China, People’s Republic

The hydrogen production technology by wind power is an effective mean to improve the utilization of wind energy and alleviate the problem of wind power curtailment. First the basic principles and technical characteristics of the hydrogen production technology by wind power are briefly introduced. Then the history of the hydrogen production technology is reviewed and on this basis the hydrogen production system by wind power is elaborated in detail. In addition the prospect of the application of the hydrogen production technology by wind power is analyzed and discussed. In the end the key technology of the hydrogen production by wind power and the problems to be solved are comprehensively reviewed. The development of hydrogen production technology by wind power is analyzed from many aspects which provides reference for future development of hydrogen production technology by wind power

Hydrogen energy attracts an amount of attention as an environmentally friendly and sustainable energy source. However hydrogen is also flammable. Hydrogen fires and explosions might occur in wet-dust-removal systems if accumulated aluminum dust reacts with water. Hydrogen inhibition is a safe method to address these issues. For this purpose we used sodium citrate a renewable and nontoxic raw material to inhibit H2 formation. Specifically hydrogen inhibition experiments with sodium citrate were carried out using custom-built equipment developed by our research group. When the concentration of sodium citrate solution was in the range of 0.4–4.0 g/L a protective coating was formed on the surface of the Al particles which prevented them from contacting with water. The inhibitory effect was achieved when the concentration of sodium citrate was in a certain range and too much or too little addition may reduce the inhibitory effect. In this paper we also discuss the economic aspects of H2 inhibition with this method because it offers excellent safety advantages and could be incorporated on a large scale. Such an intrinsic safety design of H2 inhibition to control explosions in wet-dust-removal systems could be applied to ensure the safety of other systems such as nuclear reactors.

The development of hydrogen energy is an effective solution to the energy and environmental crisis. Hydrogen fuel cells and energy storage cells as hybrid power have broad application prospects in the field of vehicle power. Energy management strategies are key technologies for fuel cell hybrid systems. The traditional optimization strategy is generally based on optimization under the global operating conditions. The purpose of this project is to develop a power allocation optimization method based on real-time load forecasting for fuel cell/lithium battery hybrid electric vehicles which does not depend on specific working conditions or causal control methods. This paper presents an energy-management algorithm based on real-time load forecasting using GRU neural networks to predict load requirements in the short time domain and then the local optimization problem for each predictive domain is solved using a method based on Pontryagin’s minimum principle (PMP). The algorithm adopts the idea of model prediction control (MPC) to transform the global optimization problem into a series of local optimization problems. The simulation results show that the proposed strategy can achieve a good fuel-saving control effect. Compared with the rule-based strategy and equivalent hydrogen consumption strategy (ECMS) the fuel consumption is lower under two typical urban conditions. In the 1800 s driving cycle under WTCL conditions the fuel consumption under the MPC-PMP strategy is 22.4% lower than that based on the ECMS strategy and 10.3% lower than the rules-based strategy. Under CTLT conditions the fuel consumption of the MPC-PMP strategy is 13.12% lower than that of the rule-based strategy and 3.01% lower than the ECMS strategy.

Direct containment heating (DCH) is one of the potential factors leading to early containment failure. DCH is closely related to safety analysis and containment performance evaluation of nuclear power plants. In this study a DCH prediction program was developed to analyze the DCH loads of containment vessel. The phenomenological model of debris dispersal metal oxidation reaction debris-atmospheric heat transfer and hydrogen jet burn was established. Code assessment was performed by comparing with several separate effect tests and integral effect tests. The comparison between the predicted results and experimental data shows that the program can predict the key parameters such as peak pressure temperature and hydrogen production in containment well and for most comparisons the relative errors can be maintained within 20%. Among them the prediction uncertainty of hydrogen production is slightly larger. The analysis shows that the main sources of the error are the difference of time scale and the oxidation of cavity debris.

Water splitting has been regarded as a sustainable and environmentally-friendly technique to realize green hydrogen generation while more energy is consumed due to the high overpotentials required for the anode oxygen evolution reaction. Urea electrooxidation an ideal substitute is thus received increasing attention in assisting water-splitting reactions. Note that highly efficient catalysts are still required to drive urea oxidation and the facile generation of high valence state species is significant in the reaction based on the electrochemical-chemical mechanisms. The high cost and rareness make the noble metal catalysts impossible for further consideration in large-scale application. Ni-based catalysts are very promising due to their cheap price facile structure tuning good compatibility and easy active phase formation. In the light of the significant advances made recently herein we reviewed the recent advances of Ni-based powder catalysts for urea oxidation in assisting water-splitting reaction. The fundamental of urea oxidation is firstly presented to clarify the mechanism of urea-assisted water splitting and then the prevailing evaluation indicators are briefly expressed based on the electrochemical measurements. The catalyst design principle including synergistic effect electronic effect defect construction and surface reconstruction as well as the main fabrication approaches are presented and the advances of various Ni-based powder catalysts for urea assisted water splitting are summarized and discussed. The problems and challenges are also concluded for the Ni-based powder catalysts fabrication the performance evaluation and their application. Considering the key influence factors for catalytic process and their application attention should be given to structure-property relationship deciphering novel Ni-based powder catalysts development and their construction in the real device; specifically the effort should be directed to the Ni-based powder catalyst with multi-functions to simultaneously promote the fundamental steps and high anti-corrosion ability by revealing the local structure reconstruction as well as the integration in the practical application. We believe the current summarization will be instructive and helpful for the Ni-based powder catalysts development and understanding their catalytic action for urea-assisted hydrogen generation via water splitting technique.

The combustion emissions of the hydrogen-fueled engines are very clean but the problems of abnormal combustion and high NOx emissions limit their applications. Nowadays hydrogen engines use exhaust gas recirculation (EGR) technology to control the intensity of premixed combustion and reduce the NOx emissions. This study aims at improving the abnormal combustion and decreasing the NOx emissions of the hydrogen engine by applying a three-dimensional (3D) computational fluid dynamics (CFD) model of a single-cylinder hydrogen-fueled engine equipped with an EGR system. The results indicated that peak in-cylinder pressure continuously increased with the increase of the ignition advance angle and was closer to the top dead center (TDC). In addition the mixture was burned violently near the theoretical air–fuel ratio and the combustion duration was shortened. Moreover the NOx emissions the average pressure and the in-cylinder temperature decreased as the EGR ratio increased. Furthermore increasing the EGR ratio led to an increase in the combustion duration and a decrease in the peak heat release rate. EGR system could delay the spontaneous combustion reaction of the end-gas and reduce the probability of knocking. The pressure rise rate was controlled and the in-cylinder hot spots were reduced by the EGR system which could suppress the occurrence of the pre-ignition in the hydrogen engine.

