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As the global shipping industry experiences rapid expansion, the imperative to address greenhouse gas emissions and environmental impact becomes increasingly paramount. Hydrogen has emerged as a pivotal and eco-friendly energy source, offering a pathway towards carbon neutrality and a complete zero-carbon transition in maritime operations. However, the widespread adoption of hydrogen-powered ships hinges on the establishment of robust regulations and technical standards. This paper conducts a comprehensive examination of hydrogen fuel cell (FC) technology in ships, scrutinizing the role of international classification societies and exploring existing standards and regulations within the maritime industry, specifically centered around hydrogen energy. The study outlines a strategic developmental roadmap for a green shipping hydrogen energy system tailored for hydrogen FC-powered ships in China. Emphasizing the differences in hydrogen application between fuel cell vehicles and ships, the paper elucidates technical challenges unique to hydrogen FC-powered ships. Furthermore, it proposes a visionary framework for future technical standards, advocating for the creation of a ship-based hydrogen energy standard system, the development of core technical standards, and a heightened focus on safety regulations. Through comprehensive analysis and compelling argumentation on hydrogen fuel cell ship technology and standards, this paper underscores the indispensable role that technical standards play in propelling the advancement of environmentally friendly shipping. Beyond serving as an informative resource, the paper aims to provide valuable guidance and direction for the future demonstration, application, and promotion of hydrogen fuel cell ship technology. Ultimately, it underscores the pivotal role of technical standards in advancing sustainable maritime transportation. • Analyze hydrogen energy technical standards from the production, storage, safety. • Comparison of hydrogen energy technical differences between vehicles and ships. • Outline the unique challenges of applying hydrogen technology to ship operations. • Constructed a technical standard framework for future hydrogen energy ships. [ABSTRACT FROM AUTHOR]

In order to meet the hydrogen refueling demand of fuel cell vehicles and reduce the cost of HRS operation process, it is necessary to study the hydrogen refueling process of cascade hydrogen storage system of hydrogen refueling station. In this paper, a thermodynamic model of the hydrogen refueling process for fuel cell vehicles is established, and the effect of the variation of these thermodynamic parameters on the specific energy consumption and utilization rate of the hydrogen refueling process is investigated in terms of the pressure ratio and capacity of the hydrogen storage tank, which is the core of the hydrogen refueling station, consisting of multiple hydrogen storage tanks. The results show that the specific energy consumption and hydrogen utilization of the hydrogen refueling station decreases as the ratio of the nominal pressure of the medium-pressure stage to the nominal pressure of the high-pressure stage increases over the course of the pressure ratio change. In addition, the capacity variation is only slightly changed as a result of the pressure ratio variation. Therefore, the lowest ratio of specific energy consumption can be found by fixing the utilization rate and by changing the pressure ratio. For example, in this paper, if the total mass of hydrogen in the station is 600 kg and the hydrogen utilization rate is required to be not less than 12 %, the optimal pressures for each level are 50.2 MPa, 65 MPa and 86.7 MPa. • A thermodynamic model of the hydrogen filling process for fuel cell vehicles is established. • The pressure ratio and capacity of cascade hydrogen storage systems were analyzed. • Specific energy consumption and hydrogen utilization are used as evaluation indicators. • The optimal pressures for each level are 50.2 MPa, 65 MPa and 86.7 MPa. [ABSTRACT FROM AUTHOR]

This paper proposes a novel energy management strategy satisfying real-time and highly efficient energy management strategies for fuel cell hybrid electric vehicles (FCHEVs). The strategy is based on model predictive control (MPC), which integrates long short-term memory (LSTM) and dynamic programming (DP). A high-precision powertrain model of the investigated FCHEV is established for subsequent simulations. After training under several typical working conditions, LSTM is designed to forecast future power demands of the entire vehicle. Using the prediction results, the DP algorithm calculates the control scheme based on model predictive control. Considering the economy and durability of power sources, the results of four different control strategies are compared: thermostat, power following, traditional DP, and MPC. The MPC proposed in this paper reduces the total usage cost per 100 km on the test set by 9%, 33.5%, and −4.6%. • The economy and durability of vehicular fuel cell system are both considered. • The LSTM neural network is imported into MPC theory for vehicular power prediction. • The key parameters of MPC and LSTM are determined by referring to the greedy algorithm. • The computational load in MPC optimisation is reduced by simplifying DP algorithm. • The real-time performance of the supposed EMS on-board is validated. [ABSTRACT FROM AUTHOR]

This paper precisely estimates the looming demand for hydrogen within the transportation sector, spanning 14 pivotal G20 nations from 2022 to 2050, anchored in the global vehicle hydrogen market penetration rate. Employing a robust techno-economic modeling methodology and leveraging Geographic Information System (GIS) for enriched visualization, it unveils distinct environmental dividends across three thoughtfully devised scenarios: Business- as -Usual, Moderate, and Aggressive. Findings herald India and China as pinnacles of hydrogen demand, with South Korea and Japan tailing closely. The study forecasts the energy consumption for solar hydrogen production in G20 countries to oscillate between 3.02 and 2.89 million GWh in 2022, while production costs are anticipated to range from $8.47/kg to $10.01/kg. In an assertive scenario, the paper illuminates a pathway towards achieving a significant CO 2 reduction, unmasking environmental savings of up to a staggering 48%, equivalent to 1.5 million mtCO 2 , by 2050. [Display omitted] • Hydrogen demand of G20 countries is analyzed using GIS and techno-economic models. • The projected adoption rates of hydrogen vary among the G20 countries. • Solar energy is crucial in determining each region's annual energy demand. • China, US, and India have the highest solar potential throughout the year. • The environmental analysis shows 850–1.5 million mtCO2 total emissions by 2050. [ABSTRACT FROM AUTHOR]

Energy and transport are the two largest contributors to carbon emissions. In recent years, the transport sector has made strides in reducing its carbon footprint by producing electric vehicles that emit zero carbon. This paper investigates the use of Fuel Cell Electric Vehicles (FCEVs) with a newly developed regenerative suspension module (RSM). The RSM uses an electromechanical mechanism to obtain regenerative electrical energy from the engine and is mounted to the passive suspension system. To determine the potential energy savings of the RSM module, a hydrogen fuel cell electric vehicle simulated under specific road geometries, speeds, and acceleration conditions. The simulation results indicate that the Regenerative Suspension Modules (RSM) mounted on each wheel of the FCEV generate 2.5 times more energy than the regenerative braking system. This result is evaluated as an increase in efficiency and range in electric vehicles. • This study aimed to investigate efficiency gains from adding an RSM to hydrogen fuel cell electric vehicles. • This is the first study in literature to integrate RSM into a Fuel Cell Electric Vehicle. • The charging efficiency of the FCEV is improved by the Regenerative Suspension Modules mounted on each wheel. • The FCEV's Regenerative Suspension Module mounted on each wheel generates 2.5 times more energy than regenerative braking. [ABSTRACT FROM AUTHOR]

