China, People’s Republic

Hydrogen blending into natural gas has attracted significant attention in domestic applications. The paper studied the effects of natural gas mixed with hydrogen at 0% (vol) 5% 10% 15% 20% and 25% on the performance of typical round-port gas stove (TRPGS) swirling strip-port gas stove (SSPGS) and radiant porous media gas stove (RPMGS). The experimental results show that flame length shortens with the increase of hydrogen proportion and the combustion remains stable when the hydrogen proportion is equal to or less than 25%. With increasing hydrogen proportion the measured heat inputs of the three types of domestic gas stoves decrease gradually and the average thermal efficiency of TRPGS and SSPGS increase by 0.82% and 1.18% respectively. In addition the average efficiency of the RPMGS first increases by 1.35% under a hydrogen proportion of 15% and then decreases by 1.36% under a hydrogen proportion of 25%. In terms of flue gas emission CO emission reduces significantly with increasing hydrogen proportion while NOX emissions remain almost unchanged.

Renewable energy complementary hydrogen production can enhance the full consumption of renewable energy and reduce the abandonment of wind and solar power. The integration of renewable energy and hydrogen production equipment through existing multi-terminal DC systems can reduce new power lines construction and save investment in distribution equipment. For integrated renewable energy/hydrogen energy in an existing multi-terminal DC system this paper investigates its potential of hydrogen production based on renewable energy while ensuring the normal performance of the existing system being not affected. The typical structure and control strategy of the integrated renewable energy/hydrogen energy in multi-terminal DC system are firstly described. Then the state space model of the system is constructed and the key parameters affecting the hydrogen production capacity are studied by using the eigenvalues analysis method. Finally the corresponding system simulation model and test platform are built and the theoretical analysis results are verified and the potential of using multi-terminal DC system to enhance hydrogen production is quantitatively analyzed. The proposed scheme can enhance the hydrogen production potential from renewable energy meanwhile the normal performance of the existing system is not affected.

The uncertainty and volatility of wind power have led to large-scale wind curtailment during grid connections. The adoption of power-to-hydrogen (P2H) system in a microgrid (MG) can mitigate the renewable curtailment by hydrogen conversion and storage. This paper conducts unified modeling for different types of P2H systems and considers the multi-energy trading in a hydrogen-coupled power market. The proposed bi-level equilibrium model is beneficial to minimize the energy cost of microgrids. Firstly a microgrid operation model applied to different P2H systems including an alkaline electrolysis cell (AEC) a proton exchange membrane electrolysis cell (PEMEC) or a solid oxide electrolysis cell (SOEC) is proposed at the upper level. Secondly an electricity market–clearing model and a hydrogen market model are constructed at the lower level. Then the diagonalization algorithm is adopted to solve the multi-market equilibrium problem. Finally case studies based on an IEEE 14-bus system are conducted to validate the proposed model and the results show that the microgrid with a P2H system could gain more profits and help increase the renewable penetration.

The consumption of hydrogen could increase by sixfold in 2050 compared to 2020 levels reaching about 530 Mt. Against this backdrop the proton exchange membrane fuel cell (PEMFC) has been a major research area in the field of energy engineering. Several reviews have been provided in the existing corpus of literature on PEMFC but questions related to their evolutionary nuances and research hotspots remain largely unanswered. To fill this gap the current review uses bibliometric analysis to analyze PEMFC articles indexed in the Scopus database that were published between 2000–2021. It has been revealed that the research field is growing at an annual average growth rate of 19.35% with publications from 2016 to 2012 alone making up 46% of the total articles available since 2000. As the two most energy-consuming economies in the world the contributions made towards the progress of PEMFC research have largely been from China and the US. From the research trend found in this investigation it is clear that the focus of the researchers in the field has largely been to improve the performance and efficiency of PEMFC and its components which is evident from dominating keywords or phrases such as ‘oxygen reduction reaction’ ‘electrocatalysis’ ‘proton exchange membrane’ ‘gas diffusion layer’ ‘water management’ ‘polybenzimidazole’ ‘durability’ and ‘bipolar plate’. We anticipate that the provision of the research themes that have emerged in the PEMFC field in the last two decades from the scientific mapping technique will guide existing and prospective researchers in the field going forward.

Ammonia can be stored as a liquid under relatively easy conditions (Ambient temperature by applying 10 bar or Ambient pressure with the temperature of 239 K). At the same time liquid ammonia has a high hydrogen storage density and is therefore a particularly promising carrier for hydrogen storage. At the same time the current large-scale industrial synthesis of ammonia has long been mature and in the future it will be possible to achieve a zero-emission ammonia regeneration cycle system by replacing existing energy sources with renewable ones. Ammonia does not contain carbon and its use in fuel cells can avoid NOx production during energy release. high temperature solid oxide fuel cells can be directly fueled by ammonia and obtain good output characteristics but the challenges inherent in high temperature solid oxide fuel cells greatly limit the implementation of this option. Whereas PEMFC has gained initial commercial use however for PEMFC ammonia is a toxic gas so the general practice is to convert ammonia to pure hydrogen. Ammonia to hydrogen requires decomposition under high temperature and purification which increases the complexity of the fuel system. In contrast PEMFC that can use ammonia decomposition gas directly can simplify the fuel system and this option has already obtained preliminary experimental validation studies. The energy efficiency of the system obtained from the preliminary validation experiments is only 34–36% which is much lower than expected. Therefore this paper establishes a simulation model of PEMFC directly using ammonia decomposition gas as fuel to study the maximum efficiency of the system and the effect of the change of system parameters on the efficiency and the results show that the system efficiency can reach up to 45% under the condition of considering certain heat loss. Increasing the ammonia decomposition reaction temperature decreases the system efficiency but the effect is small and the system efficiency can reach 44% even at a temperature of 850°C. The results of the study can provide a reference for a more scientific and quantitative assessment of the potential value of direct ammonia decomposition gas-fueled PEMFC.

With the imminent threat of the energy crises innovation in energy technologies is happening world-wide. The aim is to reduce our reliance on fossil fuels. Electric vehicles with fuel-cells that use hydrogen as an energy carrier are touted to be one of the most important potential replacements of the gasoline vehicle in both future transportation scenarios and emerging smart energy grids. However hydrogen storage is a major technical barrier that lies between where we are now and the mass application of hydrogen energy. Further exploration of onboard hydrogen storage systems (OHSS) is urgently needed and in this regard a comprehensive technology opportunity analysis will help. Hence with this research we drew on scientific papers and patents related to OHSS and developed a novel methodology for investigating the past present and future development trends in OHSS. Specifically we constructed a heterogeneous knowledge network using a unique multi-component structure with three core components: hydrogen carriers hydrogen storage materials and fuel cells. From this network we extracted both the developed and underdeveloped technological solutions in the field and applied a well-designed evaluation system and prediction model to score the future development potential of these technological solutions. What emerged was the most promising directions of research in the short medium and long term. The results show that our methodology can effectively identify technology opportunities in OHSS along with providing valuable decision support to researchers and enterprise managers associated with the development and application of OHSS.

