China, People’s Republic

Blending hydrogen with natural gas (NG) is an efficient method for transporting hydrogen on a large scale at a low cost. The manifold at the NG initial station is an important piece of equipment that enables the blending of hydrogen with NG. However there are differences in the components and component contents of imported NG from different countries. The components of hydrogen-blended NG can affect the safety and efficiency of transportation through pipeline systems. Therefore numerical simulations were performed to investigate the blending process and changes in the thermodynamic properties of four imported NGs and hydrogen in the manifold. The higher the heavy hydrocarbon content in the imported NG the longer the distance required for the gas to mix uniformly with hydrogen in the pipeline. Hydrogen blending reduces the temperature and density of NG. The gas composition is the main factor affecting the molar calorific value of a gas mixture and hydrogen blending reduces the molar calorific value of NG. The larger the content of high-molar calorific components in the imported NG the higher the molar calorific value of the gas after hydrogen blending. Increasing both the temperature and hydrogen mixing ratio reduces the Joule-Thomson coefficient of the hydrogen-blended NG. The results of this study provide technical references for the transport of hydrogen-blended NG.

This paper presents the “Three Gorges Hydrogen Boat No. 1” a novel green hydrogen-powered vessel that has been successfully delivered and is currently sailing. This vessel integrated with a hydrogen production and bunkering station at its dedicated dock achieves zero-carbon emissions. It stores 240 kg of 35 MPa gaseous hydrogen and has a fuel cell system rated at 500 kW. We analysed the engineering details of the marine hydrogen system including hydrogen bunkering storage supply fuel cell and the hybrid power system with lithium-ion batteries. In the first bunkering trial the vessel was safely refuelled with 200 kg of gaseous hydrogen in 156 min via a bunkering station 13 m above the water surface. The maximum hydrogen pressure and temperature recorded during bunkering were 35.05 MPa and 39.04 ◦C respectively demonstrating safe and reliable shore-toship bunkering. For the sea trial the marine hydrogen system operated successfully during a 3-h voyage achieving a maximum speed of 28.15 km/h (15.2 knots) at rated propulsion power. The vessel exhibited minimal noise and vibration and its dynamic response met load change requirements. To prevent rapid load changes to the fuel cells 68 s were used to reach 483 kW from startup and 62 s from 480 kW to zero. The successful bunkering and operation of this hydrogen-powered vessel demonstrates the feasibility of zero-carbon emission maritime transport. However four lessons were identified concerning bunkering speed hydrogen cylinder leakage hydrogen pressure regulator malfunctions and fuel cell room space. The novelty of this work lies in the practical demonstration of a fully operational hydrogen-powered maritime vessel achieving zero emissions encompassing its design building operation and lessons learned. These parameters and findings can be used as a baseline for further engineering research.

Using High-Temperature Gas-cooled Reactor (HTGR) for hydrogen production through steam methane reforming (SMR) offers advantages such as high hydrogen yield methane savings relatively low cost and ease of scale-up. However due to the limitation of the temperature of the heating helium gas the methane conversion ratio of SMR using HTGR is much lower than that of traditional SMR. The membrane reactor (MR) with its high conversion efficiency compact structure and low cost is a suitable way to improve the methane conversion ratio. This study establishes a one-dimensional reaction flow model for MR heated by the helium gas from HTGR. And the model is validated and applied to analyze the performance of MR. The results show that compared to the original reformer tube MR demonstrates superior performance especially at higher methane conversion ratio and hydrogen yield. And the significant impact of sweep gas and membrane thickness on the performance of MR is discussed in detail. This work offers a new insight into highly enhancing the efficiency of SMR for hydrogen production using HTGR.

To further optimize the low-carbon economy of the integrated energy system (IES) this paper establishes a two-stage P2G hydrogen-coupled electricity–heat–hydrogen–gas IES with carbon capture (CCS). First this paper refines the two stages of P2G and introduces a hydrogen fuel cell (HFC) with a hydrogen storage device to fully utilize the hydrogen energy in the first stage of power-to-gas (P2G). Then the ladder carbon trading mechanism is considered and CCS is introduced to further reduce the system’s carbon emissions while coupling with P2G. Finally the adjustable thermoelectric ratio characteristics of the combined heat and power unit (CHP) and HFC are considered to improve the energy utilization efficiency of the system and to reduce the system operating costs. This paper set up arithmetic examples to analyze from several perspectives and the results show that the introduction of CCS can reduce carbon emissions by 41.83%. In the CCS-containing case refining the P2G two-stage and coupling it with HFC and hydrogen storage can lead to a 30% reduction in carbon emissions and a 61% reduction in wind abandonment costs; consideration of CHP and HFC adjustable thermoelectric ratios can result in a 16% reduction in purchased energy costs.

With the large-scale integration of intermittent renewable energy generation presented by wind and photovoltaic power the security and stability of power system operations have been challenged. Therefore this article proposes a control strategy of a hydrogen production system based on renewable energy power generation to enable the fast frequency response of a grid. Firstly based on the idea of virtual synchronous control a fast frequency response control transformation strategy for the grid-connected interface of hydrogen production systems for renewable energy power generation is proposed to provide active power support when the grid frequency is disturbed. Secondly based on the influence of VSG’s inertia and damping coefficient on the dynamic characteristics of the system a VSG adaptive control model based on particle swarm optimization is designed. Finally based on the Matlab/Simulink platform a grid-connected simulation model of hydrogen production systems for renewable energy power generation is established. The results show that the interface-transformed electrolytic hydrogen production device can actively respond to the frequency disturbances of the power system and participate in primary frequency control providing active support for the frequency stability of the power system under high-percentage renewable energy generation integration. Moreover the system with parameter optimization has better fast frequency response control characteristics.

Coastal regions have abundant off-shore wind energy resources and surrounding areas have large-scale liquefied natural gas (LNG) receiving stations. From the engineering perspectives there are limitations in unstable off-shore wind energy and fluctuating LNG loads. This article offers a new energy scheme to combine these 2 energy units which uses surplus wind energy to produce hydrogen and use LNG cold energy to liquefy and store hydrogen. In addition in order to improve the efficiency of utilizing LNG cold energy and reduce electricity consumption for liquid hydrogen (LH2) production at coastal regions this article introduces the liquid air energy storage (LAES) technology as the intermediate stage which can stably store the cold energy from LNG gasification. A new scheme for LNG-LAES-LH2 hybrid LH2 production is built. The case study is based on a real LNG receiving station at Hainan province China and this article presents the design of hydrogen production/liquefaction process and carries out the optimizations at key nodes and proves the feasibility using specific energy consumption and exergy analysis. In a 100 MW system the liquid air storage round-trip efficiency is 71.0% and the specific energy consumption is 0.189 kWh/kg and the liquid hydrogen specific energy consumption is 7.87 kWh/kg and the exergy efficiency is 46.44%. Meanwhile the corresponding techno-economic model is built and for a LNGLAES-LH2 system with LH2 daily production 140.4 tons the shortest dynamic payback period is 9.56 years. Overall this novel hybrid energy scheme can produce green hydrogen using a more efficient and economical method and also can make full use of surplus off-shore wind energy and coastal LNG cold energy.