Safety issues such as unintentional hydrogen releases in confined spaces limit the widespread promotion of hydrogen terminal applications, especially hydrogen fuel cell vehicles (HFCVs). This paper aims to perform a systematical numerical investigation of hydrogen leakage and dispersion in a full-scale underground garage, and the effects of smoke barriers are also considered. Four sets of smoke barriers with different heights, 0.1–0.7 m with 0.2 m increment, are installed below the ceiling, and three different partition types are set. The results show that smoke barriers can reduce flammable areas but increase local hydrogen concentrations. As the height of the smoke barrier increases, its obstruction to hydrogen dispersion on the ceiling is enhanced, making it easier for hydrogen to accumulate in the area and increasing the hydrogen cloud thickness. The hydrogen concentration in the horizontal direction showed a stair-like stratification phenomenon and decreased with increasing horizontal distance from the leak point. When the height of the smoke barrier is below 0.7 m, a larger partition area is safer. This study can provide new insights into the accidental hydrogen leakage and dispersion issues in confined spaces, in particular the effects of smoke barriers, and lay a theoretical foundation for the safety design of enclosed garages for HFCVs. [Display omitted] • Typical H 2 dispersion in a full-scale underground garage is numerical investigated. • Effects of smoke barriers on hydrogen dispersion is studied. • Smoke barriers can reduce flammable areas but increase local hydrogen concentrations. • Higher smoke barriers result in thicker flammable hydrogen clouds. • Larger partition area is found to be safer for 0.5 m barrier height. [ABSTRACT FROM AUTHOR]

With the development of hydrogen fuel cell vehicles, hydrogen refuelling stations are required to operate at a higher pressure. However, the safety issue of high pressure hydrogen is always considered as the barrier of the wide application of such transportation infrastructures. In this paper, the safety evaluation is performed on a 70 MPa hydrogen dispenser, as one of the most vulnerable equipment to safety events in hydrogen refuelling stations. The numerical simulations are conducted for the hydrogen leakage and combustion for the prototype of the dispenser. The results show the high radiation during the combustion, and the environmental wind can reduce it by promoting the diffusion of hydrogen. Accordingly, the lethal ranges in different cases are manifested by radiation heat flux at the concerned height for the safety of humans. Furthermore, an improved design of the hydrogen dispenser is proposed to cancel the lower ventilation holes based on the analysis. As a result, the radiation heat fluxes due to the hydrogen combustion after leakage is significantly reduced and consequently lead to smaller lethal ranges, indicating the enhanced safety performance of the hydrogen dispenser. • A numerical study is conducted for the hydrogen combustion from a 70 MPa hydrogen dispenser. • The safety distance is evaluated for hydrogen leakage and combustion of dispensers under different wind conditions. • An improved design of the hydrogen dispenser is proposed and proved to be effective in enhancing the safety performance. [ABSTRACT FROM AUTHOR]

The proliferation of hydrogen fuel cell vehicles calls for effective planning of hydrogen supply facilities. This paper focuses on renewable energy-based distributed hydrogen supply networks (DHSNs), with on-site production and vehicle-based transport. To explore the energy synergism effect, we propose multinetwork constrained planning of hydrogen-power supplying facilities. Considering the double-layer coupling mechanism (DCM), multiple DHSN equipment planning is coordinated with the generation planning of the power distributed networks (PDN). Firstly, the DCM is proposed considering structured multi-component equipment, inter-layer hydrogen couplings, and cross-network power couplings. Secondly, to formulate the DCM, we develop a structured deployment model for DHSN equipment to enhance system integrality and non-redundancy. Specially, to release more flexibilities, inter-layer transport is modeled by proposing a spatiotemporal extended vehicle routing problem model incorporating multiple loading stations with trip coordination. Thirdly, a planning method is proposed to coordinate the planning of hydrogen-power supply facilities in coupled networks, incorporating the double-layer coupling constraints, station operation constraints, and PDN constraints. Test systems are employed to verify the effectiveness of the proposed method. • The double-layer coupling mechanism is proposed for distributed hydrogen supply network (DHSN) and power distribution network. • A structured deployment model is proposed for the DHSN equipment. • Inter-layer hydrogen transport is modeled by extended vehicle routing. • A coordinated planning method is established for the distributed generators and DHSN facilities. [ABSTRACT FROM AUTHOR]

Modern energy systems are large distributed systems and, as a rule, contain energy storage systems and, in particular, hydrogen batteries and hydrogen production systems. The use of hydrogen for energy transportation has recently been actively studied in a number of scientific projects. To ensure continuous operation of instrumentation and control equipment on long hydrogen pipelines (gas and cryogenic), it is important to ensure constant autonomous power supply to these systems. This can be solved using micromechanical energy microgeneration systems for the uninterrupted operation of various sensors, which are installed in large numbers on almost all elements of the structure and infrastructure. In addition, an important area of scientific research is the revision of the concepts and appearance of traditional devices of modern renewable energy: windmills, solar cells, turbines, etc. Fundamentally new energy devices are on the agenda, capable of recovering mechanical energy of any power and supplying it to the consumer in the form of a given specific energy flow. Collection of chaotically distributed natural energy of the environment (mechanical energy in the form of: vibrations, acoustic vibrations, wave energy, gusts of wind, tornadoes, precipitation, vibrations of the earth's crust, etc.), as well as collection of dissipated energy from artificial sources (iron and automobile highways, airstrips, spaceports, production facilities, etc.) with the help of mechanical microgenerators will allow the recovery and conversion of mechanical energy of various powers, including low power, into a universal energy carrier - hydrogen. Mechanical vibrations of artificial origin are of particular interest due to their widespread use for domestic and industrial purposes in a wide range of vibrations. The energy of mechanical vibrations can be collected and converted into electrical energy using piezoelectric, electromagnetic, triboelectric or electrostatic (capacitive) energy converters. Electrostatic microelectromechanical energy converters are considered the most promising among other energy converters, since their manufacturing processes are based on standard technology for the production of integrated circuits and microelectromechanical systems. Energy conversion by an electrostatic converter is carried out due to an external mechanical force that does work against the force of attraction of the charged electrodes of a variable capacitor. To transfer the received electrical energy to the load of the consuming device, the electrostatic converter is connected to the corresponding electrical circuits (conditioning circuits). Such a system as a whole is a kind of microgenerator or energy collector. Microenergy flow recovery systems integrated into large energy systems will ensure the collection and recovery of significant amounts of energy for remote energy consumers. At the same time, the concept of a distributed mechanical energy recovery system is quite simple: a mechanical energy receiver - a converter into electrical energy - a preliminary electrical storage device - an energy distributor - an electric energy accumulator - an electrolyser - a hydrogen accumulator - a fuel cell. To optimize the operation of the working circuit, including preliminary electrical systems for energy storage and conversion: capacitors and electric energy accumulators, electrolyzers; To ensure their durability and reliability, flexible automatic control of electrical power distribution is necessary. The real work was done to solve that problem. In addition, for extended and large power facilities it is important to ensure widespread sensory control of system parameters. At the same time, if all sensors receive power from an autonomous energy-generating device, then the costs of creating extended communications for instrumentation will be sharply reduced. In addition, the reliability of the control system will significantly increase. The results of studying operation features of a kinetic microgenerator with reduced output voltage are presented. The performance of a multi-stage modified Bennet doubler is compared to a system including a two-stage modified Bennet doubler and a diode-capacitor voltage divider. It is shown that with an increase of the number of stages in the modified Bennet doubler, the conversion of mechanical energy into electrical energy becomes less and less efficient. At the same time, for achieving the maximum energy accumulation rate (power), a two-stage power amplifier based on the Bennet doubler is preferable. It is established that when analyzing the operation of a diode-capacitor voltage divider, it is necessary to take into account the intrinsic (reverse) capacitances of the discharging diodes affecting the divider operation significantly. The divider behavior features while changing the load resistance and the intrinsic capacitances of the discharge diodes are found and analyzed. Analytical expressions linking the main characteristics of the microgenerator as a whole with the parameters of the electronic components used are derived. It is shown that for expanding the range of the "correct" division of the divider, it is necessary to use discharge diodes with minimal intrinsic capacitances, and also that connecting a load to the Bennet doubler as a voltage divider changes the permissible capacitance modulation depth of the variable capacitor. This paper examines the concepts of creating large energy-generating flows based on arrays of micromechanical energy converters placed on optimal energy-efficient receiving surfaces and analyzes the issues of cryogenic production, storage, consumption and transportation of hydrogen. Stationary and mobile cryogenic storage systems for hydrogen are considered. Much attention is paid to the safety of large cryogenic and gas hydrogen systems. [ABSTRACT FROM AUTHOR]