The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction. The catalysis of Co@C composites on the hydrogen storage behavior of Mg₉₀Ce₅Y₅ alloy was investigated in detail by XRD SEM TEM PCI and DSC method. Because of the synergistic catalytic function of C and Co in C@Co nanocomposites the Mg₉₀Ce₅Y₅ alloy with 10 wt.% C@Co shows the excellent hydrogen absorption and desorption performances. Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300 °C. Meanwhile the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol−1 H₂ after the addition of the C@Co composites. This positive effect attributes to the C layer with the high defect density and the Co nanoparticles which reduces the energy barriers for the nucleation of Mg/MgH₂ phase and the recombination of hydrogen molecule. Besides the C@Co composites also improve the activation property of the Mg₉₀Ce₅Y₅ alloy which was fully activated in the first cycle. Moreover the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased. Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy these differences are so small that the improvement on thermodynamics can hardly be seen.

According to new findings the use of alternative energy sources such as wind energy is needed to supply the energy demand of future generations. On the other hand combined renewable energy systems can be more efficient than their stand-alone systems. Therefore clean energy-based hybrid energy systems can be a suitable solution for fossil fuels. However for their widespread commercialization more detailed and powerful studies are needed. On the other hand in order to attain sustainable development for the use of renewable energy sources due to their nature energy storage is required. The motivation of this study is introduce and examine a new energy system performance for the production of electricity and hydrogen fuel as well as energy storage. So this paper presents the energy and exergy operation of a hybrid wind turbine water electrolyzer and Pumped-hydro-compressed air system. The electricity produced by the wind turbine is used to produce hydrogen fuel in electrolyzer and the excess energy is stored using the storage system. It was found that the electrolyzer needed 512.6 W of electricity to generate 5 mol/h of hydrogen fuel which was supplied by a 10 kW-wind turbine. In such a context the efficiency of the process was 74.93%. Furthermore on average the isothermal process requires 17.53% less storage capacity than the isentropic process. The effect of key parameters such as rate of hydrogen fuel production operating pressures wind speed and components efficiency on the process operation is also examined.

Hydrogen embrittlement (HE) is a critical issue that hinders the reliability of hydrogenation reactors. Hence it is of great significance to investigate the effect of hydrogen on fracture toughness of 2.25Cr-1Mo-0.25V steel and weld. In this work the fracture behavior of 2.25Cr-1Mo-0.25V steel and welds was studied by three-point bending tests under hydrogen-free and hydrogen-charged conditions. The immersion charging method was employed to pre-charge hydrogen inside specimen and the fracture toughness of these joints was evaluated quantitatively. The microstructure and grain size of the specimens were observed by scanning electron microscopy (SEM) and by metallurgical microscopy to investigate the HE mechanisms. It was found that fracture toughness for both the base metal (BM) and the weld zone (WZ) significantly decreased under hydrogen-charged conditions due to the coexistence of the hydrogen-enhanced decohesion (HEDE) and hydrogen-enhanced localized plasticity (HELP) mechanisms. Moreover the formation and growth of primary voids were observed in the BM leading to a superior fracture toughness. In addition the BM compared to the WZ shows superior resistance to HE because the finer grain size in the BM leads to a larger grain boundary area thus distributing more of the diffusive hydrogen trapped in the grain boundary and reducing the hydrogen content.

This study is a review of hydrogen station patents using the Derwent Innovation system and also a secondary screening. This was undertaken by the researchers to better understand and identify hydrogen station trends. The review focuses on analyzing the developing trends of patent technologies associated with a hydrogen station. The results of the review indicated that the countries with the major distribution of patents were Japan China the USA and Europe. Japan is leading the developmental trajectory of hydrogen stations. The results of the analysis found the leading developers of these patented technologies are Kobe Steel Nippon Oil Toyota and Honda. Other active patent developers analyzed include Linde Hyundai and Texaco. The review concludes with a suggestion that using a patent analysis methodology is a good starting point to identify evaluate and measure the trend in hydrogen station commercial development.

Medium Mn steels have been considered as the next-generation materials for use in the automotive industry due to their excellent strength and ductility balance. To reduce the total weight and improve the safety of vehicles medium Mn steels look forward to a highly promising future. However hydrogen-induced delayed cracking is a concern for the use of high strength steels. This work is focused on the service characteristics of two kinds of medium Mn steels under different relative humidity conditions (40% 60% 80% and 100%). Under normal relative humidity (about 40%) at 25 °C the hydrogen concentration in steel is 0.4 ppm. When exposed to higher relative humidity the hydrogen concentration in steel increases slowly and reaches a stable value about 0.8 ppm. In slow strain rate tensile tests under different relative humidity conditions the tensile strength changed the hydrogen concentration increased and the elongation decreased as well thereby increasing the hydrogen embrittlement sensitivity. In other words the smaller the tensile rate applied the greater the hydrogen embrittlement sensitivity. In constant load tests under different relative humidity conditions the threshold value of the delayed cracking of M7B (‘M’ referring to Mn ‘7’ meaning the content of Mn ‘B’ denoting batch annealing) steel maintains a steady value of 0.82 σb (tensile strength). The threshold value of the delayed cracking of M10B significantly changed along with relative humidity. When relative humidity increased from 60% to 80% the threshold dropped sharply from 0.63 σb to 0.52 σb. We define 80% relative humidity as the ‘threshold humidity’ for M10B.

Study of flame acceleration and deflagration-to-detonation transition (DDT) in obstructed channels is an important subject of research for hydrogen safety. Experiments and numerical simulations of DDT in channels equipped with triangular obstacles were conducted in this work. High-speed schlieren photography and pressure records were used to study the flame shape changes flame propagation and pressure build up in the experiments. In the simulations the fully compressible reactive Navier–Stokes equations coupled with a calibrated chemical-diffusion model for stoichiometric hydrogen-oxygen mixture were solved using a high-order numerical method. The simulations were in good agreement with the experiments. The results show that the triangular obstacles significantly promote the flame acceleration and provide conditions for the occurrence of DDT. In the early stages of flame acceleration vortices are generated in the gaps between adjacent obstacles which is the main cause for the flame roll-up and distortion. A positive feedback mechanism between the combustiongenerated flow and flame propagation results in the variations of the size and velocity of vortices. The flame-vortex interactions cause flame fragmentation and consequently rapid growth in flame surface area which further lead to flame acceleration. The initially laminar flame then develops into a turbulent flame with the creation of shocks shock-flame interactions and various flame instabilities. The continuously arranged obstacles interact with shocks and flames and help to create environments in which a detonation can develop. Both flame collision and flame-shock interaction can give rise to detonation in the channels with triangular obstacles.