The research motivation of this paper is to utilize the large amount of energy wasted during the LNG (liquefied natural gas) gasification process and proposes a synergistic liquefied hydrogen (LH2) production and storage process scheme for LNG receiving station and methane reforming hydrogen production process - SMR-LNG combined liquefied hydrogen production system which uses the cold energy from LNG to pre-cool the hydrogen and subsequently uses an expander to complete the liquefaction of hydrogen. The proposed process is modeled and simulated by Aspen HYSYS software and its efficiency is evaluated and sensitivity analysis is carried out. The simulation results show that the system can produce liquefied hydrogen with a flow rate of 5.89t/h with 99.99% purity when the LNG supply rate is 50t/h. The power consumption of liquefied hydrogen is 46.6kWh/kg LH2; meanwhile the energy consumption of the HL subsystem is 15.9kWh/kg LH2 lower than traditional value of 17~19kWh/kg LH2. The efficiency of the hydrogen production subsystem was 16.9%; the efficiency of the hydrogen liquefaction (HL) subsystem was 29.61% which was significantly higher than the conventional industrial value of 21%; the overall energy efficiency (EE1) of the system was 56.52% with the exergy efficiency (EE2) of 22.2% reflecting a relatively good thermodynamic perfection. The energy consumption of liquefied hydrogen per unit product is 98.71 GJ/kg LH2.

Due to having zero carbon emissions and renewable advantages hydrogen has great prospects as a renewable form of alternate energy. Engine load and hydrogen substitution rate have a considerable influence on a hydrogen–diesel dual-fuel engine’s efficiency. This experiment’s objective is to study the influence of hydrogen substitution rate on engine combustion and emission under different loads and to study the impact of exhaust gas recirculation (EGR) technology or main injection timing on the engine’s capability under high load and high hydrogen substitution rate. The range of the maximum hydrogen substitution rate was determined under different loads (30%~90%) at 1800 rpm and then the effects of the EGR rate (0%~15%) and main injection timing (−8 ◦CA ATDC~0 ◦CA ATDC) on the engine performance under 90% high load were studied. The research results show that the larger the load the smaller the maximum hydrogen substitution rate that can be added to the dual-fuel engine. Under each load with the increase of the hydrogen substitution rate the cylinder pressure and the peak heat release rate (HRR) increase the equivalent brake-specific fuel consumption (BSFCequ) decreases the thermal efficiency increases the maximum thermal efficiency is 43.1% the carbon dioxide (CO2 ) emission is effectively reduced by 35.2% and the nitrogen oxide (NOx) emission decreases at medium and low loads and the maximum increase rate is 20.1% at 90% load. Under high load with the increase of EGR rate or the delay of main injection timing the problem of NOx emission increases after hydrogen doping can be effectively solved. As the EGR rate rises from 0% to 15% the maximum reduction of NOx is 63.1% and with the delay of main injection timing from −8 ◦CA ATDC to 0 ◦CA ATDC the maximum reduction of NOx is 44.5%.

Industry is the biggest sector of energy consumption and greenhouse gas emissions whose decarbonisation is essential to achieve the Sustainable Development Goals. Carbon capture energy efficiency improvement and hydrogen are among the main strategies for industrial decarbonization. However novel approaches are needed to address the key requirements and differences between sectors to ensure they can work together to well integrate industrial decarbonisation with heat CO2 and hydrogen. The emerging Calcium Looping (CaL) is attracting interest in designing CO2-involved chemical processes for heat capture and storage. The reversibility relatively high-temperature (600 to 900 ◦C) and high energy capacity output as well as carbon capture function make CaL well-fit for CO2 capture and utilisation and waste heat recovery from industrial flue gases. Meanwhile methane dry reforming (MDR) is a promising technology to produce blue hydrogen via the consumption of two major greenhouse gases i.e. CO2 and CH4. It has great potential to combine the two technologies to achieve insitu CO2 utilization with multiple benefits. In this paper progresses on the reaction conditions and performance of CaL for CO2 capture and industrial waste heat recovery as well as MDR were screened. Secondly recent approaches to CaL-MDR synergy have been reviewed to identify the advantages. The major challenges in such a synergistic process include MDR catalyst deactivation CaL sorbents sintering and system integration. Thirdly the paper outlooks future work to explore a rational design of a multi-function system for the proposed synergistic process.

Clean energy vehicles (CEVs) e.g. battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) are being adopted gradually to substitute for internal combustion engine vehicles (ICEVs) around the world. The fueling infrastructure is one of the key drivers for the development of the CEV market. When the government develops funding policies to support the fueling infrastructure development for FCEVs and BEVs it has to assess the effectiveness of different policy options and identify the optimal policy combination which is very challenging in transportation research. In this paper we develop a system dynamics model to study the feedback mechanism between the fueling infrastructure funding policies and the medium- to long-term diffusion of FCEVs and BEVs and the competition between FCEVs and BEVs based on relevant policy and market data in Guangzhou China. The results of the modeling analysis are as follows. (1) Funding hydrogen refueling stations and public charging piles has positive implications for achieving the substitution of CEVs for ICEVs. (2) Adjusting the funding ratio of hydrogen refueling stations and public charging piles or increasing the funding budget and extending the funding cycle does not have a significant impact on the overall substitution of CEVs for ICEVs but only impacts the relative competitive advantage between FCEVs and BEVs. (3) An equal share of funding for hydrogen refueling stations and public charging piles would have better strategic value for future net-zero-emissions urban transportation. (4) Making a moderate-level full investment in hydrogen refueling stations coupled with hydrogen refueling subsidies can provide the ideal conditions for FCEV diffusion.

The integration of renewable energy resources (RES) into microgrids (MGs) poses significant challenges due to the intermittent nature of generation and the increasing complexity of multi-energy scheduling. To enhance operational flexibility and reliability this paper proposes an intelligent energy management system (EMS) for MGs incorporating a hybrid hydrogen-battery energy storage system (HHB-ESS). The system model jointly considers the complementary characteristics of short-term and long-term storage technologies. Three conflicting objectives are defined: economic cost (EC) system response stability and battery life loss (BLO). To address the challenges of multi-objective trade-offs and heterogeneous storage coordination a novel deep-reinforcement-learning (DRL) algorithm termed MOATD3 is developed based on a dynamic reward adjustment mechanism (DRAM). Simulation results under various operational scenarios demonstrate that the proposed method significantly outperforms baseline methods achieving a maximum improvement of 31.4% in SRS and a reduction of 46.7% in BLO.

Hydrogen is an ideal energy carrier in future applications due to clean byproducts and high efciency. However many challenges remain in the application of hydrogen including hydrogen production delivery storage and conversion. In terms of hydrogen storage two compression modes (mechanical and non-mechanical compressors) are generally used to increase volume density in which mechanical compressors with several classifcations including reciprocating piston compressors hydrogen diaphragm compressors and ionic liquid compressors produce signifcant noise and vibration and are expensive and inefcient. Alternatively non-mechanical compressors are faced with issues involving large-volume requirements slow reaction kinetics and the need for special thermal control systems all of which limit large-scale development. As a result modular safe inexpensive and efcient methods for hydrogen storage are urgently needed. And because electrochemical hydrogen compressors (EHCs) are modular highly efcient and possess hydrogen purifcation functions with no moving parts they are becoming increasingly prominent. Based on all of this and for the frst time this review will provide an overview of various hydrogen compression technologies and discuss corresponding structures principles advantages and limitations. This review will also comprehensively present the recent progress and existing issues of EHCs and future hydrogen compression techniques as well as corresponding containment membranes catalysts gas difusion layers and fow felds. Furthermore engineering perspectives are discussed to further enhance the performance of EHCs in terms of the thermal management water management and the testing protocol of EHC stacks. Overall the deeper understanding of potential relationships between performance and component design in EHCs as presented in this review can guide the future development of anticipated EHCs.