Hydrogen is considered as a promising fuel in the 21st century due to zero tailpipe CO 2 emissions from hydrogen-powered vehicles. The use of hydrogen as fuel in vehicles can play an important role in decarbonising the transport sector and achieving net-zero emissions targets. However, there exist several issues related to hydrogen production, efficient hydrogen storage system and transport and refuelling infrastructure, where the current research is focussing on. This study critically reviews and analyses the recent technological advancements of hydrogen production, storage and distribution technologies along with their cost and associated greenhouse gas emissions. This paper also comprehensively discusses the hydrogen refuelling methods, identifies issues associated with fast refuelling and explores the control strategies. Additionally, it explains various standard protocols in relation to safe and efficient refuelling, analyses economic aspects and presents the recent technological advancements related to refuelling infrastructure. This study suggests that the production cost of hydrogen significantly varies from one technology to others. The current hydrogen production cost from fossil sources using the most established technologies were estimated at about $0.8–$3.5/kg H 2 , depending on the country of production. The underground storage technology exhibited the lowest storage cost, followed by compressed hydrogen and liquid hydrogen storage. The levelised cost of the refuelling station was reported to be about $1.5–$8/kg H 2 , depending on the station's capacity and country. Using portable refuelling stations were identified as a promising option in many countries for small fleet size low-to-medium duty vehicles. Following the current research progresses, this paper in the end identifies knowledge gaps and thereby presents future research directions. • Technological advancements of hydrogen production, storage and transport are reviewed. • Emissions and economic aspects of production, storage, transport and fuelling are analysed. • Refuelling protocols, temperature rise issue and its control strategies are discussed. • Recent progress of mobile hydrogen refueller is explored. • Challenges of hydrogen production to fuelling and future research directions are presented. [ABSTRACT FROM AUTHOR]

Fuel cell hybrid electric vehicles (FCHEV) are one of the most promising new energy vehicles. The cost and lifetime of its powertrain have limited its commercial development. This paper proposed an energy management strategy based on nonlinear model predictive control (NMPC) technology to solve the economy and durability problem of FCHEVs. Based on Markov Monte Carlo(MCMC) method, a prediction model of multi-scale operating conditions is established, and dynamic programming(DP) is used to realize the optimal control in the predicted time domain. The "constant speed prediction" is innovatively adopted in the transition stage to improve the prediction accuracy and enable the model to be realized online. The ways to reduce calculating amount of NMPC are also discussed in this paper. This simplification leads to suboptimal fuel economy and durability of control system but can have obvious reduction in calculating time. The simulation results show that, compared with the thermostat strategy and the power following strategy, the degradation cost decrease of 11.1% and 23.9% and the total operation cost of NMPC decrease of 11.0% and 23.5% respectively. The NMPC strategy has better economy and durability than the rule-based energy management strategy, is close to the global optimal result obtained by dynamic programming and can meet the requirements of real-time control. • The economy and durability of vehicular fuel cell system are both considered. • Markov Chain Monte Carlo is imported into MPC theory for vehicular power prediction. • Adaptability to changing conditions is strengthened via "constant speed prediction". • The computational load in MPC optimization is reduced by simplifying DP algorithm. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cell vehicles (HFCVs), as an important strategic path for global sustainable development and energy transition, have now become an important support for the global energy and transportation sectors. The United Kingdom, Japan, the United States, China, and other countries are vigorously developing HFCVs and increasing the construction of hydrogen stations. Before HFCVs enter the stage of rapid commercialization and development, it is necessary to investigate the factors that influence consumer HFCV adoption. In this paper, meta-analysis used 24 pieces of literature to include in a systematic evaluation of the existing research on the factors that influence consumer willingness to purchase HFCVs, setting influencing factors as the dependent variable, to clarify the specific roles of different influencing factors and to address the problem of mixed and contradictory findings in the literature. The results of the study show that: (1) The influence of gender and age on consumer willingness to purchase HFCVs cannot be judged. (2) Education, individual income, household income, family car number, driving range, knowledge, fuel availability, hydrogen refueling station density, environmental impact, policy incentives and attitudes all have a positive effect on HFCV adoption. (3) Household size, purchase price, fuel cost, maintenance cost and refueling time have a negative effect on HFCV adoption. (4) The purchase price, knowledge, fueling time, hydrogen refueling station density, and policy incentives significantly influence HFCV adoption. This paper provides new research methods and perspectives for the HFCV field and presents theoretical references for future governmental promotion of HFCV. • Meta-analysis of 24 studies conducted for consumers' intention to purchase HFCVs. • Subgroup analysis provides evidence of heterogeneity among estimates. • Household size and the other 4 influencing factors inhibit HFCV adoption. • Education and the other 9 influencing factors promote HFCV adoption. • The purchase price and other 4 influencing factors significantly influence HFCV adoption. [ABSTRACT FROM AUTHOR]

Explosion and deflagration may occur when a fuel cell truck in driving has hydrogen leakage faults, and the complex and changeable operating conditions of the vehicle are incredibly unfavorable for fault diagnosis. Therefore, to provide real-time diagnosis on the hydrogen supply system of driving truck, a diagnosis method of hydrogen leakage faults classification based on data-driven in this paper. The faults are divided into 3 levels using the K-means algorithm, and 4 features are selected as the hydrogen leakage faults diagnosis indicators. The Principal Component Analysis (PCA) method is used to reduce the dimensions of the data, while Support Vector Machine (SVM) is used for hydrogen leakage faults diagnosis. Meanwhile, the kernel parameter σ and the penalty factor C of SVM are optimized by Sparrow Search Algorithm (SSA) to improve diagnostic accuracy. The results show that the diagnostic accuracy of the SSA-PCA-SVM method proposed in this paper is higher than that of the ordinary SVM and PCA-SVM diagnosis methods when σ = 9.79, C = 7.89, which is over 97 %. • A classification diagnostic method is proposed for hydrogen leakage faults. • The diagnostic method can perform real-time faults diagnosis for driving truck. • The fault diagnosis accuracy of the proposed SSA-PCA-SVM method exceeds 97 %. [ABSTRACT FROM AUTHOR]

