China, People’s Republic

Electrolysis of water to generate hydrogen fuel is an attractiverenewable energy storage technology. However grid-scale fresh-water electrolysis would put a heavy strain on vital water re-sources. Developing cheap electrocatalysts and electrodes that cansustain seawater splitting without chloride corrosion could ad-dress the water scarcity issue. Here we present a multilayer anodeconsisting of a nickel–iron hydroxide (NiFe) electrocatalyst layeruniformly coated on a nickel sulfide (NiSx) layer formed on porousNi foam (NiFe/NiSx-Ni) affording superior catalytic activity andcorrosion resistance in solar-driven alkaline seawater electrolysisoperating at industrially required current densities (0.4 to 1 A/cm2)over 1000 h. A continuous highly oxygen evolution reaction-active NiFe electrocatalyst layer drawing anodic currents towardwater oxidation and an in situ-generated polyatomic sulfate andcarbonate-rich passivating layers formed in the anode are respon-sible for chloride repelling and superior corrosion resistance of thesalty-water-splitting anode.

In response to environmental concerns related to carbon and nitrogen emissions hydrogen-powered aircraft (HPA) are poised for significant development over the coming decades driven by advances in power electronics technology. However HPA systems present complex multi-domain challenges encompassing electrical hydraulic mechanical and chemical disciplines necessitating efficient modeling and robust validation platforms. This paper introduces a physics-informed machine learning (PIML) approach for multi-domain HPA system modeling enhanced by hardware accelerated parallel hardware emulation to construct a real-time digital twin. It delves into the physical analysis of various HPA subsystems whose equations form the basis for both traditional numerical solution methods like Euler’s and Runge-Kutta methods (RKM) as well as the physics-informed neural networks (PINN) components developed herein. By comparing physics-feature neural networks (PFNN) and PINN with conventional neural network strategies this paper elucidates their advantages and limitations in practical applications. The final implementation on the Xilinx® UltraScale+™ VCU128 FPGA platform showcases the PIML method’s high efficiency accuracy data independence and adherence to established physical laws demonstrating its potential for advancing real-time multi-domain HPA emulation.

Hydrogen energy represents an ideal medium for energy storage. By integrating hydrogen power conversion utilization and storage technologies with distributed wind and photovoltaic power generation techniques it is possible to achieve complementary utilization and synergistic operation of multiple energy sources in the form of microgrids. However the diverse operational mechanisms varying capacities and distinct forms of distributed energy sources within hydrogen-coupled microgrids complicate their operational conditions making fine-tuned scheduling management and economic operation challenging. In response this paper proposes an energy management method for hydrogen-coupled microgrids based on the deep deterministic policy gradient (DDPG). This method leverages predictive information on photovoltaic power generation load power and other factors to simulate energy management strategies for hydrogen-coupled microgrids using deep neural networks and obtains the optimal strategy through reinforcement learning ultimately achieving optimized operation of hydrogen-coupled microgrids under complex conditions and uncertainties. The paper includes analysis using typical case studies and compares the optimization effects of the deep deterministic policy gradient and deep Q networks validating the effectiveness and robustness of the proposed method.

The introduction of several alternative marine fuels is considered an important strategy for maritime decarbonization. These alternative marine fuels include liquefied natural gas (LNG) liquefied biogas (LBG) hydrogen ammonia methanol ethanol hydrotreated vegetable oil (HVO) etc. In some studies nuclear power and electricity are also included in the scope of alternative fuels for merchant ships. However the operation of alternative-fuel-powered ships has some special risks such as fuel spills vapor dispersion and fuel pool fires. The existing international legal framework does not address these risks sufficiently. This research adopts the method of legal analysis to examine the existing international legal regime for regulating the development of alternative-fuel-powered ships. From a critical perspective it evaluates and predicts the consequences of these policies together with their shortcomings. Also this research explores the potential solutions and countermeasures that might be feasible to deal with the special marine environmental risks posed by alternative-fuel-powered ships in the future.

In this study we developed a new hybrid mathematical model that combines wind-speed range with the log law to derive the wind energy potential for wind-generated hydrogen production in Pakistan. In addition we electrolyzed wind-generated power in order to assess the generation capacity of wind-generated renewable hydrogen. The advantage of the Weibull model is that it more accurately reflects power generation potential (i.e. the capacity factor). When applied to selected sites we have found commercially viable hydrogen production capacity in all locations. All sites considered had the potential to produce an excess amount of wind-generated renewable hydrogen. If the total national capacity of wind-generated was used Pakistan could conceivably produce 51917000.39 kg per day of renewable hydrogen. Based on our results we suggest that cars and other forms of transport could be fueled with hydrogen to conserve oil and gas resources which can reduce the energy shortfall and contribute to the fight against climate change and global warming. Also hydrogen could be used to supplement urban energy needs (e.g. for Sindh province Pakistan) again reducing energy shortage effects and supporting green city programs.

Because the new energy is intermittent and uncertain it has an influence on the system’s output power stability. A hydrogen energy storage system is added to the system to create a wind light and hydrogen integrated energy system which increases the utilization rate of renewable energy while encouraging the consumption of renewable energy and lowering the rate of abandoning wind and light. Considering the system’s comprehensive operation cost economy power fluctuation and power shortage as the goal considering the relationship between power generation and load assigning charging and discharging commands to storage batteries and hydrogen energy storage and constructing a model for optimal capacity allocation of wind–hydrogen microgrid system. The optimal configuration model of the wind solar and hydrogen microgrid system capacity is constructed. A particle swarm optimization with dynamic adjustment of inertial weight (IDW-PSO) is proposed to solve the optimal allocation scheme of the model in order to achieve the optimal allocation of energy storage capacity in a wind–hydrogen storage microgrid. Finally a microgrid system in Beijing is taken as an example for simulation and solution and the results demonstrate that the proposed approach has the characteristics to optimize the economy and improve the capacity of renewable energy consumption realize the inhibition of the fluctuations of power reduce system power shortage and accelerate the convergence speed.

This paper uses established and recently introduced methods from the applied mathematics and statistics literature to study trends in the end-use sector and the capacity of low-carbon hydrogen projects in recent and upcoming decades. First we examine distributions in plants over time for various end-use sectors and classify them according to metric discrepancy observing clear similarity across all industry sectors. Next we compare the distribution of usage sectors between different continents and examine the changes in sector distribution over time. Finally we judiciously apply several regression models to analyse the association between various predictors and the capacity of global hydrogen projects. Across our experiments we see a welcome exponential growth in the capacity of zero-carbon hydrogen plants and significant growth of new and planned hydrogen plants in the 2020’s across every sector.