In response to the global climate change and the need for green and low-carbon development hydrogen energy has been recognized as a clean energy source that can achieve carbon neutrality unlike fossil fuels. As a country with a shortage of energy resources the development of hydrogen energy is of significant importance for China to adjust its energy structure and accelerate the new era of energy transformation. Based on the development of China’s hydrogen energy industry this paper elaborates on the current status and development trends of key technologies in the entire industrial chain of hydrogen energy in various stages including production storage transportation and application and identifies the problems and challenges of hydrogen energy development. The paper focuses on the analysis of hydrogen storage and transportation application scenarios and clarifies the selection of hydrogen storage and transportation technologies in different scenarios. To achieve healthy devel opment of China’s hydrogen energy industry it is necessary to strengthen top-level design make strategic planning encourage large-scale state-owned energy enterprises to play a leading role promote the development of the entire industry chain increase technological research and development efforts prevent the risk of core technology constraints and vigorously promote the application of hydrogen energy to realize the construction of a hydrogen energy society.

To enhance the accommodation capacity of renewable energy and promote the coordinated development of multiple energy this paper proposes a novel economic dispatch method for an integrated electricity–heat–hydrogen energy system on the basis of coupling three energy flows. Firstly we develop a mathematical model for the hydrogen energy system including hydrogen production storage and hydrogen fuel cells. Additionally a multi-device combined heat and power system is constructed incorporating gas boilers waste heat boilers gas turbines methanation reactors thermal storage tanks batteries and gas storage tanks. Secondly to further strengthen the carbon reduction advantages the economic dispatch model incorporates the power-to-gas process and carbon trading mechanisms giving rise to minimizing energy purchase costs energy curtailment penalties carbon trading costs equipment operation and maintenance costs. The model is linearized to ensure a global optimal solution. Finally the experimental results validate the effectiveness and superiority of the proposed model. The integration of electricity–hydrogen coupling devices improves the utilization rate of renewable energy generation and reduces the total system operating costs and carbon trading costs. The use of a tiered carbon trading mechanism decreases natural gas consumption and carbon emissions contributing to energy conservation and emission reduction.

China as both a major energy consumer and the largest carbon emitter globally views carbon capture utilization and storage (CCUS) hydrogen production as a crucial and innovative technology for achieving its dual carbon goals of carbon peaking and carbon neutrality. The development of such technologies requires strong policy guidance making the quantification of policy pathways essential for understanding their effectiveness. This study employs a data-driven framewor integrating LDA topic modeling and the PMC-TE index to analyze the regional and temporal dynamics of CCUS-hydrogen development policies. The research identifies 16 optimal policy topics highlighting gaps in policy design and implementation. The analysis uncovers significant fragmentation in policy pathways with supply-side policies receiving disproportionate attention while demand-side and environmental policies remain under-supported. Regional disparities are evident with wealthier provinces showing higher policy engagement compared to underdeveloped regions. The study also reveals that policy evolution has been largely reactive emphasizing the need for a more proactive and consistent long-term strategy. These findings provide valuable insights for creating more balanced integrated and regionally tailored policy approaches to effectively drive CCUS-hydrogen development in China.

With the large-scale deployment of renewable energy the issue of wind power consumption has become increasingly prominent leading to serious wind energy abandonment. In order to promote energy sustainability this paper proposes a low-carbon economic scheduling model of an integrated energy system (IES) that combines the flexible supply–demand response with the diversified utilization of hydrogen energy. A mixedinteger linear programming model is developed and solved using the commercial solver GUROBI to obtain the scheduling scheme that minimizes total costs. First decoupling analysis is performed for combined heat and power (CHP) units and the organic Rankine cycle (ORC) is introduced to enable dynamic output adjustments. On the demand side a flexible demand response mechanism is introduced which allows various types of loads to transfer within the scheduling cycle or substitute for each other within the same period. Additionally combining the clean characteristics of hydrogen this paper introduces hydrogen-doped CHP and other utilization strategies and develops a diversified utilization structure of hydrogen. A small IES is used for case analysis to verify the effectiveness of the above strategies. The results show that the proposed strategy can entirely consume wind power reduce total cost by 21.32% and decrease carbon emissions by 44.83% thereby promoting low-carbon economic operation and sustainable energy development of the system.

Promoting the development of China’s hydrogen energy industry is crucial for achieving green energy transition. However existing research lacks systematic studies on the spatial layout of the hydrogen industry chain. This study constructed a comprehensive theoretical framework encompassing hardware infrastructure software systems and soft power. Using multi-source heterogeneous data GIS analysis and NVivo text coding methods the current regional layout and challenges of China’s hydrogen infrastructure industry chain were systematically evaluated. The findings determined that economically developed eastern regions lead in infrastructure and soft power while central and western regions leverage their resource and manufacturing advantages. Major challenges include regional imbalances in hardware infrastructure uneven distribution of soft power and misalignment between software systems and actual needs. Analysis of the “14th Five-Year Plan” of various regions elucidated deep insights into the diversity of local hydrogen energy development strategies identifying five types of hydrogen cities: resource-advantaged market-oriented regionally collaborative innovation-driven and policy-supported. Accordingly strategies to enhance industry chain synergy clarify city roles and optimize regional ecosystems were proposed. It is recommended to integrate hydrogen infrastructure with urban planning and incorporate environmental impact assessments into spatial optimization decisions. This study provides a systematic analytical framework and progressive policy recommendations for the efficient and green layout of China’s hydrogen infrastructure offering important implications for the sustainable development of the hydrogen industry and other rapidly developing economies.

Liquid hydrogen storage is an important way of hydrogen storage and transportation which greatly improves the storage and transportation efficiency due to the high energy density but at the same time brings new safety hazards. In this study the liquid hydrogen leakage in the storage area of a hydrogen production station is numerically simulated. The effects of ambient wind direction wind speed leakage mass flow rate and the mass fraction of gas phase at the leakage port on the diffusion behavior of the liquid hydrogen leakage were investigated. The results show that the ambient wind direction directly determines the direction of liquid hydrogen leakage diffusion. The wind speed significantly affects the diffusion distance. When the wind speed is 6 m/s the diffusion distance of the flammable hydrogen cloud reaches 40.08 m which is 2.63 times that under windless conditions. The liquid hydrogen leakage mass flow rate and the mass fraction of the gas phase have a greater effect on the volume of the flammable hydrogen cloud. As the leakage mass flow rate increased from 5.15 kg/s to 10 kg/s the flammable hydrogen cloud volume increased from 5734.31 m3 to 10305.5 m3 . The installation of a barrier wall in front of the leakage port can limit the horizontal diffusion of the flammable hydrogen cloud elevate the diffusion height and effectively reduce the volume of the flammable hydrogen cloud. This study can provide theoretical support for the construction and operation of hydrogen production stations.

