China, People’s Republic

The spinning process will lead to changes in the micro-structure and mechanical properties of the materials in different positions of the high-pressure hydrogen storage cylinder which will show different hydrogen embrittlement resistance in the high-pressure hydrogen environment. In order to fully study the safety of hydrogen storage in large-volume seamless steel cylinders this chapter associates the influence of the forming process with the deterioration of a high-pressure hydrogen cylinder (≥100 MPa). The anti-hydrogen embrittlement of SA-372 grade J steel at different locations of the formed cylinders was studied experimentally in three cylinders. The hydrogen embrittlement experiments were carried out according to method A of ISO 11114-4:2005. The relationship between tensile strength microstructure and hydrogen embrittlement is analyzed which provides comprehensive and reliable data for the safety of hydrogen storage and transmission.

The steel industry represents about 7% of the world’s anthropogenic CO2 emissions due to the high use of fossil fuels. The CO2 -lean direct reduction of iron ore with hydrogen is considered to offer a high potential to reduce CO2 emissions and this direct reduction of Fe2O3 powder is investigated in this research. The H2 reduction reaction kinetics and fluidization characteristics of fine and cohesive Fe2O3 particles were examined in a vibrated fluidized bed reactor. A smooth bubbling fluidization was achieved. An increase in external force due to vibration slightly increased the pressure drop. The minimum fluidization velocity was nearly independent of the operating temperature. The yield of the direct H2 -driven reduction was examined and found to exceed 90% with a maximum of 98% under the vibration of ~47 Hz with an amplitude of 0.6 mm and operating temperatures close to 500 ◦C. Towards the future of direct steel ore reduction cheap and “green” hydrogen sources need to be developed. H2 can be formed through various techniques with the catalytic decomposition of NH3 (and CH4 ) methanol and ethanol offering an important potential towards production cost yield and environmental CO2 emission reductions.

As a high-quality secondary energy hydrogen energy has great potential in energy storage and utilization. The development of power-to-hydrogen (P2H) technology has alleviated the problem of wind curtailment and improved the coupling between the power grid and the natural gas grid. Under the premise of ensuring safety using P2H technology to mix the produced hydrogen into the natural gas network for long-distance transmission and power generation can not only promote the development of hydrogen energy but also reduce carbon emissions. This paper presents a new model for incorporating hydrogen into natural gas pipelines. To minimize the sum of wind curtailment cost operation cost and carbon emission cost an electric–gas integrated energy system (EGIES) model of hydrogen-compressed natural gas (HCNG) containing P2H for power generation is constructed. Aiming at the problem of global warming caused by a lot of abandoned wind and carbon emissions the economy and environmental protection of the system model are analyzed. The results show that the model of EGIES considering HCNG can not only absorb excess wind power but also reduce carbon emission costs and system costs which can reduce the total cost of the environmental economic dispatch of the EGIES by about 34.1%. In the context of the EGIES the proposal of this model is of great significance to the economical and environmentally friendly operation of the system.

Water electrolysis based on solid oxide electrolysis cell (SOEC) exhibits high conversion efficiency due to part of energy demand can be derived from thermal energy. Therefore it can be integrated with other sources of thermal energy to reduce the consumption of electrical energy. In this paper a diesel engine is integrated with the SOEC stacks for heat recovery steam generator (HRSG). The thermal energy from the engine exhaust gas used to heat the inlet H2O of the SOEC is carried out as the integration case. A SOEC plant using electricity as the thermal heat input is selected as the base case. Thermodynamic analysis of the benchmark and integration scheme reveals that an electrical efficiency of 73.12% and 85.17% can be achieved respectively. The diesel to power efficiency can be increased to 70% when the exhaust gas is completely utilized by the SOEC system. The impacts of some key parameters including current density and operating temperature on system performance have also been conducted and found that the system has optimized parameters of current density and operating temperature to achieve better performance.

Hydrogen can alleviate the increasing environmental pollution and has good development prospects in power generation due to its high calorific value and low environmental impact. The previously designed hydrogen-fired combined cycle ignored water recycling which led to an inefficient application of hydrogen and the wastage of water. This paper proposes the concept of a hydrogen-fired combined cycle with water recovery to reuse the condensed water as an industrial heat supply. It was applied to an F-class combined cycle power plant. The results demonstrate that the efficiency of hydrogen-fired combined cycles with and without water recovery increased by 1.92% and 1.35% respectively compared to that of the natural-gas-fired combined cycle under full working conditions. In addition an economic comparison of the three cycles was conducted. The levelized cost of energy of the hydrogen-fired combined cycle with water recovery will be 52.22% lower than that of the natural-gas-fired combined cycle in 2050. This comparative study suggested that water recovery supplementation could improve the gas turbine efficiency. The proposed hydrogen-fired combined cycle with water recovery would provide both environmental and economic benefits.

The fishing sector is faced with emission problems arising from the extensive use of diesel engines as prime movers. Energy efficiency environmental performance and minimization of operative costs through the reduction of fuel consumption are key research topics across the whole maritime sector. Ship emissions can be determined at different levels of complexity and accuracy i.e. by analyzing ship technical data and assuming its operative profile or by direct measurements of key parameters. This paper deals with the analysis of the environmental footprint of a fishing trawler operating in the Adriatic Sea including three phases of the Life-Cycle Assessment (manufacturing Well-to-Pump (WTP) and Pump-to-Wake (PTW)). Based on the data on fuel consumption the viability of replacing the conventional diesel-powered system with alternative options is analyzed. The results showed that fuels such as LNG and B20 represent the easiest solution that would result in a reduction of harmful gases and have a positive impact on overall costs. Although electrification and hydrogen represent one of the cleanest forms of energy due to their high price and complex application in an obsolete fleet they do not present an optimal solution for the time being. The paper showed that the use of alternative fuels would have a positive effect on the reduction of harmful emissions but further work is needed to find an environmentally acceptable and economically profitable pathway for redesigning the ship power system of fishing trawlers.

