hydrogen is 0.001317 kgs − 1 . This developed system emits a total of 117 tonnes of CO 2 emissions per year for these useful outputs. In conclusion, the energetic and exergetic performance of the suggested MG plant are 14.09 % and 23.35 %, respectively. • A sustainable geothermal energy-based MG is proposed. • The thermodynamic, emission, and environmental analysis is conducted. • Design and evaluation of the Green hydrogen production and storage. • Re-compressed sBC integrated into geothermal driven MG plant. • Total energy and exergy efficiency is computed as 14.09 % and 23.35 %, respectively. [ABSTRACT FROM AUTHOR]

The single-stack fuel cell system is utilized extensively in several industries. Unfortunately, the main problems are its low efficiency and durability, and unsatisfied reliability, especially in the high-power situation. Due to its significant performance, which includes high output power, durability, and reliability, multi-stack fuel cell systems (MFCS) are becoming more and more attractive. In this study, it is aimed to develope a control algorithm in parallel structure in the Matlab/Simulink software for the efficient use of hydrogen fuel consumption of PEM fuel cells – based boost converter using PI controller with PSO method. Models of both single and parallel connected PEM fuel cells were created in Matlab using mathematical equations in this paper. The analysis made in the study were applied for both models. PEMFCs were connected in parallel and only one DC-DC converter was used for the entire system. According to the load change, the required number of cells are activated due to control algorithm to provide the required power. As a result, the proposed method reduces hydrogen consumption by approximately 5 times under the same load, while optimized parameters reduce output voltage oscillation. • A new control algorithm for parallel connected PEM fuel cell has been successfully implemented. • The suggested method reduces hydrogen consumption by approximately 5 times under the same load. • Using small-capacity fuel cells instead of huge ones minimizes hydrogen consumption. • Optimized parameters decrease the voltage oscillation. [ABSTRACT FROM AUTHOR]

The mixing and combustion processes are linked and challenging for a supersonic combustion engine. Supersonic air doesn't spend much time in the combustor, making it challenging to blend fuel with supersonic air. The expansion of shear-mixing layer with shock waves and their interactions are the primary characteristics of mixing augmentation. This paper investigates the same methodology for a model scramjet combustion chamber with wedge and wavy sides. The novel scramjet combustion models include wedge and way-wall sidewalls based on the basic scramjet model. By combining the finite volume approach with a second-order upwind discretization method, the Reynolds-averaged Navier-Stokes equations are numerically analyzed. The interplay between wedge and wavy-wall effects and free stream flows is taken into consideration by using the shear stress transport (SST) k−ω turbulence model. The effect of the wedge and wavy wall combustor has been evaluated by analysing the shock production and their interactions with the mixing layer and internal flow structure. The turbulence characteristics are also examined to analyse the degree of flow disturbance for wedge and wavy-wall combustion. The wavy wall combustor model results in a 14.5% increase in turbulence intensity, which raises air-fuel mixing and there by improves mixing and combustion efficiency by 12.59% and 11.23%, compared to the base wedge type combustor. [Display omitted] • Shock-induced mixing and combustion in the scramjet combustor with wavy and wedge walls. • The combustor's flow structure has been evaluated for shock wave production and interactions. • The wavy wall combustor promotes combustion in the radial direction. • The wavy wall combustor increases turbulent intensity by 14.5%, improving air-fuel mixing. • Wavy wall combustor improve mixing and combustion efficiency by 12.59% and 11.23%, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a novel preparation method (alkyne-based anionic method), had been used to prepare graphdiyne (GDY) with lamellar structure. Nanorods CoMoO 4 and nanosphere red phosphorus (P) was in situ loaded on the graphdiyne sheets using a morphology-modified method. Double S-type heterojunction of GDY/CoMoO 4 –P was built to improve the photocatalytic activity and stability. The hydrogen production of GDY/CoMoO 4 –P reached 14155.8 μmol g−1 h−1. The result of DFT theoretical calculation, ultraviolet and in-situ X-ray photoelectron spectroscopy characterization showed the construction of double S-type heterojunction accelerates the separation of photogenerated electrons/holes pairs and the transport of photogenerated electrons, enhance the absorption and utilization of light source. Through morphology control and heterojunction construction, the photocatalytic activity and stability was largely improved. This fully validates the feasibility that organic frameworks-GDY can be artificially constructed for photocatalytic hydrogen production. [Display omitted] • GDY/CoMoO 4 –P was successfully prepared by in situ deposition. • Design a ternary composite catalyst from the two aspects of morphology and band structure. • The addition of the GDY improves the redox ability of the entire system. • The recombination of photo-generated carriers was effectively suppressed. [ABSTRACT FROM AUTHOR]

Engineering-efficient, stable and low-cost electrocatalyst is facing with essential demand for overall water cracking to generate hydrogen and oxygen. Higher activation energy and sluggish kinetics are the main limiting factors for improved yield. In this paper, ZIF-67 was applied to prepare porous metal sulfide and foreign Fe atoms were introduced to substitute Co atoms in situ in CoS to modulate the electronic structure of the active centers. The as-constructed catalytic system reveals expected pH-universal HER performance and alkaline OER activity, and requires quite small over-potentials. Our theoretical prediction verifies the effective charge transfer between the doped Fe atom and its neighboring S atoms on the surface and the chemical environment variation in the doping sites. In addition, the improved conductivity and the decreased activation energy barriers are calculated in the FeCoS catalyst, further explaining its superiority in catalyzing OER and HER processes. This strategy is expected to be expandable to multiple energy transformation applications and provide a constructive strategy for fast charge transfer in water splitting. [Display omitted] • Non-precious bifunctional electrocatalyst were facile established. • FeCoS/NF-2 exhibited excellent performance for HER in the full pH range. • The chemical environment variation in the doping sites was explored. • DFT calculation explained the reasons for the excellent properties. [ABSTRACT FROM AUTHOR]

The investigation of cost-effective and highly efficient electrocatalysts for alkaline water and simulative seawater oxidation is essential to the conversion and storage of renewable energy. In this paper, the Ce–NiSe 2 /CoP catalyst with multihole and ultrathin nanosheet structure is generated. The unique structural characteristics of Ce–NiSe 2 /CoP heterojunction nanosheets contribute the excellent OER performance under different alkaline 1 M KOH and simulated seawater (1 M KOH + 0.5 M NaCl) electrolytes. Specifically, this catalyst exhucture is generated. The unique structural characteristics of Ce–NiSe 2 /CoP heterojunction nanosheets conibits the low overpotentials of 287 and 304 mV at the current density of 10 mA cm−2, along with the Tafel slopes of 87.1 and 78.8 mV dec−1 in two solutions, respectively. Moreover, the Ce–NiSe 2 /CoP target product also displays good stability. The present study introduces a promising strategy for the advancement of high-performance electrocatalysts in green energy field. [Display omitted] • The Ce-doped NiSe 2 /CoP heterostructure nanosheets are triumphantly generated. • The Ce–NiSe 2 /CoP product possesses multihole and ultrathin lamella architecture. • Each nanosheet with coarse surface is composed of prolifically nanosecondary units. • This catalyst presents fine OER properties in alkaline water and simulative seawater. [ABSTRACT FROM AUTHOR]