This study proposes four kinds of hybrid source–grid–storage systems consisting of pho‐ tovoltaic and wind energy and a power grid including different batteries and hydrogen storage systems for Sanjiao town. HOMER‐PRO was applied for the optimal design and techno‐economic analysis of each case aiming to explore reproducible energy supply solutions for China’s industrial clusters. The results show that the proposed system is a fully feasible and reliable solution for in‐ dustry‐based towns like Sanjiao in their pursuit of carbon neutrality. In addition the source‐side price sensitivity analysis found that the hydrogen storage solution was cost‐competitive only when the capital costs on the storage and source sides were reduced by about 70%. However the hydro‐ gen storage system had the lowest carbon emissions about 14% lower than the battery ones. It was also found that power generation cost reduction had a more prominent effect on the whole system’s NPC and LCOE reduction. This suggests that policy support needs to continue to push for genera‐ tion‐side innovation and scaling up while research on different energy storage types should be en‐ couraged to serve the needs of different source–grid–load–storage systems.

Under the background of energy interconnection and low-carbon electricity integrated energy systems (IES) play an important role in energy conservation and emission reduction. To further promote the low-carbon transition of energy this paper proposes a distributed robust optimal control strategy for IESs based on energy trading. Firstly an IES model that includes an electric hydrogen module and gas hydrogen doping combined heat and power is established and ladder-type carbon trading is introduced to reduce carbon emissions. Secondly for the energy trading issues between photovoltaic (PV) prosumers and IES a bi-level model is constructed using Stackelberg game method where the IES acts as the leader and the PV prosumers as the followers. Noteworthy a distributed robust optimization method is used to address the uncertainty of renewable energy and load. Additionally the Nash bargaining method ensures an equitable balance of benefits among the various IESs and encourages them to participate in market transactions. On this basis an intermediary transaction mode is proposed to address cheating behaviors in trading. Finally the simulation results demonstrate that the proposed strategy not only effectively promotes cooperative operation among multiple IESs but also significantly reduces the system’s operating costs and carbon emissions.

This paper investigates the temperature control problem in hydrogen fuel cells based on the improved sliding mode control method specifically within the context of multirotor drone applications. The study focuses on constructing a control-oriented nonlinear thermal model which serves as a foundation for the subsequent development of a practical temperature regulation approach. Initially a novel sliding mode control strategy is proposed which significantly enhances the precision and stability of temperature control by reducing the impact of sensor errors and environmental disturbances. Subsequently the effectiveness and robustness of this control method under various dynamic loads and environmental conditions are demonstrated. The simulation results demonstrate that the improved sliding mode controller is effective in managing and regulating the fuel cell temperature ensuring optimal performance and stability.

To achieve deep decarbonization in the transportation sector this study employs life cycle assessment (LCA) and the GREET model to construct baseline and low-carbon scenarios. It simulates the evolution of emissions and energy consumption within Inner Mongolia’s public transportation energy system (including diesel buses (DBs) electric buses (EBs) and hydrogen fuel cell buses (HFCBs)) from 2022 to 2035 while exploring synergistic pathways for its low-carbon transition. Results reveal that under the baseline scenario reliance on industrial by-product hydrogen causes fuel cell bus emissions to increase by 3.64% in 2025 compared to 2022 with system energy savings below 10% and decarbonization potential will be constrained by scale limitations and storage/transportation losses in cold regions. Under the low-carbon scenario deep grid decarbonization vehicle structure optimization and green hydrogen integration reduced system emissions and energy consumption by 66.86% and 40.44% respectively compared to 2022. The study identifies a 15% green hydrogen penetration rate as the critical threshold for resource misallocation and confirms grid decarbonization as the top-priority policy tool yielding marginal benefits 1.43 times greater than standalone hydrogen policies. This study underscores the importance of multipolicy coordination and ‘technology-supply chain’ synergy particularly highlighting the critical threshold of green hydrogen penetration and the primacy of grid decarbonization offering insights for similar coal-dominated cold-region transportation energy transitions.

In rotating machinery unbalanced mass is one of the most common causes of system vibration. This paper presents an experimental investigation of the unbalance response of a gas foil bearing-rotor system based on a 30 kW-rated commercial hydrogen fuel cell vehicle air compressor. The study examines the response of the system to varying unbalanced masses at different rotational speeds. Experimental results show that after adding unbalanced mass subsynchronous vibration of the rotor is relatively slight while synchronous vibration is the main source of vibration; when unbalanced mass is added to one side of the rotor the synchronous vibration on that side initially decreases and then increases with speed while synchronous vibration on the opposite side continuously increases with speed; when unbalanced mass is added to both sides the synchronous vibration on each side increases with the phase difference of the unbalanced mass at low speed while the opposite trend occurs at high speed. The analysis of the gas foil bearingrotor system dynamics model established based on the dynamic coefficient of the bearing shows that the bending of the rotor offsets the displacement caused by the unbalanced mass which is the primary reason for the nonlinear behavior of the synchronous vibration of the rotor. These findings contribute to an improved understanding of GFB-rotor interactions under unbalanced conditions and provide practical guidance for optimizing dynamic balancing strategies in hydrogen fuel cell vehicle compressors.

As an efficient and low-carbon renewable energy source hydrogen plays a strategic role in the global energy transition particularly in the transportation sector. However the flammable and explosive nature of hydrogen makes leakage risks in enclosed environments a core challenge for the safe promotion of hydrogen fuel cell vehicles. Catalytic combustion sensors are ideal choices due to their high sensitivity and long lifespan. Nevertheless they face technical bottlenecks under vehicle operational conditions such as high-power consumption caused by elevated working temperatures slow response rates weak anti-interference capabilities and catalyst poisoning. This paper systematically reviews the research status of catalytic combustion hydrogen sensors for vehicle applications summarizes technical difficulties and development strategies from the perspectives of hydrogen-sensitive material design and integration processes and provides theoretical references and technical guidance for the development of catalytic combustion hydrogen sensors suitable for vehicle use.

Hydrogen production by seawater electrolysis is significantly hindered by high energy costs and undesirable detrimental chlorine chemistry in seawater. In this work energy-saving hydrogen production is reported by chlorine-free seawater splitting coupling tip-enhanced electric field promoted electrocatalytic sulfion oxidation reaction. We present a bifunctional needle-like Co3S4 catalyst grown on nickel foam with a unique tip structure that enhances the kinetic rate by improving the current density in the tip region. The assembled hybrid seawater electrolyzer combines thermodynamically favorable sulfion oxidation and cathodic seawater reduction can enable sustainable hydrogen production at a current density of 100 mA cm−2 for up to 504 h. The hybrid seawater electrolyzer has the potential for scale-up industrial implementation of hydrogen production by seawater electrolysis which is promising to achieve high economic efficiency and environmental remediation.