With the high-proportion accession of renewable energy and randomness of the load side in the new energy power system unbalanced feeder power and heavy overload of the transformer caused by massive access of highly uncertain source loads become more and more serious. In order to solve the aforementioned problems a honeycomb topology of the multi-station integrated system is proposed. The soft open point (SOP) is used as the key integrated equipment of the internal unit of a multi-station integrated system. The honeycomb grid structure is composed of flexible nodes and the multi-station integrated system is composed of multi-network flexible interconnection. Based on the characteristics of the regional resource endowment hydrogen energy flow is deeply coupled in parts of honeycomb grids. In order to improve the reliability and flexibility of the multi-station integrated unit the structure of the new multi-station integrated unit the power balance constraints on the unit and the switching process of SOP control mode are studied. At the same time the hydrogen electricity coupling structure and the coordinated control strategy of hydrogen electricity conversion are proposed to solve the problem of deep application of hydrogen energy. Finally the effectiveness of the proposed multi-station integrated system is verified by using three simulation models.

To address the increasing hydrogen demand and carbon emissions of industrial parks this paper proposes an integrated energy system dispatch strategy considering multi-hydrogen supply and comprehensive demand response. This model adopts power-to-gas technology to produce green hydrogen replacing a portion of gray hydrogen and incorporates a carbon capture system to effectively reduce the overall carbon emissions of the industrial park. Meanwhile incentive-based and price-based demand response strategies are implemented to optimize the load curve. A scheduling model is established targeting the minimization of procurement operation carbon emission and wind curtailment costs. The case study of a northern industrial park in China demonstrates that the joint supply of green and gray hydrogen reduces carbon emissions by 40.98% and costs by 17.93% compared to solely using gray hydrogen. The proposed approach successfully coordinates the economic and environmental performance of the integrated energy system. This study provides an effective scheduling strategy for industrial parks to accommodate high shares of renewables while meeting hydrogen needs and carbon reduction targets.

Hydrogen production using solar energy is an important way to obtain hydrogen energy. However the inherent intermittent and random characteristics of solar energy reduce the efficiency of hydrogen production. Therefore it is necessary to add an energy storage system to the photovoltaic power hydrogen production system. This paper establishes a model of a photovoltaic power generation hydrogen system and optimizes the capacity configuration. Firstly the mathematical model is modeled and analyzed and the system is modeled using Matlab/Simulink; secondly the principle of optimal configuration of energy storage capacity is analyzed to determine the optimization strategy we propose the storage capacity configuration algorithm based on the low-pass filtering principle and optimal time constant selection; finally a case study is conducted whose photovoltaic installed capacity of 30 MW verifying the effectiveness of the proposed algorithm analyzing the relationship between energy storage capacity and smoothing effect. The results show that as the cut-off frequency decreases the energy storage capacity increases and the smoothing effect is more obvious. The proposed algorithm can effectively reduce the 1 h maximum power variation of PV power generation. In which the maximum power variation of PV generation 1 h before smoothing is 4.31 MW. We set four different sets of time constants the maximum power variation of PV generation 1 h after smoothing is reduced to 0.751 0.389 0.078 and 0.04 MW respectively.

Hydrogen energy is an important technical route to achieve carbon peak and carbon neutrality. Direct injection hydrogen engine is one of the ways of hydrogen energy application. It has the advantages of high thermal efficiency and limit/reduce abnormal combustion phenomena. In order to explore the cycle characteristics of direct injection hydrogen engine based on a 2.0L direct injection hydrogen engine an experimental study on the cycle characteristics of direct injection hydrogen engine was carried out. The experimental results show that cycle variation increases from 0.67% to 1.02% with the increasing of engine speed. The cycle variation decreases from 1.52% to 0.64% with the increasing of engine load. As the equivalence ratio increases the cycle variation first decreases significantly from 2.52% to 0.35% and then stabilizes. The ignition advance angle has a better angle to minimize the cycle variation. An experimental study on the influence of the start of injection on the cycle variation was carried out. As the engine speed/engine load is 2000rpm/4bar the cycle variation increases from 0.72% to 2.42% with the start of injection changing from -280°CA to -180°CA; then rapidly decreases to 0.99% and then increases to 2.26% with the start of injection changing from -180°CA to -100°CA. The experimental results show that SOI could cause significant influence on cycle variation because of intake valve closing and shortening mixing time and both the process of intake valve closing and lagging the SOI could cause the cycle variation to increase. The SOI remarkably affects the cycle variation at low engine load/equivalence ratio and high engine speed. This study lays the foundation for the follow-up research of hydrogen engine performance matching of the cycle variation.

The combination of methane steam reforming technology and CCS (Carbon Capture and Storage) technology has great potential to reduce carbon emissions in the process of hydrogen production. Different from the traditional idea of capturing CO2 (Carbon Dioxide) in the exhaust gas with high work consumption this study simultaneously focuses on CO2 separation from fuel gas and recycling. A new hydrogen production system is developed by methane steam reforming coupled with carbon capture. Separated and captured high-purity carbon dioxide could be recycled for methane dry reforming; on this basis a new methane-dry-reforming-driven hydrogen production system with a carbon dioxide reinjection unit is innovatively proposed. In this study the energy flow and irreversible loss in the two newly developed systems are analyzed in detail through energy and exergy balance analysis. The advantages are explored from the perspective of hydrogen production rate natural gas consumption and work consumption. In addition in consideration of the integrated performance an optimal design analysis was conducted. In terms of hydrogen production the new system based on dry reforming is better with an advantage of 2.41%; however it is worth noting that the comprehensive thermal performance of the new steam reforming system is better reaching 10.95%. This study provides new ideas for hydrogen production from a low carbon emission perspective and also offers a new direction for future distributed energy system integration.

Low-carbon transition pathways oriented from different transition targets would result in a huge variation of energy system deployment and transition costs. Hydrogen is widely considered as an imperative energy carrier to reach carbon neutral targets. However hydrogen production either from non-fossil power or fossil fuels with carbon capture is closely linked with an energy supply system and has great impacts on its structure. Identifying an economically affordable transition pathway is attractive and energy infrastructure is critical due to massive investment and long life-span. In this paper a multi-regional multi-period and infrastructure-based model is proposed to quantify energy supply system transition costs with different low-carbon targets and hydrogen production alternatives and China is taken as a case study. Results show that fulfilling 2-degree and 1.5-degree temperature increase targets would result in 84% and 151% increases in system transition costs 114% and 246% increases in infrastructure investment and 211% and 339% increases in stranded investment compared to fulfilling stated policy targets. Producing hydrogen from coal would be economical when carbon capture and sequestration cost is lower than 437 yuan per tonne and reduce infrastructure investment and stranded coal investment by 16% and 35% respectively than producing hydrogen from renewable power.