The reversible/irreversible recovery of mechanical properties and the microstructure characteristics of a typical hot-stamped steel B1500HS have been studied under different conditions of hydrogen permeation. Initially all tested specimens were permeated by hydrogen atoms through an electrochemical hydrogen charging scheme. Then the comparisons between different currents and charging time were performed. The influence of different storage time was compared as well. Additionally the effect of the plastic strain introduced by pre-stretching was also investigated. The experimental results showed that the negative impact of hydrogen embrittlement was altered from reversible to irreversible as the magnitude of the charging current increased. The hydrogen blistering and the hydrogen charging-induced cracks were both observed and inspected in the tested samples regarding the irreversible situation. Moreover the adverse influence of hydrogen embrittlement was enhanced by plastic pre-straining or extending the charging period. At the micro-level hydrogen charging-induced cracks generally were generated at defect locations such as the prior austenite grain boundaries and lath martensite interfaces. Particularly crack direction occurred perpendicular to the orientation of lath martensite and transgranular fracture occurred at the prior austenite grains.

Fuel cells as clean power sources are very attractive for the maritime sector which is committed to sustainability and reducing greenhouse gas and atmospheric pollutant emissions from ships. This paper presents a technological review on fuel cell power systems for maritime applications from the past two decades. The available fuels including hydrogen ammonia renewable methane and methanol for fuel cells under the context of sustainable maritime transportation and their pre-processing technologies are analyzed. Proton exchange membrane molten carbonate and solid oxide fuel cells are found to be the most promising options for maritime applications once energy efficiency power capacity and sensitivity to fuel impurities are considered. The types layouts and characteristics of fuel cell modules are summarized based on the existing applications in particular industrial or residential sectors. The various research and demonstration projects of fuel cell power systems in the maritime industry are reviewed and the challenges with regard to power capacity safety reliability durability operability and costs are analyzed. Currently power capacity costs and lifetime of the fuel cell stack are the primary barriers. Coupling with batteries modularization mass production and optimized operating and control strategies are all important pathways to improve the performance of fuel cell power systems.

Numerous studies concerning the life cycle assessment of fuel cell vehicles (FCVs) have been conducted. However little attention has been paid to the life cycle assessment of an FCV from the perspective of the detailed vehicle components. This work conducts the life cycle assessment of Toyota Mirai with all major components considered in a Chinese context. Both the vehicle cycle and the fuel cycle are included. Both comprehensive resources and energy consumption and comprehensive environmental emissions of the life cycles are investigated. Potential environmental impacts are further explored based on CML 2001 method. Then different hydrogen production schemes are compared to obtain the most favorable solution. To explore the potential of the electrolysis the scenario analysis of the power structure is conducted. The results show that the most mineral resources are consumed in the raw material acquisition stage the most fossil energy is consumed in the use stage and global warming potential (GWP) value is fairly high in all life cycle stages of Toyota Mirai using electrolyzed hydrogen. For hydrogen production schemes the scenario analysis indicates that simply by optimizing the power structure the environmental impact of the electrolysis remains higher than other schemes. When using the electricity from hydropower or wind power the best choice will be the electrolysis.

A highly efficient low-cost and environmentally friendly photocathode with long-term stability is the goal of practical solar hydrogen evolution applications. Here we found that the Cu₃BiS₃ film-based photocathode meets the abovementioned requirements. The Cu₃BiS₃-based photocathode presents a remarkable onset potential over 0.9 V_RHE with excellent photoelectrochemical current densities (~7 mA/cm² under 0 V_RHE) and appreciable 10-hour long-term stability in neutral water solutions. This high onset potential of the Cu₃BiS₃-based photocathode directly results in a good unbiased operating photocurrent of ~1.6 mA/cm² assisted by the BiVO₄ photoanode. A tandem device of Cu₃BiS₃-BiVO₄ with an unbiased solar-to-hydrogen conversion efficiency of 2.04% is presented. This tandem device also presents high stability over 20 hours. Ultimately a 5 × 5 cm² large Cu₃BiS₃-BiVO₄ tandem device module is fabricated for standalone overall solar water splitting with a long-term stability of 60 hours.

Concentration and velocity measurements are crucial for developing and validating hydrogen jet models which  provide  scientific  bases  for hydrogen  safety  analyses.  The  concentration   fields  have  been visualized and accurately measured using laser diagnostic methods based on lase Rayleigh and Raman scattering  techniques.  However  the  velocity  measurements  are  more   challenging.  Particle  image velocimetry (PIV) has been commonly used for measuring velocities in turbulent flows by seeding tracer particles into the flow and assuming the particles intimately following the flow.  However sometimes the  particle  seeding  is  difficult  or  disturbs  the   flow.  Moreover simultaneously  concentration  and velocity measurements are very difficult when using PIV systems to measure the velocities. Therefore the optical flow velocimetry (OFV) method was used to resolve the velocity fields from the scalar fields or  particle  images  of  hydrogen   jets.  In the  present  work  the  velocity  field  and  particle  images  of hydrogen  jets   were  simulated  using  FLUENT  with  the  large  eddy simulation (LES)  model  and  the particle images were then used to resolve the velocity field by the OFV method. The OFV results were compared with the CFD simulations to verify their accuracy. The results show that the OFC method was an  efficient  low-cost  way  to  extract the  velocity  fields  from  particle  images.  The OFV  method accurately  located  the  large  vortices  in  the  flow  and  the  velocity distribution of  the  high-velocity gradients regions was consistent with the CFD results. The present study lays a foundation for using the OFV  method  to directly  resolve  the  velocity fields from  the  concentration  fields  of  hydrogen  jets measured by laser diagnostics.

Producing hydrogen by water electrolysis suffers from the kinetic barriers in the oxygen evolution reaction (OER) that limits the overall efficiency. With spin-dependent kinetics in OER to manipulate the spin ordering of ferromagnetic OER catalysts (e.g. by magnetization) can reduce the kinetic barrier. However most active OER catalysts are not ferromagnetic which makes the spin manipulation challenging. In this work we report a strategy with spin pinning effect to make the spins in paramagnetic oxyhydroxides more aligned for higher intrinsic OER activity. The spin pinning effect is established in oxideFM/oxyhydroxide interface which is realized by a controlled surface reconstruction of ferromagnetic oxides. Under spin pinning simple magnetization further increases the spin alignment and thus the OER activity which validates the spin effect in rate-limiting OER step. The spin polarization in OER highly relies on oxyl radicals (O∙) created by 1st dehydrogenation to reduce the barrier for subsequent O-O coupling.

