China, People’s Republic

Hydrogen is one of the most promising alternative sources to relieve the energy crisis and environmental pollution. Hydrogen can be stored as cryogenic compressed hydrogen (CcH2) to achieve high volumetric energy densities. Reliable safety codes and standards are needed for hydrogen production delivery and storage to promote hydrogen commercialization. Unintended hydrogen releases from cryogenic storage systems are potential accident scenarios that are of great interest for updating safety codes and standards. This study investigated the behavior of CcH2 releases and dispersion. The extremely low-temperature CcH2 jets can cause condensation of the air components including water vapor nitrogen and oxygen. An integral model considering the condensation effects was developed to predict the CcH2 jet trajectories and concentration distributions. The thermophysical properties were obtained from the COOLPROP database. The model divides the CcH2 jet into the underexpanded initial entrainment and heating flow establishment and established flow zones. The condensation effects on the heat transfer and flow were included in the initial entrainment and heating zones. The empirical coefficients in the integral model were then modified based on measured concentration results. Finally the analytical model predictions are shown to compare well with measured data to verify the model accuracy. The present study can be used to develop quantitative risk assessment models and update safety codes and standards for cryogenic hydrogen facilities.

Hydrogen leakage and explosion accidents have obvious dangers ambiguity of accident information and urgency of decision-making time. These characteristics bring challenges to the optimization of emergency alternatives for such accidents. Effective emergency decision making is crucial to mitigating the consequences of accidents and minimizing losses and can provide a vital reference for emergency management in the field of hydrogen energy. An improved VIKOR emergency alternatives optimization method is proposed based on the combination of hesitant triangular fuzzy set (HTFS) and the cumulative prospect theory (CPT) termed the HTFS-CPT-VIKOR method. This method adopts the hesitant triangular fuzzy number to represent the decision information on the alternatives under the influence of multi-attributes constructs alternatives evaluation indicators and solves the indicator weights by using the deviation method. Based on CPT positive and negative ideal points were used as reference points to construct the prospect matrix which then utilized the VIKOR method to optimize the emergency alternatives for hydrogen leakage and explosion accidents. Taking an accident at a hydrogen refueling station as an example the effectiveness and rationality of the HTFS-CPT-VIKOR method were verified by comparing with the existing three methods and conducting parameter sensitivity analysis. Research results show that the HTFS-CPT-VIKOR method effectively captures the limited psychological behavior characteristics of decision makers and enhances their ability to identify filter and judge ambiguous information making the decisionmaking alternatives more in line with the actual environment which provided strong support for the optimization of emergency alternatives for hydrogen leakage and explosion accidents.

Hydrogen fuel cell vehicles (HFCVs) represent an important breakthrough in the hydrogen energy industry. The safe utilization of hydrogen is critical for the sustainable and healthy development of hydrogen fuel cell vehicles. In this study risk factors and preventive measures are proposed for on-board hydrogen systems during the process of transportation storage and use of fuel cell vehicles. The relevant hydrogen safety standards in China are also analyzed and suggestions involving four safety strategies and three safety standards are proposed.

Given China’s ambition to realize carbon peak by 2030 and carbon neutralization by 2060 hydrogen is gradually becoming the pivotal energy source for the needs of energy structure optimization and energy system transformation. Thus hydrogen combined with renewable energy has received more and more attention. Nowadays power-to-hydrogen power-to-methanol and power-to-ammonia are regarded as the most promising three hydrogen-driven power-to-X technologies due to the many commercial or demonstration projects in China. In this paper these three hydrogen-driven power-to-X technologies and their application status in China are introduced and discussed. First a general introduction of hydrogen energy policies in China is summarized and then the basic principles technical characteristics trends and challenges of the three hydrogen-driven power-to-X technologies are reviewed. Finally several typical commercial or demonstration projects are selected and discussed in detail to illustrate the development of the power-to-X technologies in China.

Increasingly stringent emission standards have led shippers and port operators to consider alternative energy sources which can reduce emissions while minimizing capital investment. It is essential to understand whether there is a certain economic investment gap for alternative energy. The present work mainly focuses on the simulation study of ships using ammonia and hydrogen fuels arriving at Guangzhou Port to investigate the emission advantages and cost-benefit analysis of ammonia and hydrogen as alternative fuels. By collecting actual data and fuel consumption emissions of ships arriving at Guangzhou Port the present study calculated the pollutant emissions and cost of ammonia and hydrogen fuels substitution. As expected it is shown that with the increase of NH3 in fuel mixed fuels will effectively reduce CO and CO2 emissions. Compared to conventional fuel the injection of NH3 increases the NOx emission. However the cost savings of ammonia fuel for CO2 SOx and PM10 reduction are higher than that for NOx. In terms of pollutants ammonia is less expensive than conventional fuels when applied to the Guangzhou Port. However the cost of fuel supply is still higher than conventional energy as ammonia has not yet formed a complete fuel supply and storage system for ships. On the other hand hydrogen is quite expensive to store and transport resulting in higher overall costs than ammonia and conventional fuels even if no pollutants are produced. At present conventional fuels still have advantage in terms of cost. With the promotion of ammonia fuel technology and application the cost of supply will be reduced. It is predicted that by 2035 ammonia will not only have emission reduction benefits but also will have a lower overall economic cost than conventional fuels. Hydrogen energy will need longer development and technological breakthroughs due to the limitation of storage conditions.

As one core component in hydrogen fuel cells and water electrolysis cells bipolar plates (BPs) perform multiple important functions such as separating the fuel and oxidant flow providing mechanical support conducting electricity and heat connecting the cell units into a stack etc. On the path toward commercialization the manufacturing costs of bipolar plates have to be substantially reduced by adopting low-cost and easy-to-process metallic materials (e.g. stainless steel aluminum or copper). However these materials are susceptible to electrochemical corrosion under harsh operating conditions resulting in long-term performance degradation. By means of advanced thermal spraying technologies protective coatings can be prepared on bipolar plates so as to inhibit oxidation and corrosion. This paper reviews several typical thermal spraying technologies including atmospheric plasma spraying (APS) vacuum plasma spraying (VPS) and high-velocity oxygen fuel (HVOF) spraying for preparing coatings of bipolar plates particularly emphasizing the effect of spraying processes on coating effectiveness. The performance of coatings relies not only on the materials as selected or designed but also on the composition and microstructure practically obtained in the spraying process. The temperature and velocity of in-flight particles have a significant impact on coating quality; therefore precise control over these factors is demanded.