Climate concerns require immediate actions to reduce the global average temperature increase. Renewable electricity and renewable energy-based fuels and chemicals are crucial for progressive de-fossilization. Hydrogen will be part of the solution. The main issues to be considered are the growing market for H2 and the “green” feedstock and energy that should be used to produce H2 . The electrolysis of water using surplus renewable energy is considered an important development. Alternative H2 production routes should be using “green” feedstock to replace fossil fuels. We firstly investigated these alternative routes through using bio-based methanol or ethanol or ammonia from digesting agro-industrial or domestic waste. The catalytic conversion of CH4 to C and H2 was examined as a possible option for decarbonizing the natural gas grid. Secondly water splitting by reversible redox reactions was examined but using a renewable energy supply was deemed necessary. The application of renewable heat or power was therefore investigated with a special focus on using concentrated solar tower (CST) technology. We finally assessed valorization data to provide a tentative view of the scale-up potential and economic aspects of the systems and determine the needs for future research and developments.

There exists no single optimal way for transporting hydrogen and other hydrogen carriers from one port to the other globally. Its delivery depends on several factors such as the quantity distance economics and the availability of the required infrastructure for its transportation. Europe has a strategy to invest in the production of green hydrogen in Africa to meet its needs. This study assessed the economic viability of shipping liquefied hydrogen (LH2 ) and hydrogen carriers to Germany from six African countries that have been identified as countries with great potential in the production of hydrogen. The results obtained suggest that the shipping of LH2 to Europe (Germany) will cost between 0.47 and 1.55 USD/kg H2 depending on the distance of travel for the ship. Similarly the transportation of hydrogen carriers could range from 0.19 to 0.55 USD/kg H2 for ammonia 0.25 to 0.77 USD/kg H2 for LNG 0.24 to 0.73 USD/kg H2 for methanol and 0.43 to 1.28 USD/kg H2 for liquid organic hydrogen carriers (LOHCs). Ammonia was found to be the ideal hydrogen carrier since it recorded the least transportation cost. A sensitivity analysis conducted indicates that an increase in the economic life by 5 years could averagely decrease the cost of LNG by some 13.9% NH3 by 13.2% methanol by 7.9% LOHC by 8.03% and LH2 by 12.41% under a constant distance of 6470 nautical miles. The study concludes with a suggestion that if both foreign and local participation in the development of the hydrogen market is increased in Africa the continent could supply LH2 and other hydrogen carriers to Europe at a cheaper price using clean fuel.

Unprecedented investments in clean energy technology are required for a net-zero carbon energy system before temperatures breach the Paris Agreement goals. By performing a Monte-Carlo Analysis with the detailed ETSAPTIAM Integrated Assessment Model and by generating 4000 scenarios of the world’s energy system climate and economy we find that the uncertainty surrounding technology costs resource potentials climate sensitivity and the level of decoupling between energy demands and economic growth influence the efficiency of climate policies and accentuate investment risks in clean energy technologies. Contrary to other studies relying on exploring the uncertainty space via model intercomparison we find that the CO2 emissions and CO2 prices vary convexly and nonlinearly with the discount rate and climate sensitivity over time. Accounting for this uncertainty is important for designing climate policies and carbon prices to accelerate the transition. In 70% of the scenarios a 1.5 ◦C temperature overshoot was within this decade calling for immediate policy action. Delaying this action by ten years may result in 2 ◦C mitigation costs being similar to those required to reach the 1.5 ◦C target if started today with an immediate peak in emissions a larger uncertainty in the medium-term horizon and a higher effort for net-zero emissions.

H2 is clean energy and an important component of natural gas. Moreover it plays an irreplaceable role in improving the hydrocarbon generation rate of organic matter and activating ancient source rocks to generate hydrocarbon in Fischer-Tropsch (FT) synthesis and catalytic hydrogenation. Compared with hydrocarbon reservoir system a complete hydrogen (H2) accumulation system consists of H2 source，reservoirs and seal. In nature the four main sources of H2 are hydrolysis organic matter degradation the decomposition of substances such as methane and ammonia and deep mantle degassing. Because the complex tectonic activities the H2 produced in a geological environment is generally a mixture of various sources. Compared with the genetic mechanisms of H2 the migration and preservation of H2 especially the H2 trapping are rarely studied. A necessary condition for large-scale H2 accumulation is that the speed of H2 charge is much faster than diffusion loss. Dense cap rock and continuous H2 supply are favorable for H2 accumulation. Moreover H2O in the cap rock pores may provide favorable conditions for short-term H2 accumulation.

Green hydrogen produced by water electrolysis is one of the most promising technologies to realize the efficient utilization of intermittent renewable energy and the decarbonizing future. Among various electrolysis technologies the emerging anion-exchange membrane water electrolysis (AEMWE) shows the most potential for producing green hydrogen at a competitive price. In this review we demonstrate a comprehensive introduction to AEMWE including the advanced electrode design the lab-scaled testing system establishment and the electrochemical performance evaluation. Specifically recent progress in developing high activity transition metal-based powder electrocatalysts and self-supporting electrodes for AEMWE is summarized. To improve the synergistic transfer behaviors between electron charge water and gas inside the gas diffusion electrode (GDE) two optimizing strategies are concluded by regulating the pore structure and interfacial chemistry. Moreover we provide a detailed guideline for establishing the AEMWE testing system and selecting the electrolyzer components. The influences of the membrane electrode assembly (MEA) technologies and operation conditions on cell performance are also discussed. Besides diverse electrochemical methods to evaluate the activity and stability implement the failure analyses and realize the in-situ characterizations are elaborated. In end some perspectives about the optimization of interfacial environment and cost assessments have been proposed for the development of advanced and durable AEMWE.

High-accuracy gas dispersion models are necessary for predicting hydrogen movement and for reducing the damage caused by hydrogen release accidents in chemical processes. In urban areas where obstacles are large and abundant computational fluid dynamics (CFD) would be the best choice for simulating and analyzing scenarios of the accidental release of hydrogen. However owing to the large computation time required for CFD simulation it is inappropriate in emergencies and real-time alarm systems. In this study a non-linear surrogate model based on deep learning is proposed. Deep convolutional layer data-driven autoencoder and batch normalized deep neural network is used to analyze the effects of wind speed wind direction and release degree on hydrogen concentration in real-time. The typical parameters of hydrogen diffusion accidents at hydrogen refuelling stations were acquired by CFD numerical simulation approach and a database of hydrogen diffusion accident parameters is established. By establishing an appropriate neural network structure and associated activation function a deep learning framework is created and then a deep learning model is constructed. The accuracy and timeliness of the model are assessed by comparing the results of the CFD simulation with those of the deep learning model. To develop a dynamic reconfiguration prediction model for the hydrogen refuelling station diffusion scenario the algorithm is continuously enhanced and the model is improved. After training is finished the model's prediction time is measured in seconds which is 105 times quicker than field CFD simulations. The deep learning model of hydrogen release in hydrogen refuelling stations is established to realize timely and accurate prediction and simulation of accident consequences and provide decision-making suggestions for emergency rescue and personnel evacuation which is of great significance for the protection of human life health and property safety.