To improve the energy utilization rate and realize the low-carbon emission of a park integrated energy system (PIES) this paper proposes an optimal operation strategy for multiple PIESs. Firstly the electrical power cooperative trading framework of multiple PIESs is constructed. Secondly the hydrogen blending mechanism and carbon capture system and power-to-gas system joint operation model are introduced to establish the model of each PIES. Then based on the Nash bargaining game theory a multi-PIES cooperative trading and operation model with electrical power cooperative trading is constructed. Then the alternating direction method of multipliers algorithm is used to solve the two subproblems. Finally case studies analysis based on scene analysis is performed. The results show that the cooperative operation model reduces the total cost of a PIES more effectively compared with independent operation. Meanwhile the efficient utilization and production of hydrogen are the keys to achieve carbon reduction and an efficiency increase in a PIES.

In order to improve energy utilization efficiency and the flexibility of resource transfer in oceanic-island-group microgrids a water–electricity–hydrogen flexible scheduling strategy based on a multi-rate hydrogen-powered ship is proposed. First the characteristics of the seawater desalination unit (SDU) proton exchange membrane electrolyzer (PEMEL) and battery system (BS) in consuming surplus renewable energy on resource islands are analyzed. The variable-efficiency operation characteristics of the SDU and PEMEL are established and the effect of battery life loss is also taken into account. Second a spatiotemporal model for the multi-rate hydrogen-powered ship is proposed to incorporate speed adjustment into the system optimization framework for flexible resource transfer among islands. Finally with the goal of minimizing the total cost of the system a flexible water–electricity–hydrogen hybrid resource transfer model is constructed and a certain island group in the South China Sea is used as an example for simulation and analysis. The results show that the proposed scheduling strategy can effectively reduce energy loss promote renewable energy absorption and improve the flexibility of resource transfer.

The electric–hydrogen coupled integrated energy system (EHCS) is a critical pathway for the low-carbon transition of energy systems. However the inherent uncertainties of renewable energy sources present significant challenges to optimal energy management in the EHCS. To address these challenges this paper proposes an energy management method for the EHCS based on an improved proximal policy optimization (IPPO) algorithm. This method aims to overcome the limitations of traditional heuristic algorithms such as low solution accuracy and the inefficiencies of mathematical programming methods. First a mathematical model for the EHCS is established. Then by introducing the Markov decision process (MDP) this mathematical model is transformed into a deep reinforcement learning framework. On this basis the state space and action space of the system are defined and a reward function is designed to guide the agent to learn to the optimal strategy which takes into account the constraints of the system. Finally the efficacy and economic viability of the proposed method are validated through numerical simulation.

With the advancement of Fuel Cell Vehicles (FCVs) detecting hydrogen leaks is critically important in facilities such as hydrogen refilling stations. Despite its significance the dynamic response performance of hydrogen sensors in confined spaces particularly under ceilings has not been comprehensively assessed. This study utilizes a catalytic combustion hydrogen sensor to monitor hydrogen leaks in a confined area. It examines the effects of leak size and placement height on the distribution of hydrogen concentrations beneath the ceiling. Results indicate that hydrogen concentration rapidly decreases within a 0.5–1.0 m range below the ceiling and declines more gradually from 1.0 to 2.0 m. The study further explores the attenuation pattern of hydrogen concentration radially from the hydrogen jet under the ceiling. By normalizing the radius and concentration it was determined that the distribution conforms to a Gaussian model akin to that observed in open space jet flows. Utilizing this Gaussian assumption the model is refined by incorporating an impact reflux term thereby enhancing the accuracy of the predictive formula.

Rail transit as a high-energy consumption field urgently requires the adoption of clean energy innovations to reduce energy consumption and accelerate the transition to new energy applications. As an energy-saving fluid machinery the ejector exhibits significant application potential and academic value within this field. This paper reviewed the recent advances technical challenges research hotspots and future development directions of ejector applications in rail transit aiming to address gaps in existing reviews. (1) In waste heat recovery exhaust heat is utilized for propulsion in vehicle ejector refrigeration air conditioning systems resulting in energy consumption being reduced by 12~17%. (2) In vehicle pneumatic pressure reduction systems the throttle valve is replaced with an ejector leading to an output power increase of more than 13% and providing support for zero-emission new energy vehicle applications. (3) In hydrogen supply systems hydrogen recirculation efficiency exceeding 68.5% is achieved in fuel cells using multi-nozzle ejector technology. (4) Ejector-based active flow control enables precise ± 20 N dynamic pantograph lift adjustment at 300 km/h. However current research still faces challenges including the tendency toward subcritical mode in fixed geometry ejectors under variable operating conditions scarcity of application data for global warming potential refrigerants insufficient stability of hydrogen recycling under wide power output ranges and thermodynamic irreversibility causing turbulence loss. To address these issues future efforts should focus on developing dynamic intelligent control technology based on machine learning designing adjustable nozzles and other structural innovations optimizing multi-system efficiency through hybrid architectures and investigating global warming potential refrigerants. These strategies will facilitate the evolution of ejector technology toward greater intelligence and efficiency thereby supporting the green transformation and energy conservation objectives of rail transit.

The production of green hydrogen requires renewable electricity and a supply of sustainable water. Due to global water scarcity using seawater to produce green hydrogen is particularly important in areas where freshwater resources are scarce. This study establishes a system model to simulate and optimize the integrated technology of seawater desalination by membrane distillation and hydrogen production by alkaline water electrolysis. Technical economics is also performed to evaluate the key factors affecting the economic benefits of the coupling system. The results show that an increase in electrolyzer power and energy efficiency will reduce the amount of pure water. An increase in the heat transfer efficiency of the membrane distillation can cause the breaking of water consumption and production equilibrium requiring a higher electrolyzer power to consume the water produced by membrane distillation. The levelized costs of pure water and hydrogen are US$1.28 per tonne and $1.37/kg H2 respectively. The most important factors affecting the production costs of pure water and hydrogen are electrolyzer power and energy efficiency. When the price of hydrogen rises the project’s revenue increases significantly. The integrated system offers excellent energy efficiency compared to conventional desalination and hydrogen production processes and advantages in terms of environmental protection and resource conservation.