A distributed power system with renewable energy sources is very popular in recent years due to the rapid depletion of conventional sources of energy. Reasonable sizing for such power systems could improve the power supply reliability and reduce the annual system cost. The goal of this work is to optimize the size of a stand-alone hybrid photovoltaic (PV)/wind turbine (WT)/battery (B)/hydrogen system (a hybrid system based on battery and hydrogen (HS-BH)) for reliable and economic supply. Two objectives that take the minimum annual system cost and maximum system reliability described as the loss of power supply probability (LPSP) have been addressed for sizing HS-BH from a more comprehensive perspective considering the basic demand of load the profit from hydrogen which is produced by HS-BH and an effective energy storage strategy. An improved ant colony optimization (ACO) algorithm has been presented to solve the sizing problem of HS-BH. Finally a simulation experiment has been done to demonstrate the developed results in which some comparisons have been done to emphasize the advantage of HS-BH with the aid of data from an island of Zhejiang China.

When offshore wind farms are connected to a hydrogen plant with dedicated transmission lines for example high-voltage direct current the fluctuation of wind speed will influence the efficiency of the alkaline electrolyzer and deteriorate the techno-economic performance. To overcome this issue firstly an additional heating process is adopted to achieve insulation for the alkaline solution when power generated by wind farms is below the alkaline electrolyzer minimum power threshold while the alkaline electrolyzer overload feature is used to generate hydrogen when wind power is at its peak. Then a simplified piecewise model-based alkaline electrolyzer techno-economic analysis model is proposed. The improved economic performance of the islanded green hydrogen system with the proposed operation strategy is verified based on the wind speed data set simulation generated by the Weibull distribution. Lastly the sensitivity of the total return on investment to wind speed parameters was investigated and an islanded green hydrogen system capacity allocation based on the proposed analysis model was conducted. The simulation result shows the total energy utilization increased from 62.0768% to 72.5419% and the return on investment increased from 5.1303%/month to 5.9581%/month when the proposed control strategy is adopted.

The primary methods for hydrogen transportation include gaseous storage and transport liquid hydrogen storage and transport via organic liquid carriers. Among these pipeline transportation offers the lowest cost and the greatest potential for large-scale long-distance transport. Although the construction and operation costs of dedicated hydrogen pipelines are relatively high blending hydrogen into existing natural gas networks presents a viable alternative. This approach allows hydrogen to be transported to the end-users where it can be either separated for use or directly combusted thereby reducing hydrogen transport costs. This study based on the GERG-2008 equation of state conducts experimental tests on the compressibility factor of hydrogen-doped natural gas mixtures across a temperature range of −10 ◦C to 110 ◦C and a pressure range of 2 to 12 MPa with hydrogen blending ratios of 5% 10% 20% 30% and 40%. The results indicate that the hydrogen blending ratio temperature and pressure significantly affect the compressibility factor particularly under low-temperature and high-pressure conditions where an increase in the hydrogen blending ratio leads to a notable rise in the compressibility factor. These findings have substantial implications for the practical design of hydrogen-enriched natural gas pipelines as changes in the compressibility factor directly impact pipeline operational parameters compressor characteristics and other system performance aspects. Specifically the introduction of hydrogen alters the compressibility factor of the transported medium thereby affecting the pipeline’s flowability and compressibility which are crucial for optimizing and applying the performance of hydrogen-enriched natural gas in transportation channels. The research outcomes provide valuable insights for understanding combustion reactions adjusting pipeline operational parameters and compressor performance characteristics facilitating more precise decision-making in the design and operation of hydrogen-enriched natural gas pipelines.

Solid-state hydrogen storage technology has emerged as a disruptive solution to the “last mile” challenge in large-scale hydrogen energy applications garnering significant global research attention. This paper systematically reviews the Chinese research progress in solid-state hydrogen storage material systems thermodynamic mechanisms and system integration. It also quantitatively assesses the market potential of solid-state hydrogen storage across four major application scenarios: on-board hydrogen storage hydrogen refueling stations backup power supplies and power grid peak shaving. Furthermore it analyzes the bottlenecks and challenges in industrialization related to key materials testing standards and innovation platforms. While acknowledging that the cost and performance of solid-state hydrogen storage are not yet fully competitive the paper highlights its unique advantages of high safety energy density and potentially lower costs showing promise in new energy vehicles and distributed energy fields. Breakthroughs in new hydrogen storage materials like magnesium-based and vanadium-based materials coupled with improved standards specifications and innovation mechanisms are expected to propel solid-state hydrogen storage into a mainstream technology within 10–15 years with a market scale exceeding USD 14.3 billion. To accelerate the leapfrog development of China’s solid-state hydrogen storage industry increased investment in basic research focused efforts on key core technologies and streamlining the industry chain from materials to systems are recommended. This includes addressing challenges in passenger vehicles commercial vehicles and hydrogen refueling stations and building a collaborative innovation ecosystem involving government industry academia research finance and intermediary entities to support the achievement of carbon peak and neutrality goals and foster a clean low-carbon safe and efficient modern energy system.

With the increasing concern about global energy crisis and environmental pollution the integrated renewable energy system has gradually become one of the most important ways to achieve energy transition. In the context of the rapid development of hydrogen energy industry the proportion of hydrogen energy in the energy system has gradually increased. The conversion between various energy sources has also become more complicated which poses challenges to the planning and construction of park-level integrated energy systems (PIES). To solve this problem we propose a bi-level planning model for an integrated energy system with hydrogen energy considering multi-stage investment and carbon trading mechanism. First the mathematical models of each energy source and energy storage in the park are established respectively and the independent operation of the equipment is analyzed. Second considering the operation state of multi-energy coordination a bi-level planning optimization model is established. The upper level is the capacity configuration model considering the variable installation time of energy facilities while the lower level is the operation optimization model considering several typical daily operations. Third considering the coupling relationship between upper and lower models the bi-level model is transformed into a solvable single-level mixed integer linear programming (MILP) model by using Karush–Kuhn–Tucker (KKT) condition and big-M method. Finally the proposed model and solution methods are verified by comprehensive case studies. Simulation results show that the proposed model can reduce the operational cost and carbon emission of PIES in the planning horizon and provide insights for the multi-stage investment of PIES.