Low-carbon hydrogen could be an important component of a net-zero carbon economy helping to mitigate emissions in a number of hard-to-abate sectors. The United States recently introduced an escalating production tax credit (PTC) to incentivize production of hydrogen meeting increasingly stringent embodied emissions thresholds. Hydrogen produced via electrolysis can qualify for the full subsidy under current federal accounting standards if the input electricity is generated by carbon-free resources but may fail to do so if emitting resources are present in the generation mix. While use of behind-the-meter carbon-free electricity inputs can guarantee compliance with this standard the PTC could also be structured to allow producers using grid-supplied electricity to qualify subject to certain clean energy procurement requirements. Herein we use electricity system capacity expansion modeling to quantitatively assess the impact of grid-connected electrolysis on the evolution of the power sector in the western United States through 2030 under multiple possible implementations of the clean hydrogen PTC. We find that subsidized grid-connected hydrogen production has the potential to induce additional emissions at effective rates worse than those of conventional fossil-based hydrogen production pathways. Emissions can be minimized by requiring grid-based hydrogen producers to match 100% of their electricity consumption on an hourly basis with physically deliverable ‘additional’ clean generation which ensures effective emissions rates equivalent to electrolysis exclusively supplied by behind-the-meter carbon-free generation. While these requirements cannot eliminate indirect emissions caused by competition for limited clean resources which we find to be a persistent result of large hydrogen production subsidies they consistently outperform alternative approaches relying on relaxed time matching or marginal emissions accounting. Added hydrogen production costs from enforcing an hourly matching requirement rather than no requirements are less than $1 kg−1 and can be near zero if clean firm electricity resources are available for procurement.

Wind-solar hybrid hydrogen production is an effective technique route by converting the fluctuate renewable electricity into high-quality hydrogen. However the intermittency of wind and solar resources also exert chal lenges to the efficient hydrogen production. In order to address this issue this paper developed a day-ahead scheduling strategy based on multi-state transitions of the alkaline electrolyzer(AEL) which improves system flexibility by coordinating the operation of the electrolyzer with the battery. Meanwhile K-means+ + algorithm is also applied to scenario clustering and then proposed a capacity configuration method. Based on the adopted case study the wind-solar installed capacity of the designed hydrogen production system it first optimized and the power fluctuation is mitigated with the complementarity index considering volatility of 12.49%. Moreover the adopted scheduling strategy effectively reduces idle and standby states of the electrolyzer with the daily average energy utilization rate of 12 typical scenarios reaching 92.83%. In addition the wind-solar hydrogen system exhibits favorable economic potential the internal return rate and the investment payback period reach to 6.81% and 12.87 years respectively. This research provides valuable insights for efficiently producing hydrogen using renewable energy sources and promoting their synergistic operation.

With the development of energy integration technology demand response (DR) has gradually evolved into integrated demand response (IDR). In this study for the integrated energy system (IES) on the distribution grid side with electricity heat natural gas network and hydrogen energy equipment the analogy relationship between the thermal and mobile hydrogen energy storage networks is proposed. Moreover a unified model that reflects network commonalities across different energy forms is established. Then considering the time delay of the IES in the nontransient network a time-domain two-port model of the IES considering the time delay is established. This model shows the joint effect of time and space on system parameters. Finally this study validates the model in the application of DR. The verification results show that in DR the time-domain two-port model can accurately “cut peaks and fill valleys” for the IES and effectively reduce the operating cost of the IES system.

Currently the periodic inspection of composite tanks is typically achieved via hydrostatic test combined with internal and external visual inspections. Acoustic emission (AE) technology demonstrates a promising non destructive testing method for damage mode identification and damage assessment. This study focuses on AE signals characteristics and evolution behaviours for used 70 MPa Type IV hydrogen storage tanks during hydrostatic burst tests. AE-based tensile tests for epoxy resin specimen and carbon fiber tow were implemented to obtain characteristics of matrix cracking and fiber breakage. Then broadband AE sensors were used to capture AE signals during multi-step loading tests and hydrostatic burst tests. K-means ++ algorithm and wavelet packet transform are performed to cluster AE signals and verify the validity. Combining with tensile tests three clusters are manifested via matrix cracking fiber/matrix debonding and fiber breakage according to amplitude duration counts and absolute energy. The number of three clustering signals increases with the increase of pressure showing accumulated and aggravated damage. The sudden appearance of a large number of fiber breakage signals during hydrostatic burst tests suggests that the composite tank structure is becoming mechanically unstable namely the impending burst failure of the tank.

The synthesis of low-cost and highly active electrodes for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is very important for water splitting. In this work the novel amorphous iron-nickel phosphide (FeP-Ni) nanocone arrays as efficient bifunctional electrodes for overall water splitting have been in-situ assembled on conductive three-dimensional (3D) Ni foam via a facile and mild liquid deposition process. It is found that the FeP-Ni electrode demonstrates highly efficient electrocatalytic performance toward overall water splitting. In 1 M KOH electrolyte the optimal FeP-Ni electrode drives a current density of 10 mA/cm2 at an overpotential of 218 mV for the OER and 120 mV for the HER and can attain such current density for 25 h without performance regression. Moreover a two-electrode electrolyzer comprising the FeP-Ni electrodes can afford 10 mA/cm2 electrolysis current at a low cell voltage of 1.62 V and maintain long-term stability as well as superior to that of the coupled RuO2/NF‖Pt/C/NF cell. Detailed characterizations confirm that the excellent electrocatalytic performances for water splitting are attributed to the unique 3D morphology of nanocone arrays which could expose more surface active sites facilitate electrolyte diffusion benefit charge transfer and also favorable bubble detachment behavior. Our work presents a facile and cost-effective pathway to design and develop active self-supported electrodes with novel 3D morphology for water electrolysis.