A novel multi-objective robust optimization model of an integrated energy system with hydrogen storage (HIES) considering source–load uncertainty is proposed to promote the low-carbon economy operation of the integrated energy system of a park. Firstly the lowest total system cost and carbon emissions are selected as the multi-objective optimization functions. The Pareto front solution set of the objective function is applied by compromise planning and the optimal solution among them is obtained by the maximum–minimum fuzzy method. Furthermore the robust optimization (RO) approach is introduced to cope with the source–load uncertainty effectively. Finally it is demonstrated that the illustrated HIES can significantly reduce the total system cost carbon emissions and abandoned wind and solar power. Meanwhile the effectiveness of the proposed model and solution method is verified by analyzing the influence of multi-objective solutions and a robust coefficient on the Chongli Demonstration Project in Hebei Province.

Hydrogen is regarded as an ideal zero-carbon fuel for an internal combustion engine. However the low mass flow rate of the hydrogen injector and the low volume heat value of the hydrogen strongly restrict the enhancement of the hydrogen engine performance. This experimental study compared the effects of single-injectors and double-injectors on the engine performance combustion pressure heat release rate and the coefficient of variation (CoVIMEP) based on a singlecylinder 0.5 L port fuel injection hydrogen engine. The results indicated that the number of hydrogen injectors significantly influences the engine performance. The maximum brake power is improved from 4.3 kW to 6.12 kW when adding the injector. The test demonstrates that the utilization of the double-injector leads to a reduction in hydrogen obstruction in the intake manifold consequently minimizing the pumping losses. The pump mean effective pressure decreased from −0.049 MPa in the single-injector condition to −0.029 MPa in the double-injector condition with the medium loads. Furthermore the double-injector exhibits excellent performance in reducing the coefficient of variation. The maximum CoVIMEP decreased from 2.18% in the single-injector configuration to 1.92% in the double-injector configuration. This result provides new insights for optimizing hydrogen engine injector design and optimizing the combustion process.

The economic operation of the integrated energy system faces the problems of coupling between energy production and conversion equipment in the system and the imbalance of various energy demands. Therefore taking system safety as the constraint and minimum economic cost as the objective function including fuel cost operation and maintenance cost this paper proposes the operation dispatching model of the integrated energy system based on hydrogen fuel cell (HFC) including HFC photovoltaic wind turbine electric boiler electric chiller absorption chiller electric energy storage and thermal energy storage equipment. On this basis a distributionally robust optimization (DRO) model is introduced to deal with the uncertainty of wind power and photovoltaic output. In the distributionally robust optimization model Kullback–Leibler (KL) divergence is used to construct an ambiguity set which is mainly used to describe the prediction errors of renewable energy output. Finally the DRO economic dispatching model of the HFC integrated energy system (HFCIES) is established. Besides based on the same load scenario the economic benefits of hybrid energy storage equipment are discussed. The dispatching results show that compared with the scenario of only electric energy storage and only thermal energy storage the economic cost of the scenario of hybrid electric and thermal storage can be reduced by 3.92% and 7.55% respectively and the use of energy supply equipment can be reduced and the stability of the energy storage equipment can be improved.

As the main contributor of carbon emissions the low-carbon transition of the industrial sector is important for achieving the goal of carbon dioxide peaking. Hydrogen-enabled industrial energy systems (HIESs) are a promising way to achieve the low-carbon transition of industrial energy systems since the hydrogen can be well coordinated with renewable energy sources and satisfy the high and continuous industrial energy demand. In this paper the long-term capacity expansion planning problem of the HIES is formulated from the perspective of industrial parks and the targets of carbon dioxide peaking and the gradual decommissioning of existing equipment are considered as constraints. The results show that the targets of carbon dioxide peaking before different years or with different emission reduction targets can be achieved through the developed method while the economic performance is ensured to some extent. Meanwhile the overall cost of the strategy based on purchasing emission allowance is three times more than the cost of the strategy obtained by the developed method while the emissions of the two strategies are same. In addition long-term carbon reduction policies and optimistic expectations for new energy technologies will help industrial parks build more new energy equipment for clean transformation.

With the increasingly severe climate change situation and the trend of green energy transformation the development and utilization of hydrogen energy has attracted extensive attention from government industry and academia in the past few decades. Renewable energy electrolysis stands out as one of the most promising hydrogen production routes enabling the storage of intermittent renewable energy power generation and supplying green fuel to various sectors. This article reviews the evolution and development of green hydrogen policies in the United States the European Union Japan and China and then summarizes the key technological progress of renewable energy electrolysis while introducing the progress of hydrogen production from wind and photovoltaic power generation. Furthermore the environmental social and economic benefits of different hydrogen production routes are analyzed and compared. Finally it provides a prospective analysis of the potential impact of renewable energy electrolysis on the global energy landscape and outlines key areas for future research and development.

The hydrogen energy industry as one of the most important directions for future energy transformation can promote the sustainable development of the global economy and of society. China has raised the development of hydrogen energy to a strategic position. Based on the patent data in the past two decades this study investigates the collaborative innovation relationships in China’s hydrogen energy field using complex network theory. Firstly patent data filed between 2003 and 2023 are analyzed and compared in terms of time geography and institutional and technological dimensions. Subsequently a patent collaborative innovation network is constructed to explore the fundamental characteristics and evolutionary patterns over five stages. Furthermore centrality measures and community detection algorithms are utilized to identify core entities and innovation alliances within the network which reveal that China’s hydrogen energy industry is drifting toward alliance innovation. The study results show the following: (1) the network has grown rapidly in size and scope over the last two decades and evolved from the initial stage to the multi-center stage before forming innovation alliances; (2) core innovative entities are important supports and bridges for China’s hydrogen energy industry and control most resources and maintain the robustness of the whole network; (3) innovation alliances reveal the closeness of the collaborative relationships between innovative entities and the potential landscape of China’s hydrogen energy industry; and (4) most of the innovation alliances cooperate only on a narrow range of technologies which may hinder the overall sustainable growth of the hydrogen energy industry. Thereafter some suggestions are put forward from the perspective of an industrial chain and innovation chain which may provide a theoretical reference for collaborative innovation and the future development and planning in the field of hydrogen energy in China.

To solve the problems of low utilization of biomass and uncertainty and intermittency of wind power (WP) in rural winter an interval optimization model of a rural integrated energy system with biogas fermentation and electrolytic hydrogen production is constructed in this paper. Firstly a biogas fermentation kinetic model and a biogas hydrogen blending model are developed. Secondly the interval number is used to describe the uncertainty of WP and an interval optimization scheduling model is developed to minimize daily operating cost. Finally a rural integrated energy system in Northeast China is taken as an example and a sensitivity analysis of electricity price gas production and biomass price is conducted. The simulation results show that the proposed strategy can significantly reduce the wind abandonment rate and improve the economy by 3.8–22.3% compared with conventional energy storage under optimal dispatch.