Arguably one of the most important issues the world is facing currently is climate change. At the current rate of fossil fuel consumption the world is heading towards extreme levels of global temperature rise if immediate actions are not taken. Transforming the current energy system from one largely based on fossil fuels to a carbon-neutral one requires unprecedented speed. Based on the current state of development direct electrification of the future energy system alone is technically challenging and not enough especially in hard-to-abate sectors like heavy industry road trucking international shipping and aviation. This leaves a considerable demand for alternative carbon-neutral fuels such as green ammonia and hydrogen and renewable methanol. From this perspective we discuss the overarching roles of each fuel in reaching net zero emission within the next three decades. The challenges and future directions associated with the fuels conclude the current perspective paper.

To improve the renewable energy consumption capacity of integrated energy system (IES) and reduce the carbon emission level of the system a low-carbon economic dispatch model of IES with coupled power-to-gas (P2G) and hydrogen-doped gas units (HGT) under the stepped carbon trading mechanism is proposed. On the premise of wind power output uncertainty the operating characteristics of the coupled electricity-to-gas equipment in the system are used to improve the wind abandonment problem of IES and increase its renewable energy consumption capacity; HGT is introduced to replace the traditional combustion engine for energy supply and on the basis of refined P2G a part of the volume fraction of hydrogen obtained from the production is extracted and mixed with methane to form a gas mixture for HGT combustion so as to improve the low-carbon economy of the system. The ladder type carbon trading mechanism is introduced into IES to guide the system to control carbon emission behavior and reduce the carbon emission level of IES. Based on this an optimal dispatching strategy is constructed with the economic goal of minimizing the sum of system operation cost wind abandonment cost carbon trading cost and energy purchase cost. After linearization of the established model and comparison analysis by setting different scenarios the wind power utilization rate of the proposed model is increased by 24.5% and the wind abandonment cost and CO2 emission are reduced by 86.3% and 10.5% respectively compared with the traditional IES system which achieves the improvement of renewable energy consumption level and low carbon economy.

Amidst the growing imperative to address carbon emissions aiming to improve energy utilization efficiency optimize equipment operation flexibility and further reduce costs and carbon emissions of regional integrated energy systems (RIESs) this paper proposes a low-carbon economic operation strategy for RIESs. Firstly on the energy supply side energy conversion devices are utilized to enhance multi-energy complementary capabilities. Then an integrated demand response model is established on the demand side to smooth the load curve. Finally consideration is given to the RIES’s participation in the green certificate–carbon trading market to reduce system carbon emissions. With the objective of minimizing the sum of system operating costs and green certificate–carbon trading costs an integrated energy system optimization model that considers electricity gas heat and cold coupling is established and the CPLEX solver toolbox is used for model solving. The results show that the coordinated optimization of supply and demand sides of regional integrated energy systems while considering multi-energy coupling and complementarity effectively reduces carbon emissions while further enhancing the economic efficiency of system operations.

In this paper a computational fluid dynamics (CFD) model was established and verified on the basis of experimental results and then the effect of hydrogenation addition on combustion and emission characteristics of a diesel–hydrogen dual-fuel engine fueled with hydrogenation addition (0% 5% and 10%) under different hydrogenation energy shares (HESs) and compression ratios (CRs) were investigated using CONVERGE3.0 software. And this work assumed that the hydrogen and air were premixed uniformly. The correctness of the simulation model was verified by experimental data. The values of HES are in the range of 0% 5% 10% and 15%. And the values of CR are in the range of 14 16 18 and 20. The results of this study showed that the addition of hydrogen to diesel fuel has a significant effect on the combustion characteristics and the emission characteristics of diesel engines. When the HES was 15% the in-cylinder pressure increased by 10.54%. The in-cylinder temperature increased by 15.11%. When the CR was 20 the in-cylinder pressure and the in-cylinder temperature increased by 66.10% and 13.09% respectively. In all cases HC CO CO2 and soot emissions decreased as the HES increased. But NOx emission increased.

As an important energy source to achieve carbon neutrality green hydrogen has always faced the problems of high use cost and unsatisfactory environmental benefits due to its remote production areas. Therefore a liquid-gaseous cascade green hydrogen delivery scheme is proposed in this article. In this scheme green hydrogen is liquefied into high-density and low-pressure liquid hydrogen to enable the transport of large quantities of green hydrogen over long distances. After longdistance transport the liquid hydrogen is stored and then gasified at transfer stations and converted into high-pressure hydrogen for distribution to the nearby hydrogen facilities in cities. In addition this study conducted a detailed model evaluation of the scheme around the actual case of hydrogen energy demand in Chengdu City in China and compared it with conventional hydrogen delivery methods. The results show that the unit hydrogen cost of the liquid-gaseous cascade green hydrogen delivery scheme is only 51.58 CNY/kgH2 and the dynamic payback periods of long- and short-distance transportation stages are 13.61 years and 7.02 years respectively. In terms of carbon emissions this scheme only generates indirect carbon emissions of 2.98 kgCO2/kgH2 without using utility electricity. In sum both the economic and carbon emission analyses demonstrate the advantages of the liquidgaseous cascade green hydrogen delivery scheme. With further reductions in electricity prices and liquefication costs this scheme has the potential to provide an economically/environmentally superior solution for future large-scale green hydrogen applications.

The accurate determination of the potential impact radius is crucial for the design and risk assessment of hydrogen pipelines. The existing methodologies employ a single point source model to estimate radiation and the potential impact radius. However these approaches overlook the jet fire shape resulting from high-pressure leaks leading to discrepancies between the calculated values and real-world incidents. This study proposes models that account for both the mass release rate while considering the pressure drop during hydrogen pipeline leakage and the radiation while incorporating the flame shape. The analysis encompasses 60 cases that are representative of hydrogen pipeline scenarios. A simplified model for the potential impact radius is subsequently correlated and its validity is confirmed through comparison with actual cases. The proposed model for the potential impact radius of hydrogen pipelines serves as a valuable reference for the enhancement of the precision of hydrogen pipeline design and risk assessment.