Schedule maintenance activities for hydrogen fuel cell vehicles are aimed to keep them in better condition in long-term operation. In this paper, we develop a reinforcement learning based schedule maintenance strategy, which is used to comprehensively consider the balance between safety and maintenance cost, so as to find the optimal maintenance strategy. A multi-level framework is established with remaining useful life of key components, fault tree analysis, and logistics cost model to generate an exploration environment that can express the operational stability, the failure rate of components, and the cost of repair and storage. The trained agent combines a deep neural network to explore the optimal strategy under the dynamic reliability of key components. Finite steps are the constraints. Safety rates, maintenance cost, and episode of operation are incorporated into a multi-objective reward function. The hydrogen supply circuit of fuel cell vehicle is simulated via Python. The trained agent is compared with traditional time-based schedule maintenance strategy and corrective maintenance strategy. The results show that the reinforcement learning based schedule maintenance agent has optimized the total reward, cost control and accident rate by 77%, 59% and 5%, respectively, compared with the traditional time-based schedule maintenance strategy. In the safe operation management of fuel cell vehicles, efficient and stable decision-making ability has been achieved. • An adaptive maintenance strategy of deep reinforcement learning is proposed. • An exploration environment of FCV is established. • The deep Q network is proposed to solve the maintenance problem. • The efficient and stable decision-making ability is much better than time-based scheduled maintenance strategy. [ABSTRACT FROM AUTHOR]

The damage to the sealing rings of high-pressure hydrogen valves caused by extreme environmental temperatures, leading to minor hydrogen leakage, is a significant issue in the field of hydrogen safety. However, current understanding is still limited regarding the initial leakage of hydrogen through damaged gaps in sealing rings. This paper aims to explore the distribution of hydrogen leakage in sealing rings with various-shaped damage gaps under extreme environmental temperatures. Firstly, the real damage gaps of the sealing rings are obtained on an extreme temperature experimental platform. Then, a coupled hydrogen leakage model is established, which calculates the viscosity of hydrogen in real-time as temperature changes. Based on these models, the concentration, temperature, and velocity distribution of hydrogen within the sealing ring gaps under extreme environmental temperatures are studied. The results indicate that the high-pressure hydrogen within the gaps, influenced by viscosity and wall adhesion effects, tends to diffuse along the wall surfaces. The high-temperature zone along the edge lines of the gaps lasts longer than that on the centerline. Under extreme high temperature conditions, the average velocity at the inlet and outlet of the gap is 21.6% higher than under extreme low temperatures. • The actual damaged gaps of sealing rings under extreme temperatures are extracted. • A coupled hydrogen leakage model incorporating viscosity variations is developed. • Minor leakage behavior in damaged gaps at extreme temperatures is explored. [ABSTRACT FROM AUTHOR]

Facing an increasingly hostile ecological environment, the imperative for advancing hydrogen fuel cell vehicles has become more pronounced. This paper establishes a three-dimensional computational fluid dynamics model of a Roots-type hydrogen circulating pump by utilizing the generalized type line equation of the Roots rotor. Delving deep into the intricate interplay of backflow phenomena on the internal flow dynamics and operational efficiency of the Roots-type hydrogen circulation pump across various scenarios. The results reveal that mass flow rate and velocity vary continuously and with the same pulsation frequency as rotation angle or time during a complete rotation cycle. As the rotational speed increases, the number of backflow occurrences decreases, the frequency of backflow currents in the rotor basin decreases, and the temperature rise in both the suction and exhaust chambers decreases. It becomes evident that the rotational speed wields a more profound influence on the Roots pump's performance than temperature: the volumetric and isentropic efficiencies of the Roots-type hydrogen circulating pump decrease by 3.5% and 4.6%, respectively, with increasing temperature, while the volumetric and isentropic efficiencies of the pump increase by 32.6% and 24.0%, respectively, with increasing rotational speed. • The numerical simulation of hydrogen circulation pump using dynamic mesh technique. • Focus on the occurrence and impacts of backflow of hydrogen circulation pumps. • The influence of backflow on internal flow characteristics at different speeds and temperatures. • The general link between return frequency and flow pulsation is discussed in detail. [ABSTRACT FROM AUTHOR]

This study presents a hybrid power system comprising a fuel cell (FC) and a lithium-ion battery (LIB) for liquid hydrogen (LH 2) carriers, which is expected to increase globally due to the production cost gap of green hydrogen between renewable-rich and renewable-poor countries. The LH 2 carrier has a key challenge in handling the inevitably considerable boil-off hydrogen (BOH). As a target ship of a 50,000 m3 LH 2 carrier with a boil-off rate (BOR) of 0.4% per day, this study employs an optimization tool to determine the economic power dispatch between the FC and LIB aimed at minimizing the lifetime cost of the ship. The BOH is used as fuel for FC during the voyage. Moreover, when the ship is under cargo loading and unloading operations at the port, the considerable surplus BOH is utilized to generate electricity and then sold to the shore grid (StG). The results indicate that 45.2% of the BOH can be utilized as fuel for the FC, and the StG system can effectively reduce the total lifetime cost by 32.0%. Further, the paper presents the outcomes of a sensitivity analysis conducted on critical parameters. This study provides new insights into the BOH issue of LH 2 carriers and helps to increase the international green hydrogen market. [Display omitted] • An economic power dispatch of an FC-LIB hybrid system was proposed for LH 2 carriers. • A new proposal of ship-to-shore grid (StG) was proposed to reduce the BOH at ports. • About 45.2% of BOH can be reused as ship fuel through the optimal power dispatch. • The StG profit can reduce the ship's total lifetime cost by about 32.0%. [ABSTRACT FROM AUTHOR]

In this paper, the mechanism of proton exchange membrane fuel cell (PEMFC) cathode cycling is discussed and the high potential suppression control problem for fuel cell vehicles is investigated by using cathode cycling. Firstly, a rigorous single-cell experimental investigation is performed to reveal the impact mechanism of cathode recirculation on the internal polarization processes of PEMFC. Results show that an increase in the recirculation ratio leads to an increase in the polarization impedance in the low and medium frequency regions but decreases the ohmic impedance. Consequently, when the recirculation ratio increases to 1, the voltage drop rates are 2.2%, 3%, 4.6%, 5.8%, and 7% as the current density varies from 0 to 0.2 A/cm2, respectively, and the ohmic impedance decreases by 28.1%. On the basis, the optimal control scheme for high potential suppression based on cathode circulation in vehicular PEMFC system is proposed. The performance comparison of different control method is carried out on a software-in-the-loop testing platform. The results show that, for the same control objective, the model predictive control (T-S MPC) method is 55.5% and 16.7% lower than the proportional integral (PI) controller and the Takagi-Sugeno linear quadratic Gaussian (T-S LQG) in terms of controller input cost. On the contrary, the cumulative error of voltage tracking is reduced by 62% and 30.4% and the voltage response against disturbances is improved by 9.7% and 42.8%. Overall, the T-S MPC achieves the optimal control effect with less control effort. • An insight into the mechanism of cathode recirculation affecting PEMFC performance. • Cathode recirculation reduces ORR reaction rate and oxygen diffusion rate. • The T-S MPC provides optimal closed-loop control of high potential suppression. [ABSTRACT FROM AUTHOR]