Hydrogen production from renewable energy is gaining increasing attention to enhance energy consumption structure and foster a more eco-friendly and sustainable society. At the same time mixing hydrogen with natural gas and supplying it to civilians is one of the best ways to reduce carbon emissions and increase the reliability of technology while reducing the costs of storing and transporting hydrogen. Even though numerous researchers have conducted experimental and simulation studies on hydrogen-doped natural gas most of these studies have focused on the effects of hydrogen-doped ratio equivalence ratio and fuel combustion mode. The impact of burner structure on hydrogen-enriched natural gas has not received much attention. Compared with conventional direct-flow combustion swirl combustion can improve the mixing effect of the fuel mixture during combustion and the use of regions of reversed flow due to swirl can make the fuel burn more fully to achieve the reduction of pollutant emissions. Swirling flames are widely used in gas turbines and industrial furnaces because of their high stability. However the application of swirl combustion in domestic equipment is still in its infancy which deserves more researchers to explore and enhance the working conditions of domestic combustion equipment. In this paper a three-dimensional swirl burner model is utilized to examine the effect of swirl angle θ and swirl length L of the swirler on the combustion behavior of hydrogen-enriched natural gas in a swirl burner. The results indicate that the swirl angle θ and swirl length L play an essential role in the combustion of natural gas containing hydrogen. As the swirl angle θ increases the flame temperature decreases more slowly the combustion becomes more stable and the length of the flame is slightly increased. Simultaneously CO and NO emissions will gradually decrease and the combustion effect is enhanced when the swirl angle is 45◦. With increased swirl length L the flame length grows the high-temperature region expands and CO and NO emissions decrease. Meanwhile the change in swirl length has little effect on the increase of flame peak temperature when the fuel is thoroughly mixed. When the swirl length is 12 mm CO and NO emissions are lower and NO emissions are reduced by 36.11% compared to a swirl length of 6 mm. This work is a reference point for applying hydrogen-mixed natural gas in the swirl burner but it must be studied and optimized further in future research.

The crisscross progress of transportation and energy carries the migrating track of human society development and the evolution of civilization among which the decarbonization strategy is a key issue. Traffic carbon emissions account for 16.2% of total energy carbon emissions while road traffic carbon emissions account for 11.8% of total energy carbon emissions. Therefore road traffic is a vital battlefield in attaining the goal of decarbonization. Employing clean energy as an alternative fuel is of great significance to the transformation of the energy consumption structure in road transportation. Hydrogen and ammonia are renewable energy with the characteristics of being widely distributed and clean. Both exist naturally in nature and the products of complete combustion are substances (water and nitrogen) that do not pollute the atmosphere. Because it can promote agricultural production ammonia has a long history in human society. Both have the potential to replace traditional fossil fuel energy. An overview of the advantages of hydrogen and ammonia as well as their development in different countries such as the United States the European Union Japan and other major development regions is presented in this paper. Related research topics of hydrogen and ammonia’s production storage and transferring technology have also been analyzed and collated to stimulate the energy production chain for road transportation. The current cost of green hydrogen is between $2.70–$8.80 globally which is expected to approach $2–$6 by 2030. Furthermore the technical development of hydrogen and ammonia as a fuel for engines and fuel cells in road transportation is compared in detail and the tests practical applications and commercial popularization of these technologies are summarized respectively. Opportunities and challenges coexist in the era of the renewable energy. Based on the characteristics and development track of hydrogen and ammonia the joint development of these two types of energy is meant to be imperative. The collaborative development mode of hydrogen and ammonia together with the obstacles to their development of them are both compared and discussed. Finally referring to the efforts and experiences of different countries in promoting hydrogen and ammonia in road transportation corresponding constructive suggestions have been put forward for reference. At the end of the paper a framework diagram of hydrogen and ammonia industry chains is provided and the mutual promotion development relationship of the two energy sources is systematically summarized.

As a fuel for power generation high-pressure hydrogen gas is widely used for transportation and its efficient storage promotes the development of fuel cell vehicles (FCVs). However as the filling process takes such a short time the maximum temperature in the storage tank usually undergoes a rapid increase which has become a thorny problem and poses great technical challenges to the steady operation of hydrogen FCVs. For security reasons SAE J2601/ISO 15869 regulates a maximum temperature limit of 85 ◦C in the specifications for refillable hydrogen tanks. In this paper a two-dimensional axisymmetric and a three-dimensional numerical model for fast charging of Type III 35 MPa and 70 MPa hydrogen vehicle cylinders are proposed in order to effectively evaluate the temperature rise within vehicle tanks. A modified standard k-ε turbulence model is utilized to simulate hydrogen gas charging. The equation of state for hydrogen gas is adopted with the thermodynamic properties taken from the National Institute of Standards and Technology (NIST) database taking into account the impact of hydrogen gas’ compressibility. To validate the numerical model three groups of hydrogen rapid refueling experimental data are chosen. After a detailed comparison it is found that the simulated results calculated by the developed numerical model are in good agreement with the experimental results with average temperature differences at the end time of 2.56 K 4.08 K and 4.3 K. The present study provides a foundation for in-depth investigations on the structural mechanics analysis of hydrogen gas vessels during fast refueling and may supply some technical guidance on the design of charging experiments.

Extreme disasters have become increasingly common in recent years and pose significant dangers to the integrated energy system’s secure and dependable energy supply. As a vital part of an integrated energy system the energy storage system can help with emergency rescue and recovery during major disasters. In addition it can improve energy utilization rates and regulate fluctuations in renewable energy under normal conditions. In this study the sizing scheme of multienergy storage equipment in the electric–thermal–hydrogen integrated energy system is optimized; economic optimization in the regular operating scenario and resilience enhancement in extreme disaster scenarios are also considered. A refined model of multi-energy storage is constructed and a two-layer capacity configuration optimization model is proposed. This model is further enhanced by the integration of a Markov two-state fault transmission model which simulates equipment defects and improves system resilience. The optimization process is solved using the tabu chaotic quantum particle swarm optimization (TCQPSO) algorithm to provide reliable and accurate optimization results. The results indicate that addressing severe disaster situations in a capacity configuration fully leverages the reserve energy function of energy storage and enhances system resilience while maintaining economic efficiency; furthermore adjusting the load loss penalty coefficients offers a more targeted approach to the balancing of the system economy and resilience. Thus new algorithmic choices and planning strategies for future research on enhancing the resilience of integrated energy systems under extreme disaster scenarios are provided.

The Japanese government has announced a commitment to net-zero greenhouse gas emissions by 2050. It envisages an important role for hydrogen in the nation’s future energy economy. This paper explores the possibility that a significant source for this hydrogen could be produced by electrolysis fueled by power generated from offshore wind in China. Hydrogen could be delivered to Japan either as liquid or bound to a chemical carrier such as toluene or as a component of ammonia. The paper presents an analysis of factors determining the ultimate cost for this hydrogen including expenses for production storage conversion transport and treatment at the destination. It concludes that the Chinese source could be delivered at a volume and cost consistent with Japan’s idealized future projections.

In this work cryogenic hydrogen fires at fixed pressures and various initial temperatures were investigated experimentally. Flame length width heat fluxes and temperatures in down-stream regions were measured for the scenarios with 1.6-3 mm jet nozzle 106 to 273 K 2-5 barabs. The results show that the flame size is related to not only the jet nozzle diameter but also the release pressure and initial temperature. The correlations of normalized flame length and width are proposed with the stagnation pressure and the ratio of ambient and stagnation temperatures. Under constant pressure the flame size total radiative power and radiation fraction increase with the decrease of temperature due to lower choked flow velocity and higher density of cryogenic hydrogen. The correlation of radiation fraction proposed by Molina et al. at room temperature is not suitable to predict the cryogenic hydrogen jet fires. Based on piecewise polynomial law

In the context of carbon trading energy conservation and emissions reduction are the development directions of integrated energy systems. In order to meet the development requirements of energy conservation and emissions reduction in the power grid considering the different responses of the system in different time periods a wind-hydrogen integrated multi-time scale energy scheduling model was established to optimize the energy-consumption scheduling problem of the system. As the scheduling model is a multiobjective nonlinear problem the artificial fish swarm algorithm–shuffled frog leaping algorithm (AFS-SFLA) was used to solve the scheduling model to achieve system optimization. In the experimental test process the Griewank benchmark function and the Rosenbrock function were selected to test the performance of the proposed AFS-SFL algorithm. In the Griewank environment compared to the SFLA algorithm the AFS-SFL algorithm was able to find a feasible solution at an early stage and tended to converge after 110 iterations. The optimal solution was −4.83. In the test of total electric power deviation results at different time scales the maximum deviation of early dispatching was 14.58 MW and the minimum deviation was 0.56 MW. The overall deviation of real-time scheduling was the minimum and the minimum deviation was 0 and the maximum deviation was 1.89 WM. The integrated energy system adopted real-time scale dispatching with good system stability and low-energy consumption. Power system dispatching optimization belongs to the objective optimization problem. The artificial fish swarm algorithm and frog algorithm were innovatively combined to solve the dispatching model which improved the accuracy of power grid dispatching. The research content provides an effective reference for the efficient use of clean and renewable energy.

