China, People’s Republic

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.