Precooling gaseous hydrogen fuel to a cold temperature before refueling a heavy-duty (HD) hydrogen fuel cell electric vehicle (HFCEV) is essential to avoid overheating the vehicle tank, as well as achieving a high state of charge (SOC). Because a large volume of hydrogen is dispensed during each fill, the need for a shorter fill time amplifies the need to precool each load for refueling a HFCEV. Thus, the design and operation of a precooling unit (PCU), as well as the associated capital and operating costs, plays a pivotal role in any plans for heavy-duty hydrogen refueling stations. In this paper, we present a thermodynamic and technoeconomic analysis of a PCU in a gaseous hydrogen refueling station (HRS) for HD HFCEVs. By employing Argonne National Laboratory's hydrogen station cost optimization and performance evaluation (H2SCOPE) model, the refueling of 50 kg of hydrogen on-board type IV tank at ambient temperatures of 15–45 °C and varying fill rates is simulated. The required degree of precooling temperature to obtain either 100% or the maximum possible SOC is obtained from the simulation. Additionally, the simulation results demonstrate that the average flow rate of hydrogen is approximately 40% lower than the maximum flow rate during a typical fill; which motivates further evaluation of the instantaneous hydrogen mass flow rate profile and suggests the scope of improving precooling unit design. Accordingly, a hybrid strategy of precooling hydrogen has been proposed to address the cooling load by sizing the refrigeration unit for the average flow rate of hydrogen, while supplementing the above average peak hydrogen flow cooling load through thermal buffering. The combined technique enables the downsizing of the original PCU capacity by 25–40% and demonstrates a potential cost reduction of the PCU by approximately 30%, which translates to an installed cost reduction of ∼$125,000 per dispenser. • Hydrogen fill rate during refueling has a strong influence on the precooling load. • Bell-shaped profile of the fill rate advises a scope of improving precooling. • Hybrid strategy of on-demand cooling aided with partial thermal buffer is proposed. • The hybrid precooling approach downsizes the refrigerator capacity by 25–40%. • A potential reduction in the capital cost of precooling unit is 30%. [ABSTRACT FROM AUTHOR]

The use of hydrogen fuel cell vehicles is an important way to achieve carbon emission reduction in China's commercial vehicle field. The development of the hydrogen automobile industry needs policy guidance. To determine the characteristics and effects of China's hydrogen automobile industrial policy, this paper first uses a text mining method to analyze policy characteristics from three aspects: potency rank, policy subject and policy objectives. Then, from the perspective of policy tools, a policy quantitative system and standards are constructed to quantify the policy. Then, the sales data of hydrogen fuel cell vehicles from August 2018 to December 2022 were collected to empirically analyze the effect of the policy. The results showed that policy comprehensiveness significantly promoted the use of hydrogen fuel cell vehicles, but the effects of the different policy tools differed. Finally, some policy suggestions are proposed for the development of the hydrogen automobile industry. • China's hydrogen vehicle industry policy focuses on technology upgrading and application demonstration. • The use of hydrogen fuel cell vehicles is the most concerned industrial chain link in the policy. • Policy comprehensiveness has a significant positive effect on the promotion of hydrogen fuel cell vehicles in China. • Different policy tools play different roles, with supply-based policy tools and demand-based playing a more prominent role. [ABSTRACT FROM AUTHOR]

Green hydrogen, produced from renewable electricity, can be transported long distances in multiple mediums. In this paper, a Techno-economic model is proposed to show the economic viability of global green hydrogen transport along 15 major regional routes such as Australia to Asia and Europe for the first time. A Monte Carlo-based technique is presented to assess the levelised cost of green hydrogen for different regions for the next 30 years. Depending on the specific route, green hydrogen can be transported in different forms, including ammonia, Liquid Organic Hydrogen Carrier (LOHC), Hydrogen Slush, compressed or liquefied hydrogen, etc. form and using different modes including shipping, truck, train, and pipeline. A linear programming analysis has been conducted for different regions, showing that among the global projected 300Mt of green hydrogen demand in 2050, 85% will need to be transported between regions to achieve the most economically optimal distribution. • Techno-economic analysis of green H 2 export via 15 worldwide regional trade routes. • Export model includes H2 generation, conversion, transport, and carbon prices. • In 2030, North America will be the largest exporter, followed by Australia. • Higher carbon prices allow for rapid growth in the green hydrogen industry. • Shipping is the most likely and cheapest H 2 export mode for distant transport. [ABSTRACT FROM AUTHOR]

This paper addresses the critical need for improving fuel cell electric vehicles (FCEVs) reliability to promote their commercialization. A physics-based observer that combines an Extended Kalman Filter (EKF) with a Sequential Probability Ratio Test (SPRT) has been employed to address two major failure modes in FCEV stacks: flooding and reduction of Electrochemical Active Surface Area (ECSA). Furthermore, the observer estimates the hidden states of a standard automotive airpath system to enable state-feedback control. Therefore, the proposed observer is a novel approach which holistically tackles three coupled problems (i.e., flooding, ECSA loss, and airpath state estimation) which are typically addressed individually. Additionally, the observer is computationally affordable and relies solely on typical vehicle sensors. The observer performance has been validated through simulations, testing various dynamic scenarios in the presence of flooding, ECSA loss failures, and sensors uncertainty. The estimation errors have been confined within a 3% error band for all test cases while the health indicators coherently responded in the presence of faults. • Electrochemical Active Surface Area (ECSA) tracking via parameters estimation. • Single observer supports flooding and ECSA loss detection, and state-feedback control. • Mean value plant model implementation with faults simulation capability. • Flooding detection through Sequential Probability Ratio Test algorithm. [Display omitted] [ABSTRACT FROM AUTHOR]

Neural Networks (NNs) can be used for energy management of hybrid vehicles, but they are hard to tune in inference to adapt to different driving conditions. To make the NN-based energy management strategy more flexible, this paper proposes a controllable NN for optimal energy management of fuel cell hybrid electric vehicles. Inspired by the equivalent factor in the Equivalent Consumption Minimization Strategy (ECMS), we introduce an adjustable target variable for the final state as an input to the NN-based strategy. During training, classification and regression networks with single-step and multi-step inputs are considered. An efficient shooting method and an adaptive method are then introduced to realize the precise control of the final state and online parameter adaptation. Simulations of the proposed method and the benchmarking method are carried out in different battery discharge modes. Results demonstrate that the proposed shooting neural classifier can achieve 99.7% fuel optimality of dynamic programming in a similar computational time to the shooting ECMS, and the proposed adaptive neural classifier can adapt to different driving conditions and has better fuel economy than the adaptive ECMS. • A controllable neural model for energy management of fuel cell vehicles is proposed. • Neural regressors and classifiers are trained under single-step and multi-step inputs. • A shooting method and an adaptive method for neural models are proposed. • The proposed method is comprehensively analyzed and compared with benchmarks. [ABSTRACT FROM AUTHOR]

Hydrogen storage cylinder is an important component in high-pressure gaseous hydrogen (HPGH 2) storage system, and plays a key role in hydrogen-powered transportation including land vehicles, ships and aircrafts. Over the past decade, the number of hydrogen fuel cell vehicles (HFCVs) has rapidly increased worldwide. In order to promote the application of hydrogen storage cylinder, guide its design, manufacture, inspection and testing, a series of regulations, codes and standards have been issued. The Chinese national standard, GB/T 42612, for type IV hydrogen storage cylinders has also been issued. This paper first gives a brief overview to these regulations, codes and standards. Furthermore, the specifications including scope, category, filling cycles, service life, materials, design, manufacture, qualification tests and periodic inspections are analyzed and compared. Issues about evaluation method for hydrogen compatibility of non-metallic materials, welded joints of plastic liner, joint between boss and liner are also discussed. Notably, the performance requirements in GB/T 42612 are generally in accordance with the international ones, but the requirements of materials, design and manufacture are more detailed. • The regulations, codes and standards for on-board high-pressure hydrogen storage cylinders are compared. • An in-depth analysis of scope, category, filling cycles, service life, materials, design, manufacture, etc. is provided. • The requirements for materials, design and manufacture in GB/T 42612 are more detailed than the others. • NDT methods for welded joints of plastic liner and joints between plastic liner and metal boss need to be developed. • Effective periodic inspection methods other than visual inspection need to be further researched. [ABSTRACT FROM AUTHOR]