In this paper, composite proton exchange membranes (PEMs) based on functionalized graphene oxide (NGO) and carboxylated sulfonated poly aryl ether ketone sulfone (C-SPAEKS) were successfully synthesized. Functionalized graphene oxide was synthesized using graphene oxide as a substrate, and then diethylenetriamine (DETA) was chemically bound to the graphene oxide. The 1H NMR, FT-IR and XPS were used to characterize the NGO and composite membranes. The results show that the composite membranes have good proton conductivity, dimensional stability and electrochemical performance. The swelling rate of all the composite membranes was less than 18%, which indicates that they have good dimensional stability. Compared to C-SPAEKS membrane (34.8 mS cm-1 at 20 °C, 109.8 mS cm-1 at 90 °C), the proton conductivities of C-SPAEKS/GO-0.75 membrane (52.4 mS cm-1 at 20 °C, 171.1 mS cm-1 at 90 °C) were significantly improved. Meanwhile, the C-SPAEKS/NGO-0.75 achieved peak power density of 407.77 mW cm-2 at high OCV of 0.9576 V. Such a result is much superior to the C-SPAEKS membrane (0.8973 V, 190.72 mW cm-2) and the Nafion 117 (0.99 V, 302 mW cm-2), and demonstrated good single-fuel cell performance. In summary, it can be well concluded that functionalized GO as filler makes an significant contribution in improving the overall performance of the composite membranes. • Functionalized GO containing amino group was synthesized. • An efficient and orderly proton transport channel was constructed. • The hybrid PEMs showed good proton conductivity (171.1 mS cm-1, at 90 °C). • The hybrid PEMs showed good single cell performance (407.77 mW cm-2, 80 °C, 100% RH). • Acid-base combination could improve proton conductivity effectively. [ABSTRACT FROM AUTHOR]

In this paper, numerical simulations and experimental methods are utilized to investigate the near-field jet structures and far-field concentration distributions after the release of circular, equilateral triangular, square, and rectangular (AR2, AR4, AR8) nozzles. For all nozzle shapes, the hydrogen concentration along the jet centerline is inversely proportional to the distance from the nozzle. Circular nozzles exhibit the slowest decay of hydrogen concentration along the jet centerline, while rectangular nozzles show the fastest decay. Under the studied pressures, the concentration distributions along the jet centerline after the release of all nozzles are summarized into an equation. For the near-field jet structure, all nozzle except the circular nozzle experience varying degrees of deflection. When the aspect ratio is greater than or equal to 4, the Mach disk cannot be formed. An empirical formula for the position of the shock waves of the rectangular nozzle jet is proposed. [Display omitted] • AR8 nozzles exhibit the fastest decay of concentration along the centerline. • The concentrations along the centerline are summarized into an equation. • All nozzles except the circular nozzle experience a deflection phenomenon. • When the aspect ratio is greater than or equal to 4, the Mach disk cannot form. [ABSTRACT FROM AUTHOR]

To reveal the deflagration hazard and propagation law of hydrogen-enriched natural gas (H 2 NG) in closed spaces, this paper studied the deflagration characteristic parameters under different H 2 blended ratio (λ) and inert gas dilution fraction (X dilution) in slender closed pipelines with steel circular hole obstacles. The results indicate that the positive feedback mechanism's sustained effect, failure, and re-action leads to a "three-zone" distribution of H 2 NG explosion overpressure along the pipeline, namely the acceleration, attenuation, and rebound zones. The maximum explosion overpressure (P max), maximum pressure rise rate ((dP/dt) max), and peak shock wave propagation velocity (V p) all increase with the increase of λ. The rise of λ has the most significant enhancement effect on (dP/dt) max , while the enhancement effect on V p is the smallest. This is because the main reasons affecting their increase are different. P max , (dP/dt) max , and V p exhibit exponential decay with increased N 2 and CO 2. However, CO 2 has a more significant inhibitory effect on the H 2 NG deflagration process. When X CO2 = 25% and X CO2 = 30%, the deflagration process of H 2 NG with λ = 20% and λ = 80% can be inhibited entirely, respectively, which has important guiding significance for the safe application of H 2 NG. • The evolution law of deflagration shock waves in slender closed pipelines by H 2 NG was researched. • Effects of H 2 blended ratio and N 2 /CO 2 dilution fraction on H 2 NG deflagration characteristics were revealed. • The effects of N 2 /CO 2 dilution fraction on the P max , (dP/dt) max , and V p were predicted by an exponential model. [ABSTRACT FROM AUTHOR]

In the field of research on renewable energy conversion and storage methods, the development of catalysts with excellent properties and outstanding stability for oxygen evolution reaction (OER) acting at various pH values has become a much-anticipated research focus. RuO 2 as a benchmark OER catalyst, its wide application has always been limited by slow reaction kinetics and limited persistence. In this paper, Mn-doped RuO 2 material was developed and the optimum doping ratio was identified for using as an OER electrocatalyst under general purpose pH media. Mn 0.1 Ru 0.9 O 2 exhibited a lower overpotential value of 224 mV in acidic environment with a Tafel slope value of 51.62 mV dec−1. Moreover, in alkaline and neutral environments, overpotentials of 231 mV and 376 mV were required to obtain a current density of 10 mA cm−2, respectively. In addition, through continuous stability testing over 24 h in alkaline, acidic and neutral solutions, it has been further demonstrated that the Mn-doped RuO 2 material exhibits extremely high stability. The advancements in this research offer crucial insight into the rational development of efficient and durable RuO 2 -based catalysts. [Display omitted] • Mn 0.1 Ru 0.9 O 2 is successfully synthesized by a facile sol-gel method. • Mn doping modulates the electronic structure of RuO 2. • The catalyst exhibits enhanced OER activity and stability in pH-Universal media. [ABSTRACT FROM AUTHOR]

Introducing the second metal is an effective strategy to ameliorate oxygen reduction reaction (ORR) performance of cobalt and nitrogen doped carbon materials (Co-NC). In this study, Sn modulated Co-NC catalysts with enriched active sites (CoSn-NC) were synthesized by using formamide as ligand. Co and Sn bimetals coexist on nitrogen-doped carbon carriers and coordinated with nitrogen to form M − N active centers. Compared with Co-NC, CoSn -NC exhibited outstanding catalytic activity in terms of early initial potential of 1.04 V and positive half-wave potential of 0.89 V. Electrochemical testing and XPS characterization proved that the addition of Sn enriched the active site of Co-NC. More importantly, the electronic structure of Co–N is adjusted to perfect adsorption energy of the intermediate. The study puts forward a new idea and direction for optimizing single metal Co-NC catalyst. Synopsis: This paper is committed to developing Cobalt-based bimetallic materials with enrich active sites to replace scarce Pt/C for ORR. [Display omitted] • Co and Sn bimetals coexist on nitrogen-doped carbon carriers. • Sn Modulated Co-NC catalysts with enriched active sites. • The M − N structure is the main catalytic site by SCN− toxicity experiments. • CoSn-NC shows enhanced ORR catalytic activity, stability and methanol resistance. [ABSTRACT FROM AUTHOR]

