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.