Hydrogen is a versatile energy carrier and storage medium that is expected to have a key role in the energy transition, as it can be employed in a variety of applications. Hydrogen can be produced from different feedstocks and using different processes. Based on the production technology used, hydrogen is conventionally identified by a color. In this work, we compare different hydrogen generation processes: (i) green hydrogen, obtained by electrolysis of water using electricity from floating photovoltaic platforms, (ii) grid hydrogen, also obtained by electrolysis but using grid electricity, (iii) grey hydrogen, produced from natural gas using steam reforming and (iv) blue hydrogen, which is similar to grey hydrogen, but uses hot potassium carbonate as the solvent for carbon capture and storage. The paper considers the production of hydrogen necessary for 2 trips per day of a medium size ferryboat to navigate full electric for 7 h in the Adriatic Sea. Process simulation is applied to solve material and energy balances for each process investigated, as well as for the evaluation of capital and operating costs. Process simulation outcomes are then used to estimate three key performance indicators focused on energetic, economic, and environmental sustainability issues: the energy return on energy invested, the levelized cost of hydrogen, and the life cycle assessment. The energy indicator for grid and green hydrogen has a value of 13.39–14.29, versus a value of 4.59–5.48 for other hydrogen production methods from natural gas. The cost for green hydrogen is slightly higher (8.76) compared to the blue hydrogen (5.50) however green hydrogen has a much lower impact to the environment. Considering the combined results obtained by all the indicators, it is concluded that the most sustainable hydrogen production method is green hydrogen. • Process simulation provides data to design hydrogen production processes. • Green hydrogen has larger return of energy invested than natural gas-based routes. • Floating photovoltaic production is competitive for green hydrogen production. • Life cycle assessment shows excellent results for green hydrogen. • Indicators are evaluated for hydrogen use in the maritime industry. [ABSTRACT FROM AUTHOR]

Polymer-carbon composite bipolar plates (PCCBP) are accepted over graphite bipolar plates (BP) for their use in proton exchange membrane fuel cell (PEMFC), specially in hydrogen fuel cell-powered electric vehicles. This study developed a novel copper fiber-filled PCCBP with epoxy resin as the binder and natural flake graphite (NFG), carbon black (CB), and Cu fiber as filler materials. The fabrication is done by compression molding. Both electrical conductivity and flexural strength increased with the addition of Cu fiber. The composite BP fabricated with 8 vol % Cu fiber, 10 vol % CB, and 42 vol % NFG exhibited electrical conductivity of 169 S/cm, flexural strength of 43 MPa, thermal conductivity of 17 W m−1 K−1 and corrosion current density of 0.972 μA/cm2. The composite also showed acceptable results for contact angle, density and thermal stability tests. This research paper provides insights into further developments of the metal-based PCCBP. • Novel Cu fiber-filled composite bipolar plates were developed for PEM fuel cells. • Effect of content of epoxy resin, carbon black, and copper fiber was investigated. • Enhancement of electrical conductivity and flexural strength achieved concurrently. • Provides insights into future developments of the metal-based PCCBP. [ABSTRACT FROM AUTHOR]

Hydrogen refueling stations (HRSs) are crucial infrastructures for the advancement of hydrogen energy. To promote and construct HRSs, a cost-benefit analysis is essential. Factors such as hydrogen transportation, storage, production technology, and subsidy policies can impact the costs. This paper aims to analyze the economics of HRSs under four operation modes, ie., on-site hydrogen production, off-site production with pipeline transportation, off-site production with tube trailer, and off-site production with liquid hydrogen tanker. Two life-cycle analysis models, an annualized cost model for hydrogen transportation and a levelized cost model for HRSs, are established for economic assessment. The study reveals that hydrogen supply costs account for over 50% of the LCOH for off-site station, and power costs drive up the LCOH for on-site station. Among the four operation modes, off-site station with pipeline is most economical, and the cost advantage increases as pipeline capacity utilization rate reaches 100%, but decreases as it drops to 20%. off-site station with long tubes is economical within 300 km, and off-site station with liquid hydrogen tankers is more economical within 300km∼1,000 km. On-site hydrogen production by water electrolysis is not economical at a cost of 35.24 CNY/kg. The optimal operation scheme under different hydrogen source distances is proposed. • An annualized cost model for hydrogen transportation modes and A levelized cost model for HRSs were established. • The comprehensive costs analysis throughout the full life cycle was conducted in four different operation modes of HRSs. • The factors affecting HRS costs were analyzed in depth:hydrogen source distance, pipeline utilization, and cost structure. • On-site hydrogen production in integrated station is not yet economically feasible. [ABSTRACT FROM AUTHOR]

The joint consideration of hydrogen supply chain networks and electric power systems can promote hydrogen-fueled transportation and the penetration of renewable energy. This paper develops a low-carbon scheduling approach for an Integrated Hydrogen Transport and Energy System (IHTES). To reduce carbon emissions, the environmental cost from the hydrogen supply chain network and electric power system is jointly minimized with the operational cost of IHTES. To consider the timeliness of hydrogen deliveries, hydrogen transport via tube trailers is innovatively modeled as an extended vehicle routing problem with time windows, and delays are penalized. The scheduling problem is formulated as a mixed-integer linear programming problem so that it can be efficiently solved using the branch-and-cut method. Case studies illustrate and validate the proposed model, and demonstrate the computational efficiency of our approach. Carbon emissions are reduced by 47.8% when the emission cost is co-optimized with the operational cost. The operational cost of the hydrogen supply chain network is reduced by 7.3% when the timeliness of hydrogen deliveries is modeled. • Emission-operation optimization of Integrated Hydrogen Transport and Energy System. • The timeliness of hydrogen deliveries is modeled with delays penalized. • The scheduling problem is formulated as a mixed-integer linear programming problem. [ABSTRACT FROM AUTHOR]

Hydrogen, seen as a promising secondary renewable energy carrier, can becompressed or liquefied as well as chemically bound to enable a more economic storage and transportation. All conditioned hydrogen options obtain specific advantages and disadvantages. Thus, this paper assess the energy efficiency and the cost of a green hydrogen supply from well to tank exemplified for fuel cell heavy-duty vehicles in Germany related to the years 2030 and 2050. Therefore, compressed gaseous hydrogen, liquid hydrogen, liquid organic hydrogen carriers, methanol and ammonia are considered and different hydrogen production regions in North and Central Germany, as well as an import from Tunisia and Argentina (Patagonia) are assumed. The assessment shows that a hydrogen supply chain in its state of aggregation as finally demanded is the lowest cost option leading to 700 bar compressed gaseous hydrogen filling costs of 5 € 2020 /kg H2 in 2030 and 4 € 2020 /kg H2 in 2050 and liquid hydrogen filling costs around 7 € 2020 /kg H2 in 2030 and 6 € 2020 /kg H2 in 2050. • Well to tank analysis for a hydrogen supply of filling stations. • Gaseous hydrogen supply chains are the lowest cost options for gaseous filling. • Liquid hydrogen supply chains show the lowest supply costs for liquid filling. • LOHC obtain high supply costs, especially for long transportation distances. [ABSTRACT FROM AUTHOR]