A potential enabler of a low carbon economy is the energy vector hydrogen. However issues associated with hydrogen storage and distribution are currently a barrier for its implementation. Hence other indirect storage media such as ammonia and methanol are currently being considered. Of these ammonia is a carbon free carrier which offers high energy density; higher than compressed air. Hence it is proposed that ammonia with its established transportation network and high flexibility could provide a practical next generation system for energy transportation storage and use for power generation. Therefore this review highlights previous influential studies and ongoing research to use this chemical as a viable energy vector for power applications emphasizing the challenges that each of the reviewed technologies faces before implementation and commercial deployment is achieved at a larger scale. The review covers technologies such as ammonia in cycles either for power or CO₂ removal fuel cells reciprocating engines gas turbines and propulsion technologies with emphasis on the challenges of using the molecule and current understanding of the fundamental combustion patterns of ammonia blends.

For commercial applications the durability and economy of the fuel cell hybrid system have become obstacles to be overcome which are not only affected by the performance of core materials and components but also closely related to the energy management strategy (EMS). This paper takes the 7.9 t fuel cell logistics vehicle as the research object and designed the EMS from two levels of qualitative and quantitative analysis which are the composite fuzzy control strategy optimized by genetic algorithm and Pontryagin’s minimum principle (PMP) optimized by objective function respectively. The cost function was constructed and used as the optimization objective to prolong the life of the power system as much as possible on the premise of ensuring the fuel economy. The results indicate that the optimized PMP showed a comprehensive optimal performance the hydrogen consumption was 3.481 kg/100 km and the cost was 13.042 $/h. The major contribution lies in that this paper presents a method to evaluate the effect of different strategies on vehicle performance including fuel economy and durability of the fuel cell and battery. The comparison between the two totally different strategies helps to find a better and effective solution to reduce the lifetime cost.

The widespread penetration of hydrogen in mainstream energy systems requires hydrogen production processes to be economically competent and environmentally efficient. Hydrogen if produced efficiently can play a pivotal role in decarbonizing the global energy systems. Therefore this study develops a framework which evaluates hydrogen production processes and quantifies deficiencies for improvement. The framework integrates slack-based data envelopment analysis (DEA) with fuzzy analytical hierarchy process (FAHP) and fuzzy technique for order of preference by similarity to ideal solution (FTOPSIS). The proposed framework is applied to prioritize the most efficient and sustainable hydrogen production in Pakistan. Eleven hydrogen production alternatives were analyzed under five criteria including capital cost feedstock cost O&M cost hydrogen production and CO2 emission. FAHP obtained the initial weights of criteria while FTOPSIS determined the ultimate weights of criteria for each alternative. Finally slack-based DEA computed the efficiency of alternatives. Among the 11 three alternatives (wind electrolysis PV electrolysis and biomass gasification) were found to be fully efficient and therefore can be considered as sustainable options for hydrogen production in Pakistan. The rest of the eight alternatives achieved poor efficiency scores and thus are not recommended.

In this work a low-temperature symmetrical solid oxide fuel cell with Ni-NCAL|SDC/NCAL|Ni-NCAL (70 SDC:30 NCAL) configuration was successfully constructed by a simple dry press method. At 500 and 550 ◦C the peak power densities of the cell in ammonia were 501 and 755 mW cm− 2 and in hydrogen were 670 and 895 mW cm− 2 respectively. EIS data showed that the Rp values of the cell in ammonia and hydrogen at 550 ◦C were 0.250 and 0.246 Ω cm− 2 respectively indicating the excellent catalytic activity of the Ni-NCAL electrode toward ammonia decomposition and hydrogen oxidation. The different cell output can be ascribed to additional ammonia decomposition steps compared to hydrogen. The noticeable reaction product on the surface of the Ni foam was detrimental to ammonia decomposition. In summary a symmetrical cell with SDC/NCAL semi-conductor electrolyte and Ni-NCAL electrodes exhibited higher electrochemical performance at low temperature than the results reported to date. Therefore higher electrochemical performance can be expected from this cell configuration with more efficient ammonia decomposition catalysts.

Herein the hydrogen embrittlement of a heat-affected zone (HAZ) was examined using slow strain rate tension in situ hydrogen charging. The influence of hydrogen on the crack path of the HAZ sample surfaces was determined using electron back scatter diffraction analysis. The hydrogen embrittlement susceptibility of the base metal and the HAZ samples increased with increasing current density. The HAZ samples have lower resistance to hydrogen embrittlement than the base metal samples in the same current density. Brittle circumferential cracks located at the HAZ sample surfaces were perpendicular to the loading direction and the crack propagation path indicated that five or more cracks may join together to form a longer crack. The fracture morphologies were found to be a mixture of intergranular and transgranular fractures. Hydrogen blisters were observed on the HAZ sample surfaces after conducting tensile tests at a current density of 40 mA/cm2 leading to a fracture in the elastic deformation stage.

Photocatalytic hydrogen generation is one of the most promising solutions to convert solar power into green chemical energy. In this work a multi-component TiO₂–Ag–Cu₂O composite was obtained through simple impregnation-calcination of Cu₂O and subsequent photodeposition of Ag onto electrospun TiO₂ nanotubes. The resulting TiO₂–Ag–Cu₂O photocatalyst exhibits excellent photocatalytic H₂ evolution activity due to the synergetic effect of Ag and Cu₂O on electrospun TiO₂nanotubes. A dual Z-scheme charge transfer pathway for photocatalytic reactions over TiO₂–Ag–Cu₂O composite was proposed and discussed. This work provides a prototype for designing Z-scheme photocatalyst with Ag as an electron mediator.

Hydrogen separation through oxygen transport membranes (OTMs) has attracted much attention. Asymmetric membranes with thin dense layers provide low bulk diffusion resistances and high overall hydrogen separation performances. However the resistance in the porous support layer (PSL) limits the overall separation performance significantly. Engineering the structure of the PSL is an appropriate way to enable fast gas transport and increase the separation performance. There is no relevant research on studying the influence of the PSL on hydrogen separation performance so far. Herein we prepared Ce_0.85Sm_0.15O_1.925 – Sm_0.6Sr_0.4Cr_0.3Fe_0.7O_3-δ (SDC-SSCF) asymmetric membranes with straight grooves in PSL by tape-casting and laser grooving. A ~30% improvement in the hydrogen separation rate was achieved by grooving in the PSLs. It indicates that the grooves may reduce the concentration polarization resistance in PSL for the hydrogen separation process. This work provides a straight evidence on optimizing the structures of PSL for improving the hydrogen separation performance of the membrane reactors.