Hydrogen spillover phenomenon of metal-supported electrocatalysts can significantly impact their activity in hydrogen evolution reaction (HER). However design of active electrocatalysts faces grand challenges due to the insufficient understandings on how to overcome this thermodynamically and kinetically adverse process. Here we theoretically profile that the interfacial charge accumulation induces by the large work function difference between metal and support (∆Φ) and sequentially strong interfacial proton adsorption construct a high energy barrier for hydrogen transfer. Theoretical simulations and control experiments rationalize that small ∆Φ induces interfacial charge dilution and relocation thereby weakening interfacial proton adsorption and enabling efficient hydrogen spillover for HER. Experimentally a series of Pt alloys-CoP catalysts with tailorable ∆Φ show a strong ∆Φ-dependent HER activity in which PtIr/CoP with the smallest ∆Φ = 0.02 eV delivers the best HER performance. These findings have conclusively identified ∆Φ as the criterion in guiding the design of hydrogen spillover-based binary HER electrocatalysts

The development of visible-light-responsive photocatalysts with high efficiency stability and eco-friendly nature is beneficial to the large-scale application of solar hydrogen production. In this work the production of biosynthetic ternary ZnCdS photocatalysts (Eg = 2.35–2.72 eV) by sulfate-reducing bacteria (SRB) under mild conditions was carried out for the first time. The huge amount of biogenic S²⁻ and inherent extracellular proteins (EPs) secreted by SRB are important components of rapid extracellular biosynthesis. The ternary ZnCdS QDs at different molar ratios of Zn2+and Cd2+ from 15:1 to 1:1 were monodisperse spheres with good crystallinity and average crystallite size of 6.12 nm independent of the molar ratio of Cd²⁺ to Zn²⁺. All the ZnCdS QDs had remarkable photocatalytic activity and stability for hydrogen evolution under visible light without noble metal cocatalysts. Especially ZnCdS QDs at Zn/Cd = 3:1 showed the highest H₂ production activity of 3.752 mmol·h⁻¹·g⁻¹. This excellent performance was due to the high absorption of visible light the high specific surface area and the lower recombination rate between photoexcited electrons and holes. The adhered inherent EPs on the ZnCdS QDs slowed down the photocorrosion and improved the stability in photocatalytic hydrogen evolution. This study provides a new direction for solar hydrogen production.

As the energy crisis becomes worse hydrogen as a clean energy source is more and more widely used in industrial production and people’s daily life. However there are hidden dangers in hydrogen storage and transportation because of its flammable and explosive features. Gas detection is the key to solving this problem. High quality sensors with more practical and commercial value must be able to accurately detect target gases in the environment. Emerging porous metal-organic framework (MOF) materials can effectively improve the selectivity of sensors as a result of high surface area and coordinated pore structure. The application of MOFs for surface modification to improve the selectivity and sensitivity of metal oxides sensors to hydrogen has been widely investigated. However the influence of MOF modified film thickness on the selectivity of hydrogen sensors is seldom studied. Moreover the mechanism of the selectivity improvement of the sensors with MOF modified film is still unclear. In this paper we prepared nano-sized ZnO particles by a homogeneous precipitation method. ZnO nanoparticle (NP) gas sensors were prepared by screen printing technology. Then a dense ZIF-8 film was grown on the surface of the gas sensor by hydrothermal synthesis. The morphology the composition of the elements and the characters of the product were analyzed by X-ray diffraction analysis (XRD) transmission electron microscope (TEM) scanning electron microscope (SEM) energy dispersive spectrometer (EDS) Brunauer-Emmett-Teller (BET) and differential scanning calorimetry (DSC). It is found that the ZIF-8 film grown for 4 h cannot form a dense core-shell structure. The thickness of ZIF-8 reaches 130 nm at 20 h. Through the detection and analysis of hydrogen (1000 ppm) ethanol (100 ppm) and acetone (50 ppm) from 150 °C to 290 °C it is found that the response of the ZnO@ZIF-8 sensors to hydrogen has been significantly improved while the response to ethanol and acetone was decreased. By comparing the change of the response coefficient when the thickness of ZIF-8 is 130 nm the gas sensor has a significantly improved selectivity to hydrogen at 230 °C. The continuous increase of the thickness tends to inhibit selectivity. The mechanism of selectivity improvement of the sensors with different thickness of the ZIF-8 films is discussed.

This work aims to understand the gasification performance of municipal solid waste (MSW) by means of thermodynamic analysis. Thermodynamic analysis is based on the assumption that the gasification reactions take place at the thermodynamic equilibrium condition without regard to the reactor and process characteristics. First model components of MSW including food green wastes paper textiles rubber chlorine-free plastic and polyvinyl chloride were chosen as the feedstock of a steam gasification process with the steam temperature ranging from 973 K to 2273 K and the steam-to-MSW ratio (STMR) ranging from 1 to 5. It was found that the effect of the STMR on the gasification performance was almost the same as that of the steam temperature. All the differences among the seven types of MSW were caused by the variation of their compositions. Next the gasification of actual MSW was analyzed using this thermodynamic equilibrium model. It was possible to count the inorganic components of actual MSW as silicon dioxide or aluminum oxide for the purpose of simplification due to the fact that the inorganic components mainly affected the reactor temperature. A detailed comparison was made of the composition of the gaseous products obtained using steam hydrogen and air gasifying agents to provide basic knowledge regarding the appropriate choice of gasifying agent in MSW treatment upon demand.

Power to hydrogen (P2H) provides a promising solution to the geographic mismatch between sources of renewable energy and the market due to its technological maturity flexibility and the availability of technical and economic data from a range of active demonstration projects. In this review we aim to provide an overview of the status of P2H analyze its technical barriers and solutions and propose potential opportunities for future research and industrial demonstrations. We specifically focus on the transport of hydrogen via natural gas pipeline networks and end-user purification. Strong evidence shows that an addition of about 10% hydrogen into natural gas pipelines has negligible effects on the pipelines and utilization appliances and may therefore extend the asset value of the pipelines after natural gas is depleted. To obtain pure hydrogen from hydrogen-enriched natural gas (HENG) mixtures end-user separation is inevitable and can be achieved through membranes adsorption and other promising separation technologies. However novel materials with high selectivity and capacity will be the key to the development of industrial processes and an integrated membrane-adsorption process may be considered in order to produce high-purity hydrogen from HENG. It is also worth investigating the feasibility of electrochemical separation (hydrogen pumping) at a large scale and its energy analysis. Cryogenics may only be feasible when liquefied natural gas (LNG) is one of the major products. A range of other technological and operational barriers and opportunities such as water availability byproduct (oxygen) utilization and environmental impacts are also discussed. This review will advance readers’ understanding of P2H and foster the development of the hydrogen economy.