In the quest to achieve “double carbon” goals the urgency to develop an efficient Integrated Energy System (IES) is paramount. This study introduces a novel approach to IES by refining the conventional Power-to-Gas (P2G) system. The inability of current P2G systems to operate independently has led to the incorporation of hydrogen fuel cells and the detailed investigation of P2G’s dual-phase operation enhancing the integration of renewable energy sources. Additionally this paper introduces a carbon trading mechanism with a refined penalty–reward scale and a detailed pricing tier for carbon emissions compelling energy suppliers to reduce their carbon footprint thereby accelerating the reduction in system-wide emissions. Furthermore this research proposes a flexible adjustment mechanism for the heat-to-power ratio in cogeneration significantly enhancing energy utilization efficiency and further promoting conservation and emission reductions. The proposed optimization model in this study focuses on minimizing the total costs including those associated with carbon trading and renewable energy integration within the combined P2G-Hydrogen Fuel Cell (HFC) cogeneration system. Employing a bacterial foraging optimization algorithm tailored to this model’s characteristics the study establishes six operational modes for comparative analysis and validation. The results demonstrate a 19.1% reduction in total operating costs and a 22.2% decrease in carbon emissions confirming the system’s efficacy low carbon footprint and economic viability.

This paper proposes and assesses three different control approaches for the hydrocarbon natural gas (HCNG) penetrated integrated energy system (IES). The three control approaches adopt mixed integer linear programing conditional value at risk (CVaR) and robust optimization (RO) respectively aiming to mitigate the renewable generation uncertainties. By comparing the performance and efficiency the most appropriate control approach for the HCNG penetrated IES is identified. The numerical analysis is conducted to evaluate the three control approaches in different scenarios where the uncertainty level of renewable energy (within the HCNG penetrated IES) varies. The numerical results show that the CVaR-based approach outperforms the other two approaches when renewable uncertainty is high (approximately 30%). In terms of the cost to satisfy the energy demand the operational cost of the CVaR-based method is 8.29% lower than the RO one while the RO-based approach has a better performance when the renewable uncertainty is medium (approximately 5%) and it is operational is 0.62% lower than that of the CVaR model. In both evaluation cases mixed integer linear programing approach cannot meet the energy demand. This paper also compares the operational performance of the IES with and without HCNG. It is shown that the IES with HCNG can significantly improve the capability to accommodate renewable energy with low upgrading cost.

The sorption-enhanced steam gasification of biomass (SEBSG) is considered a prospective thermo-chemical technology for high-purity H2 production with in-situ CO2 capture. Fundamental concepts and operating conditions of SEBSG technology were summarized in this review. Considerable industrial demonstration units have been conducted on pilot scales for large-scale availability of the SEBSG process. The influence of process parameters such as reaction temperature Steam/Biomass (S/B) ratio feedstock characteristics cyclic CO2 capture capacity of CaO-based sorbents and catalysis were critically reviewed to provide theoretical recommendations for industrial operation. Bifunctional materials that have high catalytic activity and CO2 capture activity are crucial for ensuring high H2 production in the SEBSG. The application of density functional theory (DFT) and reactive force field molecular dynamic (ReaxFF MD) simulations on microcosmic reaction mechanisms in the SEBSG process such as pyrolysis WGS and reforming reactions and CO2 capture of CaO-based materials are comprehensively overviewed. Several research gaps like the exploitation of more efficient and low-cost bifunctional material integrated process economics and revelation of well-rounded mechanisms need to be filled for the following large-scale industrial applications.

In the context of energy interconnection and low-carbon power the power-to-gas (P2G) carbon trading mechanism is integrated into the integrated energy system (IES) model of multi-energy coupling units to achieve lowcarbon economic dispatch considering both the economic and environmental benefits of system operation. First the characteristics of each unit in the system are comprehensively considered and a joint dispatch structure for a regionally integrated energy system is developed including P2G equipment energy source equipment storage equipment and conversion equipment. The working mechanism of P2G is analyzed and its carbon trading model is established. Next a comprehensive energy system optimization model is formulated with the goal of maximizing system operating profit while accounting for carbon transaction costs. Finally Cplex and Yalmip software are used to perform simulation analysis in MATLAB to verify the effectiveness of the proposed model in reducing system carbon emissions through participation in the carbon trading market ensuring system economy and reducing the dependence of the integrated energy system on the external market.

To reduce hydrogen consumption by hydrogen fuel cell vehicles (HFCVs) an adaptive power-following control strategy based on gated recurrent unit (GRU) neural network operating condition recognition was proposed. The future vehicle speed was predicted based on a GRU neural network and a driving cycle condition recognition model was established based on k-means cluster analysis. By predicting the speed over a specific time horizon feature parameters were extracted and compared with those of typical operating conditions to determine the categories of the parameters thus the adjustment of the power-following control strategy was realized. The simulation results indicate that the proposed control strategy reduces hydrogen consumption by hydrogen fuel cell vehicles (HFCVs) by 16.6% with the CLTC-P driving cycle and by 4.7% with the NEDC driving cycle compared to the conventional power-following control strategy. Additionally the proposed strategy effectively stabilizes the battery’s state of charge (SOC).

Recent advancements in membrane-assisted seawater electrolysis powered by renewable energy offer a sustainable path to green hydrogen production. However its large-scale implementation faces challenges due to slow powerto-hydrogen (P2H) conversion rates. Here we report a modular forward osmosis-water splitting (FOWS) system that integrates a thin-film composite FO membrane for water extraction with alkaline water electrolysis (AWE) denoted as FOWSAWE. This system generates high-purity hydrogen directly from wastewater at a rate of 448 Nm3 day−1 m−2 of membrane area over 14 times faster than the state-of-the-art practice with specific energy consumption as low as 3.96 kWh Nm−3 . The rapid hydrogen production rate results from the utilisation of 1 M potassium hydroxide as a draw solution to extract water from wastewater and as the electrolyte of AWE to split water and produce hydrogen. The current system enables this through the use of a potassium hydroxide-tolerant and hydrophilic FO membrane. The established waterhydrogen balance model can be applied to design modular FO and AWE units to meet demands at various scales from households to cities and from different water sources. The FOWSAWE system is a sustainable and an economical approach for producing hydrogen at a record-high rate directly from wastewater marking a significant leap in P2H practice.

Energy scheduling for hybrid unmanned aerial vehicles (UAVs) is of critical importance to their safe and stable operation. However traditional approaches predominantly rule-based often lack the dynamic adaptability and stability necessary to address the complexities of changing operational environments. To overcome these limitations this paper proposes a novel energy scheduling framework that integrates the Model Predictive Control (MPC) with a Deep Reinforcement Learning algorithm specifically the Deep Deterministic Policy Gradient (DDPG). The proposed method is designed to optimize energy management in hydrogen-powered UAVs across diverse flight missions. The energy system comprises a proton exchange membrane fuel cell (PEMFC) a lithium-ion battery and a hydrogen storage tank enabling robust optimization through the synergistic application of MPC and DDPG. The simulation results demonstrate that the MPC effectively minimizes electric power consumption under various flight conditions while the DDPG achieves convergence and facilitates efficient scheduling. By leveraging advanced mechanisms including continuous action space representation efficient policy learning experience replay and target networks the proposed approach significantly enhances optimization performance and system stability in complex continuous decision-making scenarios.