The utilization of hydrogen-based direct reduction methods for magnetite ore smelting is an important way to achieve the goal of reducing carbon emissions. At present, the coupling mechanism of the multi-step reaction during the reduction process is unclear, which restricts the understanding of the rate-limiting steps and the accurate description of kinetic parameters. In this paper, the reaction characteristics and multi-step kinetics of isothermal reduction of magnetite by hydrogen with varying concentrations are investigated at 600–900 °C. Results indicate that the coupling relationship between Fe 3 O 4 →FeO and FeO→Fe two steps is temperature-dependent. In the low-temperature range (600–700 °C), the coupling relationship between the two steps can be described by the parallel model. In the high-temperature range (750–900 °C), the coupling relationship can be described by the series model. Meanwhile, the first-step reaction Fe 3 O 4 →FeO is controlled by the nucleation or chemical reaction model, and the apparent activation energies are determined to range from 27.25 to 48.59 kJ/mol. The second-step reaction FeO→Fe is controlled by the combination of nucleation and diffusion models, and the apparent activation energies are determined to range from 30.70 to 45.14 kJ/mol. • Multistep kinetics of isothermal reduction of magnetite by hydrogen are studied by TGA. • The coupling relationship of two-step reduction is found to be temperature-dependent. • The parallel model and series model are used to decouple the two-step reactions in two temperature ranges respectively. • The relationship between activation energy and hydrogen concentration is obtained. [ABSTRACT FROM AUTHOR]

As an essential part of hydrogen removal system in nuclear power plants, PARs could effectively eliminate released hydrogen and prevent potential hydrogen combustion during severe accidents. Serving as a basic composition in the catalytic section of PARs, catalytic element has a direct influence on the hydrogen removal capability of the PAR device. The CFD software STAR-CCM+ was utilized to develop models of catalytic channels containing three common catalytic elements (including catalytic plates, catalytic cylinders, and catalytic spheres). The elementary reaction mechanism was employed as the reaction kinetics model to define the chemical reaction process. This paper aims to evaluate the hydrogen removal capability of the catalytic elements in same operating conditions and analyze important factors for designing the structure of catalytic elements. All the catalytic surface area of catalytic elements was set to 0.045 m2 and inlet boundary conditions were settled identically. Our findings show that catalytic sphere exhibits the best hydrogen removal capability, which is attributed to the large lower half catalytic surface area of spheres. Catalytic plate with a lower height also demonstrates excellent hydrogen removal capability because of the presence of a larger catalytic area in the leading section. However, the hydrogen removal capability of catalytic cylinder is affected by the boundary layer separation vortex. A noticeable decrease in reaction rate occurs on the lower part of the sidewall surface, especially in the catalytic cylinder with a larger radius. In the structure design of catalytic elements, enlarging the catalytic surface area in the leading section and avoiding boundary layer separation on the catalytic surface are essential to further improve the hydrogen removal capability. • Investigation on hydrogen removal capability of common catalytic elements. • Catalytic sphere exhibits the best hydrogen removal capability. • Enlarging catalytic surface area in the leading section eliminate more hydrogen. • Boundary layer separation retards the hydrogen removal rate. [ABSTRACT FROM AUTHOR]

Recently, transition metal dichalcogenide photocatalysts have been substantially explored as efficient catalysts for water splitting. This paper systematically investigates the electronic structure and related properties of four, hitherto uninvestigated, Janus MoSSe/Ga 2 SSe vdW heterostructures using first-principles calculations. The results indicate that two out of the four heterostructures exhibit a type-II energy band arrangement, which facilitates the effective separation of electron-hole pairs in space. Additionally, the electrostatic potential, charge density difference and Bader charges analyses indicate that charge transfer in the interfacial region creates a built-in electric field that effectively inhibits electron and hole complexation, and that one out of the four heterostructures corresponds to a direct Z-scheme heterojunction. The optical absorption coefficients show that the MoSSe/Ga 2 SSe vdW heterostructures have a broad absorption range from visible to ultraviolet. These findings suggest that the Janus SMoSe/SGa 2 Se and SMoSe/SeGa 2 S vdW heterostructures could be suitable for photocatalytic water decomposition. The SMoSe/SGa 2 Se and SMoSe/SeGa 2 S vdW heterostructures have high corrected solar-to-hydrogen (STH) efficiency of 11.84% and 10.13%, respectively. [Display omitted] • Two Janus MoSSe/Ga 2 SSe vdW heterostructures are found type-II heterojunctions. • One of the type-II heterojunctions is a candidate as direct Z-scheme photocatalyst. • The built-in electric field can promote the separation of charge carriers. • Heterostructures band positioning are suitable for water splitting. • The heterostructures exhibit a broad absorption range from visible to ultraviolet. [ABSTRACT FROM AUTHOR]

Dry reforming of methane (DRM) takes advantage of greenhouse gases (CH 4 and CO 2) and mitigates their eco-environmental consequences. However, the biggest obstacle for DRM reactions has been the design of catalysts with high resistance to sintering and carbon deposition. In this paper, the embedded bimetallic nickel-cobalt@ silicalite-1 (S1) catalysts (NiCo@S1), with high resistance to sintering and lower carbon deposition, were prepared by grinding crystallization method. The physicochemical characterizations demonstrated that the embedded catalyst for NiCo@S1 could effectively control the size and dispersion of the active metal Ni–Co in the catalyst compared to the supported catalysts for 10Ni/SiO 2 and 10Ni/S1, which further enhance the interaction between the active metal phase and the carrier S1, and greatly minimize the amount of carbon accumulation on the catalysts. After being subjected to a reaction at 700 °C for 6 h, the 10Ni2.5Co@S1 exhibited a significant performance improvement. The instantaneous conversion rate of CH 4 increased from 63.17% to 86.39% (an increase of 23.22%), and the instantaneous conversion rate of CO 2 rose from 70.20% to 88.62% (an increase of 18.42%). Additionally, carbon deposition reduced from 14.58% to 0.82% (a decrease of 13.76%). Therefore, the conceptual design provided a new perspective for designing Ni-based dry reforming catalysts. • An industry-friendly grinding crystallization method has been introduced. • The grinding crystallization method can effectively promote the dispersion of active components、enhance metal-support interaction and prevent the migration of metal nanoparticles and their agglomeration, avoiding sintering, and thus reducing carbon deposition. • 10Ni2.5Co@S1 catalyst showed excellent performance in dry reforming of methane reactions. [ABSTRACT FROM AUTHOR]