This paper presents the development and implementation of a system supervisory controller in a hydrogen-based fuel cell electric vehicle. The controller's primary function is to ensure the safe control of the fuel cell system processes while facilitating coordination among various subsystems, including the balance of plant subsystems, vehicle control unit, diagnosis unit, and powertrain. The supervisory controller comprises of three primary parts: a State Machine, an Optimal Setpoint Generator, and a Power Limit Calculator. The State Machine, which serves as the central part of the supervisory controller, coordinates the fuel cell system's different operational states, including the complex processes of start-up and shutdown. To maximize the fuel cell system's efficiency and minimize the stack's degradation, the Optimal Setpoint Generator produces the subsystem's setpoints by solving an optimization problem and considering the manufacturer's requirements. The Power Limit Calculator assesses the stack's power output capability and calculates the current setpoint for the DC/DC converter. It then provides this data to the Energy Management System (EMS), which oversees the distribution of power between the fuel cell system and the batteries. The proposed fuel cell system supervisory controller is verified using the Worldwide Harmonized Light Vehicles Test Cycles (WLTC) in a real-world car. The designed control structure is implemented in a prototype hydrogen-based electric car at both PowerCell and CEVT facilities under the framework of the INN-BALANCE Horizon 2020 European project. • State machine-based supervisory controller for fuel cell system is designed. • The designed control structure is implemented in a prototype hydrogen-based vehicle. • The controller comprises: State Machine, Setpoint Generator, Power Limit Calculator. • The proposed control structure handles the startup and shutdown process of PEMFC. • Minimizing stack degradation by implementing a fuel cell power limit calculator. [ABSTRACT FROM AUTHOR]

In order to ensure the safety of hydrogen refueling systems and fuel cell vehicles under various filling conditions, the filling parameters are usually set very conservatively, leading to waste energy consumption and investment. The lumped parameter hydrogen gas model and one-dimension tank wall model of the hydrogen filling process previously proposed by our team were extended and improved to the entire hydrogen refueling system by considering the Joule-Thomson effect, kinetic energy and using a more accurate model of the heat transfer coefficients between the inner tank wall and hydrogen gas and between the outer tank wall and ambient. Based on our validated model, the effects of constant and two-stage average pressure ramp rates (APRRs) and precooling/inlet temperatures on refueling performances were investigated, respectively. Compared with the optimal filling strategy of the reference paper, where a constant APRR is the best, our two-stage APRRs can further reduce the cooling power for various inlet temperatures without increasing the cooling energy. For example, maximum cooling power can be reduced by 23.8% at the inlet temperature of −20 °C. Compared with the previous research result obtained using a constant inlet temperature solved by the analytical solution, the two-stage inlet temperatures can further reduce the cooling power by 16.3% at an APRR of 0.428 MPa/s without increasing the cooling energy. • A thermodynamic model for a hydrogen refueling system is improved and well validated. • Joule-Thomson effect, kinetic energy and accurate heat transfer model are considered. • Effects of two-stage average pressure ramp rates and inlet temperatures are studied. • Two-stage strategies can reduce cooling power without increasing cooling energy. [ABSTRACT FROM AUTHOR]

The article describes the method of synthesis of the simulation model of pulse converters with the control system, intended for implementation in FPGA. The technique is based on the structural representation of integro-differential and algebraic equations and the method of switching breaking functions. The models you develop allow you to bring modeling time closer to real. The method is described by an example of a solar battery energy conversion channel of an automatic spacecraft power supply system. The paper considers the possibility of implementing a solar-hydrogen energy supply scheme. This concept involves the accumulation of excess energy in the form of chemical energy on board the spacecraft. [ABSTRACT FROM AUTHOR]

The paper emphasizes the significance of sustainable energy solutions centered around electric vehicles (EVs). This involves Electric Intelligent Parking Lots (IPLs) that are interconnected with Renewable Energy Sources (RES) and Hydrogen Storage Systems (HSS) to achieve both technical and environmental goals. The study introduces a probabilistic approach to managing HSS-based energy in IPLs, employing the Probabilistic Two-Point Estimate Method (TPEM) to consider variables like sun radiation, temperature, wind speed, and IPL load. The Honey Badger Algorithm (HBA) is employed for optimization, striving to minimize operational costs related to energy distribution while maximizing profits by exploring revenue opportunities within the IPL system. This strategy enhances energy management and intelligent EV charging in IPLs, improving efficiency and economic viability. The approach is tested in a standard IPL environment integrated with RES and load demand, showcasing its successful technical and financial outcomes. Results reveal a 7.8 % profit increase from renewable resources and an additional 4.89 % when uncertainties are factored in. Ultimately, the proposed energy management framework utilizing HSS and RES integration proves effective in achieving objectives, with the potential for greater profitability through renewable resource incorporation and uncertainty consideration. • Optimal energy management framework proposed for electric vehicle integration in intelligent parking lots. • Simulation of efficient charging and discharging strategy in an IPL for electric vehicles. • Impact of renewable sources integration (wind and solar) on IPL efficiency and revenue generation. • Uncertainty analysis of renewable sources and load demands in IPL using two-point estimation method. • Smart integration of renewable sources, hydrogen storage, and electric vehicle charging for optimal operation of IPL. [ABSTRACT FROM AUTHOR]

The hydrogen pump is an important component in the hydrogen circulation system of fuel cells. Excessive pulsation at the outlet of the pump is challenging when the Roots hydrogen pump is used, which has a negative impact on the operation performance. To reduce the impact of excessive fluctuations in the hydrogen circulation system, a new structure of reflow grooves is proposed in this paper, which connects the different chambers and adjusts the pressure using a diversion method. The internal flow of the two pumps was studied for comparison, using a three-dimensional simulation model established by Computational Fluid Dynamics (CFD) method. Results showed that the reflow grooves reduce the exhaust pressure and mass flow pulsations, which has a positive effect on the pressure stabilization of the hydrogen circulation system and the anode inlet pressure of the fuel cell stack, contributing to the long durability and stability of the fuel cell stack. [Display omitted] • A novel reflow structure is proposed for the Roots hydrogen pump. • The internal flow of the pump is simulated by the dynamic grid method. • The gas pressure variation in one compression in the Roots pump was analysed. • The reductions in flow fluctuations at different rotational speeds are compared. • Pressure fluctuation is supressed at high rotation speed by the reflow structure. [ABSTRACT FROM AUTHOR]

Encountering complex traffic conditions such as the dynamic interference of preceding and rear vehicles and gradients, a control strategy that simultaneously considers inter-vehicle cooperative control and energy economy is one of the key technologies, that improves traffic efficiency and exploits the energy-saving potential of platoon vehicles. In this paper, a hierarchical optimization control strategy is proposed for the intelligent fuel cell hybrid electric vehicles (FCHEV) platoon in a network-connected environment. The hierarchical control framework consists of upper speed control and lower power distribution. In the upper layer, the improved particle swarm optimization (PSO) algorithm is applied to calculate the global optimal speed trajectory, and then the model predictive control (MPC) is adopted for global speed trajectory tracking and self-adaptation, which can ensure the ego vehicle tracks the pre-calculated speed trajectory, and can re-plan the vehicle speed under the condition of safety priority when sudden disturbances occur in the foreground. The lower layer utilizes Q-learning (QL) to achieve power distribution between hybrid power sources, reducing the number of fuel cell starts and stops, slowing battery degradation and improving vehicle economy. Simulation results based on complex road conditions show that the proposed controller has good energy economy and tracking performance. Under the condition of the slope, the total platoon cost of the proposed strategy is reduced by 3.99% compared with the constant speed cruise strategy, and under the interference condition, the total platoon consumption cost of the proposed strategy decreased by 6.79% compared with adaptive cruise control (ACC). • A hierarchical strategy of IFCHEV platoon in complex conditions is proposed. • Speed planning is conducted using offline optimization with real-time adjustment. • Online adjustment adopts fixed headway to ensure platoon stability and safety. • Complex working conditions are considered to guarantee strategy adaptability. [ABSTRACT FROM AUTHOR]