Energy storage plays an essential role in stabilizing fluctuations in renewable energy sources such as wind and solar enabling surplus electricity retention and delivering dynamic frequency regulation. However relying solely on a single form of storage often proves insufficient due to constraints in performance capacity and cost-effectiveness. To tackle frequency regulation challenges in remote desert-based renewable energy hubs— where traditional power infrastructure is unavailable—this study introduces a planning framework for an electro-hydrogen energy storage system with grid-forming capabilities designed to supply both inertia and frequency response. At the system design stage a direct current (DC) transmission network is modeled integrating battery and hydrogen storage technologies. Using this configuration the capacity settings for both grid-forming batteries and hydrogen units are optimized. This study then explores how hydrogen systems—comprising electrolyzers storage tanks and fuel cells—and grid-forming batteries contribute to inertial support. Virtual inertia models are established for each technology enabling precise estimation of the total synthetic inertia provided. At the operational level this study addresses stability concerns stemming from renewable generation variability by introducing three security indices. A joint optimization is performed for virtual inertia constants which define the virtual inertia provided by energy storage systems to assist in frequency regulation and primary frequency response parameters within the proposed storage scheme are optimized in this model. This enhances the frequency modulation potential of both systems and confirms the robustness of the proposed approach. Lastly a real-world case study involving a 13 GW renewable energy base in Northwest China connected via a ±10 GW HVDC export corridor demonstrates the practical effectiveness of the optimization strategy and system configuration.

Photovoltaic (PV) is promising to supply power for residential buildings. Battery is the most widely employed storage method to mitigate the intermittence of PV and to overcome the mismatch between production and load. Hydrogen storage is another promising method that it is suitable for long-term storage. This study focuses on the comparison of self-sufficiency ratio and cost performance between battery storage and hydrogen storage for a residential building in Sweden. The results show that battery storage is superior to the hydrogen storage in the studied case. Sensitivity study of the component cost within the hydrogen storage system is also carried out. Electrolyzer cost is the most sensitive factor for improving system performance. A hybrid battery and hydrogen storage system which can harness the advantages of both battery and hydrogen storages is proposed in the last place.

Biomass is plant or animal material that stores both chemical and solar energies and that is widely used for heat production and various industrial processes. Biomass contains a large amount of the element hydrogen so it is an excellent source for hydrogen production. Therefore biomass is a sustainable source for electricity or hydrogen production. Although biomass power plants and reforming plants have been commercialized it remains a difficult challenge to develop more effective and economic technologies to further improve the conversion efficiency and reduce the environmental impacts in the conversion process. The use of biomass-based flow fuel cell technology to directly convert biomass to electricity and the use of electrolysis technology to convert biomass into hydrogen at a low temperature are two new research areas that have recently attracted interest. This paper first briefly introduces traditional technologies related to the conversion of biomass to electricity and hydrogen and then reviews the new developments in flow biomass fuel cells (FBFCs) and biomass electrolysis for hydrogen production (BEHP) in detail. Further challenges in these areas are discussed.

Hydrogen energy as a clean and renewable energy has attracted much attention in recent years. Water electrolysis via the hydrogen evolution reaction at the cathode coupled with the oxygen evolution reaction at the anode is a promising method to produce hydrogen. Given the shortage of freshwater resources on the planet the direct use of seawater as an electrolyte for hydrogen production has become a hot research topic. Direct use of seawater as the electrolyte for water electrolysis can reduce the cost of hydrogen production due to the great abundance and wide availability. In recent years various high-efficiency electrocatalysts have made great progress in seawater splitting and have shown great potential. This review introduces the mechanisms and challenges of seawater splitting and summarizes the recent progress of various electrocatalysts used for hydrogen and oxygen evolution reaction in seawater electrolysis in recent years. Finally the challenges and future opportunities of seawater electrolysis for hydrogen and oxygen production are presented.

Hydrogen was doped in austenitic stainless steel (ASS) 316L tensile samples produced by the laser-powder bed fusion (L-PBF) technique. For this aim an electrochemical method was conducted under a high current density of 100 mA/cm² for three days to examine its sustainability under extreme hydrogen environments at ambient temperatures. The chemical composition of the starting powders contained a high amount of Ni approximately 12.9 wt.% as a strong austenite stabilizer. The tensile tests disclosed that hydrogen charging caused a minor reduction in the elongation to failure (approximately 3.5% on average) and ultimate tensile strength (UTS; approximately 2.1% on average) of the samples using a low strain rate of 1.2 × 10⁻⁴ s⁻¹. It was also found that an increase in the strain rate from 1.2 × 10⁻⁴ s⁻¹ to 4.8 × 10⁻⁴ s⁻¹ led to a reduction of approximately 3.6% on average for the elongation to failure and 1.7% on average for UTS in the pre-charged samples. No trace of martensite was detected in the X-ray diffraction (XRD) analysis of the fractured samples thanks to the high Ni content which caused a minor reduction in UTS × uniform elongation (UE) (GPa%) after the H charging. Considerable surface tearing was observed for the pre-charged sample after the tensile deformation. Additionally some cracks were observed to be independent of the melt pool boundaries indicating that such boundaries cannot necessarily act as a suitable area for the crack propagation.

Hydrogen crossover rate is an important indicator for characterizing the membrane degradation and failure in proton exchange membrane fuel cell. Several electrochemical methods have been applied to quantify it. But most of established methods are too rough to support follow-up applications. In this paper a systematic and consistent theoretical foundation for electrochemical measurements of hydrogen crossover is established for the first time. Different electrochemical processes occurring throughout the courses of applying potentiostatic or galvanostatic excitations on fuel cell are clarified and the linear current–voltage behavior observed in the steady-state voltammogram is reinterpreted. On this basis we propose a modified galvanostatic charging method with high practicality to achieve accurate electrochemical measurement of hydrogen crossover and the validity of this method is fully verified. This research provides an explicit framework for implementation of galvanostatic charging method and offers deeper insights into the principles of electrochemical methods for measuring hydrogen crossover.

A systematic study of different ratios of CO CO₂ N₂ gas components on the hydrogen storage properties of the Na₃AlH₆ complex hydride with 4 mol% TiCl3 8 mol% aluminum and 8 mol% activated carbon is presented in this paper. The different concentrations of CO and CO₂in H₂ and CO CO₂ N₂ in H₂ mixture were investigated. Both CO and CO₂gas react with the complex hydride forming Al oxy-compounds NaOH and Na₂CO₃ that consequently cause serious decline in hydrogen storage capacity. These reactions lead to irreversible damage of complex hydride under the current experimental condition. Thus after 10 cycles with 0.1 vol % CO + 99.9 vol %H₂ and 1 vol % CO + 99 vol %H₂ the dehydrogenation storage capacity of the composite material decreased by 17.2% and 57.3% respectively. In the case of investigation of 10 cycles with 1 vol % CO₂ + 99 vol % H₂ gas mixture the capacity degradation was 53.5%. After 2 cycles with 10 vol % CO +90 vol % H₂  full degradation was observed whereas after 6 cycles with 10 vol % CO₂+ 90 vol % H₂ degradation of 86.8% was measured. While testing with the gas mixture of 1.5 vol % CO + 10 vol % CO₂+ 27 vol % H₂ + 61.5 vol % N2 the degradation of 94% after 6 cycles was shown. According to these results it must be concluded that complex aluminum hydrides cannot be used for the absorption of hydrogen from syngas mixtures without thorough purification.