With the rapid development of hydrogen pipelines their safety issues have become increasingly prominent. In order to evaluate the properties of pipeline materials under a highpressure hydrogen environment this study investigates the hydrogen embrittlement sensitivity of X70 welded pipe in a 10 MPa high-pressure hydrogen environment using slow strain rate testing (SSRT) and low-cycle fatigue (LCF) analysis. The microstructure slow tensile and fatigue fracture morphology of base metal (BM) and weld metal (WM) were characterized and analyzed by means of ultra-depth microscope scanning electron microscope (SEM) electron backscattering diffraction (EBSD) and transmission electron microscope (TEM). Results indicate that while the high-pressure hydrogen environment has minimal impact on ultimate tensile strength (UTS) for both BM and WM it significantly decreases reduction of area (RA) and elongation (EL) with RA reduction in WM exceeding that in BM. Under the nitrogen environment the slow tensile fracture of X70 pipeline steel BM and WM is a typical ductile fracture while under the high-pressure hydrogen environment the unevenness of the slow tensile fracture increased and a large number of microcracks appeared on the fracture surface and edges with the fracture mode changing to ductile fracture + quasicleavage fracture. In addition the high-pressure hydrogen environment reduces the fatigue life of the BM and WM of X70 pipeline steel and the fatigue life of the WM decreases more than that of the BM as well. Compared to the nitrogen environment the fatigue fracture specimens of BM and WM in the hydrogen environment showed quasi-cleavage fracture patterns and the fracture area in the instantaneous fracture zone (IFZ) was significantly reduced. Compared with the BM of X70 pipeline steel although the effective grain size of the WM is smaller WM’s microstructure with larger Martensite/austenite (M/A) constituents and MnS and Al-rich oxides contributes to a heightened embrittlement sensitivity. In contrast the second-phase precipitation of nanosized Nb V and Ti composite carbon-nitride in the BM acts as an effective irreversible hydrogen trap which can significantly reduce the hydrogen embrittlement sensitivity

A reliable and sustainable energy source is essential for human survival and progress. Hydrogen energy is both clean and environmentally friendly which highlights the need for the development of effective photocatalysts to enhance the efficiency of photocatalytic hydrogen production. Near-infrared (NIR) light makes up a significant part of the solar spectrum and possesses strong penetration capabilities. Therefore it is important to enhance research on photocatalysis that utilizes both NIR and visible light. Metal-organic frameworks (MOFs) possess outstanding photocatalytic characteristics and are utilized in various applications for the photocatalytic generation of hydrogen. Consequently this minireview examines the fundamental characteristics of MOFs focusing on their classification the mechanisms of hydrogen production and the use of MOFs composites in photocatalytic hydrogen production. It discusses MOFs materials that feature type I II III Z and S heterojunctions along with strategies for modifying MOFs through elemental doping and the addition of co-catalysts. The study investigates methods to expand the photo-response range through up-conversion reduce the band gap of photocatalyst materials and utilize plasmon resonance and photothermal effects. This minireview lays the groundwork for achieving photocatalysis that responds to near-infrared and visible light thereby enhancing photocatalytic efficiency for hydrogen production. Finally the guidance and obstacles for upcoming studies on MOFs materials in the context of photocatalytic hydrogen production are examined.

Hydrogen as one of the most promising renewable clean energy sources holds significant strategic importance and vast application potential. However as a high-energy combustible gas hydrogen poses risks of fire and explosion in the event of a leakage. Hydrogen production plants typically feature large spatial volumes and complex obstacles which can significantly influence the diffusion pathways and localized accumulation of hydrogen during a short-term high-volume release further increasing the risk of accidents. Implementing effective hydrogen leakage monitoring measures can mitigate these risks ensuring the safety of personnel and the environment to the greatest extent possible. Therefore this paper uses CFD methods to simulate the hydrogen leakage process in a hydrogen production plant. The study examines the molar fraction distribution characteristics of hydrogen in the presence of obstacles by varying the ventilation speed of the plant and the directions of leakage. The main conclusions are as follows: enhancing ventilation can effectively prevent the rapid increase in hydrogen concentration with higher ventilation speeds yielding better suppression. After a hydrogen leak in a confined space hydrogen tends to diffuse along the walls and accumulate in corner areas indicating that hydrogen monitoring equipment should be placed in corner locations.

In response to the growing significance of hydrogen as a clean energy carrier this study investigates the advanced rectifier technologies employed in electrolytic hydrogen production. First the topologies of three rectifiers typically employed in industry—24-pulse thyristor rectifiers insulated gate bipolar transistor (IGBT) rectifiers and 24-pulse diode rectifiers with multi-phase choppers—are described in detail. Subsequently at a constant 5 MW power level the three rectifiers are compared in terms of rectifier efficiency gridside power quality power factor and overall investment cost. The results indicate that in comparison to the other two rectifiers the thyristor rectifier provides superior efficiency and cost advantages thereby maintaining a dominant market share. Additionally case studies of rectifier power supplies from three real-world industrial projects are presented along with actual grid-side power quality data. Finally the challenges potential applications and future prospects of rectifiers in renewable energy-based hydrogen production are discussed and summarized.

As the main body of resource aggregation Virtual Power Plant (VPP) not only needs to participate in the external energy market but also needs to optimize the management of internal resources. Different from other energy storage hydrogen energy storage systems can participate in the hydrogen market in addition to assuming the backup supplementary function of electric energy. For the Virtual Power Plant Operator (VPPO) it needs to optimize the scheduling of internal resources and formulate bidding strategies for the electric-hydrogen market based on external market information. In this study a two-stage model is constructed considering the internal and external interaction mechanism. The first stage model optimizes the operation of renewable energy flexible load extraction storage and hydrogen energy storage system based on the complementary characteristics of internal resources; the second stage model optimizes the bidding strategy to maximize the total revenue of the electricity energy market auxiliary service market and hydrogen market. Finally a typical scenario is constructed and the rationality and effectiveness of the strategy are verified. The results show that the hybrid VPP with hydrogen storage has better economic benefits resource benefits and reliability.

A 3.5 tonne forklift containing proton exchange membrane fuel cells (PEMFCs) and lithium-ion batteries was manufactured and tested in a real factory. The work efficiency and economic applicability of the PEMFC forklift were compared with that of a lithium-ion battery-powered forklift. The results showed that the back-pressure of air was closely related to the power density of the stack whose stability could be improved by a reasonable control strategy and membrane electrode assemblies (MEAs) with high consistency. The PEMFC powered forklift displayed 40.6% higher work efficiency than the lithium-ion battery-powered forklift. Its lower use-cost compared to internal engine-powered forklifts is beneficial to the commercialization of this product.

With the massive use of traditional fossil fuels greenhouse gas emissions are increasing and environmental pollution is becoming an increasingly serious problem which led to an imminent energy transition. Therefore the development and application of renewable energy are particularly important. This paper reviews a wide range of issues associated with hybrid renewable energy systems (HRESs). The issues concerning system configurations energy storage options simulation and optimization with artificial intelligence are discussed in detail. Storage technology options are introduced for stand-alone (off-grid) and grid-connected (on-grid) HRESs. Different optimization methodologies including classical techniques intelligent techniques hybrid techniques and software tools for sizing system components are presented. Besides the artificial intelligence methods for optimizing the solar/wind HRESs are discussed in detail.