Implementation of non-precious electrocatalysts is key-enabling for water electrolysis to relieve challenges in energy and environmental sustainability. Self-supporting Ni-V₂O₃.electrodes consisting of nanostrip-like V₂O₃.perpendicularly anchored on Ni meshes are herein constructed via the electrochemical reduction of soluble NaVO₃ in molten salts for enhanced electrocatalytic hydrogen evolution. Such a special configuration in morphology and composition creates a well confined interface between Ni and V₂O₃. Experimental and Density-Functional-Theory results confirm that the synergy between Ni and V₂O₃.accelerates the dissociation of H₂O for forming hydrogen intermediates and enhances the combination of H* for generating H₂.

The effects of hot stamping (HS) and tempering on the hydrogen embrittlement (HE) behavior of a low-carbon boron-alloyed steel were studied by using slow strain rate tensile (SSRT) tests on notched sheet specimens. It was found that an additional significant hydrogen desorption peak at round 65–80 °C appeared after hydrogen-charging the corresponding hydrogen concentration (CHr) of the HS specimen was higher than that of the directed quenched (DQ) specimen and subsequent low-temperature tempering gave rise to a decrease of CHr. The DQ specimen exhibited a comparatively high HE susceptibility while tempering treatment at 100 °C could notably alleviate it by a relative decrease of ~24% at no expanse of strength and ductility. The HS specimen demonstrated much lower HE susceptibility compared with the DQ specimen and tempering at 200 °C could further alleviate its HE susceptibility. SEM analysis of fractured SSRT surfaces revealed that the DQ specimen showed a mixed transgranular-intergranular fracture while the HS and low-temperature tempered specimens exhibited a predominant quasi-cleavage transgranular fracture. Based on the obtained results we propose that a modified HS process coupled with low-temperature tempering treatment is a promising and feasible approach to ensure a low HE susceptibility for high-strength automobile parts made of this type of steel.

Solid oxide fuel cells (SOFCs) produce electricity with high electrical efficiency and fuel flexibility without pollution for example CO₂ NO_x SO_x and particles. Still numerous issues hindered the large‐scale commercialization of fuel cell at a large scale such as fuel storage mechanical failure catalytic degradation electrode poisoning from fuel and air for example lifetime in relation to cost. Computational fluid dynamics (CFD) couples various physical fields which is vital to reduce the redundant workload required for SOFC development. Modeling of SOFCs includes the coupling of charge transfer electrochemical reactions fluid flow energy transport and species transport. The Butler‐Volmer equation is frequently used to describe the coupling of electrochemical reactions with current density. The most frequently used is the activation‐ and diffusion‐controlled Butler‐Volmer equation. Three different electrode reaction models are examined in the study which is named case 1 case 2 and case 3 respectively. Case 1 is activation controlled while cases 2 and 3 are diffusion‐controlled which take the concentration of redox species into account. It is shown that case 1 gives the highest reaction rate followed by case 2 and case 3. Case 3 gives the lowest reaction rate and thus has a much lower current density and temperature. The change of activation overpotential does not follow the change of current density and temperature at the interface of the anode and electrolyte and interface of cathode and electrolyte which demonstrates the non‐linearity of the model. This study provides a reference to build electrochemical models of SOFCs and gives a deep understanding of the involved electrochemistry.

The development of hydrogen-blended natural gas (HBNG) increases the risk of gas transportation and presents challenges for pipeline security in utility tunnels. The objective of this study is to investigate the diffusion properties of HBNG in utility tunnels and evaluate the effectiveness of various ventilation mechanisms. The numerical simulation software Fluent 2023 R1 is applied to simulate and analyze the leakage of small holes in a HBNG pipeline in the natural gas compartment. By examining the leaking behavior of HBNG through small holes in different circumstances we aimed to identify the most unfavorable operational situation for leakage. Subsequently we analyzed the ventilation strategy for sub-high-pressure pipes at various pressure levels in this unfavorable condition. This study’s findings demonstrate that blending hydrogen improves the gas diffusion capacity and increases the likelihood of explosion. The primary factors that influence the pattern of leakage are the size of the leaking holes and the pressure of the pipeline. The gas compartment experiences the most unfavorable working conditions for natural gas pipeline leaks when there are higher pressures wider leak openings higher hydrogen blending ratios (HBRs) and leaks in close proximity to an air inlet. When the HBR is 20% the minimum accident ventilation rates for pressures of 0.4 MPa and 0.8 MPa are 15 air changes per hour and 21 air changes per hour respectively. The maximum allowable wind speed for accident ventilation is 5 m/s as regulated by China’s national standard GB 50838-2015. This regulation makes it difficult to minimize the risk of leakage in a 1.6 MPa gas pipeline. It is recommended to install a safety interlock device to quickly shut off the pipeline in the event of a leak in order to facilitate the dispersion of the substance.

A new integrated energy system (IES) framework is created in order to encourage the consumption of renewable energy which is represented by wind and solar energy and lower carbon emissions. The connection between the units in the composite system is examined in this research. In-depth analysis is done on how energy is transferred between electricity heat gas and hydrogen. The system model and constraints are used to build an objective function with the lowest total operating cost. The calculation of carbon trading includes the ladder carbon trading method. And set up 6 cases for analysis which verifies the effectiveness of the participation of the concentrated solar power plant (CSPP) in the heat supply and power to hydrogen system (P2HS) in reducing the total operating cost of the system reducing wind curtailment and light curtailment and reducing carbon emissions. Under the model considered in this paper reduces the total operating cost reduces by 27.04% when the concentrated solar power plant is involved in the supply of thermal load. And the carbon emission is reduced by 14.529%. Compared with the traditional power to gas considers the power to hydrogen system in this paper which reduces the total operating cost by 4.79%.