Global climate change caused by geological processes is one of the main causes of the 5 global mass extinctions in geological history. Human industrialization activities have caused serious damage to the ecosystem the greenhouse effect of atmospheric CO2 has intensified and the living environment is facing threats and challenges. Carbon neutrality is the active action and common goal of mankind in the face of the climate change crisis therefore probing into its theoretical and technological connotation scientific and technological innovation system has far-reaching significance and broad prospects. Studies indicate that (1) Carbon neutrality reflects the theoretical connotations of “energy science” and “carbon neutrality science” including technical connotations of carbon emission reduction zero carbon emission negative carbon emission and carbon trading. (2) Carbon neutrality spawns new industries such as carbon industry centering on CO2 capture utilization and storage (CCUS or CO2 capture and storage CCS) and hydrogen industry centering on green hydrogen. “Gray carbon” and “black carbon” are the two application attributes of CO2. “Carbonþ” “Carbon” and “Carbon¼” are three carbon-neutral products and technologies. (3) China faces three major challenges in achieving the goal of carbon neutrality: first energy transition is large in scale and the cycle is short; Second there are many problems in the process of energy transition such as security uncertainties economic utilization and unpredictable disruptive technologies; Third after transition we may face new key techno-logical “bottlenecks” and “broken chain” of key mineral resources. (4) Based on current knowledge to predict the top 10 disruptive technologies and industries in the energy field: underground coal gasification in-situ conversion process of medium and low-mature shale oil CCUS/CCS hydrogen energy and fuel cells bio-photovoltaic power generation space-based solar power generation optical storage smart micro-grid super energy storage controllable nuclear fusion wisdom energy Internet. Five strategic projects will be implemented including energy conservation and efficiency improvement carbon reduction and sequestration scientific and technological innovation emergency reserve and policy support. (5) In the future different types of energy will have different orientations. Coal will play the role of ensuring the national energy strategy “reserve” and “guarantee the bottom line”. Petroleum will play the role of ensuring national energy security “urgent need” and the “cornerstone” of raw materials in people's livelihood. Natural gas will play the role in ensuring national energy “safety” and “best partner” of new energy. New energy will play the role in ensuring the “replacement” and “main force” of the national energy strategy. (6) Carbon neutrality is a major practice of the green industrial revolution carbon reduction energy revolution and ecological technology revolution which will bring new and profound changes to human society the environment and the economy. (7) Carbon neutrality needs to follow the four principles of “disruptive breakthroughs in technology guarantee of energy security realization of economic feasibility and controllable social stability”. We should rely on technological innovation and management changes to ensure the realization of national energy “independence” and carbon neutrality goal and make China's contribution to the construction of a livable earth green development and ecological civilization.

With the gradual maturity of wind power technology China’s wind power generation has grown rapidly over the recent years. However due to the on-site inconsumable electricity the phenomenon of large-scale “wind curtailment” occurs in some areas. In this paper a novel hybrid hydrogen/electricity refueling station is built near a wind farm and a part of the surplus wind power is used to charge electric trucks and the other part of the surplus power is used to produce “green hydrogen”. According to real-time load changes different amounts of liquid hydrogen and gas hydrogen can be properly coordinated to provide timely energy supply for hydrogen trucks. For a 400 MW wind farm in the western Inner Mongolia China the feasibility of the proposed system has been carried out based on the sensitivity and reliability analysis the static and dynamic economic modeling with an entire life cycle analysis. Compared to the conventional technology the initial investment of the proposed scheme (700.07 M$) decreases by 13.97% and the dynamic payback period (10.93 years) decreases by 25.87%. During the life cycle of the proposed system the accumulative NPV reaches 184.63 M$ which increases by 3.14 times compared to the case by conventional wind technology.

Hydrogen energy is regarded as an ideal solution for addressing climate change issues and an indispensable part of future integrated energy systems. The most environmentally friendly hydrogen production method remains water electrolysis where the electrolyzer constructs the physical interface between electrical energy and hydrogen energy. However few articles have reviewed the electrolyzer from the perspective of power supply topology and control. This review is the first to discuss the positioning of the electrolyzer power supply in the future integrated energy system. The electrolyzer is reviewed from the perspective of the electrolysis method the market and the electrical interface modelling reflecting the requirement of the electrolyzer for power supply. Various electrolyzer power supply topologies are studied and reviewed. Although the most widely used topology in the current hydrogen production industry is still single-stage AC/DC the interleaved parallel LLC topology constructed by wideband gap power semiconductors and controlled by the zero-voltage switching algorithm has broad application prospects because of its advantages of high power density high efficiency fault tolerance and low current ripple. Taking into account the development trend of the EL power supply a hierarchical control framework is proposed as it can manage the operation performance of the power supply itself the electrolyzer the hydrogen energy domain and the entire integrated energy system.

Renewable hydrogen production from biomass thermochemical conversion is an emerging technology to reduce fossil fuel consumptions and carbon emissions. Biomass-derived hydrogen can be produced by pyrolysis gasification alkaline thermal treatment etc. However the removal of impurities from biomass thermochemical conversion products to improve hydrogen purity is currently technical bottleneck. It is important to assess and investigate the types and properties of impurities the difficulty of separation and the impact on downstream utilization of hydrogen in the biomass-derived hydrogen production process. The key objectives of this comprehensive review are: (1) to reveal the current status and necessity of developing biomass-derived hydrogen production; (2) to evaluate the types devices and impurities distribution of biomass thermochemical conversion; (3) to explore the formation pathways and removal technologies of typical impurities of tar CO2 sulfides and nitrides in hydrogen production process; and (4) to propose future insights on the separation technologies of typical impurities to promote the gradual substitution of biomass-derived hydrogen for fossil-derived energy.

The use of hydrogen-blended natural gas presents an efficacious pathway toward the rapid large-scale implementation of hydrogen energy with pipeline transportation being the principal method of conveyance. However pipeline materials are susceptible to hydrogen embrittlement in high-pressure hydrogen environments. Natural gas contains various impurity gases that can either exacerbate or mitigate sensitivity to hydrogen embrittlement. In this study we analyzed the mechanisms through which multiple impurity gases could affect the hydrogen embrittlement behavior of pipeline steel. We examined the effects of O2 and CO2 on the hydrogen embrittlement behavior of L360 pipeline steel through a series of fatigue crack growth tests conducted in various environments. We analyzed the fracture surfaces and assessed the fracture mechanisms involved. We discovered that CO2 promoted the hydrogen embrittlement of the material whereas O2 inhibited it. O2 mitigated the enhancing effect of CO2 when both gases were mixed with hydrogen. As the fatigue crack growth rate increased the influence of impurity gases on the hydrogen embrittlement of the material diminished.

Integrated hydrogen energy systems (IHESs) have attracted extensive attention in miti-gating climate problems. As a kind of large-scale hydrogen storage device undergroundhydrogen storage (UHS) can be introduced into IHES to balance the seasonal energy mis-match while bringing challenges to optimal operation of IHES due to the complex geolog-ical structure and uncertain hydrodynamics. To address this problem a deep deterministicpolicy gradient (DDPG)-based optimal scheduling method for underground space basedIHES is proposed. The energy management problem is formulated as a Markov decisionprocess to characterize the interaction between environmental states and policy. Based onDDPG theory the actor-critic structure is applied to approximate deterministic policy andactor-value function. Through policy iteration and actor-critic network training the oper-ation of UHS and other energy conversion devices can be adaptively optimised which isdriven by real-time response data instead of accurate system models. Finally the effective-ness of the proposed optimal scheduling method and the benefits of underground spaceare verified through time-domain simulations.