The low-carbon development of China’s iron and steel industry (ISI) is important but challenging work for the attainment of China’s carbon neutrality by 2060. However most previous studies related to the low-carbon development of China’s ISI are fragmented from different views such as production-side mitigation demand-side mitigation or mitigation technologies. Additionally there is still a lack of a comprehensive overview of the long-term pathway to the low-carbon development of China’s ISI. To respond to this gap and to contribute to better guide policymaking in China this paper conducted a timely and comprehensive review following the technology roadmap framework covering the status quo future vision and key actions of the low-carbon development of the world and China’s ISI. First this paper provides an overview of the technology roadmap of low-carbon development around the main steel production countries in the world. Second the potential for key decarbonization actions available for China’s ISI are evaluated in detail. Third policy and research recommendations are put forward for the future low-carbon development of China’s ISI. Through this comprehensive review four key actions can be applied to the low-carbon development of China’s ISI: improving energy efficiency shifting to Scrap/EAF route promoting material efficiency strategy and deploying radical innovation technologies.

To maximize the utilization of renewable energy (RE) as much as possible in cold areas while reducing traditional energy use and carbon dioxide emissions a three-layer configuration optimization and scheduling model considering a multi-park integrated energy system (MPIES) a shared energy storage power station (SESPS) and a hydrogen refueling station (HRS) cooperation based on the Wasserstein generative adversarial networks the simultaneous backward reduction technique and the Quantity-Contour (WGAN-SBR_QC) method is proposed. Firstly the WGAN-SBR_QC method is used to generate typical scenarios of RE output. Secondly a three-layer configuration and schedule optimization model is constructed using MPIES SESPS and HRS. Finally the model’s validity is investigated by selecting a multi-park in Eastern Mongolia. The results show that: (1) the typical scenario of RE output improved the overall robustness of the system. (2) The profits of the MPIES and HRS increased by 1.84% and 52.68% respectively and the SESPS profit increased considerably. (3) The proposed approach increased RE utilization to 99.47% while reducing carbon emissions by 32.67%. Thus this model is a reference for complex energy system configuration and scheduling as well as a means of encouraging RE use.

Hydrogen energy represents a crucial pathway towards achieving carbon neutrality and is a pivotal facet of future strategic emerging industries. The safe and efficient transportation of hydrogen is a key link in the entire chain development of the hydrogen energy industry’s “production storage and transportation”. Mixing hydrogen into natural gas pipelines for transportation is the potential best way to achieve large-scale long-distance safe and efficient hydrogen transportation. Welds are identified as the vulnerable points in natural gas pipelines and compatibility between hydrogen-doped natural gas and existing pipeline welds is a critical technical challenge that affects the global-scale transportation of hydrogen energy. Therefore this article systematically discusses the construction and weld characteristics of hydrogen-doped natural gas pipelines the research status of hydrogen damage mechanism and mechanical property strengthening methods of hydrogen-doped natural gas pipeline welds and points out the future development direction of hydrogen damage mechanism research in hydrogen-doped natural gas pipeline welds. The research results show that: 1 Currently there is a need for comprehensive research on the degradation of mechanical properties in welds made from typical pipe materials on a global scale. It is imperative to systematically elucidate the mechanism of mechanical property degradation due to conventional and hydrogeninduced damage in welds of high-pressure hydrogen-doped natural gas pipelines worldwide. 2 The deterioration of mechanical properties in welds of hydrogen-doped natural gas pipelines is influenced by various components including hydrogen carbon dioxide and nitrogen. It is necessary to reveal the mechanism of mechanical property deterioration of pipeline welds under the joint participation of multiple damage mechanisms under multi-component gas conditions. 3 Establishing a fundamental database of mechanical properties for typical pipeline steel materials under hydrogen-doped natural gas conditions globally is imperative to form a method for strengthening the mechanical properties of typical high-pressure hydrogen-doped natural gas pipeline welds. 4 It is essential to promptly develop relevant standards for hydrogen blending transportation welding technology as well as weld evaluation testing and repair procedures for natural gas pipelines.

Hydrogen energy is regarded as an important way to achieve carbon emission reduction. This paper focuses on the combination of the design of the hydrogen supply chain network and the location of hydrogen refueling stations on the expressway. Based on the cost analysis of the hydrogen supply chain a multi-objective model is developed to determine the optimal scale and location of hydrogen refueling stations on the hydrogen expressway. The proposed model considers the hydrogen demand forecast hydrogen source selection hydrogen production and storage and transportation hydrogen station refueling mode etc. Taking Dalian City China as an example with offshore wind power as a reliable green hydrogen supply to select the location and capacity of hydrogen refueling stations for the hydrogen energy demonstration section of a certain expressway under multiple scenarios. The results of the case show that 4 and 5 stations are optimized on the expressway section respectively and the unit hydrogen cost is $14.3 /kg H2 and $11.8 /kg H2 respectively which are equal to the average hydrogen price in the international range. The optimization results verify the feasibility and effectiveness of the model.

The increasingly severe energy crisis has strengthened the determination todevelop environmentally friendly energy. And hydrogen has emerged as a candi-date for clean energy. Among many hydrogen generation methods biohydrogenstands out due to its environmental sustainability simple operating environ-ment and cost advantages. This review focuses on the rational design of catalystsfor fermentative hydrogen production. The principles of microbial dark fermen-tation and photo-fermentation are elucidated exhaustively. Various strategiesto increase the efficiency of fermentative hydrogen production are summa-rized and some recent representative works from microbial dark fermentationand photo-fermentation are described. Meanwhile perspectives and discussionson the rational design of catalysts for fermentative hydrogen production areprovided.

Water electrolysis is the most promising method for efficient production of high purity hydrogen (and oxygen) while the required power input for the electrolysis process can be provided by renewable sources (e.g. solar or wind). The thus produced hydrogen can be used either directly as a fuel or as a reducing agent in chemical processes such as in Fischer–Tropsch synthesis. Water splitting can be realized both at low temperatures (typically below 100 °C) and at high temperatures (steam water electrolysis at 500– 1000 °C) while different ionic agents can be electrochemically transferred during the electrolysis process (OH− H+ O2− ). Singular requirements apply in each of the electrolysis technologies (alkaline polymer electrolyte membrane and solid oxide electrolysis) for ensuring high electrocatalytic activity and long-term stability. The aim of the present article is to provide a brief overview on the effect of the nature and structure of the catalyst–electrode materials on the electrolyzer’s performance. Past findings and recent progress in the development of efficient anode and cathode materials appropriate for large-scale water electrolysis are presented. The current trends limitations and perspectives for future developments are summarized for the diverse electrolysis technologies of water splitting while the case of CO2/H2O co-electrolysis (for synthesis gas production) is also discussed.