With the proposal of China’s green energy strategy the research and development technologies of green energy such as wind energy and hydrogen energy are becoming more and more mature. However the phenomenon of wind abandonment and anti-peak shaving characteristics of wind turbines have a great impact on the utilization of wind energy. Therefore this study firstly builds a distributed wind-hydrogen hybrid energy system model then proposes the power dispatching optimization technology of a wind-hydrogen integrated energy system. On this basis a power allocation method based on the AUKF (adaptive unscented Kalman filter) algorithm is proposed. The experiment shows that the power allocation strategy based on the AUKF algorithm can effectively reduce the incidence of battery overcharge and overdischarge. Moreover it can effectively deal with rapid changes in wind speed. The wind hydrogen integrated energy system proposed in this study is one of the important topics of renewable clean energy technology innovation. Its grid-connected power is stable with good controllability and the DC bus is more secure and stable. Compared with previous studies the system developed in this study has effectively reduced the ratio of abandoned air and its performance is significantly better than the system with separate grid connected fans and single hydrogen energy storage. It is hoped that this research can provide some solutions for the research work on power dispatching optimization of energy systems.

In this paper based on the operating states and characteristics of fuel cell/supercapacitor hybrid trams an optimal hydrogen energy management method is proposed. This method divides the operating states into two parts: traction state and non-traction state. In the traction state the real-time loss function of the hybrid power system which is used to obtain the fuel cell optimal output power under the different demand powers and supercapacitor voltage is established. In the non-traction state the constant-power charging method which is obtained by solving the power-voltage charging model is used to ensure the supercapacitor voltage of the beginning-state and the end-state in an entire operation cycle are the same. The RT-LAB simulation platform is used to verify that the proposed method has the ability to control the hybrid real-time system. Using the comparative experiment between the proposed method and power-follow method the results show that the proposed method offers a significant improvement in both fuel cell output stability and hydrogen consumption in a full operation cycle.

Hydrogen has the physical and chemical characteristics of being flammable explosive and prone to leakage and its safety is the main issue faced by the promotion of hydrogen as an energy source. The most common scene in vehicle application is the longitudinal wind generated by driving and the original position of hydrogen concentration sensors (HCSs) did not consider the influence of longitudinal wind on the hydrogen leakage trajectory. In this paper the computational fluid dynamics (CFD) software STAR CCM 2021.1 is used to simulate the hydrogen leakage and diffusion trajectories of fuel cell vehicles (FCVs) at five different leakage locations the longitudinal wind speeds of 0 km/h 37.18 km/h and 114 km/h and it is concluded that longitudinal wind prolongs the diffusion time of hydrogen to the headspace and reduces the coverage area of hydrogen in the headspace with a decrease of 81.35%. In order to achieve a good detection effect of fuel cell vehicles within the longitudinal wind scene based on the simulated hydrogen concentration–time matrix the scene clustering method based on vector similarity evaluation was used to reduce the leakage scene set by 33%. Then the layout position of HCSs was optimized according to the proposed multi-scene full coverage response time minimization model and the response time was reduced from 5 s to 1 s.

With the urbanization construction and the advancement of the carbon peaking and carbon neutrality goals urban energy systems are characterized by coupling multi-energy networks and a high proportion of renewable energy. Urban energy systems need to improve the quality of energy use as well as to achieve energy conservation and emission reduction. Inter-seasonal heat technology has satisfactory engineering application prospects in promoting renewable energy consumption and the energy supply of urban multi-energy systems. Considering inter-seasonal heat storage and electric hydrogen production a joint optimization method of planning and operation is proposed for the urban multi-energy flow system. First the operation framework of inter-seasonal heat storage and electric hydrogen production system is established which clarifies the energy flow of the urban multi-energy system. Secondly aiming at the goals of minimizing the equipment’s annual investment cost and the multi-energy system annual operation cost combined with the time series period division method a planning operation model has been established considering multi-objectives. Through case study it is shown that the proposed model can promote the renewable energy consumption and reduce the operation cost of the whole system.

As a clean and renewable energy source for sustainable development hydrogen energy has gained a lot of attention from the general public and researchers. Hydrogen production by electrolysis of water is the most important approach to producing hydrogen and it is also the main way to realize carbon neutrality. In this paper the main technologies of hydrogen production by electrolysis of water are discussed in detail; their characteristics advantages and disadvantages are analyzed; and the selection criteria and design criteria of catalysts are presented. The catalysts used in various hydrogen production technologies and their characteristics are emphatically expounded aiming at optimizing the existing catalyst system and developing new high-performance high-stability and low-cost catalysts. Finally the problems and solutions in the practical design of catalysts are discussed and explored.

The hydrogen supply system is one of the important components of a hydrogen fuel cell engine and its performance has an important impact on the economy and power of the engine system. In this paper a hydrogen supply system based on cyclic mode is designed for a hydrogen fuel cell stack with a full load power of 150 kW and the corresponding hydrogen fuel cell engine simulation model is built and validated. The control strategy of the fuel cell hydrogen supply system is developed and its effect is verified through bench tests. The results show that the developed control strategy can keep the volume fraction of nitrogen below 6% the hydrogen excess ratio does not exceed 1.5 under medium and high operating conditions the anode pressure is relatively stable and the stack can operate efficiently and reliably.

In recent years sustainable development has become a challenge for many societies due to natural or other disruptive events which have disrupted economic environmental and energy infrastructure growth. Developing hydrogen energy infrastructure is crucial for sustainable development because of its numerous benefits over conventional energy sources. However the complexity of hydrogen energy infrastructure including production utilization and storage stages requires accounting for potential vulnerabilities. Therefore resilience needs to be considered along with sustainable development. This paper proposes a decision-making framework to evaluate the resilience of hydrogen energy infrastructure by integrating resilience indicators and sustainability contributing factors. A holistic taxonomy of resilience performance is first developed followed by a qualitative resilience assessment framework using a novel Intuitionistic fuzzy Weighted Influence Nonlinear Gauge System (IFWINGS). The results highlighted that Regulation and legislation Government preparation and Crisis response budget are the most critical resilience indicators in the understudy hydrogen energy infrastructure. A comparative case study demonstrates the practicality capability and effectiveness of the proposed approach. The results suggest that the proposed model can be used for resilience assessment in other areas.

With the development of the hydrogen fuel automobile industry higher requirements are put forward for the construction of hydrogen energy infrastructure the matching of parameters and the control strategy of hydrogen filling rate in the hydrogen charging process of hydrogen refueling stations. At present the technological difficulty of hydrogen fueling is mainly reflected in the balanced treatment of reducing the temperature rise of hydrogen and shortening the filling time during the fast filling process. Vehicle hydrogen storage cylinder (VHSC) is one of the important components of hydrogen fuel cell vehicles. This study proposed a theoretical model for calculating the temperature rise in the VHSC during the high pressure refueling process and revealed the hydrogen temperature rise during refueling. A hydrogen temperature rise prediction model was constructed to elucidate the relationship between filling parameters and temperature rise. The filling process of VHSC was analyzed from the theoretical method. The theoretical analysis results were consistent with the simulation and experimental analysis results which provided a theoretical basis for the current hydrogen temperature control algorithm of the gas source in the hydrogen refueling station and then reduced the energy consumption required for hydrogen cooling in the hydrogen refueling station.