Hydrogen production from renewable energy sources is a crucial pathway to achieving the carbon peak target and realizing the vision of carbon neutrality. The hydrogen production from offshore superconducting wind power (HPOSWP) integrated systems as an innovative technology in the renewable energy hydrogen production field holds significant market potential and promising development prospects. This integrated technology based on research into high-temperature superconducting generator (HTSG) characteristics and electrolytic water hydrogen production (EWHP) technology converts offshore wind energy (OWE) into hydrogen energy locally through electrolysis with hydrogen storage being shipped and controlled liquid hydrogen (LH2) circulation ensuring a stable low-temperature environment for the HTSGs’ refrigeration system. However due to the significant instability and intermittency of offshore wind power (OWP) this HPOSWP system can greatly affect the dynamic adaptability of the EWHP system resulting in impure hydrogen production and compromising the safety of the LH2 cooling system and reduce the fitness of the integrated system for wind electricity–hydrogen heat multi-field coupling. This paper provides a comprehensive overview of the fundamental structure and characteristics of this integrated technology and further identifies the key challenges in its application including the dynamic adaptability of electrolytic water hydrogen production technology as well as the need for large-capacity long-duration storage solutions. Additionally this paper explores the future technological direction of this integrated system highlighting the need to overcome the limitations of electrical energy adaptation within the system improve product purity and achieve large-scale applications.

In this study a 3D model is developed to simulate multi-hole leakage scenarios in buried pipelines transporting hydrogen-blended natural gas (HBNG). By introducing three parameters—the First Dangerous Time (FDT) Ground Dangerous Range (GDR) and Farthest Dangerous Distance (FDD)—to characterize the diffusion hazard of the gas mixture this study further analyzes the effects of the number of leakage holes hole spacing hydrogen blending ratio (HBR) and soil porosity on the diffusion hazard of the gas mixture during leakage. Results indicate that gas leakage exhibits three distinct phases: initial independent diffusion followed by an intersecting accelerated diffusion stage and culminating in a unified-source diffusion. Hydrogen exhibits the first two phases whereas methane undergoes all three and dominates the GDR. Concentration gradients for multi-hole leakage demonstrate similarities to single-hole scenarios but multi-hole leakage presents significantly higher hazards. When the inter-hole spacing is small diffusion characteristics converge with those of single-hole leakage. Increasing HBR only affects the gas concentration distribution near the leakage hole with minimal impact on the overall ground danger evolution. Conversely variations in soil porosity substantially impact leakage-induced hazards. The outcomes of this study will support leakage monitoring and emergency management of HBNG pipelines.

Direct seawater electrolysis (DSE) has emerged as a compelling route to sustainable hydrogen production leveraging the vast global reserves of seawater. However the inherently complex composition of seawater—laden with halide ions multivalent cations (Mg2+ Ca2+) and organic/biological impurities—presents formidable challenges in maintaining both selectivity and durability. Chief among these obstacles is mitigating chloride corrosion and suppressing chlorine evolution reaction (ClER) at the anode while also preventing the precipitation of magnesium and calcium hydroxides at the cathode. This review consolidates recent advances in material engineering and cell design strategies aimed at controlling undesired side reactions enhancing electrode stability and maximizing energy efficiency in DSE. We first outline the fundamental thermodynamic and kinetic hurdles introduced by Cl⁻ and other impurities. This discussion highlights how these factors accelerate catalyst degradation and drive suboptimal reaction pathways. We then delve into innovative approaches to improve selectivity and durability of DSE—such as engineering protective barrier layers tuning electrolyte interfaces developing corrosion-resistant materials and techniques to minimize Mg/Ca-related precipitations. Finally we explore emerging reactor configurations including asymmetric and membrane-free electrolyzers which address some barriers for DSE commercialization. Collectively these insights provide a framework for designing next-generation DSE systems which can achieve large-scale cost-effective and environmentally benign hydrogen production.

This review aims to summarize the recent advancements and prevailing challenges within the realm of hydrogen storage and transportation thereby providing guidance and impetus for future research and practical applications in this domain. Through a systematic selection and analysis of the latest literature this study highlights the strengths limitations and technological progress of various hydrogen storage methods including compressed gaseous hydrogen cryogenic liquid hydrogen organic liquid hydrogen and solid material hydrogen storage as well as the feasibility efficiency and infrastructure requirements of different transportation modes such as pipeline road and seaborne transportation. The findings reveal that challenges such as low storage density high costs and inadequate infrastructure persist despite progress in high-pressure storage and cryogenic liquefaction. This review also underscores the potential of emerging technologies and innovative concepts including metal–organic frameworks nanomaterials and underground storage along with the potential synergies with renewable energy integration and hydrogen production facilities. In conclusion interdisciplinary collaboration policy support and ongoing research are essential in harnessing hydrogen’s full potential as a clean energy carrier. This review concludes that research in hydrogen storage and transportation is vital to global energy transformation and climate change mitigation.

Low-cost alkaline water electrolysis from renewable energy sources (RESs) is suitable for large-scale hydrogen production. However fluctuating RESs lead to poor performance of alkaline water electrolyzers (AWEs) at low loads. Here we explore two urgent performance issues: inefficiency and inconsistency. Through detailed operation process analysis of AWEs and the established equivalent electrical model we reveal the mechanisms of inefficiency and inconsistency of low-load AWEs are related to the physical structure and electrical characteristics. Furthermore we propose a multi-mode self-optimization electrolysis converting strategy to improve the efficiency and consistency of AWEs. In particular compared to a conventional dc power supply we demonstrate using a lab-scale and large-scale commercially available AWE that the maximum efficiency can be doubled while the operation range of the electrolyzer can be extended from 30–100% to 10–100% of rated load. Our method can be easily generalized and can facilitate hydrogen production from RESs.

Sorption-enhanced steam reforming (SorESR) is an advanced thermochemical process integrating in-situ CO2 capture via solid sorbents to significantly enhance hydrogen production and purity. By coupling CO2 adsorption with steam reforming SorESR shifts the reaction equilibrium toward increased H₂ yield surpassing the limitations of conventional steam reforming (SR). The efficacy of SorESR critically depends on the physicochemical properties of the solid CO2 sorbents employed. This review critically evaluates widely studied sorbents including Ca-based Mg-based hydrotalcite-like and alkali ceramic sorbents focusing on their CO2 capture capacity reaction kinetics thermal stability and cyclic durability under SR conditions. Furthermore recent progress in multifunctional sorbent-catalysts that synergistically facilitate catalytic steam reforming alongside CO2 sorption is critically discussed. Moreover the review summarises recent performance achievements and proposes strategies to improve sorbent capacity and reaction kinetics thereby making the SorESR process more appealing for commercial applications. Large-scale SorESR implementation is expected to substantially increase hydrogen production efficiency while concurrently reducing CO2 emissions and advancing sustainable energy technologies. This review offers novel insights into the development of advanced sorbent-catalyst systems and provides new strategies for enhancing SorESR efficiency and scalability for commercial H2 Production.

The inherent randomness and intermittency of offshore renewable energy sources such as wind and solar power pose significant challenges to the stable and secure operation of the power grid. These fluctuations directly affect the performance of grid-connected systems particularly in terms of harmonic distortion and load response. This paper addresses these challenges by proposing a novel harmonic control strategy and load response optimization approach. An integrated three-winding transformer filter is designed to mitigate high-frequency harmonics and a control strategy based on converter-side current feedback is implemented to enhance system stability. Furthermore a hybrid PI-VPI control scheme combined with feedback filtering is employed to improve the system’s transient recovery capability under fluctuating load and generation conditions. Experimental results demonstrate that the proposed control algorithm based on a transformer-oriented model effectively suppresses low-order harmonic currents. In addition the system exhibits strong anti-interference performance during sudden voltage and power variations providing a reliable foundation for the modulation and optimization of offshore wind–solar coupled hydrogen production power supply systems.