This paper presents a wind-methanol-fuel cell system with hydrogen storage. It can manage various energy flow to provide stable wind power supply produce constant methanol and reduce CO2 emissions. Firstly this study establishes the theoretical basis and formulation algorithms. And then computational experiments are developed with MATLAB/Simulink (R2016a MathWorks Natick MA USA). Real data are used to fit the developed models in the study. From the test results the developed system can generate maximum electricity whilst maintaining a stable production of methanol with the aid of a hybrid energy storage system (HESS). A sophisticated control scheme is also developed to coordinate these actions to achieve satisfactory system performance.

To investigate the leakage characteristics of pure hydrogen and hydrogen-blended natural gas in medium- and low-pressure buried pipelines this study establishes a three-dimensional leakage model based on Computational Fluid Dynamics (CFD). The leakage characteristics in terms of pressure velocity and concentration distribution are obtained and the effects of operational parameters ground hardening degree and leakage parameters on hydrogen diffusion characteristics are analyzed. The results show that the first dangerous time (FDT) for hydrogen leakage is substantially shorter than for natural gas emphasizing the need for timely leak detection and response. Increasing the hydrogen blending ratio accelerates the diffusion process and decreases the FDT posing greater risks for pipeline safety. The influence of soil hardening on gas diffusion is also examined revealing that harder soils can restrict gas dispersion thereby increasing localized concentrations. Additionally the relationship between gas leakage time and distance is determined aiding in the optimal placement of gas sensors and prediction of leakage timing. To ensure the safe operation of hydrogen-blended natural gas pipelines practical recommendations include optimizing pipeline operating conditions improving leak detection systems increasing pipeline burial depth and selecting materials with higher resistance to hydrogen embrittlement. These measures can mitigate risks associated with hydrogen leakage and enhance the overall safety of the pipeline infrastructure.

As an important piece of equipment for hydrogen energy application the hydrogen internal combustion engine is helpful for the realization of zero carbon emissions where the aluminum connecting rod is one of the key core components. A semi-solid forging forming process for the 7075 aluminum alloy connecting rod is proposed in this work. The influence of process parameters such as the forging ratio sustaining temperature and duration time on the microstructures of the semi-solid blank is experimentally investigated. The macroscopic morphology metallographic structure and physical properties of the connecting-rod parts are analyzed. Reasonable process parameters for preparing the semi-solid blank are obtained from the experimental results. Under the reasonable parameters the average grain size is 41.48~42.57 µm and the average shape factor is 0.80~0.81. The yield strength and tensile strength improvement ratio of the connecting rod produced by the proposed process are 47.07% and 20.89% respectively.

The depletion of fossil fuel reserves has resulted from their application in the industrial and energy sectors. As a result substantial efforts have been dedicated to fostering the shift from fossil fuels to renewable energy sources via technological advancements in industrial processes. Microalgae can be used to produce biofuels such as biodiesel hydrogen and bioethanol. Microalgae are particularly suitable for hydrogen production due to their rapid growth rate ability to thrive in diverse habitats ability to resolve conflicts between fuel and food pro duction and capacity to capture and utilize atmospheric carbon dioxide. Therefore microalgae-based bio hydrogen production has attracted significant attention as a clean and sustainable fuel to achieve carbon neutrality and sustainability in nature. To this end the review paper emphasizes recent information related to microalgae-based biohydrogen production mechanisms of sustainable hydrogen production factors affecting biohydrogen production by microalgae bioreactor design and hydrogen production advanced strategies to improve efficiency of biohydrogen production by microalgae along with bottlenecks and perspectives to over come the challenges. This review aims to collate advances and new knowledge emerged in recent years for microalgae-based biohydrogen production and promote the adoption of biohydrogen as an alternative to con ventional hydrocarbon biofuels thereby expediting the carbon neutrality target that is most advantageous to the environment.

Hydrogen–gasoline hybrid refueling stations can minimize construction and management costs and save land resources and are gradually becoming one of the primary modes for hydrogen refueling stations. However catastrophic consequences may be caused as both hydrogen and gasoline are flammable and explosive. It is crucial to perform an effective risk assessment to prevent fire and explosion accidents at hybrid refueling stations. This study conducted a risk assessment of the refueling area of a hydrogen–gasoline hybrid refueling station based on the improved Accident Risk Assessment Method for Industrial Systems (ARAMIS). An improved probabilistic failure model was used to make ARAMIS more applicable to hydrogen infrastructure. Additionally the accident consequences i.e. jet fires and explosions were simulated using Computational Fluid Dynamics (CFD) methods replacing the traditional empirical model. The results showed that the risk levels at the station house and the road near the refueling area were 5.80 × 10−5 and 3.37 × 10−4 respectively and both were within the acceptable range. Furthermore the hydrogen dispenser leaked and caused a jet fire and the flame ignited the exposed gasoline causing a secondary accident considered the most hazardous accident scenario. A case study was conducted to demonstrate the practicability of the methodology. This method is believed to provide trustworthy decisions for establishing safe distances from dispensers and optimizing the arrangement of the refueling area.

This paper proposes an energy management strategy for a fuel cell (FC) hybrid power system based on dynamic programming and state machine strategy which takes into account the durability of the FC and the hydrogen consumption of the system. The strategy first uses the principle of dynamic programming to solve the optimal power distribution between the FC and supercapacitor (SC) and then uses the optimization results of dynamic programming to update the threshold values in each state of the finite state machine to realize real-time management of the output power of the FC and SC. An FC/SC hybrid tramway simulation platform is established based on RTLAB real-time simulator. The compared results verify that the proposed EMS can improve the durability of the FC increase its working time in the high-efficiency range effectively reduce the hydrogen consumption and keep the state of charge in an ideal range.

The most challenging aspect of developing a green hydrogen economy is long-distance oceanic transportation. Hydrogen liquefaction is a transportation alternative. However the cost and energy consumption for liquefaction is currently prohibitively high creating a major barrier to hydrogen supply chains. This paper proposes using solid nitrogen or oxygen as a medium for recycling cold energy across the hydrogen liquefaction supply chain. When a liquid hydrogen (LH2) carrier reaches its destination the regasification process of the hydrogen produces solid nitrogen or oxygen. The solid nitrogen or oxygen is then transported in the LH2 carrier back to the hydrogen liquefaction facility and used to reduce the energy consumption cooling gaseous hydrogen. As a result the energy required to liquefy hydrogen can be reduced by 25.4% using N2 and 27.3% using O2. Solid air hydrogen liquefaction (SAHL) can be the missing link for implementing a global hydrogen economy.