To study the effect of hydrogen-blended natural gas on the combustion stability and emission of domestic gas water heater a test system is built in this paper taking a unit of the partial premixed burner commonly used in water heaters as the object. Under the heat load of 0.7~2.3kW the changes of flame shape burner temperature and pollutant emission of natural gas with hydrogen volume ratio of 0~40% are studied with independent control of primary air supply and mixing. The results show that: with the increase of hydrogen blending ratio the inner flame height increases firstly and then reduces while the change of burner temperature is opposite. The maximum inner flame height and the minimum temperature of the burner both appear at the hydrogen blending ratio of 10~20%. It can be seen that the limit of hydrogen blending ratio which can maintain the burner operate safely and stably under rated heat load is 40% through the maximum temperature distribution on the burner surface. The CO emission in the flue gas gradually decreases with the increase of hydrogen blending ratio while the NOx emission fluctuates slightly when the hydrogen blending ratio is less than 20% but then decreases gradually.

Hydrogen energy and fuel cell technology are critical clean energy roads to pursue carbon neutrality. The proton exchange membrane fuel cell (PEMFC) has a wide range of commercial application prospects due to its simple structure easy portability and quick start-up. However the cost and durability of the PEMFC system are the main barriers to commercial applications of fuel cell vehicles. In this paper the core hydrogen recirculation components of fuel cell vehicles including mechanical hydrogen pumps ejectors and gas–water separators are reviewed in order to understand the problems and challenges in the simulation design and application of these components. The types and working characteristics of mechanical pumps used in PEMFC systems are summarized. Furthermore corresponding design suggestions are given based on the analysis of the design challenges of the mechanical hydrogen pump. The research on structural design and optimization of ejectors for adapting wide power ranges of PEMFC systems is analyzed. The design principle and difficulty of the gas–water separator are summarized and its application in the system is discussed. In final the integration and control of hydrogen recirculation components controlled cooperatively to ensure the stable pressure and hydrogen supply of the fuel cell under dynamic loads are reviewed.

A combined ultra-short-term wind power prediction strategy with high robustness based on least squares support vector machine (LSSVM) has been proposed in order to solve the wind abandonment caused by wind power randomness and realize efficient hydrogen production under wide power fluctuation. Firstly the original wind power data is decomposed into sub-modes with different bandwidth by variational modal decomposition (VMD) which reduces the influence of random noise and mode mixing significantly. Then dragonfly algorithm (DA) is introduced to optimize LSSVM kernel function and the combined ultra-short-term wind power prediction strategy which meets the time resolution and accuracy requirements of electrolytic cell control has been established finally. This model is validated by a wind power hydrogen production demonstration project output in the middle east of China. The superior prediction accuracy for high volatility wind power data is verified and the algorithm provides theoretical basis to improve the control of wind power hydrogen production system

In recent years the problem of environmental pollution especially the emission of greenhouse gases has attracted people’s attention to energy infrastructure. At present the fuel consumed by transportation mainly comes from fossil energy and the strong traffic demand has a great impact on the environment and climate. Fuel cell electric vehicles (FCEVs) use hydrogen energy as a clean alternative to fossil fuels taking into account the dual needs of transportation and environmental protection. However due to the low power density and high manufacturing cost of hydrogen fuel cells their combination with other power supplies is necessary to form a hybrid power system that maximizes the utilization of hydrogen energy and prolongs the service life of hydrogen fuel cells. Therefore the hybrid power system control mode has become a key technology and a current research hotspot. This paper first briefly introduces hydrogen fuel cells then summarizes the existing hybrid power circuit topology categorizes the existing technical solutions and finally looks forward to the future for different scenarios of hydrogen fuel cell hybrid power systems. This paper provides reference and guidance for the future development of renewable hydrogen energy and hydrogen fuel cell hybrid electric vehicles.

As one kind of clean zero carbon and sustainable energy hydrogen energy has been regarded as the most potential secondary energy. Recently hydrogen refueling station gradually becomes one of important distribution infrastructures that provides hydrogen sources for transport vehicles and other distribution devices. However the highly combustible nature of hydrogen may bring great hazards to environment and human. The safety design of hydrogen usage has been brought to public too. This paper is mainly focused on the hydrogen leakage and dispersion process. A new solver for gaseous buoyancy dispersion process is developed based on OpenFOAM [1]. Thermodynamic and transport properties of gases are updated by library Mutation ++ [2]. For validation two tests of hydrogen dispersion in partially opened space and closed space are presented. Numerical simulation of hydrogen dispersion behavior in hydrogen refueling station is carried out in this paper as well. From the results three phases of injection dispersion and buoyancy can be seen clearly. The profile of hydrogen concentration is tend to be Gaussian in dispersion region. Subsonic H2 jet in stagnant environment is calculated for refueling station the relationship between H2 concentration decay and velocity along the jet trajectory is obtained.

In response to the issues of insufficient flexibility in the operation of hydrogen storage and hydrogen production equipment with poor economic viability when operated independently in the park firstly a comprehensive energy system model for hydrogen storage and power generation which considering the multi-operational conditions of alkaline electrolyzers (ELE) is constructed. This model is integrated into the comprehensive en ergy system of the park as a multi-energy supply device. Multiple park comprehensive energy systems are then interconnected to form a park comprehensive energy system cluster through the sharing of electric energy. Subsequently an operational optimization strategy is proposed to address the issues of electric energy sharing and profit settlement in the park cluster system. This strategy consists of two stages. In the first stage the alternating direction method of multipliers with dynamic step size (DSS-ADMM) is employed to solve the electric energy transaction volume among parks. In the second stage based on the operating costs of the park cluster system under different degrees of electric energy sharing the Shapley value method from cooperative game theory is used to settle park profits. Finally the results indicate that the operational mode of hydrogen storage which considering the multi-operational conditions of alkaline ELE effectively enhances the flexibility in pre paring hydrogen during electrolysis meeting various energy supply needs within the park. The sharing of electric energy among parks promotes the reduction of park operating costs resulting in a 6.05 % decrease in the total cost of the park cluster system. Meanwhile the Shapley value method effectively settles park profits with in dividual parks receiving profits of 1652.9583 ¥ 404.2334 ¥ and 734.7739 ¥ respectively