The integration of renewable energy sources such as wind and solar power at high proportions has become an inevitable trend in the development of power systems under the new power system framework. The construction of a microgrid system incorporating hydrogen energy storage and battery energy storage can leverage the complementary advantages of long-term and short-term hybrid storage achieving power and energy balance across multiple time scales in the power system. To prevent frequent startstop cycles of hydrogen storage devices and lithium battery storage under overcharge and overdischarge conditions a coordinated control strategy for power distribution in a microgrid with hydrogen storage is proposed. First a fuzzy control algorithm is used for power distribution between hydrogen storage and lithium battery storage. Then the hydrogen storage tank’s state of health (SOH) and the lithium battery’s state of charge (SOC) are compared with the goal of selecting a multi-stack fuel cell system operating at its optimal efficiency point where each fuel cell stack outputs 10 kW. This further ensures that the SOC and SOH remain within reasonable ranges. Finally simulations are conducted in MATLAB/Simulink R2018b to verify that the proposed strategy maintains stability in the DC bus and alleviates issues of overcharge and overdischarge ensuring that both the system’s SOC and SOH remain within a reasonable range thereby enhancing equipment lifespan and system stability

This paper proposes a novel dual-fuel dual-mode dual-thermodynamic cycle aviation propulsion system for the first time and conducts theoretical research on it based on a moderately simplified mathematical model. It is specifically designed to significantly reduce carbon emissions for wide-body aircraft. A comprehensive thermodynamic model is developed for this hybrid power system which integrates a high-temperature proton exchange membrane fuel cell with a dual-rotor turbofan engine. The matching characteristics between aircraft and engine performance are analyzed by systematically varying the fuselage length of the dual-fuel aircraft configuration. Results show that the specific fuel consumption of the proposed engine is decreased by 12.6% compared with that of the traditional turbofan engine as the Mach number increases. Conversely as the relative physical rotational speed decreases the thrust of the novel engine is increased by 10%. With a 20 % extension in fuselage length the dual-fuel aircraft operating on 100 % hydrogen fuel can achieve an endurance exceeding 17 h representing a 20 % endurance improvement over conventional aviation kerosene-powered aircraft. In this case the aircraft weight can be reduced by 96.79 tons and CO2 emissions can be decreased by 301.65 tons.

Enhancing system durability and fuel economy stands as a crucial factor in the energy management of fuel cell hybrid vehicles. This paper proposes an Equivalent Consumption Minimization Strategy (ECMS) based on the Genetic Algorithm (GA) aiming to minimize the overall operating cost of the system. First this study establishes a dynamic model of the hydrogen–electric hybrid vehicle a static input–output model of the hybrid power system and an aging model. Next a speed prediction method based on an Autoregressive Integrated Moving Average (ARIMA) model is designed. This method fits a predictive model by collecting historical speed data in real time ensuring the robustness of speed prediction. Finally based on the speed prediction results an adaptive Equivalence Factor (EF) method using a GA is proposed. This method comprehensively considers fuel consumption and the economic costs associated with the aging of the hydrogen–electric hybrid system forming a total operating cost function. The GA is then employed to dynamically search for the optimal EF within the cost function optimizing the system’s economic performance while ensuring real-time feasibility. Simulation outcomes demonstrate that the proposed energy management strategy significantly enhances both the durability and fuel economy of the fuel cell hybrid vehicle.

During the development of hydrogen fuel cell systems with the augmentation of power conventional air-cooling systems which are frequently employed in portable scenarios encounter difficulties in maintaining the balance between radiator heat dissipation and power consumption. In contrast liquid-cooling systems are widely adopted in high-power applications. In this regard aiming to address the heat dissipation problem and make use of the wastewater from the stack tailpipe a novel spray cooling system integrated with the traditional air-cooling for the radiator of hydrogen fuel cell systems is put forward. Through experimental investigations based on heat transfer theory and the design principles of fuel cell systems it is discovered that under specific nozzle apertures and spray water pressures the heat dissipation rate can be enhanced by 40 % and 30 % respectively. With particular radiator internal water flow rates and fan speeds the heat dissipation rate can be increased by 30 % and 108 % respectively. And the spray angle of 60 ◦ is the best angle. In contrast to the conventional air-cooling system the spray-air cooling system exhibits a heat dissipation rate that is approximately 50 % higher. Exper imental analyses demonstrate that the new system effectively harnesses water resources and enhances the heat dissipation performance of the radiator thereby providing a technical reference for the application of spray cooling in the radiators of hydrogen fuel cell systems.

Ammonia a molecule that is gaining more interest as a fueling vector has been considered as a candidate to power transport produce energy and support heating applications for decades. However the particular characteristics of the molecule always made it a chemical with low if any benefit once compared to conventional fossil fuels. Still the current need to decarbonize our economy makes the search of new methods crucial to use chemicals such as ammonia that can be produced and employed without incurring in the emission of carbon oxides. Therefore current efforts in this field are leading scientists industries and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector moving through all of the steps in the production distribution utilization safety legal considerations and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes legal barriers that will be faced to achieve its deployment safety and environmental considerations that impose a critical aspect for acceptance and wellbeing and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein this work sets the principles research practicalities and future views of a transition toward a future where ammonia will be a major energy player.

The transformation from a fossil fuel economy to a low-carbon economy has reshaped the way energy is transmitted. As most renewable energy is obtained in the form of electricity using green electricity to produce hydrogen is considered a promising energy carrier. However most studies have not considered the transportation mode of hydrogen. In order to encourage the utilization of renewable energy and hydrogen this paper proposes a comprehensive energy system optimization operation strategy considering multi-mode hydrogen transport. Firstly to address the shortcomings in the optimization operation of existing systems regarding hydrogen transport modeling is conducted for multi-mode hydrogen transportation through hydrogen tube trailers and pipelines. This model reflects the impact of multi-mode hydrogen delivery channels on hydrogen utilization which helps promote the consumption of new energy in electrolysis cells to meet application demands. Based on this the constraints of electrolyzers combined heat and power units hydrogen fuel cells and energy storage systems in integrated energy systems (IESs) are further considered. With the objective of minimizing the daily operational cost of the comprehensive energy system an optimization model for the operation considering multi-mode hydrogen transport is constructed. Lastly based on simulation examples the impact of multi-mode hydrogen transportation on the operational cost of the system is analyzed in detail. The results indicate that the proposed optimization strategy can reduce the operational cost of the comprehensive energy system. Hydrogen tube trailers and pipelines will have a significant impact on operational costs. Properly allocating the quantity of hydrogen tube trailers and pipelines is beneficial for reducing the operational costs of the system. Reasonable arrangement of hydrogen transportation channels is conducive to further promoting the green and economic operation of the system.