With the energy revolution and the proposal of "double carbon" background, hydrogen energy with rich reserves, clean and low carbon and broad application prospects has gradually become a global hot spot. The combination of seawater hydrogen production and offshore wind power is undoubtedly the focus of research in this field. However, this new research field is not yet mature and is still in its infancy, so in order to reduce unnecessary losses, it is crucial to identify the key risks and prevent them. Secondly, the adaptability of a single model is no longer reliable for the risk assessment of this emerging field, especially the conversion from offshore wind to electric energy to hydrogen energy. Based on the above, this paper first considers the ambiguity and uncertainty of information, as well as the risk attitude of decision makers in the evaluation process, and develops a novel evaluation model. The reliability and optimization of the model are verified by sensitivity analysis and comparative analysis, and a case is introduced for practical analysis. The final results show that the key risks of hydrogen production from offshore wind power are seawater electrolysis technology, hydrogen energy storage technology and high-quality wind energy resources. The overall risk is 0.4198, which is medium risk. Decision-making managers can make targeted risk prevention to reduce losses and promote the stable operation of offshore wind power hydrogen production. [Display omitted] • Offshore wind power combined with seawater hydrogen production. • An improved model based on spherical fuzzy theory and cumulative prospect theory. • Taking China 's first large-scale offshore wind power hydrogen production project as a case study. • Key risks: seawater electrolysis technology, hydrogen storage technology and wind energy resources. • The quantitative result of the overall risk assessment was 0.4198. [ABSTRACT FROM AUTHOR]

Safety issues such as unintentional hydrogen releases in confined spaces limit the widespread promotion of hydrogen terminal applications, especially hydrogen fuel cell vehicles (HFCVs). This paper aims to perform a systematical numerical investigation of hydrogen leakage and dispersion in a full-scale underground garage, and the effects of smoke barriers are also considered. Four sets of smoke barriers with different heights, 0.1–0.7 m with 0.2 m increment, are installed below the ceiling, and three different partition types are set. The results show that smoke barriers can reduce flammable areas but increase local hydrogen concentrations. As the height of the smoke barrier increases, its obstruction to hydrogen dispersion on the ceiling is enhanced, making it easier for hydrogen to accumulate in the area and increasing the hydrogen cloud thickness. The hydrogen concentration in the horizontal direction showed a stair-like stratification phenomenon and decreased with increasing horizontal distance from the leak point. When the height of the smoke barrier is below 0.7 m, a larger partition area is safer. This study can provide new insights into the accidental hydrogen leakage and dispersion issues in confined spaces, in particular the effects of smoke barriers, and lay a theoretical foundation for the safety design of enclosed garages for HFCVs. [Display omitted] • Typical H 2 dispersion in a full-scale underground garage is numerical investigated. • Effects of smoke barriers on hydrogen dispersion is studied. • Smoke barriers can reduce flammable areas but increase local hydrogen concentrations. • Higher smoke barriers result in thicker flammable hydrogen clouds. • Larger partition area is found to be safer for 0.5 m barrier height. [ABSTRACT FROM AUTHOR]

Over the past years, several efforts have been made to reduce greenhouse gas emissions coming from the transport sector. Due to the highly efficient CO2-free combustion and low manufacturing costs, Hydrogen Internal Combustion engines (H2ICEs) are considered one of the most promising solutions for the future of medium and heavy duty vehicles. However, the combustion of an air-hydrogen mixture presents challenges related to the production of nitrogen oxides (NOx) and high knock tendency, mainly due to the chemical characteristics of the fuel. Although these problems can be mitigated by the use of a lean mixture, which is also useful to increase the combustion efficiency, the presence of excess air reduces exhaust temperatures and, consequently, the enthalpy content in the exhaust would be limited, leading to a reduced boosting capability. Therefore, a proper control of mixture preparation and combustion phasing is mandatory to limit NOx emissions, avoid abnormal combustions, and maximize efficiency without performance limitations. This paper focuses on the design of a dedicated control strategy for H2ICEs. Starting from a previously validated 1-D engine model operated with hydrogen, a 0-D Artificial Neural Network (ANN) - based engine model has been designed and calibrated. By using the obtained fast running ANN-based model, an innovative torque-based engine controller has been developed and both engine and controller models have been tested covering different torque profiles. The results show good accuracy within a range of ±5% on producing the requested torque by controlling the centre of combustion. [Display omitted] • Hydrogen represents an optimal solution for the abatement of CO2 emissions related to the transport sector. • Hydrogen combustion is prone to abnormal combustions and NOx emissions. • Dedicated control strategies are needed to achieve an efficient, clean and reliable H2 combustion. • Model in the Loop approach aimed at testing the proposed control strategy. • Artificial neural network – based fast running engine model enabled testing the control system in relevant running conditions. [ABSTRACT FROM AUTHOR]

Injecting CO 2 and foaming agents can effectively improve the recovery rate of high cycle steam huff and puff. In this paper, firstly, the influence of oil saturation and injection plug on recovery rate is analyzed using a sand filled pipe physical simulation device. Then, combined with reservoir parameters, the influence of reservoir thickness, interlayer thickness, and oil saturation on the economic limits of development is elucidated. Thirdly, reservoir engineering methods are used to analyze the appropriate timing for injecting foaming agents into the study area. Results show that (a) CO 2 dissolves in crude oil, increasing its internal elastic energy and forming a solution gas drive. (b) When the oil saturation is 40 %, the cyclic oil increase is 109 tons, and the oil to gas ratio is 1.09; when the oil saturation is 35 %, the cyclic oil increase rapidly decreases to 38 tons. (c) For the research area, foaming agents should be intervened as early as possible. Foaming agent concentration is 0.4%. • The influence of oil saturation and injection plug on recovery rate is analyzed. • The influence of reservoir parameters on development economic limits is elucidated. • eservoir engineering methods are used to analyze appropriate timing for injecting foaming agents. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3), hydrogen (H 2) and methane (CH 4) as zero- or low-carbon fuels are considered as highly promising alternative fuels. Turbulent non-premixed jet combustion is a prospective way in practical combustion devices for ammonia, hydrogen and methane, but the relevant experimental researches are rare, while such information is critical for the development and validation of numerical models. In this paper, the laser diagnostic studies are carried out in a constant volume combustion chamber to investigate the characteristics of the 50%NH 3 +50%H 2 blend jet with or without ignition in comparison to H 2 , CH 4 and NH 3 jets. Firstly, the morphological developments and concentration distributions of the four gas jets without ignition are compared. Then, the OH or NO distributions in the non-premixed gas jet flames are clarified by the planar laser-induced fluorescence techniques. The generation and consumption processes of OH and NO are elucidated by the one-dimensional simulation. The results show that the four jets exhibit a similar morphological development with the nearly same jet angles, except for a little slower tip penetration of 50%NH 3 +50%H 2 blend. The equivalence ratio of the 50%NH 3 +50%H 2 blend and NH 3 jets along the jet axis are lower than those in the CH 4 and H 2 jets due to the difference in the flow rate and stoichiometric number. The H 2 jet exhibits the highest combustion intensity, featuring faster flame propagation, the shortest lift-off length and an apparently higher OH radical intensity, while the NH 3 jet fails to develop a stable flame. The mixture in the 50%NH 3 +50%H 2 blend jet is too lean, resulting in a weaker combustion intensity than the H 2 and CH 4 jets. However, the NO intensity in the 50%NH 3 +50%H 2 jet flame is remarkably stronger than those of the H 2 and CH 4 jet, due to the much higher amount of fuel-type NO converted from NH 3 than that of thermal NO. A self-reducing (SR) zone can be observed where OH is produced and then consumed in the 50%NH 3 +50%H 2 blend, H 2 and CH 4 jet flames. However, the NO SR zone is only observable in the 50%NH 3 +50%H 2 blend jet flames, probably owing to the consumption by the NH 2 and NH radicals. • The laser diagnostic was used to obtained the OH and NO distributions. • The 50%NH 3 +50%H 2 , H 2 , CH 4 and NH 3 jets exhibit a similar morphologic development. • The equivalence ratios of the 50%NH 3 +50%H 2 blend and NH 3 jets are the lowest. • The fuel-type NO makes the strongest NO intensity in 50%NH 3 +50%H 2 blend flames. • For the first time a self-reducing zone was observed for the OH and NO. [ABSTRACT FROM AUTHOR]