Methanol reforming is considered to be one of the most promising hydrogen production technologies for hydrogen fuel cells. It is expected to solve the problem of hydrogen storage and transportation because of its high hydrogen production rate low cost and good safety. However the strong nonlinearity and slow response of the pressure and temperature subsystems pose challenges to the tracking control of the methanol reforming hydrogen production system. In this paper two internal model-based temperature and pressure controllers are proposed in which the temperature is adjusted by controlling the air flow and the pressure is adjusted by controlling the opening of the backpressure valve. Firstly a lumped parameter model of the methanol reforming hydrogen production system is constructed using MATLAB/Simulink® (produced by MathWorks in Natick Massachusetts USA). In addition the transfer function model of the system is obtained by system identification at the equilibrium point and the internal model controller is further designed. The simulation results show that the control method achieves the robustness of the system and the temperature and pressure of the reforming reactor can quickly and accurately track the target value when the load changes. Small-load step tests indicate stable tracking of the temperature and pressure for the reforming reactor without steady-state errors. Under large-temperature step signal testing the response time for the reforming temperature is about 148 s while the large-pressure step signal test shows that the response time for the reforming pressure is about 8 s. Compared to the PID controller the internal model controller exhibits faster response zero steady-state error and no overshoot. The results show that the internal model control method has strong robustness and dynamic characteristics.

Demand response (DR) is a crucial element in the optimization of integrated energy systems (IESs) that incor porate distributed generation (DG). However its inherent uncertainty poses significant challenges to the eco nomic viability of IESs. This research presents a novel economic dispatch model for IESs utilizing information gap decision theory (IGDT). The model integrates various components to improve IES performance and dispatch efficiency. With a focus on hydrogen energy the model considers users’ energy consumption patterns thereby improving system flexibility. By applying IGDT the model effectively addresses the uncertainty associated with DR and DG overcoming the limitations of traditional methods. The research findings indicate that in relation to the baseline method the proposed model has the potential to reduce operating costs by 6.3 % and carbon emissions by 4.2 %. The integration of a stepwise carbon trading mechanism helps boost both economic and environmental advantages achieving a 100 % wind power consumption rate in the optimized plan. In addition the daily operating costs are minimized to 23758.99 ¥ while carbon emissions are significantly reduced to 34192 kg. These findings provide quantitative decision support for IES dispatch planners to help them develop effective dispatch strategies that are consistent with low-carbon economic initiatives.

Reversible solid oxide fuel cell (RSOFC) is an energy device that flexibly interchanges between electrical and chemical energy according to people’s life and production needs. The development of cell materials affects the stability and cost of the cell but also restricts its market-oriented development. After decades of research by scientists a lot of achievements and progress have been made on RSOFC materials. According to the composition and requirements of each component of RSOFC this article summarizes the research progress based on materials and discusses the merits and demerits of current cell materials in electrochemical performance. According to the efficiency of different materials in solid oxide fuel cell (SOFC mode) and solid oxide electrolyzer (SOEC mode) the challenges encountered by RSOFC in the operation are evaluated and the future development of RSOFC materials is boldly prospected.

With increasingly stringent maritime environmental regulations hybrid fuel cell ships have garnered significant attention due to their advantages in low emissions and high efficiency. However challenges related to the coordinated control of multi-energy systems and fuel cell degradation remain significant barriers to their practical implementation. This paper proposes an innovative multi-timescale energy management strategy that focuses on optimizing the lifespan decay synergy of fuel cells and lithium batteries. The study designs an attention-based CNN-LSTM hybrid model for power prediction and constructs a twostage optimization framework: The first stage employs Model Predictive Control (MPC) for long-term power planning to optimize equivalent hydrogen consumption while the second stage focuses on real-time power allocation considering both power source degradation and system operational efficiency. The simulation results demonstrate that compared to single-layer MPC and the Equivalent Consumption Minimization Strategy (ECMS) the proposed method exhibits significant advantages in reducing single-voyage costs minimizing differences in power source degradation rates and alleviating power source stress. The overall performance of this strategy approaches the global optimal solution obtained through Dynamic Programming comprehensively validating its superiority in simultaneously optimizing system economics and durability.

Hydrogen clean efficient and zero-carbon is seen as a most promising energy source. The use of existing gas pipelines for hydrogenenatural gas transportation is considered to be an effective way to achieve long-distance large-scale efficient and economical hydrogen transportation. However the pipelines for hydrogenenatural gas transportation contain lots of impurities (e.g. CH4 high-pressure H2 H2S and CO2) and free water which will inevitably lead to corrosion and hydrogen embrittlement. This paper presents a systematic review of research and an outlook for corrosion and hydrogen embrittlement in hydrogenenatural gas pipeline transportation. The results show that gasphase hydrogen charging is suitable for hydrogenenatural gas transportation but this technique lacks technical standards. By contrast the liquid-phase hydrogen charging technique is more mature but has large deviation from the engineering reality. In the hydrogenenatural gas transportation pipelines corrosion and hydrogen embrittlement are synergetic and competitive but the failure mechanism and change law when corrosion and hydrogen embrittlement coexist remain unclear which need to be further clarified by experiments. The failure mechanism is believed to be mainly sensitive to three key factors i.e. the H2S/CO2 partial pressure ratio the hydrogen blending ratio and material strength. The increase of the three factors will make the pipeline materials more corrosive and more sensitive to hydrogen embrittlement. The research findings can be used as a reference for research and development of long-distance hydrogenenatural gas transportation technology and will drive the high-quality development of the hydrogenenatural gas blending industry.

Water splitting is an effective strategy to produce renewable and sustainable hydrogen energy. Especially seawater splitting avoiding use of the limited freshwater resource is more intriguing. Nowadays electrocatalysts explored for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using natural seawater or saline electrolyte have been increasingly reported. To better understand the current status and challenges of the electrocatalysts for HER and OER from seawater we comprehensively review the recent advances in electrocatalysts for seawater splitting. The fundamentals challenges and possible strategies for seawater splitting are firstly presented. Then the recently reported electrocatalysts that explored for HER and OER from seawater are summarized and discussed. Finally the perspectives in the development of high-efficient electrocatalysts for seawater splitting are also proposed.

In this paper a two-layer optimization approach is proposed to facilitate the multi-energy complementarity and coupling and optimize the system configuration in an electric-hydrogen-integrated energy system (EH-IES). Firstly an EH-IES with virtual energy storage is proposed to reduce the cost of physical energy storage equipment. Secondly a two-layer optimal allocation method is proposed under a multi-timescale strategy to examine the comprehensive evaluation index of environmental protection and economy. The upper layer utilizes the NSGA-II multi-objective optimization method for system capacity allocation while the lower layer performs economic dispatch at the lowest cost. Ultimately the output includes the results of the equipment capacity allocation of the EH-IES that satisfies the reliability constraint interval and the daily scheduling results of the equipment. The results demonstrate that the electric-hydrogen-integrated energy system with the coupling of multiple energy equipment not only enhances the utilization of renewable energy sources but also reduces the usage of fossil energy and improves the system’s reliability.