In the vehicle-to-everything scenario the fuel cell bus can accurately obtain the surrounding traffic information and quickly optimize the energy management problem while controlling its own safe and efficient driving. This paper proposes an energy management strategy (EMS) that considers speed control based on deep reinforcement learning (DRL) in complex traffic scenarios. Using SUMO simulation software (Version 1.15.0) a two-lane urban expressway is designed as a traffic scenario and a hydrogen fuel cell bus speed control and energy management system is designed through the soft actor–critic (SAC) algorithm to effectively reduce the equivalent hydrogen consumption and fuel cell output power fluctuation while ensuring the safe efficient and smooth driving of the vehicle. Compared with the SUMO–IDM car-following model the average speed of vehicles is kept the same and the average acceleration and acceleration change value decrease by 10.22% and 11.57% respectively. Compared with deep deterministic policy gradient (DDPG) the average speed is increased by 1.18% and the average acceleration and acceleration change value are decreased by 4.82% and 5.31% respectively. In terms of energy management the hydrogen consumption of SAC–OPT-based energy management strategy reaches 95.52% of that of the DP algorithm and the fluctuation range is reduced by 32.65%. Compared with SAC strategy the fluctuation amplitude is reduced by 15.29% which effectively improves the durability of fuel cells.

The combustion of hydrogen increases the water content of the combustion products affecting the aerodynamic performance of turbines using hydrogen as a fuel. This study aims to design a radial turbine using the differential evolution (DE) algorithm to improve its characteristics and optimize its aerodynamic performance through an orthogonal experiment and analysis of means (ANOM). The effects of varying water content in combustion products ranging from 12% to 22% on the performance of the radial turbine are also investigated. After optimization the total–static efficiency of the radial turbine increased to 89.12% which was 1.59% higher than the preliminary design. The study found that flow loss in the impeller primarily occurred at the leading edge trailing edge and the inlet of the suction surface tip and outlet. With a 10% increase in water content the enthalpy dropped Mach number increased and turbine power increased by 4.64% 1.71% and 2.41% respectively. However the total static efficiency and mass flow rate decreased by 0.71% and 2.13% respectively. These findings indicate that higher water content in hydrogen combustion products enhances the turbine’s output power while reducing the combustion products’ mass flow rate.

Historically it has been a challenge to simulate the experimentally observed cellular structures and marginal behavior of multidimensional hydrogen-oxygen detonations in the presence of losses even with detailed chemistry models. Very recently a quasi-two-dimensional inviscid approach was pursued where losses due to viscous boundary layers were modeled by the inclusion of an equivalent mass divergence in the lateral direction using Fay’s source term formulation with Mirels’ compressible boundary layer solutions. The same approach was used for this study along with the inclusion of thermally perfect detailed chemistry in order to capture the correct ignition sensitivity of the gas to dynamic changes in the thermodynamic state behind the detonation front. In addition the strength of transverse waves and their impact on the detonation front was investigated. Here the detailed San Diego mechanism was applied and it has been found that the detonation cell sizes can be accurately predicted without the need to prescribe specific parameters for the combustion model. For marginal cases where the detonation waves approach their failure limit quasi-stable mode behavior was observed where the number of transverse waves monotonically decreased to a single strong wave over a long enough distance. The strong transverse waves were also found to be slightly weaker than the detonation front indicating that they are not overdriven in agreement with recent studies.

Hydrogen is a key pillar in the global Net Zero strategy. Rapid scaling up of hydrogen production transport distribution and utilization is expected. This entails that hydrogen which is traditionally an industrial gas will come into proximity of populated urban areas and in some situations handled by the untrained public. To realize all their benefits hydrogen and its technologies must be safely developed and deployed. The specific properties of hydrogen involving wide flammability range low ignition energy and fast flame speed implies that any accidental release of hydrogen can be easily ignited. Comparing with conventional fuels combustion systems fueled by hydrogen are also more prone to flame instability and abnormal combustion. This paper aims to provide a comprehensive review about combustion research related to hydrogen safety. It starts with a brief introduction which includes some overview about risk analysis codes and standards. The core content covers ignition fire explosions and deflagration to detonation transition (DDT). Considering that DDT leads to detonation and that detonation may also be induced directly under special circumstances the subject of detonation is also included for completeness. The review covers laboratory medium and large-scale experiments as well as theoretical analysis and numerical simulation results. While highlights are provided at the end of each section the paper closes with some concluding remarks highlighting the achievements and key knowledge gaps.

In the process of building a new power system with new energy sources as the mainstay wind power and photovoltaic energy enter the multiplication stage with randomness and uncertainty and the foundation and support role of large-scale long-time energy storage is highlighted. Considering the advantages of hydrogen energy storage in large-scale cross-seasonal and cross-regional aspects the necessity feasibility and economy of hydrogen energy participation in long-time energy storage under the new power system are discussed. Firstly power supply and demand production simulations were carried out based on the characteristics of new energy generation in China. When the penetration of new energy sources in the new power system reaches 45% long-term energy storage becomes an essential regulation tool. Secondly by comparing the storage duration storage scale and application scenarios of various energy storage technologies it was determined that hydrogen storage is the most preferable choice to participate in large-scale and long-term energy storage. Three long-time hydrogen storage methods are screened out from numerous hydrogen storage technologies including salt-cavern hydrogen storage natural gas blending and solid-state hydrogen storage. Finally by analyzing the development status and economy of the above three types of hydrogen storage technologies and based on the geographical characteristics and resource endowment of China it is pointed out that China will form a hydrogen storage system of “solid state hydrogen storage above ground and salt cavern storage underground” in the future.

With the goal of achieving “carbon peak in 2030 and carbon neutrality in 2060” as clearly proposed by China the transportation sector will face long–term pressure on carbon emissions and the application of hydrogen fuel cell vehicles will usher in a rapid growth period. However true “zero carbon” emissions cannot be separated from “green hydrogen”. Therefore it is of practical significance to explore the feasibility of renewable energy hydrogen production in the context of hydrogen refueling stations especially photovoltaic hydrogen production which is applied to hydrogen refueling stations (hereinafter referred to “photovoltaic hydrogen refueling stations”). This paper takes a hydrogen refueling station in Shanghai with a supply capacity of 500 kg/day as the research object. Based on a characteristic analysis of the hydrogen demand of the hydrogen refueling station throughout the day this paper studies and analyzes the system configuration operation strategy environmental effects and economics of the photovoltaic hydrogen refueling station. It is estimated that when the hydrogen price is no less than 6.23 USD the photovoltaic hydrogen refueling station has good economic benefits. Additionally compared with the conventional hydrogen refueling station it can reduce carbon emissions by approximately 1237.28 tons per year with good environmental benefits.