Greenhouse gas emission was effectively reduced and the energy crisis was alleviated by decomposing seawater into hydrogen energy. Producing hydrogen from seawater through electrolysis poses particular challenges, such as competition between oxygen and chlorine evolution reactions on the anode and low conductivity of seawater, and therefore, researchers are actively working towards finding innovative solutions to overcome these obstacles. An in-depth overview of the principles and progress of seawater electrolysis for hydrogen energy production was provided in this paper. Various design strategies for electrocatalysts (such as transition metal nitrides, transition metal sulfides and transition metal phosphates), electrocatalysts performance evaluation index and the electrolysis mechanism were summarized. Finally, prospects and challenges of using seawater electrolysis for hydrogen energy production in future were proposed. • A comprehensive overview for transition metal-based electrocatalysts for hydrogen production from seawater. • Various design strategies for electrocatalysts, performance evaluation index and the electrolysis mechanism were summarized. • Prospects and challenges of seawater electrolysis for hydrogen production were proposed. [ABSTRACT FROM AUTHOR]

In response to climate change and the imperative for sustainable energy solutions, this study investigates the feasibility of producing green hydrogen and associated e-fuels (methane, methanol, and ammonia) using a renewable energy hybrid system in Dakhla, Morocco. Utilizing the System Advisor Model (SAM) software for simulation-based analysis, the research evaluates a hybrid system combining concentrated solar power (CSP) and photovoltaic (PV) plants against standalone counterparts. Various simulations comparing standalone PV and CSP plants with a novel CSP/PV hybrid concept were carried out. The hybrid system demonstrates significant promise, exhibiting increased annual energy yield and capacity factors up to 90%, leading to enhanced efficiency, performance, and cost savings with a Levelized Cost of Electricity (LCOE) approximating 17 cents/kWh. Furthermore, this paper conducts an in-depth exploration into the feasible production of hydrogen and its derived synthetic fuels utilizing hybrid renewable systems. The study provides a thorough examination of the production processes, yields, and efficiencies of hydrogen and its derivative e-fuels, with a focus on green hydrogen production through water electrolysis, CO2 hydrogenation, the Sabatier process, and the Haber-Bosch process. It sheds light on the potential applications of these fuels in the transportation sector, including in electric and hydrogen vehicles and aviation. The insights garnered are indispensable for crafting future strategies and policies in sustainable energy planning. These findings not only provide valuable direction for forthcoming initiatives in renewable energy but also underscore the pivotal role of hybridization in enhancing the efficient production and utilization of hydrogen within both renewable energy and transportation sectors. • PV and CSP systems to generate electricity for the Dakhla city was investigated. • A Hybrid system optimization has been proposed. • The Electricity surplus was used to produce hydrogen and hydrogen-based products. • Various scenarios for the heavy-duty application of e-fuel were presented and discussed. [ABSTRACT FROM AUTHOR]

The development of high-efficient non-precious metal catalysts for hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) is beneficial to enhance hydrogen evolution efficiency and reduce the cost of electrolyzers. In this paper, nitrogen doped carbon coated NiMoO x rod array (NiMoO x @NC) is successfully synthesized on nickel foam (NF). The nitrogen-doped carbon layer protects the unique rod array structure of the catalyst, making it exhibit both superhydrophilicity and superaerophobicity underwater. This facilitates the full diffusion of the electrolyte on the catalyst surface and the rapid departure of the hydrogen bubbles from the catalyst surface. Consequently, NiMoO x @NC demonstrates an electrocatalytic performance of 1.380 V (vs RHE) at 25 mA cm−2 for UOR and an overpotential of 126 mV at 25 mA cm−2 for HER. Employing NiMoO x @NC as both the anode and cathode in the urea-assisted hydrogen evolution, the system outputs 50 mA cm−2 at 1.680 V. This breakthrough provides an efficient and cost-effective approach for fabricating nickel molybdenum-based metal oxides. [Display omitted] • A unique core-shell structure is successfully constructed. • The nanorod array can be maintained with the protection of carbon layer. • The catalyst exhibits superhydrophilicity and superaerophobicity. • The as-prepared catalyst displays outstanding performance for HER and UOR. [ABSTRACT FROM AUTHOR]

Green hydrogen is central to the global energy transition. This paper introduces a renewable hydrogen production system model that optimizes hydrogen production on a worldwide 50 km × 50 km grid, considering country-specific investment risks. Besides the renewable energy's impact on the hydrogen production system (HPS) design, we analyze the effect of country-specific interest rates on the levelized cost of hydrogen (LCOH) production. Over one-third (40.0%) of all cells have an installed solar PV capacity share between 50% and 70%, 76.4% have a hybrid (onshore wind and solar PV) configuration. Hydrogen storage is deployed rather than battery storage to balance hydrogen production via electrolysis and hydrogen demand. Hybrid HPSs can significantly reduce the LCOH production compared to non-hybrid designs, whereas country-specific interest rates can lead to significant increases, diminishing the relative competitiveness of countries with abundant renewable energy resources compared to countries with fewer resources but fewer investment risks. [Display omitted] • Worldwide levelized cost of hydrogen production on a 50 km × 50 km grid resolution. • Impact of country risk premiums on the levelized cost of hydrogen production. • Cost-optimal hybrid hydrogen production system design per grid cell. • All results are available on an open-data license. [ABSTRACT FROM AUTHOR]

Mixing characteristics play an important role on the operational process of rotating detonation combustor (RDC). In this paper, a series of numerical calculations were conducted to analyze the influence of injection diameter, injection position, reactant mass flow rate, and equivalence ratio on mixing characteristics. Mixing performance parameters and total pressure loss in combustor dome and ignition zone were analyzed in detail. The findings indicated that all four injection conditions had significant influence on mixing characteristics, among which injection position was the most significant factor. When injection position was in convergent section, the mixing characteristics were better than those in ignition section. Reducing the fuel diameter gradually improved mixing characteristics, but also increased total pressure loss. The change of reactant mass flow rate had a minimal effect on mixing characteristics. As equivalence ratio decreased, mixing characteristics decreased and total pressure loss decreased. In addition, the comparative analysis also showed that penetration depth of hydrogen had an impact on flow field disturbance and distribution of return region, which led to the difference in mixing characteristics. When hydrogen was injected into the convergent structure section where air flow velocity did not reach sonic speed and was in acceleration phase, total pressure loss would be effectively reduced in combustor dome. • A new rotating detonation combustor model with convergent inlet structure was built. • Mixing performance parameters and total pressure loss in combustor dome and ignition zone were analyzed using RANS and LES. • Mixing characteristics of RDC were significantly enhanced when the injection position was in convergent structure section. [ABSTRACT FROM AUTHOR]