Faced with a global consensus on net-zero emissions the use of clean fuels to entirely or substantially replace traditional fuels has emerged as the industry’s primary development direction. Alcohol–hydrogen fuels primarily based on methanol are a renewable and sustainable energy source. This research focuses on energy sustainability and presents a boiler fuel blending system that uses methanol–hydrogen combinations. This system uses the boiler’s waste heat to catalytically decompose methanol into a gas mostly consisting of H2 and CO which is then co-combusted with the original fuel to improve thermal efficiency and lower emissions. A comparative experimental study considering natural gas (NG) blending with hydrogen and dissociated methanol gas (DMG) was carried out in a small natural gas boiler. The results indicate that with a controlled mixed fuel flow of 10 m3/h and an excess air coefficient of 1.2 a 10% hydrogen blending ratio maximizes the boiler’s thermal efficiency (ηt) resulting in a 3.5% increase. This ratio also results in a 1% increase in NOx emissions a 25% decrease in HC emissions and a 5.66% improvement in the equivalent economics (es). Meanwhile blending DMG at 15% increases the boiler’s ηt by 3% reduces NOx emissions by 13.8% and HC emissions by 20% and improves the es by 8.63%. DMG as a partial substitute for natural gas outperforms hydrogen in various aspects. If this technology can be successfully applied and promoted it could pave a new path for the sustainable development of energy in the boiler sector.

This paper provides a systematic visualization of the development current status and challenges of salt cavern hydrogen storage technology based on the relevant literature from the past five years in the Web of Science Core Collection database. Using VOSviewer (version 1.6.20) and CiteSpace software (advanced version 6.3.R3) this study analyzes the field from a knowledge mapping perspective. The findings reveal that global research hotspots are primarily focused on multi-energy collaboration integration of renewable energy systems and exploration of commercialization highlighting the essential role of salt cavern hydrogen storage in driving the energy transition and promoting sustainable development. In China research mainly concentrates on theoretical innovations and technological optimizations to address complex geological conditions. Despite the rapid growth in the number of Chinese publications unresolved challenges remain such as the complexity of layered salt rock and thermodynamic coupling effects during highfrequency injection and extraction as well as issues concerning permeability and microbial activity. Moving forward China’s salt cavern hydrogen storage technology should focus on strengthening engineering practices suited to local geological conditions and enhancing the application of intelligent technologies thereby facilitating the translation of theoretical research into practical applications.

This paper focuses on the critical role of long-duration energy storage (LDES) technologies in facilitating renewable energy integration and achieving carbon neutrality. It presents a systematic review of four primary categories: mechanical energy storage chemical energy storage electrochemical energy storage and thermal energy storage. The study begins by analyzing the technical advantages and geographical constraints of pumped hydro energy storage (PHES) and compressed air energy storage (CAES) in high-capacity applications. It then explores the potential of hydrogen and synthetic fuels for long-duration clean energy storage. The section on electrochemical energy storage highlights the high energy density and flexible scalability of lithium-ion batteries and redox flow batteries. Finally the paper evaluates innovative advancements in large-scale thermal energy storage technologies including sensible heat storage latent heat storage and thermochemical heat storage. By comparing the performance metrics application scenarios and development prospects of various energy storage technologies this work provides theoretical support and practical insights for maximizing renewable energy utilization and driving the sustainable transformation of global energy systems.

Large-scale hydrogen (H2 ) production is an essential gear in the future bioeconomy. Hydrogen production through electrocatalytic seawater splitting is a crucial technique and has gained considerable attention. The direct seawater electrolysis technique has been designed to use seawater in place of highly purified water which is essential for electrolysis since seawater is widely available. This paper offers a structured approach by briefly describing the chemical processes such as competitive chloride evolution anodic oxygen evolution and cathodic hydrogen evolution that govern seawater electrocatalytic reactions. In this review advanced technologies in transition metal phosphide-based seawater electrolysis catalysts are briefly discussed including transition metal doping with phosphorus the nanosheet structure of phosphides and structural engineering approaches. Application progress catalytic process efficiency opportunities and problems related to transition metal phosphides are also highlighted in detail. Collectively this review is a comprehensive summary of the topic focusing on the challenges and opportunities.

The pressure to move to sustainable energy sources is obvious in today's fast changing energy environment. In this context green hydrogen appears as a beacon of hope with the potential to reinvent the paradigms of energy consumption particularly in the transportation and aviation sectors. Hydrogen has long been intriguing owing to its unique characteristics. It is not only an energy transporter; it has the power to alter the game. Its growing significance is due to its capacity to decarbonize energy generation. Traditional hydrogen generation techniques have contributed considerably to world CO2 emissions accounting for over 2% of total emissions. This environmental problem is successfully addressed by the development of green hydrogen which is created from renewable energy sources. The International Energy Agency (IEA) predicts a 25 to 30 percent increase in global energy consumption by 2040 which is a very grim scenario. If continue to rely on coal and oil this growing demand will result in greater CO2 emissions exacerbating climate change's consequences. In this situation green hydrogen is not only an option but a need. Because green hydrogen has properties with conventional fuels it can be simply integrated into current infrastructure. This harmonic integration ensures that the shift to hydrogen-based solutions in these sectors would not demand a complete redesign of the present systems assuring cost-effectiveness and practicality. However like with any energy source green hydrogen has obstacles. Its combustibility and probable explosiveness have been cited as causes for concern. However developments in safety measures have successfully mitigated these dangers ensuring that hydrogen may be used safely and efficiently across various applications. A further difficulty is its energy density particularly in comparison to conventional fuels. While its energy-to-weight ratio may be good its bulk poses challenges particularly in the aviation industry where space is at a premium. Beyond its direct use as a fuel green hydrogen has potential in auxiliary capacities. It may be used as a dependable backup energy source during power outages as well as in a variety of different sectors and uses ranging from manufacturing to residential. Green hydrogen's adaptability demonstrates its potential to infiltrate all sectors of our economy. Storage is an important enabler for broad hydrogen use. Effective hydrogen storage technologies guarantee not only its availability but also its viability as a source of energy. Current research and advancements in this field are encouraging which strengthens the argument for green hydrogen. At conclusion green hydrogen is in the vanguard of sustainable energy solutions particularly for the transportation and aviation industries. In our collaborative quest of a sustainable future its unique features and environmental advantages make it a vital asset. As we explore further into the complexities of green hydrogen in this publication we want to shed light on its potential obstacles and future route.

With the continuous development of hydrogen storage systems power-to-gas (P2G) and combined heat and power (CHP) the coupling between electricity–heat–hydrogen–gas has been promoted and energy conversion equipment has been transformed from an independent operation with low energy utilization efficiency to a joint operation with high efficiency. This study proposes a low-carbon optimization strategy for a multi-energy coupled IES containing hydrogen energy storage operating jointly with a two-stage P2G adjustable thermoelectric ratio CHP. Firstly the hydrogen energy storage system is analyzed to enhance the wind power consumption ability of the system by dynamically absorbing and releasing energy at the right time through electricity–hydrogen coupling. Then the two-stage P2G operation process is refined and combined with the CHP operation with an adjustable thermoelectric ratio to further improve the low-carbon and economic performance of the system. Finally multiple scenarios are set up and the comparative analysis shows that the addition of a hydrogen storage system can increase the wind power consumption capacity of the system by 4.6%; considering the adjustable thermoelectric ratio CHP and the twostage P2G the system emissions reduction can be 5.97% and 23.07% respectively and the total cost of operation can be reduced by 7.5% and 14.5% respectively.