Hydrogen storage in solid-state materials is believed to be a most promising hydrogen-storage technology for high efficiency low risk and low cost. Mg(BH4)2 is regarded as one of most potential materials in hydrogen storage areas in view of its high hydrogen capacities (14.9 wt% and 145–147 kg cm3 ). However the drawbacks of Mg(BH4)2 including high desorption temperatures (about 250 C–580 C) sluggish kinetics and poor reversibility make it difficult to be used for onboard hydrogen storage of fuel cell vehicles. A lot of researches on improving the dehydrogenation reaction thermodynamics and kinetics have been done mainly including: additives or catalysts doping nanoconfining Mg(BH4)2 in nanoporous hosts forming reactive hydrides systems multi-cation/anion composites or other derivatives of Mg(BH4)2. Some favorable results have been obtained. This review provides an overview of current research progress in magnesium borohydride including: synthesis methods crystal structures decomposition behaviors as well as emphasized performance improvements for hydrogen storage.

Metal oxide semiconductor (MOS) is promising in developing hydrogen detectors. However typical MOS materials usually work between 200-500°C which not only restricts their application in flammable and explosive gases detection but also weakens sensor stability and causes high power consumption. This paper studies the sensing properties of UV enhanced Pd-SnO2 nano-spherical composites at 80-360 ℃. In the experiment Pd of different molar ratios (0.5 2.5 5.0 10.0) was doped into uniform spherical SnO2 nanoparticles by a hydrothermal synthesis method. A xenon lamp with a filter was used as the ultraviolet excitation light source to examine the response of the spherical Pd- SnO2 nanocomposite to 50-1000 ppm H2 gas. The influence of different intensities of ultraviolet light on the gas-sensing properties of composite materials compared with dark condition was analyzed. The experiments show that the conductivity of the composites can be greatly stabilized and the thermal excitation temperature can be reduced to 180 ℃ under the effect of UV enhancement. A rapid response (4.4/ 17.4 s) to 200 ppm of H2 at 330 °C can be achieved by the Pd-SnO2 nanocomposites with UV assistance. The mechanism may be attributed to light motivated electron-hole pairs due to built-in electric fields under UV light illumination which can be captured by target gases and lead to UV controlled gas sensing performance. Catalytic active sites of hydrogen are provided on the surface of the mixed material by Pd. The results in this study can be helpful in reducing the response temperature of MOS materials and improving the performance of hydrogen detectors."

This study focuses on a renewable energy power plant equipped with electrolytic hydrogen production system aiming to optimize energy management to smooth renewable energy generation fluctuations participate in peak shaving auxiliary services and increase the absorption space for renewable energy. A multi-objective energy management model and corresponding algorithms were developed incorporating considerations of cost pricing and the operational constraints of a renewable energy generating unit and electrolytic hydrogen production system. By introducing uncertain programming the uncertainty issues associated with renewable energy output were successfully addressed and an improved particle swarm optimization algorithm was employed for solving. A simulation system established on the Matlab platform verified the effectiveness of the model and algorithms demonstrating that this approach can effectively meet the demands of the electricity market while enhancing the utilization rate of renewable energies.

Hydrogen as fuel has been considered as a feasible energy carry and which offers a clean and efficient alternative for transportation. During the high pressure filling the temperature in the hydrogen storage tank (HST) may rise rapidly due to the hydrogen compression. The high temperature may lead to safety problem. Thus for fast and safely refueling the hydrogen several key factors need to be considered. In the present study by the thermodynamics theories a mathematical model is established to simulate and analyze the high pressure filling process of the storage tank for the hydrogen station. In the analysis the physical parameters of normal hydrogen are introduced to make the simulation close to the actual process. By the numerical simulation for 50 MPa compressed hydrogen tank the temperature and pressure trends during filling are obtained. The simulation results for non-adiabatic filling were compared with the theoretically calculated ones for adiabatic conditions and the simulation results for non-adiabatic filling were compared with the simulation ones for adiabatic conditions. Then the influence of working pressure initial temperature mass flow rate initial pressure and inlet temperature on the temperature rise were analyzed. This study provides a theoretical research basis for high pressure hydrogen energy storage and hydrogenation technology.

Adding hydrogen to the fuel can change the combustion characteristics and greatly improve the pollutants emission for the gas turbine. The numerical method was adopted to study the combustion process in a counter-flow combustor of a 100 kW micro gas turbine using methane doped by hydrogen and various distribution schemes of air flow. The combustion characteristics and pollutant emissions were explored to ascertain the influence of air distribution based on solving the validated models. It was shown that as the amount of premixed air increased in the swirling gas the range of the recirculation region became larger and the range of the high-temperature zone in the combustion chamber gradually enlarged. When the amount of premixed air was 30% the outlet temperature distribution of the combustor was excellent and the average temperature was 1172 K. Moreover the concentration of NOX gradually increased and reached a maximum value of 23.46 ppm (@15% O2) as the premixed air increased in the range of the ratio less than 40%. It was reduced to 0.717 ppm (@15% O2) when the amount of premixed air increased to 50%. These findings may support the running of the micro gas turbine using the hybrid fuel of hydrogen and methane.

Hydrogen has emerged as a new energy vector beyond its usual role as an industrial feedstock primarily for the production of ammonia methanol and petroleum refining. In addition to environmental sustainability issues energy-scarce developed countries such as Japan and Korea are also facing an energy security issue and hydrogen or hydrogen carriers such as ammonia and methylcyclohexane seem to be options to address these long-term energy availability issues. China has been eagerly developing renewable energy and hydrogen infrastructure to meet their sustainability goals and the growing energy demand. In this review we focus on hydrogen electrification through proton-exchange membrane fuel cells (PEMFCs) which are widely believed to be commercially suitable for automotive applications particularly for vehicles requiring minimal hydrogen infrastructure support such as fleets of taxies buses and logistic vehicles. This review covers all the key components of PEMFCs thermal and water management and related characterization techniques. A special consideration of PEMFCs in automotive applications is the highlight of this work leading to the infrastructure development for hydrogen generation storage and transportation. Furthermore national strategies toward the use of hydrogen are reviewed thereby setting the rationale for the hydrogen economy.

Through data mining and analysis of the word frequency and occurrence position of industrial policy keywords the main policy parameters affecting industrial development are determined and the functional relationship between industrial policy and industrial development is obtained through multi-parameter non-linear regression: Yit−1 (y1 y2 y3 y4 y5) = β1it X1 + β2it ln X2 + β3it ln X3 + β4it X1it ∗ ln X3 + εit . The time series function of the industrial development index: Y (t) = 0.174 ∗ e (0.256∗t) is established and the industrial development under the influence of next year’s policy is predicted. It is concluded from the mathematical expression of the statistical model that there is a certain coupling effect between different policies and that industrial development is influenced by the joint effect on the parent and sub-industries. This ultimately proves that there is a clear correlation between policy and industry development.