The accidental leakage of gaseous hydrogen from hydrogen refueling station facilities has the potential to result in a large fire and explosion catastrophe. The ability to forecast the spatiotemporal evolution of hydrogen plumes in real-time is crucial for monitoring the distribution of plume concentrations and mitigating the risk of fire and explosion. The utilization of deep learning has been extensively employed in a diverse range of spatiotemporal forecasting tasks. However, these approaches encounter limitations in accurately quantifying uncertainty when predicting spatiotemporal concentrations and plume boundaries. This research paper introduces a novel model called DPSTNN_H 2 Evolution, which is a deep probabilistic spatial-temporal neural network designed for forecasting the spatiotemporal evolution of hydrogen plumes. The benchmark dataset is constructed by the implementation of numerical simulations pertaining to the inadvertent leak of hydrogen within a hydrogen refueling station. The findings of the study indicate that incorporating quantified uncertainty information might enhance the precision of plume boundaries and the resilience of plume concentrations when predicting the spatiotemporal development of hydrogen. By employing Monte Carlo sampling with a sample size of m = 100 and a dropout rate of p = 0.1 , the model demonstrates the ability to provide real-time inference for 10 instances of plumes, while maintaining a high level of accuracy with R2 = 0.9829. In comparison to the current state-of-the-art model, the proposed model demonstrates superior accuracy and robustness in forecasting the spatiotemporal evolution of hydrogen plumes. In general, our proposed model has the potential to serve as a dependable option for the development of a digital twin for emergency management of hydrogen refueling stations. • Probabilistic spatial-temporal neural network model for hydrogen plume evolutions is proposed. • Normalized uncertainty contours and uncertainty intervals to improve accuracy and robustness. • Numerical experiment of hydrogen leakage and dispersion in refueling station are conducted. • Optimal hyper-parameters of the proposed model are determined • Comparison between the proposed model with point-estimation based model is conducted [ABSTRACT FROM AUTHOR]

In order to solve the problems of uneven component diffusion, weak mass transfer capability and flow field flooding in the conventional flow field of proton exchange membrane fuel cell (PEMFC), and to improve the cell output power. In this paper, a novel folded porous cathode flow field is proposed. A numerical model of three-dimensional multiphase flow is established for comparative study, which reveals the relationship between the component flow characteristics and mass transfer performance of PEMFC. The folding rib structure of the novel flow field triggers gas vortices in the channel and generates secondary flow, improves the mass transfer capability of reactants between the channel and the GDL, and alleviates the drainage problem of the porous layer under the rib. The angle, length and number of folding at the rib of the flow field were mainly changed, and the mass fraction difference coefficient (CV Mi) was used to compare the uniformity of the distribution of the components of the flow field, and the optimal flow field structure was obtained as FP6-7, which increased the current density by 44.9% compared with the traditional linear flow field. For the first time, the secondary flow evaluation criterion absolute vortex flux number J ABS n was introduced to evaluate the mass transfer performance. The influence of fluid flow characteristics on the mass transfer performance is revealed. • The folded porous (FP) flow field improves the mass transfer capacity. • The current density of PEMFC based on FP6-7 flow field was increased by 44.9%. • The mass fraction difference coefficient (CV Mi) was used to evaluate the uniformity of water-air distribution in the flow field. • The absolute vortex flux (J ABS n ) is used for the first time to evaluate the mass transfer characteristics. • The relationship between the flow characteristics of components and the mass transfer capacity in the flow field is revealed. [ABSTRACT FROM AUTHOR]

Oxygen starvation in proton exchange membrane fuel cells (PEMFCs) could lead to uneven internal current distribution, which is unfavorable to the fuel cell performance and lifetime. As oxygen starvation could occur locally, investigating the internal dynamic characteristics of PEMFC is critical to understanding the performance degradation mechanism. In this paper, the self-designed segmented cell of 396 segments is used to measure the dynamic current distributions of the automotive PEMFC with active area of 406 cm2 during oxygen starvation operation by decreasing air flow rate. As the air stoichiometry decreases from 2.4 to 0.8, the cell voltage drops gradually to 0.005 V and the internal current distribution becomes extremely nonuniform. The local current density increases to 1.64 A/cm2 at the air inlet and decreases to 0.25 A/cm2 at air outlet under the load current density of 0.6 A/cm2, which is dominated by the localized oxygen starvation around air outlet. When air flow rate is decreased to 0, the cell voltage reverses with a negative value of −0.042 V and the current distribution uniformity recovers. Under the negative cell voltage condition without air supply, the current distribution is determined by the membrane water content rather than the oxygen concentration. It is also found that larger step variation of air flow rate leads to a more significant overshoot of local current at air inlet and undershoot at air outlet. The different mechanisms for the internal current evolution of PEMFC is analyzed under Rich-Oxygen, Lack-Oxygen and No-Oxygen conditions, which are beneficial to improve air supply control strategy and the fuel cell design. • Dynamic internal performance of PEMFC under oxygen starvation is studied. • Segmented cell with 396 segments is used to measure the dynamic current distributions. • Uneven oxygen distribution worsens the uniformity of the current distribution significantly. • Under No-Oxygen condition cell voltage reverses with recovered internal current uniformity. • Step variation of air flow rate leads to overshoot and undershoot of local currents. [ABSTRACT FROM AUTHOR]

With the development of hydrogen fuel cell vehicles, hydrogen refuelling stations are required to operate at a higher pressure. However, the safety issue of high pressure hydrogen is always considered as the barrier of the wide application of such transportation infrastructures. In this paper, the safety evaluation is performed on a 70 MPa hydrogen dispenser, as one of the most vulnerable equipment to safety events in hydrogen refuelling stations. The numerical simulations are conducted for the hydrogen leakage and combustion for the prototype of the dispenser. The results show the high radiation during the combustion, and the environmental wind can reduce it by promoting the diffusion of hydrogen. Accordingly, the lethal ranges in different cases are manifested by radiation heat flux at the concerned height for the safety of humans. Furthermore, an improved design of the hydrogen dispenser is proposed to cancel the lower ventilation holes based on the analysis. As a result, the radiation heat fluxes due to the hydrogen combustion after leakage is significantly reduced and consequently lead to smaller lethal ranges, indicating the enhanced safety performance of the hydrogen dispenser. • A numerical study is conducted for the hydrogen combustion from a 70 MPa hydrogen dispenser. • The safety distance is evaluated for hydrogen leakage and combustion of dispensers under different wind conditions. • An improved design of the hydrogen dispenser is proposed and proved to be effective in enhancing the safety performance. [ABSTRACT FROM AUTHOR]