In order to improve the consumption of renewable energy and reduce the carbon emissions of integrated energy systems (IESs) this paper proposes an optimal operation strategy for an integrated energy system considering the coordination of electricity and hydrogen in the context of carbon trading. The strategy makes full use of the traditional power-to-gas hydrogen production process and establishes a coupling model comprising cogeneration and carbon capture equipment an electrolytic cell a methane reactor and a hydrogen fuel cell. Taking a minimum daily operating cost and minimal carbon emissions from the system as objective functions a mixed-integer nonlinear optimal scheduling model is established. This paper designs examples based on MATLAB R2021b and uses the GUROBI solver to solve them. The results show that compared with the traditional two-stage operation process the optimization method can reduce the daily operation cost of an IES by 26.01% and its carbon emissions by 90.32%. The results show that the operation mode of electro-hydrogen synergy can significantly reduce the carbon emissions of the system and realize a two-way flow of electro-hydrogen energy. At the same time the addition of carbon capture equipment and the realization of carbon recycling prove the scheduling strategy’s ability to achieve a lowcarbon economy of the scheduling strategy.

Hydrogen-based multi-microgrid systems (HBMMSs) are beneficial for energy saving and emission reductions. However the optimal sizing of HBMMSs lacks a practical configuration optimization model and a reasonable solution method. To address these problems we designed a novel structure of HBMMSs that combines conventional energy renewable energy and a hydrogen energy subsystem. Then we established a bi-level multi-objective capacity optimization model while considering electricity market trading and different hydrogen production strategies. The objective of the inner model which is the minimum annual operation cost and the three objectives of the outer model which are the minimum total annual cost (TAC); the annual carbon emission (ACE); and the maximum self-sufficiency rate (SSR) are researched simultaneously. To solve the above optimization model a two-stage solution method which considers the conflicts between objectives and the objectivity of objective weights is proposed. Finally a case study is performed. The results show that when green hydrogen production strategies are adopted the three objectives of the best configuration optimization scheme are USD 404.987 million 1.106 million tons and 0.486 respectively.

Liquid hydrogen is one of the high-quality energy carriers but a large leak of liquid hydrogen can pose significant safety risks. Understanding its diffusion law after accidental leakage is an important issue for the safe utilization of hydrogen energy. In this paper a series of open-space large-volume liquid hydrogen release experiments are performed to observe the evolution of visible clouds during the release and an array of hydrogen concentration sensors is set up to monitor the fluctuation in hydrogen concentration at different locations. Based on the experimental conditions the diffusion of hydrogen clouds in the atmosphere under different release hole diameters and different ground materials is compared. The results show that with the release of liquid hydrogen the white visible cloud formed by air condensation or solidification is generated rapidly and spread widely and the visible cloud is most obvious near the ground. With the termination of liquid hydrogen release solid air is deposited on the ground and the visible clouds gradually shrink from the far field to the release source. Hydrogen concentration fluctuations in the far field in the case of the cobblestone ground are more dependent on spontaneous diffusion by the hydrogen concentration gradient. In addition compared with the concrete ground the cobblestone ground has greater resistance to liquid hydrogen extension; the diffusion of hydrogen clouds to the far field lags. The rapid increase stage of hydrogen concentration at N8 in Test 7 lags about 3 s behind N12 in Test 6 N3 lags about 7.5 s behind N1 and N16 lags about 8.25 s behind N14. The near-source space is prone to high-concentration hydrogen clouds. The duration of the high-concentration hydrogen cloud at N12 is about 15 s which is twice as long as the duration at N8 increasing the safety risk of the near-source space.

Reactor structure design plays an important role in the performance of solar-thermal methane reforming reactors. Based on a conventional preheating reactor this study proposed a cylindrical solar methane reforming reactor with multiple inlets to vary the temperature field distribution which improved the temperature of the reaction region in the reactor thereby improving the reactor performance. A multi-physical model that considers mass momentum species and energy conservation as well as thermochemical reaction kinetics of methane reforming was applied to numerically investigate the reactor performance and analyze the factors that affect performance improvement. It was found that compared with a conventional preheating reactor the proposed cylindrical reactor with inner and external inlets for gas feeding enhanced heat recovery from the exhausted gas and provided a more suitable temperature field for the reaction in the reactor. Under different operating conditions the methane conversion in the cylindrical reactor with multi-inlet increased by 9.5% to 19.1% and the hydrogen production was enhanced by 12.1% to 40.3% in comparison with the conventional design even though the total reaction catalyst volume was reduced.

A significant effort is required to reduce China’s dependency on fossil fuels while also supporting worldwide efforts to reduce climate change and develop hydrogen energy systems. A hydrogen economy must include renewable energy sources (RESs) which can offer a clean and sustainable energy source for producing hydrogen. This study uses an integrated fuzzy AHP–fuzzy TOPSIS method to evaluate and rank renewable energy sources for developing a hydrogen economy in China. This is a novel approach because it can capture the uncertainty and vagueness in the decision-making process and provide a comprehensive and robust evaluation of the alternatives. Moreover it considers multiple criteria and sub-criteria that reflect the environmental economic technical social and political aspects of RESs from the perspective of a hydrogen economy. This study identified five major criteria fifteen sub-criteria and six RES alternatives for hydrogen production. This integrated approach uses fuzzy AHP to evaluate and rank the criteria and sub-criteria and fuzzy TOPSIS to identify the most suitable and feasible RES. The results show that environmental economic and technical criteria are the most important criteria. Solar wind and hydropower are the top three RES alternatives that are most suitable and feasible. Furthermore biomass geo-thermal and tidal energy were ranked lower which might be due to the limitations and challenges in their adoption and performance in the context of the criteria and sub-criteria used for the analysis. This study’s findings add to the literature on guidelines to strategize for renewable energy adoption for the hydrogen economy in China.