In the fast filling process in order to control the temperature of the vehicle-mounted storage tank not to exceed the upper limit of 85 ◦C it is an effective method to add a hydrogen pre-cooling system upstream of the hydrogenation machine. In this paper Fluent is used to simulate the heat transfer process of high-pressure hydrogen in a shell-and-tube heat exchanger and the phase change process of refrigerant R23. The accuracy of the model is proven by a comparison with the data in the references. Using this model the temperature field and gas volume fraction in the heat transfer process are obtained which is helpful to analyze the heat transfer mechanism. At the same time the influence of hydrogen inlet temperature hydrogen inlet pressure and refrigerant flow rate on the refrigeration performance was studied. The current work shows that the model can be used to determine the best working parameters in the pre-cooling process and reduce the operating cost of the hydrogen refueling station.

Hydrogen safety is an important topic for hydrogen energy application. Unintended hydrogen releases and combustions are potential accident scenarios which are of great interest for developing and updating the safety codes and standards. In this paper hydrogen releases and delayed ignitions were studied.

The concerns over food security and protein scarcity driven by population increase and higher standards of living have pushed scientists toward finding new protein sources. A considerable proportion of resources and agricultural lands are currently dedicated to proteinaceous feed production to raise livestock and poultry for human consumption. The 1st generation of microbial protein (MP) came into the market as land-independent proteinaceous feed for livestock and aquaculture. However MP may be a less sustainable alternative to conventional feeds such as soybean meal and fishmeal because this technology currently requires natural gas and synthetic chemicals. These challenges have directed researchers toward the production of 2nd generation MP by integrating renewable energies anaerobic digestion nutrient recovery biogas cleaning and upgrading carbon-capture technologies and fermentation. The fermentation of methane-oxidizing bacteria (MOB) and hydrogen-oxidizing bacteria (HOB) i.e. two protein rich microorganisms has shown a great potential on the one hand to upcycle effluents from anaerobic digestion into protein rich biomass and on the other hand to be coupled to renewable energy systems under the concept of Power-to-X. This work compares various production routes for 2nd generation MP by reviewing the latest studies conducted in this context and introducing the state-of-the-art technologies hoping that the findings can accelerate and facilitate upscaling of MP production. The results show that 2nd generation MP depends on the expansion of renewable energies. In countries with high penetration of renewable electricity such as Nordic countries off-peak surplus electricity can be used within MP-industry by supplying electrolytic H2 which is the driving factor for both MOB and HOB-based MP production. However nutrient recovery technologies are the heart of the 2nd generation MP industry as they determine the process costs and quality of the final product. Although huge attempts have been made to date in this context some bottlenecks such as immature nutrient recovery technologies less efficient fermenters with insufficient gas-to-liquid transfer and costly electrolytic hydrogen production and storage have hindered the scale up of MP production. Furthermore further research into techno-economic feasibility and life cycle assessment (LCA) of coupled technologies is still needed to identify key points for improvement and thereby secure a sustainable production system.

The construction of hydrogen refueling stations is an important part of the promotion of fuel cell vehicles. In this paper a multi-period hydrogen refueling station location model is presented that can be applied to the planning and construction of hydrogen infrastructures. Based on the hydrogen demand of fuel cell passenger cars and commercial vehicles the model calculates the hydrogen demand of each zone by a weighting method according to population economic level and education level. Then the hydrogen demand of each period is calculated using the generalized Bass diffusion model. Finally the set covering model is improved to determine the locations of the stations. The new model is applied to the scientific planning of hydrogen refueling stations in Jiading District Shanghai; the construction location and sequence of hydrogen refueling stations in each period are given and the growth trend of hydrogen demand and the promoting effect of hydrogen refueling stations are analyzed. The model adopted in this model is then compared with the other two kinds of node-based hydrogen refueling station location models that have previously been proposed.

Due to the simple structure and quick refueling process of the compressed hydrogen storage tank it is widely used in fuel cell vehicles at present. However temperature rise may lead to a safety problem during charging of a compressed hydrogen storage tank. To ensure the refueling safety the thermal effects need to be studied carefully during hydrogen refueling process. In this paper based on the mass and energy balance equations a general heat transfer model for refueling process of compressed hydrogen storage tank is established. According to the geometric model of the tank wall structure we have built three lumped parameter models: single-zone (hydrogen) dual-zone (hydrogen and tank wall) and triple-zone (hydrogen tank wall liner and shell) model. These three lumped parameter models are compared with U.S. Naval gas charging model and SAE MC method based refueling model. Under adiabatic and diathermic conditions four models are built in Matlab/Simulink software to simulate the hydrogen refueling process under corresponding conditions. These four models are: single-zone singletemperature (hydrogen) dual-zone single-temperature (hydrogen) dual-zone dual-temperature (hydrogen and tank wall temperatures) and triple-zone triple-temperature (hydrogen tank wall liner and tank wall shell temperatures). By comparing the analytical solution and numerical solution the temperature rise of the compressed hydrogen storage tank can be described. The analytical and numerical solutions on the heat transfer during hydrogen refueling process will provide theoretical guidance at actual refueling station so as to improve the refueling efficiency and to enhance the refueling safety.

In this review we primarily analyze the hydrogen production technologies based on water and biomass including the economic technological and environmental impacts of different types of hydrogen production technologies based on these materials and comprehensively compare them. Our analyses indicate that all renewable energy-based approaches for hydrogen production are more environmentally friendly than fossil-based hydrogen generation approaches. However the technical ease and economic efficiency of hydrogen production from renewable sources of energy needs to be further improved in order to be applied on a large scale. Compared with other renewable energy-based methods hydrogen production via biomass electrolysis has several advantages including the ease of directly using raw biomass. Furthermore its environmental impact is smaller than other approaches. Moreover using a noble metal catalyst-free anode for this approach can ensure a considerably low power consumption which makes it a promising candidate for clean and efficient hydrogen production in the future.