Hydrogen-enriched compressed natural gas (HCNG) technology is one of the most critical developments in the natural gas industry. To ensure the safe utilization of HCNG, the mixing effect of the two gases must be characterized and evaluated. In this paper, five types of static mixers were developed and numerically simulated. The results showed that the velocity, hydrogen blending ratio (HBR), mixer types, element aspect ratio, torsion angle, and number of elements affected the mixing effect to different degrees. Specifically, the increase in velocity and HBR improved the mixing uniformity of hydrogen and methane, but with a limited impact. Additionally, the mixing uniformity increased with the increase in the torsion angle and the number of elements, as well as the decrease in the element aspect ratio. Overall, the torsion angle had the most significant effect on mixing uniformity. Comparing the five types of static mixers, it was found that the new LPD static mixers yielded the best mixing effect, while the Y-type static mixers had the worst mixing effect. It is noted here that all the static mixers could satisfy the mixing uniformity requirements of industrial production. [Display omitted] • The influence of five models on the gas mixing effect is comprehensively analyzed. • The gas mixing effect is analyzed by three evaluation indexes. • The effects of operating conditions and spoilers on the mixing effect are studied. • The new LPD static mixer has the best effect on gas mixing. [ABSTRACT FROM AUTHOR]

The first part of the current study highlights the importance of developing a clean hydrogen supply chain (CHSC) in Iran to enhance energy security and contribute to global efforts towards sustainable energy transition. Depending on whether the focus is on domestic consumption or export of hydrogen, the study provides valuable insights into the prioritization of CHSC development pathways via multi-criteria decision-making tools (AHP, AHOP-TOPSIS, and AHP-VIKOR). The results show that for domestic hydrogen consumption (internal scenario), the best path of the supply chain includes blue hydrogen from steam methane reforming coupled with carbon capture and storage, H 2 -carriers (ammonia and methanol), natural gas grid for transportation and distribution, and industry sector as the end user. In the external scenario, however, the best path of the CHSC consists of green hydrogen production based on solar energy, and the other parts of the path include liquid hydrogen as the storage method, ship as the distribution and transportation, and industrial sector as the end user. By identifying the most suitable methods and technologies for each stage of the supply chain, this paper offers a comprehensive analysis that can guide decision-making in CHSC development. [ABSTRACT FROM AUTHOR]

There is a great desire to integrate multiple energy systems by forming low-carbon energy hubs. Among various energy platforms, the integration of power and gas networks via Power-to-Gas (PtG) technologies is introduced as a promising solution to enhance the flexibility of power grids and facilitate seamless adoption for high penetration levels of renewable energy resources. In addition, the production of green hydrogen from waste/inexpensive clean electricity has recently been identified as a potential means for large-scale energy storage, deployment of hydrogen mobility, and decarbonization of several processes that utilize hydrogen. As integrated hydrogen-based energy hubs (H 2 Hubs) attract more attention for widespread deployment, the security of such new platforms against various cyberattacks is also becoming a critical topic for investigation. This paper proposes a new data estimation technique, developed and integrated with H 2 Hubs scheduling models, for real-time optimal adaptive collection and organization of the system operating parameters for cybersecurity assessment. A new formulation is presented for the adaptive formation of a newly proposed concept, referred to as the system feasibility area , via real-time acquisition of the system operating information. The created feasibility areas are utilized for real-time post-occurrence detection of the bad scheduling data that is invisible to the existing cybersecurity layers. Numerical studies are conducted to demonstrate the efficacy and feasibility of the proposed model. The results demonstrate that the historical data can be adaptively collected in real time and successfully utilized to create feasibility areas to categorize the system operating points. • An optimal scheduling model is proposed for hydrogen-based energy hubs (H 2 Hubs). • A new data estimation method is developed and integrated with the scheduling model. • A new formulation is given for the adaptive creation of the feasibility area. • Simulation case studies are presented and discussed. [ABSTRACT FROM AUTHOR]

Hydrogen is crucial in the forthcoming low-carbon energy systems offering the potential to reduce CO 2 emissions and its versatility to be utilized across diverse energy sectors. Precise assessment of hydrogen thermo-physical characteristics is vital for the effective design and execution of numerous processes encompassing hydrogen production, transportation, storage, and utilization. In this paper, various distinct machine learning (ML) approaches, namely extreme gradient boosting (XGBoost), Random Forest (RF), Adaptive boosting (AdaBoost), and Light gradient boosting machine (LightGBM) were implemented to estimate thermo-physical properties, namely thermal conductivity, density, viscosity, and diffusivity in water based on pressure and temperature variables. For this purpose, comprehensive experimental data points covering a broad range of pressures and temperatures were acquired from the literature. The results demonstrated a strong agreement between the predictions generated by all proposed techniques and the experimental data. Furthermore, XGBoost yielded a root mean square error (RMSE) of 0.0085, 2.1548, 0.3343, and 1.5308 for the estimation of thermal conductivity, density, viscosity, and diffusivity, respectively, demonstrating superior accuracy in predicting all outcomes. In the sensitivity evaluation, it was observed that temperature, with absolute relevancy factor 0.88, 0.54, 0.246, and 0.92 had the most significant influence on the hydrogen thermo-physical properties in the order mentioned above. Furthermore, the trend analysis of the model indicated that all thermo-physical properties of hydrogen experience positive effects from temperature and pressure, except for density, which decreases as temperature increases. The leverage technique confirmed the statistical validity of both the experimental dataset used for modeling and the model's development. This study's results provide the efficient design and secure operation of hydrogen storage, refueling stations, transportation infrastructure, and production facilities. [Display omitted] • Hydrogen holds great importance in the forthcoming low-carbon energy. • XGBoost, RF, AdaBoost, and LightGBM are utilized for modeling the thermo-physical properties of hydrogen. • XGBoost demonstrates its superior accuracy in predicting thermal conductivity, density, viscosity, and diffusivity. • Temperature has the most significant influence on the hydrogen thermo-physical properties. [ABSTRACT FROM AUTHOR]

Chemical equilibrium represents the highest efficiency achievable by a thermochemical cycle under specific operational conditions. This study delves into two-step thermochemical water splitting cycles, which dissociate water into hydrogen (H 2) and oxygen (O 2) via sequential thermal reduction and re-oxidation processes. Building on the thermal reduction analysis presented in Part 1, this paper zeroes in on the re-oxidation reaction within the optimal reactor framework – the counter-current reactor. It elucidates the equilibrium pathway, delineating the progression of chemical equilibrium at each incremental stage of re-oxidation. Using ceria (CeO 2) as a model redox-active metal oxide, the investigation analyzes the influence of operational parameters on the re-oxidation reaction. Findings reveal the theoretical feasibility of maintaining near constant temperature (±2.5 °C) during re-oxidation, achieving a total extent of reduction of 0.038 and a hydrogen conversion yield of 32%. While near adiabatic operation is also achievable, practicality is constrained by a maximum total extent of reduction of 6.5·10−3. The study also explores the economic implications of thermochemical water splitting, particularly focusing on the steam-to-hydrogen output ratio. It highlights the severe economic hurdles associated with hydrogen yields below approximately 1%. Furthermore, the investigation reveals that the addition of inert gas to the re-oxidation step offers no significant advantages. Concluding the analysis, a comparative assessment exposes negligible differences in outcomes when substituting carbon dioxide (CO 2) for water (H 2 O) as the oxidant in low-temperature scenarios (800 °C). This comprehensive study not only advances the understanding of re-oxidation dynamics in thermochemical water splitting but also informs practical and economic considerations crucial for the advancement of this technology. • Reversible/equilibrium re-oxidation pathway defined for water splitting cycles. • Reversible quasi-constant temperature and quasi-adiabatic re-oxidation is feasible. • Limited impact of gas purity on re-oxidation at fixed flow/minimum temperature. • Inert gas addition offers no thermodynamic advantage in re-oxidation. • Low re-oxidation temperatures expand the solution space for high cycle efficiency. [ABSTRACT FROM AUTHOR]