Methanol as a liquid phase hydrogen storage carrier has broad prospects. Although the on-board methanol reforming hydrogen fuel cell system (MRFC) has long been proposed to replace the traditional hydrogen fuel cell vehicle the inherent safety of the system itself has rarely been studied. This paper adopted the improved method of Inherently Safer Process Piping (ISPP) to evaluate the pipeline inherent safety of MRFC. The process data such as temperature pressure viscosity and density were obtained by simulating the MRFC in ASPEN HYSYS. The Process Stream Characteristic Index (PSCI) and risk assessment of jet fire and vapor cloud explosion was carried out for the key streams with those simulated data. The results showed the risk ranks of different pipelines in the MRFC and the countermeasures were given according to different risk ranks. Through the in-depth study of the evaluation results this paper demonstrates the risk degree of the system in more detail and reduces the fuzziness of risk rating. By applying ISPP to the small integrated system of MRFC this paper realizes the leap of inherent safety assessment method in the object and provides a reference for the inherent safety assessment of relevant objects in the future.

Innovation in key low-carbon technologies plays a supporting role in achieving a high-quality low-carbon transition in the power sector. This paper aims to integrate research on the power transition pathway under the “dual carbon” goals with key technological innovation layouts. First it deeply analyzes the development trends of three key low-carbon technologies in the power sector—new energy storage CCUS and hydrogen energy—and establishes a quantitative model for their technological support in the low-carbon transition of the power sector. On this basis the objective function and constraints of traditional power planning models are improved to create an integrated optimization model for the power transition pathway and key low-carbon technologies. Finally a simulation analysis is conducted using China’s power industry “dual carbon” pathway as a case study. The optimization results include the power generation capacity structure power generation mix carbon reduction pathway and key low-carbon technology development path for China from 2020 to 2060. Additionally the impact of uncertainties in breakthroughs in new energy storage CCUS and hydrogen technologies on the power “dual carbon” pathway is analyzed providing technological and decision-making support for the low-carbon transition of the power sector.

This paper describes a renewable energy system incorporating a hydrogen production unit to address the imbalance between energy supply and demand. The system utilizes renewable energy and hydrogen production energy to release energy to fill the power gap during peak demand power supply for demand peaking and valley filling. The system is optimized by analyzing marine predator behavioral logic and optimizing the system for maximum operational efficiency and best economic value. The results of the study show that after the optimized scheduling of the hydrogen production coupled renewable energy integrated energy system using the improved marine predator optimization algorithm the energy distribution of the whole energy system is good with the primary energy saving rate maintained at 24.75% the CO2 emission reduction rate maintained at 42.32% and the cost saving rate maintained at 0.78%. In addition this paper uses the Adaboost-BP prediction model to predictively analyze the system. The results show that as the price of natural gas increases the advantages of the combined hydrogen production renewable integrated energy system proposed in this paper become more obvious and the cumulative cost over three years is better than other related systems. These research results provide an important reference for the application and development of the system.

The pressing global challenge of climate change necessitates a concerted effort to limit greenhouse gas emissions particularly carbon dioxide. A critical pathway is to replace fossil fuel sources by electrification including transportation. While electrification of light-duty vehicles is rapidly expanding the heavy-duty vehicle sector is subject to challenges notably the logistical drawbacks of the size and weight of high-capacity batteries required for range as well as the time for battery charging. This Perspective highlights the potential of hydrogen fuel-cell vehicles as a viable alternative for heavy-duty road transportation. We evaluate the implications of hydrogen integration into the freight economy energy dynamics and CO2 mitigation and envision a roadmap for a holistic energy transition. Our critical opinion presented in this Perspective is that federal incentives to produce hydrogen could foster growth in the nascent hydrogen economy. The pathway that we propose is that initial focus on operators of large fleets that could control their own fueling infrastructure. This opinion was formed from private discussions with numerous stakeholders during the formation of one of the awarded hydrogen hubs if they focus on early adopters that could leverage the hydrogen supply chain.

Integrating carbon capture and storage (CCS) technology into an integrated energy system (IES) can reduce its carbon emissions and enhance its low-carbon performance. However the full CCS of flue gas displays a strong coupling between lean and rich liquor as carbon dioxide liquid absorbents. Its integration into IESs with a high penetration level of renewables results in insufficient flexibility and renewable curtailment. In addition integrating split-flow CCS of flue gas facilitates a short capture time giving priority to renewable energy. To address these limitations this paper develops a carbon capture utilization and storage (CCUS) method into which storage tanks for lean and rich liquor and a two-stage power-to-gas (P2G) system with multiple utilizations of hydrogen including a fuel cell and a hydrogen-blended CHP unit are introduced. The CCUS is integrated into an IES to build an electricity–heat–hydrogen–gas IES. Accordingly a deep low-carbon economic optimization strategy for this IES which considers stepwise carbon trading coal consumption renewable curtailment penalties and gas purchasing costs is proposed. The effects of CCUS the twostage P2G system and stepwise carbon trading on the performance of this IES are analyzed through a case-comparative analysis. The results show that the proposed method allows for a significant reduction in both carbon emissions and total operational costs. It outperforms the IES without CCUS with an 8.8% cost reduction and a 70.11% reduction in carbon emissions. Compared to the IES integrating full CCS the proposed method yields reductions of 6.5% in costs and 24.7% in emissions. Furthermore the addition of a two-stage P2G system with multiple utilizations of hydrogen further amplifies these benefits cutting costs by 13.97% and emissions by 12.32%. In addition integrating CCUS into IESs enables the full consumption of renewables and expands hydrogen utilization and the renewable consumption proportion in IESs can reach 69.23%.

The energy efficiency of water electrolysis is limited by the sluggish kinetics of the anodic oxygen evolution reaction (OER) which simultaneously produces a low-value product oxygen. A promising strategy to address this challenge is to replace OER with a more favorable oxidation reaction that yields a valuable co-product. In this study we investigate the electrochemical reforming of glycerol in alkaline media to simultaneously produce hydrogen at a Pt cathode and formate at a NiSe₂ anode. The NiSe₂ electrode achieves a glycerol oxidation reaction (GOR) current density of up to 100 mA cm−2 in a 1 M KOH solution containing 1 M glycerol significantly outperforming a reference elemental Ni electrode. Both electrodes exhibit high Faradaic efficiencies (FE) achieving around 93 % for formate production at an applied potential of 1.6 V vs. RHE. To rationalize this exceptional performance density functional theory (DFT) calculations were conducted revealing that the incorporation of Se into NiSe₂ enhances the glycerol adsorption and modulates the electron density thereby lowering the energy barrier for the initial dehydrogenation step in the formate formation pathway. These findings provide valuable insights for the design of cost-effective high-performance electrocatalysts for organic oxidation-assisted hydrogen production advancing a more sustainable and economically attractive route for hydrogen generation and chemical valorization.