Previous studies have shown that the two-layer model more accurately predicts hydrogen dispersion than the conventional notional nozzle models without significantly increasing the computational expense. However the model was only validated for predicting the concentration distribution and has not been adequately validated for predicting the velocity distributions. In the present study particle imaging velocimetry (PIV) was used to measure the velocity field of an underexpanded hydrogen jet released at 10 bar from a 1.5 mm diameter orifice. The two-layer model was the used to calculate the inlet conditions for a two-dimensional axisymmetric CFD model to simulate the hydrogen jet downstream of the Mach disk. The predicted velocity spreading and centerline decay rates agreed well with the PIV measurements. The predicted concentration distribution was consistent with data from previous planar Rayleigh scattering measurements used to verify the concentration distribution predictions in an earlier study. The jet spreading was also simulated using several widely used notional nozzle models combined with the integral plume model for comparison. These results show that the velocity and concentration distributions are both better predicted by the two-layer model than the notional nozzle models to complement previous studies verifying only the predicted concentration profiles. Thus this study shows that the two-layer model can accurately predict the jet velocity distributions as well as the concentration distributions as verified earlier. Though more validation studies are needed to improve confidence in the model and increase the range of validity the present work indicates that the two-layer model is a promising tool for fast accurate predictions of the flow fields of underexpanded hydrogen jets.

The potential of catalytic pyrolysis of biomass for hydrogen and bio‐oil production has drawn great attention due to the concern of clean energy utilization and decarbonization. In this paper the catalytic pyrolysis of pine sawdust with calcined dolomite was carried out in a novel moving bed reactor with a two‐stage screw feeder. The effects of pyrolysis temperature (700–900 °C) and catalytic temperature (500–800 °C) on pyrolysis performance were investigated in product distribution gas composition and gas properties. The results showed that with the temperature increased pyrolysis gas yield in‐ creased but the yield of solid and liquid products decreased. With the increase in temperature the CO and H2 content increased significantly while the CO2 and CH4 decreased correspondingly. The calcined dolomite can remove the tar by 44% and increased syngas yield by 52.9%. With the increasing catalytic temperature the catalytic effect of calcined dolomite was also enhanced.

The Pr and Sm co-doped ceria (with up to 20 mol.% of dopants) compounds were examined as catalytic layers on the surface of SOFC anode directly fed by biogas to increase a lifetime and the efficiency of commercially available DIR-SOFC without the usage of an external reformer.

The XRD SEM and EDX methods were used to investigate the structural properties and the composition of fabricated materials. Furthermore the electrical properties of SOFCs with catalytic layers deposited on the Ni-YSZ anode were examined by a current density-time and current density-voltage dependence measurements in hydrogen (24 h) and biogas (90 h). Composition of the outlet gasses was in situ analysed by the FTIR-based unit.

It has been found out that Ce_0.9Sm_0.1O_2-δ and Ce_0.8Pr_0.05Sm_0.15O_2-δ catalytic layers show the highest stability over time and thus are the most attractive candidates as catalytic materials in comparison with other investigated lanthanide-doped ceria enhancing direct internal reforming of biogas in SOFCs.

The high energy consumption and production of undesired oxygen greatly restrict the wide adoption of water electrolysis for hydrogen production. In a paper recently published in Nature Catalysis Wang and coworkers rationally introduce aldehydes for oxidation at anode to replace oxygen evolution reaction which can produce hydrogen and value-added products at low potential realizing efficient bipolar hydrogen production with high-purity. Moreover these aldehydes are biomass-derived and contribute to sustainable hydrogen production

The increasing penetration of renewable and distributed resources signals a global boom in energy transition but traditional grid utilities have yet to share in much of the triumph at the current stage. Higher grid management costs lower electricity prices fewer customers and other challenges have emerged along the path toward renewable energy but many more opportunities await to be seized. Most importantly there are insufficient studies on how grid utilities can thrive within the hydrogen economy. Through a case study on the State Grid Corporation of China we identify the strengths weaknesses opportunities and threats (SWOT) of grid utilities within the hydrogen economy. Based on these factors we recommend that grids integrate hydrogen into the energy-as-a-service model and deliver it to industrial customers who are under decarbonization pressure. We also recommend that grid utilities fund a joint venture with pipeline companies to optimize electricity and hydrogen transmissions simultaneously.

Integrating the exergy and economic analyses of water electrolyzers is the pivotal way to comprehend the interplay of system costs and improve system performance. For this a 3D numerical model based on COMSOL Multiphysics Software (version 5.6 COMSOL Stockholm Sweden) is integrated with the exergy and exergoeconomic analysis to evaluate the exergoeconomic performance of the proton exchange membrane water electrolysis (PEMWE) under different operating conditions (operating temperature cathode pressure current density) and design parameter (membrane thickness). Further the gas crossover phenomenon is investigated to estimate the impact of gas leakage on analysis reliability under various conditions and criteria. The results reveal that increasing the operating temperature or decreasing the membrane thickness improves both the efficiency and cost of hydrogen exergy while increasing the gas leakage through the membrane. Likewise raising the current density and the cathode pressure lowers the hydrogen exergy cost and improves the economic performance. The increase in exergy destroyed and hydrogen exergy cost as well as the decline in second law efficiency due to the gas crossover are more noticeable at higher pressures. As the cathode pressure rises from 1 to 30 bar at a current density of 10000 A/m2 the increase in exergy destroyed and hydrogen exergy cost as well as the decline in second law efficiency are increased by 37.6 kJ/mol 4.49 USD/GJ and 7.1% respectively. The cheapest green electricity source which is achieved using onshore wind energy and hydropower reduces hydrogen production costs and enhances economic efficiency. The growth in the hydrogen exergy cost is by about 4.23 USD/GJ for a 0.01 USD/kWh increase in electricity price at the current density of 20000 A/m2. All findings would be expected to be quite useful for researchers engaged in the design development and optimization of PEMWE.

Wind curtailment and weak inertia characteristics are two factors that shackle the permeability of wind power. An electric hydrogen production device consumes electricity to produce hydrogen under normal working conditions to solve the problem of abandoning wind. When participating in frequency regulation it serves as a load reduction method to assist the system to rebuild a power balance and improve the wind power permeability. However due to its own working characteristics an electric hydrogen production device cannot undertake the high-frequency component of the frequency regulation power command; therefore an energy storage device was selected to undertake a high-frequency power command to assist the electric hydrogen production device to complete the system frequency regulation. This paper first proposes and analyzes the architecture of a wind storage hydrogen-generating station for centralized hydrogen production with a distributed energy storage and proposes the virtual inertia and droop characteristic mechanism of the wind storage hydrogen-generating station to simulate a synchronous unit. Secondly an alkaline electrolysis cell suitable for large-scale engineering applications is selected as the research object and its mathematical model is established the matching between different energy storage devices and their cooperation in power grid frequency regulation is analyzed and a super capacitor is selected. A control strategy for the wind storage hydrogen-generating power station to participate in power grid frequency regulation with a wide time scale is then proposed. Using the first-order low-pass filter the low-frequency component of the frequency regulation power command is realized by an electric hydrogen production device load reduction and a high-frequency component is realized by the energy storage device. Finally the effectiveness and rationality of the proposed control strategy are verified by establishing the simulation model of the wind storage hydrogen-generating power station with different initial wind speed states comparing the system frequency dip values under the proposed multi-energy cooperative control strategy and a single energy device control strategy.