The resilience and sustainable development of modern power distribution systems faces escalating challenges due to increasing renewable integration and extreme events. Traditional single-system approaches often overlook the spatiotemporal coordination of cross-domain restoration resources. In this paper we propose a multi-stage resilience enhancement method that employs transportation and hydrogen energy systems. This approach coordinates the pre-event preventive allocation and multi-stage collaborative scheduling of diverse restoration resources including remote-controlled switches (RCSs) mobile hydrogen emergency resources (MHERs) and hydrogen production and refueling stations (HPRSs). The proposed framework supports cross-stage dynamic optimization scheduling enabling the development of adaptive resource dispatch strategies tailored to the characteristics of different stages including prevention fault isolation and service restoration. The model is applicable to complex scenarios involving dynamically changing network topologies and is formulated as a mixed-integer linear programming (MILP) problem. Case studies based on the IEEE 33-bus system show that the proposed method can restore a distribution system’s resilience to approximately 87% of its normal level following extreme events.

Currently there are many gaps in the research on the safety of hydrogen-powered trains and the hazardous points vary across different scenarios. It is necessary to conduct safety analysis for various scenarios in order to develop effective accident response strategies. Considering the implementation of hydrogen power in the rail transport sector this paper reviews the development status of hydrogen-powered trains and the hydrogen leak hazard chain. Based on the literature and industry data a thorough analysis is conducted on the challenges faced by hydrogen-powered trains in the scenario of electrified railways tunnels train stations hydrogen refueling stations and garages. Existing railway facilities are not ready to deal with accidental hydrogen leakage and the promotion of hydrogen-powered trains needs to be cautious.

Introduction: With the increasing demand for energy utilization efficiency and minimization of environmental carbon emissions in industrial parks optimizing the configuration and scheduling of integrated energy systems has become crucial. This study focuses on integrated energy systems with massive flexible load resources aiming to maximize energy utilization efficiency while reducing environmental impact. Methods: To model the uncertainties in wind and solar power outputs we employed three-parameter Weibull distribution models and Beta distribution models. Flexible loads were categorized into three types to match different electricity consumption patterns. Additionally an enhanced Kepler Optimization Algorithm (EKOA) was proposed incorporating chaos mapping and adaptive learning rate strategies to improve search scope convergence speed and solution efficiency. The effectiveness of the proposed optimization scheduling and configuration methods was validated through a case study of an industrial park located in a coastal area of southeastern China. Results: The results show that using three-parameter Weibull distribution models and Beta distribution models more accurately reflects the variations in actual wind speeds and solar irradiance levels achieving peak shaving and valley filling effects and enhancing renewable energy utilization. The EKOA algorithm significantly reduced curtailment rates of wind and solar power generation while achieving substantial economic benefits. Compared with other operation modes of hydrogen the daily average cost is reduced by 12.92% and external electricity purchases are reduced by an average of 20.2 MW h/day. Discussion: Although our approach shows potential in improving energy utilization efficiency and economic gains this paper only considered hydrogen energy for single-use pathways and did not account for the economic benefits from selling hydrogen in the market. Future research will further incorporate hydrogen demand response mechanisms and optimize the output of integrated energy systems from the perspective of spot markets. These findings provide valuable references for relevant engineering applications.

Hydrogen internal combustion engines are pivotal components of the power industry for achieving zero-carbon emissions. However the development of hydrogen engines is still in its infancy and experimental research on their injection strategies lacks systematization. In this study the individual impacts of hydrogen injection pressure (within low-pressure ranges) and injection timing as well as their coupling effects on combustion characteristics engine efficiency and exhaust emissions were experimentally investigated. Results show that under fixed timing an injection pressure of 25–27.5 bar yields the highest and earliest peak in-cylinder pressures whereas at 15 bar the ignition delay increases to 14.7°CA the flame development duration extends to 8.57°CA and the late combustion duration shortens to 41.37°CA; the exhaust gas temperature peaks at 628 K at 20 bar and NOX peaks at 537 ppm at 25 bar. BTE (brake thermal efficiency) exhibits a U-shaped relationship with pressure with the minimum efficiency occurring near 25 bar when timing is held constant; advancing start of injection from 130° BTDC to 170° BTDC reduces both NOX and exhaust gas temperature with the optimal fuel economy at 140° BTDC and a peak in-cylinder pressure that is approximately 7 % higher and occurs 2–3°CA earlier at 130–140° BTDC. In the pressure–timing maps IMEP (indicated mean effective pressure) is maximized at 30 bar and 90° BTDC; BTE reaches 33.5 % at 25 bar and 100° BTDC; NOX attains a minimum at 25 bar and 110° BTDC while the exhaust gas temperature is lowest at 25 bar and 120° BTDC. Injection pressure is the primary lever for regulating fuel economy and emissions while injection timing mainly adjusts combustion phasing and IMEP. The results provide clear guidance for calibrating low-pressure hydrogen injection systems supply benchmark data for model validation and support the development of practical control strategies for hydrogen engines.

Solid oxide electrolysis cells (SOECs) represent a promising technology because they have the potential to achieve greater efficiency than existing electrolysis methods making them a strong candidate for sustainable hydrogen production. SOECs utilize a solid oxide electrolyte which facilitates the migration of oxygen ions while maintaining gas impermeability at temperatures between 600 ◦C and 900 ◦C. This review provides an overview of the recent advancements in research and development at the intersection of machine learning and SOECs technology. It emphasizes how data-driven methods can improve performance prediction facilitate material discovery and enhance operational efficiency with a particular focus on materials for cathode-supported cells. This paper also addresses the challenges associated with implementing machine learning for SOECs such as data scarcity and the need for robust validation techniques. This paper aims to address challenges related to material degradation and the intricate electrochemical behaviors observed in SOECs. It provides a description of the reactions that may be involved in the degradation mechanisms taking into account thermodynamic and kinetic factors. This information is utilized to construct a fault tree which helps categorize various faults and enhances understanding of the relationship between their causes and symptoms.

Model predictive control (MPC) requires high accuracy of the model. However the actual power system has complex dynamic characteristics. There must be unmodeled dynamics in the system modeling process which makes it difficult for MPC to perform the function of optimal control. ESO has the ability to observe and suppress errors combining the both can solve this problem. Thus this paper proposes a coordinated control strategy of hydrogen-energy storage system based on disturbance-rejection model predictive controller. Firstly this paper constructs the state-space model of the system and improves MPC. By connecting ESO and MPC in series this paper designs a matched disturbance-rejection model predictive controller and analyzes the robustness of the research system. Finally this paper verifies the effectiveness and feasibility of the disturbance-rejection model predictive controller under various working conditions. Compared with the method using only MPC the dynamic response time of the system frequency regulation under the proposed strategy in this paper is increased by about 29.9 % and the frequency drop rate is slowed down by 13.5 %. In addition under the AGC command and continuous load disturbance working conditions the maximum frequency deviation of the system under the proposed strategy is reduced by about 54.01 % and 48.96 %. The results clearly show that the proposed strategy in this paper significantly improves the dynamic response ability of the system and reduces the frequency fluctuation of the system after disturbance.