For the safe and efficient utilization of hydrogen-enriched natural gas combustion in industrial gas-fired boilers the present study adopted a combination of numerical simulation and field tests to investigate its adaptability. Firstly the combustion characteristics of hydrogen-enriched natural gas with different hydrogen blending ratios and equivalence ratios were evaluated by using the Chemkin Pro platform. Secondly a field experimental study was carried out based on the WNS2- 1.25-Q gas-fired boiler to investigate the boiler’s thermal efficiency heat loss and pollutant emissions after hydrogen addition. The results show that at the same equivalence ratio with the hydrogen blending ratio increasing from 0% to 25% the laminar flame propagation speed of the fuel increases the extinction strain rate rises and the combustion limit expands. The laminar flame propagation speed of premixed methane/air gas reaches the maximum value when the equivalence ratio is 1.0 and the combustion intensity of the flame is the highest at this time. In the field tests as the hydrogen blending ratio increases from 0% to nearly 10% with the increasing excess air ratio the boiler’s thermal efficiency decreases as well as the NOx emission. This indicates that there exists a tradeoff between the boiler thermal efficiency and NOx emission in practice.

Unlike the typical low-temperature (< 150 °C) continental geothermal systems usually characterized by high N2 CH4 and CO2 concentrations but a trace H2 concentration the sandstone-dominated Jimo hot spring on China's eastern coast exhibits: (1) abnormally high H2 concentrations (2.4–12.5 vol%) and H2/CH4 (up to 46.5); (2) depleted δD-H2 (−822 to −709‰) comparable to the Kansas hot springs near the Mid-Continent rift system with the most depleted δD-H2 (−836 to −740‰) recorded in nature; and (3) dramatic gas concentration and isotope ratio variations within an area of 0.2 km2 . Gas chemistry and H-C-He-Ne isotope ratios are studied with reference to published H2 isotope data from various systems. The origin of the gas is most likely attributed to: (a) allochthonous abiotic H2 generated by the reduction of water and oxidation of FeII-rich pyroxene and olivine (serpentinization) in the basalt located 2 km away under near-surface conditions and migration to the deep sandstone reservoir; (b) primary thermogenic CH4 produced in the sandstone; (c) mixing with a considerable amount of microbial H2 from shallow fresh and marine sediments; and (d) biotic CH4 with typical abiotic signatures resulting from isotope exchanges with fluids high in H2/CH4 and CO2/CH4 ratios. Allochthonous abiotic H2 in a sandstone-dominated continental geothermal system and massive microbial fermentation-based H2 production in shallow fresh and residual marine sediments with insignificant but differential consumption activity are highlighted. The published hydrogen isotope ratios for H2 produced under various natural geological environmental and experimental conditions have been collected systematically to provide a fundamental framework and an initial tool for restricting the dominant origin of H2.

The UK government plans to phase out pure diesel trains by 2040 and fully decarbonize railways by 2050. Hydrogen fuel cell (HFC) trains electrified trains using pantographs (Electrified Trains) and battery electric multiple unit (BEMU) trains are considered the main solutions for decarbonizing railways. However the range of these decarbonization options’ line upgrade cost advantages is unclear. This paper analyzes the upgrade costs of three types of trains on different lines by constructing a cost model and using particle swarm optimization (PSO) including operating costs and fixed investment costs. For the case of decarbonization of the London St. Pancras to Leicester line the electrified train option is more cost-effective than the other two options under the condition that the service period is 30 years. Then the traffic density range in which three new energy trains have cost advantages on different line lengths is calculated. For route distances under 100 km and with a traffic density of less than 52 trips/day BEMU trains have the lowest average cost while electrified trains are the most costeffective in other ranges. For route distances over 100 km the average cost of HFC trains is lower than that of electrified trains at traffic densities below about 45 trips/day. In addition if hydrogen prices fall by 26 % the cost advantage range of HFC trains will increase to 70 trips per day. For route distances under 100 km BEMU trains still maintain their advantages in terms of lower traffic density.

The International Maritime Organization (IMO)’s annual operational carbon intensity index (CII) rating requires that from 1 January 2023 all applicable ships meet both technical and operational energy efficiency requirements. In this paper we conduct a comparative study of different alternative fuel options based on a CII model from the perspective of shipowners. The advantages and disadvantages of alternative fuel options such as liquefied natural gas (LNG) methanol ammonia and hydrogen are presented. A numerical example using data from three China Ocean Shipping (Group) shipping lines is analyzed. It was found that the overall attained CII of different ship types showed a decreasing trend with the increase of the ship’s deadweight tonnage. A larger ship size choice can obtain better carbon emission reduction for the carbon emission reduction investment program using alternative fuels. The recommended options of using LNG fuel and zero-carbon fuel (ammonia and hydrogen) on Route 1 and Route 3 during the study period were analyzed for the shipowners. Carbon reduction scenarios using low-carbon fuels (LNG and methanol) and zero-carbon fuels (ammonia and hydrogen) on Route 2 are in line with IMO requirements for CII.

The affordability and availability of water and energy have a huge impact on food production. Research has shown that there exists a direct and indirect link between power production and clean water generation. Hence the inclusion/importance given to the energy-water-food (EWF) nexus in the United Nations’ sustainable development goals. Acknowledging the importance of decarbonization to the global future there exists a gap in literature on the development of models that can enhance the EWF nexus reduce energy poverty and achieve 100% renewable energy in the electricity sector. Therefore the technical and economic prospect of geothermal energy for bridging the aforementioned gaps in existing works of literature is presented in this study. The energy poverty/wealthy status of a country has been confirmed to have a significant impact on economic development as economic development is largely reflected in the food-water availability. Ditto this study is focused on the interconnectivity of the EWF nexus while incorporating global decarbonization targets. Geothermal energy is of the utmost significance in East Africa due to its abundant potential and distinctive geological features. Located in the Great Rift Valley the region has an abundance of geothermal reservoirs making it an ideal location for geothermal power generation. This study is novel as a comprehensive assessment framework for energy poverty is developed and innovative models utilizing primarily the geothermal resource in the East African region to mitigate this problem are proposed and analyzed. The role of hydrogen generation from critical excess electricity production is also analyzed. The East Africa region is considered the case study for implementing the models developed. A central renewable energy grid is proposed/modelled to meet the energy demand for seven East African countries namely; Ethiopia Tanzania Uganda Djibouti Comoros Eritrea and Rwanda. This study considers 2030 2040 and 2050 as the timestamp for the implementation of the proposed models. The hybrid mix of the biomass power plant solar photovoltaic (PV) pumped hydro storage system and onshore wind power is considered to furthermore show the potency of renewable energy resources in this region. Results showed that the use of geothermal energy to meet energy demands in the case study will mitigate energy poverty and enhance the region’s EWF.

Hydrogen safety is a critical issue during the construction and development of the hydrogen energy industry. Hydrogen refueling stations play a pivotal role in the hydrogen energy chain. In the event of an accidental hydrogen leak at a hydrogen refueling station the ability to quickly predict the leakage location is crucial for taking immediate and effective measures to prevent disastrous consequences. Therefore the development of precise and efficient technologies to predict leakage locations is vital for the safe and stable operation of hydrogen refueling stations. This paper studied the localization technology of high-risk leakage locations in the fuel cell system of a skid-mounted hydrogen refueling station. The hydrogen leakage and diffusion processes in the fuel cell system were predicted using CFD simulations and the hydrogen concentration data at various monitoring points were obtained. Then a multilayer feedforward neural network was developed to predict leakage locations using simulated concentration data as training samples. After multiple adjustments to the network structure and hyperparameters a final model with two hidden layers was selected. Each hidden layer consisted of 10 neurons. The hyperparameters included a learning rate of 0.0001 a batch size of 32 and 10-fold cross-validation. The Softmax classifier and Adam optimizer were used with a training set for 1500 epochs. The results show that the algorithm can predict leakage locations not included in the training set. The accuracy achieved by the model was 95%. This approach addresses the limitations of sensor detection in accurately locating leaks and mitigates the risks associated with manual inspections. This paper provides a feasible method for locating hydrogen leakage in hydrogen energy application scenarios.