The paper describes a new method for determining the energy efficiency of the life cycles of wind farms by the aggregated data of energy costs. The rationale for the use of aggregated data to determine energy costs during the life cycle of the wind farms is given. The classification of wind turbines and wind farms elements by the parameters and technical characteristics of the elements with subsequent division into groups for which aggregated data of energy costs are determined is given. Within the framework of the method have been developed an algorithm for determining energy costs on the production of elements of wind turbines and wind farms and formulas for their calculation during the life cycle of wind farms. In order to test the method, energy cost was calculated during the life cycle for two wind farms with wind turbines that differ parameters and technical characteristics of the elements and their energy efficiency was determined. It has been shown that the use of a hydrogen storage unit as part of a wind turbine makes it possible to efficiently use energy during down periods and increase the efficiency of the installation by 25–30%. It is noteworthy that a wind-hydrogen farm allows not only to accumulate excess energy during lean periods, but also to save the resource of wind turbines. When the energy reserve in the hydrogen battery reaches close to full, part of the wind turbines of the wind-hydrogen farm can be automatically temporarily stopped in a given order. This technology can provide an extension of the warranty service life for each wind turbine. [ABSTRACT FROM AUTHOR]

Mackinawite FeS is the most common corrosion product in the early stage of steel in H 2 S environment and also has an effective catalysis for hydrodesulfurization, hydrogen release reactions and heavy metal ion removal since its high specific surface area and reactive surface like other van der Waals materials. In this paper, ab initio molecular dynamics (AIMD) is used to study the interactions between small molecules (H 2 S, H 2 O and H) and FeS at 300 K. The calculation results show that the primary dissociation of H 2 S only occurs on the FeS(111) surface and H 2 S is chemically adsorbed on the (011) and (100) surfaces but physically adsorbed on the (001) surface. It will dissociate and generate H atoms when different amounts H 2 S or H 2 O molecules appear in the interlayer of FeS, in which H 2 S is more prone to dissociation. The dissociated H atoms will be "captured" by Fe/S atoms in mackinawite FeS, leading to the shrink of layer. Moreover, H atoms could combine into H 2 , which suggests that layered FeS has great potential for hydrogen generation. The diffusion coefficient of H atoms in mackinawite FeS layer is estimated about 1.67 × 10−8 m2/s. These findings have significant meaning for application of mackinawite FeS in corrosion science, hydrogen generation, hydrogen storage and other fields. • Visually show the adsorption, dissociation and diffusion of wet H 2 S on different mackinawite surface. • Clarify the effect when different molecules (H 2 S, H 2 O, H) appear in the interlayer of FeS. • Demonstrate the barrier properties of layered mackinawite to H atoms. • Give new insights into the application of mackinawite in hydrogen production and storage. [ABSTRACT FROM AUTHOR]

Due to the increase in electric energy consumption and the significant growth in the number of electric vehicles (EV) at the level of the distribution network, new networks have started using new fuels such as hydrogen to improve environmental indicators and at the same time better efficiency from the excess capacity of renewable resources. In this article, the services that can be provided by hydrogen refueling stations and charging electric vehicles in the optimal performance of microgrids have been investigated. The model proposed in this paper includes a two-stage stochastic framework for scheduling resources in microgrids, especially hydrogen refueling stations and electric vehicle charging. In this model, two main goals of cost minimization and greenhouse gas emissions are considered. In the proposed framework and in the first stage, the service range of microgrids is determined precisely according to the electrical limitations of distribution systems in emergency situations. Then, in the second stage, the problem of energy management in each microgrid will be solved centrally. In this situation, various indicators including the output energy of renewable sources, smart charging of hydrogen and electric vehicle charging stations (EV/FCV) and flexible loads (FL) are evaluated. The final mathematical model is implemented as a multivariate integer multiple linear problem (MILP) using the GUROBI solver in GAMS software. The simulation results on the modified IEEE 118-Bus network show the positive effect of the presence of flexible loads and smart charging strategies by charging stations. Also, the numerical derivation shows that the operating costs of the entire system can be reduced by 4.77% and the use of smart charging strategies can reduce greenhouse gas emissions by 49.13%. • Embedding network security constraints to ensure that each microgrid operates within safe voltage levels and avoids line capacity. • Examining the impacts of flexible loads and the charging patterns of EVs and FCVs on operational costs. • Incorporating hydrogen storage systems and refueling stations in the model to mitigate the adverse effects of renewable energy fluctuations. • Establishing a multi-objective model to consider both economic and environmental aspects of energy management in the proposed model. [ABSTRACT FROM AUTHOR]

Accurate and swift estimation of the future performance degradation of Proton Exchange Membrane Fuel Cells (PEMFCs) is crucial for the health management of PEMFC. However, most existing studies primarily concentrate on uncovering the inherent patterns of performance degradation parameters, neglecting the fundamental relationships and pattern variations between performance degradation and other characteristic parameters (such as flow rate, temperature, and pressure). This paper seeks to address this research gap. To that end, we delve into feature parameters, extracting underlying patterns of feature evolution to construct a feature exploration-based framework for predicting PEMFC performance degradation. Initially, Time-Varying Filtered Empirical Mode Decomposition (TVF-EMD) is employed to decompose each feature variable, isolating the core information of the features. Furthermore, to reduce the computational burden caused by redundant features, Uniform Manifold Approximation and Projection (UMAP) is used to perform dimensionality reduction on the decomposed feature subsequences, ensuring the efficiency and representativeness of the extracted features. Finally, to overcome the shortcomings of long short-term memory networks (LSTM) in terms of convergence and the effective use of time series information, we introduce an innovative Mogrifier LSTM (M-LSTM) model to enhance the accuracy of PEMFC performance degradation predictions. The experimental and validation results demonstrate that the extraction of feature parameters significantly enhances the predictive precision of the baseline model. Relative to the compared models, there was an improvement of at least 16.859% in Root Mean Square Error (RMSE), a minimum increase of 23.333% in Mean Absolute Error (MAE), and a boost of no less than 0.913% in the coefficient of determination (R 2 ). Simultaneously, the proposed predictive framework demonstrates good stability and accuracy in predicting PEMFC performance degradation. • Developed a novel feature processing framework for predicting the performance degradation of PEMFC. • Employed TVF-EMD in conjunction with UMAP to extract evolving trends and cyclical patterns of feature parameters. • Introduced an innovative M-LSTM network to enhance the interaction between historical information and current inputs. • Feature processing framework improves single-model performance degradation predictions [ABSTRACT FROM AUTHOR]