This study investigates the techno-economic feasibility of an off-grid integrated solar/wind/hydrokinetic plant to co-generate electricity and hydrogen for a remote micro-community. In addition to the techno-economic viability assessment of the proposed system via HOMER (hybrid optimization of multiple energy resources) a sensitivity analysis is conducted to ascertain the impact of ±10% fluctuations in wind speed solar radiation temperature and water velocity on annual electric production unmet electricity load LCOE (levelized cost of electricity) and NPC (net present cost). For this a far-off village with 15 households is selected as the case study. The results reveal that the NPC LCOE and LCOH (levelized cost of hydrogen) of the system are equal to $333074 0.1155 $/kWh and 4.59 $/kg respectively. Technical analysis indicates that the PV system with the rated capacity of 40 kW accounts for 43.7% of total electricity generation. This portion for the wind turbine and the hydrokinetic turbine with nominal capacities of 10 kW and 20 kW equates to 23.6% and 32.6% respectively. Finally the results of sensitivity assessment show that among the four variables only a +10% fluctuation in water velocity causes a 20% decline in NPC and LCOE.

Harnessing surplus wind and solar energy for water electrolysis boosts the efficiency of renewable energy utilization and supports the development of a low-carbon energy framework. However the intermittent and unpredictable nature of wind and solar power generation poses significant challenges to the dynamic stability and hydrogen production efficiency of electrolyzers. This study introduces a multi-state rotational control strategy for a hybrid electrolyzer system designed to produce hydrogen. Through a detailed examination of the interplay between electrolyzer power and efficiency—along with operational factors such as load range and startup/shutdown times—six distinct operational states are categorized under three modes. Taking into account the differing dynamic response characteristics of proton exchange membrane electrolyzers (PEMEL) and alkaline electrolyzers (AEL) a power-matching mechanism is developed to optimize the performance of these two electrolyzer types under varied and complex conditions. This mechanism facilitates coordinated scheduling and seamless transitions between operational states within the hybrid system. Simulation results demonstrate that compared to the traditional sequential startup and shutdown approach the proposed strategy increases hydrogen production by 10.73% for the same input power. Moreover it reduces the standard deviation and coefficient of variation in operating duration under rated conditions by 27.71 min and 47.04 respectively thereby enhancing both hydrogen production efficiency and the dynamic operational stability of the electrolyzer cluster.

To mitigate the risk of hydrogen leakage in ship fuel systems powered by internal combustion engines a Bayesian network model was developed to evaluate the risk of hydrogen fuel leakage. In conjunction with the Bow-tie model fuzzy set theory and the Noisy-OR Gate model an in-depth analysis was also conducted to examine both the causal factors and potential consequences of such incidents. The Bayesian network model estimates the likelihood of hydrogen leakage at approximately 4.73 × 10−4 and identifies key risk factors contributing to such events including improper maintenance procedures inadequate operational protocols and insufficient operator training. The Bowtie model is employed to visualize the causal relationships between risk factors and their potential consequences providing a clear structure for understanding the events leading to hydrogen leakage. Fuzzy set theory is used to address the uncertainties in expert judgments regarding system parameters enhancing the robustness of the risk analysis. To mitigate the subjectivity inherent in root node probabilities and conditional probability tables the NoisyOR Gate model is introduced simplifying the determination of conditional probabilities and improving the accuracy of the evaluation. The probabilities of flash or pool fires jet fires and vapor cloud explosions following a leakage are calculated as 4.84 × 10−5 5.15 × 10−5 and 4.89 × 10−7 respectively. These findings highlight the importance of strengthening operator training and enforcing stringent maintenance protocols to mitigate the risks of hydrogen leakage. The model provides a valuable framework for safety evaluation and leakage risk management in hydrogen-powered ship fuel systems.

The burgeoning adoption of photovoltaic and wind energy has limitations of volatility and intermittency which hinder their application. Electro-hydrogen coupling energy storage systems emerge as a promising solution to address this issue. This technology combines renewable energy power generation with hydrogen production through water electrolysis and hydrogen fuel cell power generation effectively enabling the consumption and peak load management of renewable energy sources. This paper presents a power system with a 10 kW photovoltaic system and lithium battery energy storage system designed for hydrogen-electric coupled energy storage validated through the physical experiments. The results demonstrate the system's effectiveness in mitigating the impact of randomness and volatility in photovoltaic power generation. Moreover the energy management system can adjust bus power based on load demand. Testing the system in the absence of photovoltaic power generation reveals its capability to supply energy to the load for three hours with a minimum operating load power of 3 kW even under weather conditions unsuitable for photovoltaic power generation. These findings showed the potential of electro-hydrogen coupling energy storage systems in addressing the challenges associated with renewable energy integration paving the way for a reliable and sustainable energy supply.

Under the guidance of energy-saving and emission reduction goals a lowcarbon economic operation method for integrated energy systems (IES) has been proposed. This strategy aims to enhance energy utilization efficiency bolster equipment operational flexibility and significantly cut down on carbon emissions from the IES. Firstly a thorough exploration of the two-stage operational framework of Power-to-Gas (P2G) technology is conducted. Electrolyzers methane reactors and hydrogen fuel cells (HFCs) are introduced as replacements for traditional P2G equipment with the objective of harnessing the multiple benefits of hydrogen energy. Secondly a cogeneration and HFC operational strategy with adjustable heat-to-electricity ratio is introduced to further enhance the IES’s low-carbon and economic performance. Finally a step-by-step carbon trading mechanism is introduced to effectively steer the IES towards carbon emission control.

Driven by the current round of technological revolution and industrial transformation and based on a consensus among countries around the world the world’s energy landscape is undergoing profound adjustments to promote a transition to clean low-carbon energy in order to cope with global climate change. As a clean and carbon-free secondary energy source hydrogen energy is an important component of the energy strategy in various countries. Fuel cell technology is also of great importance in directing the current global energy technology revolution. China has clarified its sustainable energy goals: to peak its carbon dioxide emissions [1] and achieve carbon neutrality [2]. With thorough development of technology and the industry hydrogen energy will play a significant role in achieving these goals.