The imperative to address traditional energy crises and environmental concerns has accelerated the need for energy structure transformation. However the variable nature of renewable energy poses challenges in meeting complex practical energy requirements. To address this issue the construction of a multifunctional large-scale stationary energy storage system is considered an effective solution. This paper critically examines the battery and hydrogen hybrid energy storage systems. Both technologies face limitations hindering them from fully meeting future energy storage needs such as large storage capacity in limited space frequent storage with rapid response and continuous storage without loss. Batteries with their rapid response (90%) excel in frequent short-duration energy storage. However limitations such as a selfdischarge rate (>1%) and capacity loss (~20%) restrict their use for long-duration energy storage. Hydrogen as a potential energy carrier is suitable for large-scale long-duration energy storage due to its high energy density steady state and low loss. Nevertheless it is less efficient for frequent energy storage due to its low storage efficiency (~50%). Ongoing research suggests that a battery and hydrogen hybrid energy storage system could combine the strengths of both technologies to meet the growing demand for large-scale long-duration energy storage. To assess their applied potentials this paper provides a detailed analysis of the research status of both energy storage technologies using proposed key performance indices. Additionally application-oriented future directions and challenges of the battery and hydrogen hybrid energy storage system are outlined from multiple perspectives offering guidance for the development of advanced energy storage systems.

This paper mainly introduces the main pain point of China's civil hydrogen energy supply chain - the problem of storage and transportation and analyzes the safety economy and scale effect and other issues of the existing hydrogen energy storage and transportation compares with other storage and transportation technology solutions and comprehensively screens out the storage and transportation technology solution mainly based on liquid hydrogen technology. The liquid hydrogen technology solution has significant advantages over the existing compressed hydrogen system in terms of safety economy and scale effect especially for future large-scale hydrogen energy application scenarios. In addition the future hydrogen energy storage and transportation system based on liquid hydrogen technology can help improve the overall utilization efficiency of country’s renewable energy promote the country's energy transition promote the electrification of the country's transportation sector and help achieve China's carbon emission reduction 2030/2060 target.

Decarbonizing heavy-duty trucks (HDTs) is both challenging and crucial for achieving carbon neutrality in the transport sector. Renewable hydrogen (H2) methanol (MeOH) and ammonia (NH3) offer potential solutions yet their economic viability and emission benefits remain largely unexplored. This study presents for the first time a comprehensive techno-economic analysis of using these three renewable fuels to decarbonize HDTs through detailed fuel and vehicle modeling. Six pathways are compared: hydrogen fuel cell electric trucks (FCET-H2) internal combustion engine trucks using MeOH (ICET-MeOH) and NH3 (ICET-NH3) as well as three indirect pathways that utilize these fuels for power generation to charge battery electric trucks (BETs). A novel “target powertrain cost” metric is introduced to assess the economic viability of FCET-H2 ICET-NH3 and ICET-MeOH relative to BETs. The results reveal that while BET pathways demonstrate higher well-to-wheel efficiencies significant opportunities exist for ICET-MeOH and ICET-NH3 in medium- and long-haul applications. Further more FCET-H2 achieves the lowest life cycle carbon emissions while ICET-MeOH and ICET-NH3 become more cost-effective as electricity costs decline. This study offers valuable insights and benchmarks for powertrain developers and policymakers addressing a critical gap in the comparative analysis of these three fuels for decarbonizing HDTs.

Underground hydrogen (H2) storage (UHS) and carbon dioxide (CO2) geo-storage (CGS) are prominent methods of meeting global energy needs and enabling a low-carbon global economy. The pore-scale distribution reservoir-scale storage capacity and containment security of H2 and CO2 are significantly influenced by interfacial properties including the equilibrium contact angle (θE) and solid-liquid and solid-gas interfacial tensions (γSL and γSG). However due to the technical constraints of experimentally determining these parameters they are often calculated based on advancing and receding contact angle values. There is a scarcity of θE γSL and γSG data particularly related to the hydrogen structural sealing potential of caprock which is unavailable in the literature. Young's equation and Neumann's equation of state were combined in this study to theoretically compute these three parameters (θE γSL and γSG) at reservoir conditions for the H2 and CO2 geo-storage potential. Pure mica organic-aged mica and alumina nano-aged mica substrates were investigated to explore the conditions for rock wetting phenomena and the sealing potential of caprock. The results reveal that θE increases while γSG decreases with increasing pressure organic acid concentration and alkyl chain length. However γSG decreases with increasing temperatures for H2 gas and vice versa for CO2. In addition θE and γSL decrease whereas γSG increases with increasing alumina nanofluid concentration from 0.05 to 0.25 wt%. Conversely θE and γSL increase whereas γSG decreases with increasing alumina nanofluid concentration from 0.25 to 0.75 wt%. The hydrogen wettability of mica (a proxy of caprock) was generally less than the CO2 wettability of mica at similar physio-thermal conditions. The interfacial data reported in this study are crucial for predicting caprock wettability alterations and the resulting structural sealing capacity for UHS and CGS.

The liner of a carbon fiber fully reinforced composite tank with thermoplastic liner (type IV) works in a hydrogen environment with varying temperature and pressure profiles. The ageing performance of the thermoplastic liner may affect hydrogen permeability and the consequent storage capacity degrade the mechanical properties and even increase the leakage risks of type IV tanks. In this paper both testing procedures and evaluation parameters of an ageing test in a hydrogen environment required in several standards are compared and analyzed. Hydrogen static exposure in a high-temperature condition with a constant temperature and pressure is suggested to be a reasonable way to accelerate the ageing reaction of thermoplastic materials. A total of 192 h is considered a superior ageing test duration to balance the test economy and safety. The ageing test temperature in the high-temperature condition is suggested as no lower than 85 ◦C while the upper limit of test pressure is suggested to be 1.25 NWP. In addition the hydrogen permeation coefficient and mechanical properties are recognized as important parameters in ageing performance evaluation. Considering the actual service conditions the influence of temperature/pressure cycling depressurization rate and humidity on the ageing performance of thermoplastics in hydrogen are advised to be investigated experimentally.

Magnesium-based hydrogen storage alloys have attracted significant attention as promising materials for solid-state hydrogen storage due to their high hydrogen storage capacity abundant reserves low cost and reversibility. However the widespread application of these alloys is hindered by several challenges including slow hydrogen absorption/desorption kinetics high thermodynamic stability of magnesium hydride and limited cycle life. This comprehensive review provides an in-depth overview of the recent advances in magnesium-based hydrogen storage alloys covering their fundamental properties synthesis methods modification strategies hydrogen storage performance and potential applications. The review discusses the thermodynamic and kinetic properties of magnesium-based alloys as well as the effects of alloying nanostructuring and surface modification on their hydrogen storage performance. The hydrogen absorption/desorption properties of different magnesium-based alloy systems are compared and the influence of various modification strategies on these properties is examined. The review also explores the potential applications of magnesium-based hydrogen storage alloys including mobile and stationary hydrogen storage rechargeable batteries and thermal energy storage. Finally the current challenges and future research directions in this field are discussed highlighting the need for fundamental understanding of hydrogen storage mechanisms development of novel alloy compositions optimization of modification strategies integration of magnesium-based alloys into hydrogen storage systems and collaboration between academia and industry.