Fuel cell hybrid systems due to their combination of the high energy density of fuel cells and the rapid response capability of power batteries have become an important category of new energy vehicles. This paper discusses energy management strategies in hydrogen fuel cell vehicles. Firstly a detailed comparative analysis of existing PID control strategies and Adaptive Equivalent Consumption Minimization Strategies (A-ECMSs) is conducted. It was found that although A-ECMS can balance the energy utilization of the fuel cell and power battery well the power fluctuations of the fuel cell are significant leading to increased hydrogen consumption. Therefore this paper proposes an improved Adaptive Low-Pass Filter Equivalent Consumption Minimization Strategy (A-LPF-ECMS). By introducing low-pass filtering technology transient changes in fuel cell power are smoothed effectively reducing fuel consumption. Simulation results show that under the 6*FTP75 cycle the energy loss of A-LPF-ECMS is reduced by 10.89% (compared to the PID strategy) and the equivalent hydrogen consumption is reduced by 7.1%; under the 5*WLTC cycle energy loss is reduced by 5.58% and equivalent hydrogen consumption is reduced by 3.18%. The research results indicate that A-LPF-ECMS performs excellently in suppressing fuel cell power fluctuations under idling conditions significantly enhancing the operational efficiency of the fuel cell and showing high application value.

Hydrogen-Integrated energy systems (HIESs) are pivotal in driving the transition to a low-carbon energy structure in China. This paper proposes a low-carbon economic scheduling strategy to improve the operational efficiency and reduce the carbon emissions of HIESs. The approach begins with the implementation of a stepwise carbon trading framework to limit the carbon output of the system. This is followed by the development of a joint operational model that combines hydrogen energy use and carbon capture. To improve the energy supply flexibility of HIESs modifications to the conventional combined heat and power (CHP) unit are made by incorporating a waste heat boiler and an organic Rankine cycle. This results in a flexible CHP response model capable of adjusting both electricity and heat outputs. Furthermore a comprehensive demand response model is designed to optimize the flexible capacities of electric and thermal loads thereby enhancing demand-side responsiveness. The integration of electric vehicles (EVs) into the system is analyzed with respect to their energy consumption patterns and dispatch capabilities which improves their potential for flexible scheduling and enables an optimized synergy between the demand-side flexibility and system operations. Finally a low-carbon economic scheduling model for the HIES is developed with the objective of minimizing system costs. The results show that the proposed scheduling method effectively enhances the economy low-carbon performance and flexibility of HIES operation while promoting clean energy consumption deep decarbonization of the system and the synergistic complementarity of flexible supply–demand resources. In the broader context of expanding clean energy and growing EV adoption this study demonstrates the potential of energy-saving emissionreduction systems and vehicle-to-grid (V2G) strategies to contribute to the sustainable and green development of the energy sector.

Solar energy is the largest energy source on Earth. In contrast to the limited andgreenhouse gases-emitting fossil fuels solar energy is inexhaustible carbonneutral and nonpolluting. The conversion of this most abundant but highlydiffused source into hydrogen is increasingly attractive. In nature photosyntheticmicroorganisms exploit solar energy to produce hydrogen via photosynthesiswhich is also known as photobiological hydrogen production. More recentlyvarious types of artificial materials have been developed to hybrid microorgan-isms for converting solar energy into hydrogen namely semiartificial photo-synthesis hydrogen production. Herein the strategies for converting solar energyinto hydrogen with whole-cell biocatalyst are summarized and their potentials forfuture social sustainable development are discussed.

The dynamic response characteristics between the multiple energy flows of electricity-hydrogen-heat in the renewable energy DC off-grid hydrogen production system are highly coupled and nonlinear which leads to the complexity of its energy conversion and transmission law. This study proposes a model to describe the dynamic nonlinear energy conversion and transmission laws specific to such systems. The model develops a nonlinear admittance framework and a conversion characteristic matrix for multi-heterogeneous energy flow subsystems based on the operational characteristics of each subsystem within the DC off-grid hydrogen production system. Building upon this foundation an energy hub model for the hydrogen production system is established yielding the electrical thermal and hydrogen energy outputs along with their respective conversion efficiencies for each subsystem. By discretizing time the energy flow at each time node within the hydrogen production system is computed revealing the system’s dynamic energy transfer patterns. Experiments were conducted using measured wind speed and irradiance data from a specific location in eastern China. Results from selected typical days were analyzed and discussed revealing that subsystem characteristics exhibit nonlinear variation patterns. This highlights the limitations of traditional models in accurately capturing these dynamics. Finally a simulation platform incorporating practical control methods was constructed to validate the model’s accuracy. Validation results demonstrate that the model possesses high accuracy providing a solid theoretical foundation for further in-depth analysis of DC off-grid hydrogen production systems.

The type IV hydrogen storage tank with a polymer liner is a promising storage solution for fuel cell electric vehicles (FCEVs). The polymer liner reduces the weight and improves the storage density of tanks. However hydrogen commonly permeates through the liner especially at high pressure. If there is rapid decompression damage may occur due to the internal hydrogen concentration as the concentration inside creates the pressure difference. Thus a comprehensive understanding of the decompression damage is significant for the development of a suitable liner material and the commercialization of the type IV hydrogen storage tank. This study discusses the decompression damage mechanism of the polymer liner which includes damage characterizations and evaluations influential factors and damage prediction. Finally some future research directions are proposed to further investigate and optimize tanks.

The iron and steel industry (ISI) plays a significant role in carbon emissions contributing approximately 15% of the nation’s total emissions in China. Transitioning to low-carbon practices is crucial for achieving the country’s carbon neutrality goals. This paper reviews the current state of China’s ISI and assesses the feasibility of various decarbonization technologies including hydrogen utilization biomass substitution zero-carbon electricity Carbon Capture Utilization and Storage (CCUS) as well as their combinations. The blast furnace–basic oxygen furnace (BF-BOF) process currently dominates the industry with an overwhelming share of around 90% presenting significant challenges for decarbonization. In contrast the Direct Reduced Iron–Electric Arc Furnace (DRI-EAF) process is still at the demonstration project stage but it is rapidly growing and shows great potential for achieving net-zero emissions. Electric arc furnaces (EAFs) that use scrap steel account for about 9% of production and have the lowest energy consumption. However their production capacity is limited by the availability of scrap steel. Among numerous options blue hydrogen carbon-neutral biomass and CCUS technologies have relatively low costs and high technological maturity. Nevertheless no single technology can currently achieve deep decarbonization while significantly reducing costs. The nation needs to select the most suitable decarbonization strategies based on geographical location infrastructure and economic conditions. The government should enact corresponding policies provide economic incentives and ensure mitigation of the environmental and social impacts during the decarbonization transition.