The coupling of renewable energy sources with electrolyzers under standalone conditions significantly enhances the operational efficiency and improves the costeffectiveness of electrolyzers as a technologically viable and sustainable solution for green hydrogen production. To address the configuration optimization challenge in hybrid electrolyzer systems integrating alkaline water electrolysis (AWE) and proton exchange membrane electrolysis (PEME) this study proposes an innovative methodology leveraging the morphological analysis of Pareto frontiers to determine the optimal solutions under multi-objective functions including the hydrogen production cost and efficiency. Then the complementary advantages of AWE and PEME are explored. The proposed methodology demonstrated significant performance improvements compared with the single-objective optimization function. When contrasted with the economic optimization function the hybrid system achieved a 1.00% reduction in hydrogen production costs while enhancing the utilization efficiency by 21.71%. Conversely relative to the efficiency-focused optimization function the proposed method maintained a marginal 5.22% reduction in utilization efficiency while achieving a 6.46% improvement in economic performance. These comparative results empirically validate that the proposed hybrid electrolyzer configuration through the implementation of the novel optimization framework successfully establishes an optimal balance between the economy and efficiency of hydrogen production. Additionally a discussion on the key factors affecting the rated power and mixing ratio of the hybrid electrolyzer in this research topic is provided.

Hydrogen specifications for different scenarios are various. Based on national standards for China a comparison of hydrogen specification standards is discussed in this paper including specification standards for industrial hydrogen pure hydrogen high pure hydrogen ultrapure hydrogen hydrogen for electronic industry and hydrogen for PEM FCVs. Hydrogen purity for electronic industry is greater than that for industrial hydrogen pure hydrogen and hydrogen for PEM FCVs. Specifications of general contaminants in hydrogen for electronic industry including H2O O2 N2 CO CO2 and total hydrocarbons are stricter than that in hydrogen for PEM FCVs. Hydrogen purity for PEM FCVs is less than that for electronic industry and pure hydrogen. However contaminants in hydrogen for PEM FCVs are strict. Contaminants in hydrogen for PEM FCVs should include not only H2O O2 N2 CO CO2 Ar and total hydrocarbons but also helium total sulfur compounds formaldehyde formic acid ammonia halogenated compounds and particulates.

To mitigate challenges arising from renewable energy volatility and multi-energy load uncertainty this paper introduces a dynamic hydrogen blending (DHB) strategy for an integrated energy system. The strategy is categorized into Continuous Hydrogen Blending (CHB) and Time-phased Hydrogen Blending (THB) based on the temporal variations in the hydrogen blending ratio. To evaluate the regulatory effect of DHB on uncertainty a datadriven distributionally robust optimization method is employed in the day-ahead stage to manage system uncertainties. Subsequently a hierarchical model predictive control framework is designed for the intraday stage to track the day-ahead robust scheduling outcomes. Experimental results indicate that the optimized CHB ratio exhibits step characteristics closely resembling the THB configuration. In terms of cost-effectiveness CHB reduces the day-ahead scheduling cost by 0.87% compared to traditional fixed hydrogen blending schemes. THB effectively simplifies model complexity while maintaining a scheduling performance comparable to CHB. Regarding tracking performance intraday dynamic hydrogen blending further reduces upper- and lower-layer tracking errors by 4.25% and 2.37% respectively. Furthermore THB demonstrates its advantage in short-term energy regulation effectively reducing tracking errors propagated from the upper layer MPC to the lower layer resulting in a 2.43% reduction in the lower-layer model’s tracking errors.

The existence of a large number of abandoned salt caverns in China has posed a great threat to geological safety and environmental protection and it also wasted enormous underground space resources. To address such problems comprehensive utilization of these salt caverns has been proposed both currently and in the future mainly consisting of energy storage and waste disposal. Regarding energy storage in abandoned salt caverns the storage media such as gas oil compressed air and hydrogen have been introduced respectively in terms of the current development and future implementation with siteselection criteria demonstrated in detail. The recommended burial depth of abandoned salt caverns for gas storage is 1000–1500 m while it should be less than 1000 m for oil storage. Salt cavern compressed air storage has more advantages in construction and energy storage economics. Salt cavern hydrogen storage imposes stricter requirements on surrounding rock tightness and its location should be near the hydrogen production facilities. The technical idea of storing ammonia in abandoned salt caverns (indirect hydrogen storage) has been proposed to enhance the energy storage density. For the disposal of wastes including low-level nuclear waste and industrial waste the applicable conditions technical difficulties and research prospects in this field have been reviewed. The disposal of nuclear waste in salt caverns is not currently recommended due to the complex damage mechanism of layered salt rock and the specific locations of salt mines in China. Industrial waste disposal is relatively mature internationally but in China policy and technical research require strengthening to promote its application. Furthermore considering the recovery of salt mines and the development of salt industries the cooperation between energy storage regions and salt mining regions has been discussed. The economic and environmental benefits of utilizing abandoned salt caverns have been demonstrated. This study provides a solution to handle the abandoned salt caverns in China and globally.

Hydrogen energy as a medium for long-term energy storage needs to ensure the continuous and stable operation of the electrolyzer during the production of green hydrogen using wind energy. In this paper based on the overall model of a wind power hydrogen production system an integrated control strategy aimed at improving the quality of wind power generation smoothing the hydrogen production process and enhancing the stability of the system is proposed. The strategy combines key measures such as the maximum power point tracking control of the wind turbine and the adaptive coordinated control of the electrochemical energy storage system which can not only efficiently utilize the wind resources but also effectively ensure the stability of the bus voltage and the smoothness of the hydrogen production process. The simulation results show that the electrolyzer can operate at full power to produce hydrogen while the energy storage device is charging when wind energy is sufficient; the electrolyzer continuously produces hydrogen according to the wind energy when the wind speed is normal; and the energy storage device will take on the task of maintaining the operation of the electrolyzer when the wind speed is insufficient to ensure the stability and reliability of the system.

MgH2 shows significant potential for a solid-state hydrogen storage medium due to the advantages of high hydrogen capacity excellent reversibility and low cost. However its large-scale application still requires overcoming significant thermodynamic and kinetic hurdles. Catalyst design and optimization enhancements are crucial for the hydrogen storage properties of MgH2 wherein single-atom catalysts characterized by their small size and high proportion of unsaturated coordination sites have recently demonstrated a significant advance and considerable promise in this regard. This review presents recent progress on state-of-the-art single-atom catalysts for enhancing MgH2 hydrogen storage examining both supported and unsupported catalyst types i.e. transition metal @ N-modified carbon materials and transition metal @ transition metal compounds and metallene-derived compounds and single-atom alloys respectively. We systematically discussed the single-atom catalysts in MgH2 hydrogen storage systems focusing on synthesis strategies characterization techniques catalytic mechanisms as well as existing challenges and future perspectives. We aimed to provide a comprehensive and cohesive understanding for researchers in the field and promote the development of single-atom catalysts and their significant optimization of the hydrogen storage performance of MgH2.