With the unprecedented development of green and renewable energy sources the proportion of clean hydrogen (H2 ) applications grows rapidly. Since H2 has physicochemical properties of being highly permeable and combustible high-performance H2 sensors to detect and monitor hydrogen concentration are essential. This review discusses a variety of fiber-optic-based H2 sensor technologies since the year 1984 including: interferometer technology fiber grating technology surface plasma resonance (SPR) technology micro lens technology evanescent field technology integrated optical waveguide technology direct transmission/reflection detection technology etc. These technologies have been evolving from simply pursuing high sensitivity and low detection limits (LDL) to focusing on multiple performance parameters to match various application demands such as: high temperature resistance fast response speed fast recovery speed large concentration range low cross sensitivity excellent long-term stability etc. On the basis of palladium (Pd)-sensitive material alloy metals catalysts or nanoparticles are proposed to improve the performance of fiberoptic-based H2 sensors including gold (Au) silver (Ag) platinum (Pt) zinc oxide (ZnO) titanium oxide (TiO2 ) tungsten oxide (WO3 ) Mg70Ti30 polydimethylsiloxane (PDMS) graphene oxide (GO) etc. Various microstructure processes of the side and end of optical fiber H2 sensors are also discussed in this review.

Aiming to solve the problems of insufficient dynamic responses the large loss of energy storage life of a single power cell and the large fluctuation in DC (direct current) bus voltage in fuel cell vessels this study takes a certain type of fuel cell ferry as the research object and proposes an improved equivalent minimum hydrogen consumption energy management strategy based on fuzzy logic control. First a hybrid power system including a fuel cell a lithium–iron–phosphate battery and a supercapacitor is proposed with the simulation of the power system of the modified mother ship. Second a power system simulation model and a double-closed-loop PI (proportion integration) control model are established in MATLAB/Simulink to design the equivalent hydrogen consumption model and fuzzy logic control strategy. The simulation results show that under the premise of meeting the load requirements the control strategy designed in this paper improves the Li-ion battery’s power the Li-ion battery’s SOC (state of charge) the bus voltage stability and the equivalent hydrogen consumption significantly compared with those before optimization which improves the stability and economy of the power system and has certain practical engineering value.

To cope with climate change emerging fuels- hydrogen ammonia and methanol- have been proposed as promising energy carriers that will replace part of the liquefied natural gas (LNG) in future maritime scenarios. Energy efficiency is an important indicator for evaluating the system but the maritime supply system for emerging fuels has yet to be revealed. In this study the energy efficiency of the maritime supply chain of hydrogen ammonia methanol and natural gas is investigated considering processes including production storage loading transport and unloading. A sensitivity analysis of parameters such as ambient temperature storage time pipeline length and sailing time is also carried out. The results show that hydrogen (2.366%) has the highest daily boil-off gas (BOG) rate and wastes more energy than LNG (0.413%) with ammonia and methanol both being lower than LNG. The recycling of BOG is of great importance to the hydrogen supply chain. When produced from renewable energy sources methanol (98.02%) is the most energy efficient followed by ammonia with hydrogen being the least (89.10%). This assessment shows from an energy efficiency perspective that ammonia and methanol have the potential to replace LNG as the energy carrier of the future and that hydrogen requires efficient BOG handling systems to increase competitiveness. This study provides some inspirations for the design of global maritime supply systems for emerging fuels.

Scaling up clean hydrogen supply in the near future is critical to achieving China’s hydrogen development target. This study established an electrolytic hydrogen development mechanism considering the generation mix and operation optimization of power systems with access to hydrogen. Based on the incremental cost principle we quantified the provincial and national clean hydrogen production cost performance levels in 2030. The results indicated that this mechanism could effectively reduce the production cost of clean hydrogen in most provinces with a national average value of less than 2 USD·kg−1 at the 40-megaton hydrogen supply scale. Provincial cooperation via power transmission lines could further reduce the production cost to 1.72 USD·kg−1. However performance is affected by the potential distribution of hydrogen demand. From the supply side competitiveness of the mechanism is limited to clean hydrogen production while from the demand side it could help electrolytic hydrogen fulfil a more significant role. This study could provide a solution for the ambitious development of renewables and the hydrogen economy in China.

With the adjustment of energy structure the utilization of hydrogen energy has been widely attended. China’s carbon neutrality targets make it urgent to change traditional coal-fired power generation. The paper investigates the combustion of pulverized coal blended with hydrogen to reduce carbon emissions. In terms of calorific value the pulverized coal combustion with hydrogen at 1% 5% and 10% blending ratios is investigated. The results show that there is a significant reduction in CO2 concentration after hydrogen blending. The CO2 concentration (mole fraction) decreased from 15.6% to 13.6% for the 10% hydrogen blending condition compared to the non-hydrogen blending condition. The rapid combustion of hydrogen produces large amounts of heat in a short period which helps the ignition of pulverized coal. However as the proportion of hydrogen blending increases the production of large amounts of H2O gives an overall lower temperature. On the other hand the temperature distribution is more uniform. The concentrations of O2 and CO in the upper part of the furnace increased. The current air distribution pattern cannot satisfy the adequate combustion of the fuel after hydrogen blending.

High-pressure hydrogen tanks which are composed of an aluminum alloy liner and a carbon fiber wound layer are currently the most popular means to store hydrogen on vehicles. Nevertheless the aluminum alloy is easily affected by high-pressure hydrogen which leads to the appearance of hydrogen embrittlement (HE). Serious HE of hydrogen tank represents a huge dangers to the safety of vehicles and passengers. It is critical and timely to outline the mainstream approach and point out potential avenues for further investigation of HE. An analysis including the mechanism (including hydrogen-enhanced local plasticity model hydrogen-enhanced decohesion mechanism and hydrogen pressure theory) the detection (including slow strain rate test linearly increasing stress test and so on) and methods for the prevention of HE on aluminum alloys of hydrogen vehicles (such as coating) are systematically presented in this work. Moreover the entire experimental detection procedures for HE are expounded. Ultimately the prevention measures are discussed in detail. It is believed that further prevention measures will rely on the integration of multiple prevention methods. Successfully solving this problem is of great significance to reduce the risk of failure of hydrogen storage tanks and improve the reliability of aluminum alloys for engineering applications in various industries including automotive and aerospace.