The development of sustainable energy sources has become a major challenge for society. Green hydrogen, produced through the electrolysis of water using renewable energy sources, offers a potential solution to reducing our dependence on fossil fuels. The paper examines the integration of green hydrogen into various sectors, such as transportation, industry, power generation, and heating, highlighting its potential to decarbonize traditionally carbon-intensive areas. Furthermore, it analyses the strategies and policies employed by the European Union, Australia, Japan, the United States, and Canada to drive the development and adoption of green hydrogen technologies. The challenges and barriers that need to be addressed to fully realize the potential of green hydrogen, such as technological limitations, infrastructure development, costs and economic feasibility, regulatory and policy frameworks, and public perception and acceptance, have been investigated. Recommendations for overcoming these challenges and accelerating the adoption of green hydrogen technologies are provided, and the importance of research and development in this sector is emphasized. • Green hydrogen offers a sustainable solution to reduce fossil fuel dependency, decarbonizing key sectors. • Analyzed policies from the EU, Australia, Japan, the US, and Canada to foster green hydrogen technologies. • Discussing challenges: green hydrogen potential, tech limits, infrastructure, costs, regs, and public views. • Emphasized the importance of R&D and offers accelerating the adoption of green hydrogen technologies. [ABSTRACT FROM AUTHOR]

An in-depth understanding of the local mass transport process is essential for precisely regulating the catalyst layer structure in fuel cells. The ionomer on the Pt surface in the catalyst plays a crucial role in the local transport of oxygen and protons. While most models assume that Pt is completely covered by ionomer, experiments have indicated that Pt is partially covered by ionomer in some cause. In this paper, an improved local mass transport model is proposed to investigate the effect of ionomer coverage on internal mass transport process and fuel cell performance. The results show that the current density first increases and then decreases as the ionomer coverage rises from 10% to 90% under 0.6 V. The optimal performance is achieved with a coverage of 40%. Oxygen is more easily transported in water, while ionomer is a better proton conductor. Variations in ionomer coverage lead to different distances for oxygen and proton transfer, which have an important effect on reactant concentration. Furthermore, further study reveals that the current density is greatest at the interface between water and ionomer. Increasing the interface can effectively reduce the comprehensive transport distance of reactants in ionomer and water to improve performance, which is more pronounced than increasing the oxygen transfer coefficient in the ionomer. Overall, this study provides new ideas for the design of high-performance catalyst layers. • An improved fine-structure model of local mass transport in CCL is developed. • Simulate the effect of local oxygen and proton transport on cell performance. • The best cell performance is obtained with an ionomer coverage of 40% under 0.6 V. • Increasing the ionomer/water interface can significantly improve cell performance. • Increasing interface is more effective than enhancing oxygen diffusion in ionomer. [ABSTRACT FROM AUTHOR]

With the rise of the hydrogen energy industry, countries worldwide have introduced relevant policies to elevate the development of the hydrogen energy industry to the height of national energy strategy, and hydrogen energy will become a significant factor affecting the future industrial structure and national competitiveness. The path of technology evolution can trace the history of technology development and predict the trend of technology development, which can help to grasp the first opportunity of technological innovation and lead the direction of technological development. However, there are fewer studies on technology evolution in hydrogen energy. The existing studies mainly use bibliometrics to mine a single technology, and the studies using text mining suffer from the defect that keywords are difficult to decipher. Given this, this paper conducts research on identifying the technology evolution path in the field of hydrogen energy, adopts text mining methods to mine patent data, and introduces document vectorization and phrase mining algorithms to improve the mining depth while increasing the interpretability of the results. It is found that the hydrogen energy industry is in a period of rapid development; the succession and integration of hydrogen energy technologies are good, and the technological development trend focuses on hydrogen storage materials, hydrogen fuel cell vehicles, and green hydrogen preparation. • Identify the mesh evolution path of hydrogen energy technology using text mining. • Introduce a phrase-mining algorithm to make interpreting the results easier. • Analyze the overall development trend of hydrogen energy technology. • Explore the technological themes and evolution patterns in the field of hydrogen energy. [ABSTRACT FROM AUTHOR]

Hydrogen fuel has shown promise as a clean, alternative fuel aiding in the reduction of fossil fuel dependence within the transportation sector. However, hydrogen refueling stations and infrastructure remains a barrier and are a prerequisite for consumer adoption of low-cost and low-emission fuel cell electric vehicles (FCEVs). The costs for FCEV fueling include both station capital costs and operation and maintenance (O&M) costs. Contributing to these O&M costs, unscheduled maintenance is presently more costly and more frequent than for similar gasoline fueling infrastructure and is asserted to be a limiting factor in achieving FCEV customer acceptance and cost parity. Unscheduled maintenance leads to longer station downtime, therefore, causing an increase in missed fueling opportunities, which forces customers to seek refueling at other operable stations that may be significantly farther away. This research proposes a framework for a hydrogen station prognostics health monitoring (H2S PHM) model that can minimize unexpected downtime by predicting the remaining useful life for primary hydrogen station components within the major station subsystems. The H2S PHM model is a data-driven statistical model, based on O&M data collected from 34 retail hydrogen stations located in the U.S. The primary subcomponents studied are the dispenser, compressor, and chiller. The remaining useful life calculations are used to decide whether or not maintenance should be completed based on the prediction and expected future station use. This paper presents the background, method, and results for the H2S PHM model as for a means for improving station availability and customer confidence in FCEVs and hydrogen infrastructure. • Hydrogen station reliability is a key contributor to market success. • Mean fills between failure and station availability are lower than conventional technologies. • A prognostics health monitoring system can improve hydrogen station availability. • Estimated remaining useful life of primary components assists in maintenance decisions. [ABSTRACT FROM AUTHOR]

A model to locate hydrogen refueling stations (HRSs) for hydrogen fuel cells vehicles (HFCVs) or hydrogen internal combustion engines vehicles (HICEVs) is proposed in this paper. The model integrated the flow-capturing location allocation (FCLA) model and stochastic user-equilibrium (SUE) status of network flow. An equilibrium algorithm obviating cannibalization was also presented. We compared the effectiveness between node location and link location determined by FCLA between SUE status and non-equilibrium status of the transportation network taking the city of Anaheim in California in America as an example. The results showed that the capture ratios of node-serving and link-serving are different. For the non-equilibrium case, equilibrium case, and hybrid case, the capture ratios of node-serving are 77.72%, 69.51%, and 60.25%, respectively, while the capture ratios of link-serving are 54.37%, 46.34%, and 31.49%, respectively. This means Node-serving performs better than link-serving in terms of capturing flow, either in equilibrium status or non-equilibrium status. The node locations or link locations obtained by the FCLA method in SUE status should be used for locating HRSs because they are consistent with peoples' route choice behavior and thus can fully capture the expected flow in reality. Practically speaking, link locations are preferable to node locations in locating HRSs because the construction and operation of HRSs on nodes are relatively difficult to implement. • A model of FCLA in SUE status to locate hydrogen refueling stations. • Node-serving and link-serving determined by non-equilibrium flow. • Node-serving and link-serving determined by SUE flow. • Compare the effectiveness between node-serving and link-serving in both cases. [ABSTRACT FROM AUTHOR]