In order to effectively combat the effects of global warming all sectors must actively reduce greenhouse gas emissions in a sustainable and substantial manner. Sector coupling has emerged as a critical technology that can integrate energy systems and address the temporal imbalances created by intermittent renewable energy sources. Despite its potential current sector coupling capabilities remain underutilized and energy modeling approaches face challenges in understanding the intricacies of sector coupling and in selecting appropriate modeling tools. This paper presents a comprehensive review of sector coupling technologies and their role in the energy transition with a specific focus on the integration of electricity heat/cooling and transportation as well as the importance of hydrogen in sector coupling. Additionally we conducted an analysis of 27 sector coupling models based on renewable energy sources with the goal of aiding deciders in identifying the most appropriate model for their specific modeling needs. Finally the paper highlights the importance of sector coupling in achieving climate protection goals while emphasizing the need for technological openness and market-driven conditions to ensure economically efficient implementation.

The natural gas (NG) reforming is currently one of the low-cost methods for hydrogen production. However the mixture of H2 and CO2 in the produced gas inevitably includes CO2 and necessitates the costly CO2 separation. In this work a novel double chemical looping involving both combustion (CLC) and sorption-enhanced reforming (SE-CLR) was proposed towards the co-production of H2 and CO (CLC-SECLRHC) in two separated streams. CLC provides reactant CO2 and energy to feed SECLRHC which generates hydrogen in a higher purity as well as the calcium cycle to generate CO in a higher purity. Techno-economic assessment of the proposed system was conducted to evaluate its efficiency and economic competitiveness. Studies revealed that the optimal molar ratios of oxygen carrier (OC)/NG and steam/NG for reforming were recommended to be 1.7 and 1.0 respectively. The heat integration within CLC and SECLRHC units can be achieved by circulating hot OCs. The desired temperatures of fuel reactor (FR) and reforming reactor (RR) should be 850 °C and 600 °C respectively. The heat coupling between CLC and SECLRHC units can be realized via a jacket-type reactor and the NG split ratio for reforming and combustion was 0.53:0.47. Under the optimal conditions the H2 purity the H2 yield and the CH4 conversion efficiency were 98.76% 2.31 mol mol-1 and 97.96% respectively. The carbon and hydrogen utilization efficiency respectively were 58.60% and 72.45% in terms of the total hydrogen in both steam and NG. The exergy efficiency of the overall process reached 70.28%. In terms of the conventional plant capacity (75×103 t y-1 ) and current raw materials price (2500 $ t-1 ) the payback period can be 6.2 years and the IRR would be 11.5 demonstrating an economically feasible and risk resistant capability.

Hydrogen is of great significance for replacing fossil fuels and reducing carbon dioxide emissions. The application of hydrogen mixing with natural gas in gas network transportation not only improves the utilization rate of hydrogen energy but also reduces the cost of large-scale updating household or commercial appliance. This paper investigates the necessity of a gas mixing device for adding hydrogen to existing natural gas pipelines in the industrial gas network. A three-dimensional helical static mixer model is developed to simulate the mixing behavior of the gas mixture. In addition the model is validated with experimental results. Parametric studies are performed to investigate the effect of mixer on the mixing performance including the coefficient of variation (COV) and pressure loss. The research results show that based on the the optimum number of mixing units is three. The arrangement of the torsion angle of the mixing unit has a greater impact on the COV. When the torsion angle θ = 120◦ the COV has a minimum value of 0.66% and when the torsion angle θ = 60◦ the COV has a maximum value of 8.54%. The distance of the mixing unit has little effect on the pressure loss of the mixed gas but has a greater impact on the COV. Consecutive arrangement of the mixing units (Case A) is the best solution. Increasing the distance of the mixing unit is not effective for the gas mixing effect. Last but not least the gas mixer is optimized to improve the mixing performance.

Hydrogen production and refueling integrated station can play an important role in the development of hydrogen transportation and fuel cell vehicles and actively promote the energy transformation. By using DC system for hydrogen production and refueling the conversion links can be reduced and the system efficiency can be effectively improved. In this paper a new scheme of DC interconnection for hydrogen production and refueling integrated station is proposed and the modular modeling and operation capability evaluation method are proposed including the characteristic analysis of integrated station the modular modeling and evaluation method for multiple integrated stations under DC interconnection. The DC interconnection system of five integrated stations is constructed and operation capability improvement of integrated stations after adopting the innovative DC interconnection scheme is analyzed. On this basis the system simulation model based on MATLAB/Simulink and physical test platform are built to verify the effectiveness of the theoretical analysis.

Now it is time to set up reliable water electrolysis stacks with active and robust electro‐ catalysts to produce green hydrogen. Compared with catalytic kinetics much less attention has been paid to catalyst stability and the weak understanding of the catalyst deactivation mechanism restricts the design of robust electrocatalysts. Herein we discuss the issues of catalysts’ stability evaluation and characterization and the degradation mechanism. The systematic understanding of the degradation mechanism would help us to formulate principles for the design of stable catalysts. Particularly we found that the dissolution rate for different 3d transition metals differed greatly: Fe dissolves 114 and 84 times faster than Co and Ni. Based on this trend we designed Fe@Ni and FeNi@Ni core‐shell structures to achieve excellent stability in a 1 A cm−2 current density as well as good catalytic activity at the same time

New energy vehicles (NEVs) especially electric vehicles (EVs) address the important task of reducing the greenhouse effect. It is particularly important to measure the environmental efficiency of new energy vehicles and the life cycle analysis (LCA) model provides a comprehensive evaluation method of environmental efficiency. To provide researchers with knowledge regarding the research trends of LCA in NEVs a total of 282 related studies were counted from the Web of Science database and analyzed regarding their research contents research preferences and research trends. The conclusion drawn from this research is that the stages of energy resource extraction and collection carrier production and energy transportation maintenance and replacement are not considered to be research links. The stages of material equipment and car transportation and operation equipment settling and forms of use need to be considered in future research. Hydrogen fuel cell electric vehicles (HFCEVs) vehicle type classification the water footprint battery recovery and reuse and battery aging are the focus of further research and comprehensive evaluation combined with more evaluation methods is the direction needed for the optimization of LCA. According to the results of this study regarding EV and hybrid power vehicles (including plug-in hybrid electric vehicles (PHEV) fuel-cell electric vehicles (FCEV) hybrid electric vehicles (HEV) and extended range electric vehicles (EREV)) well-to-wheel (WTW) average carbon dioxide (CO2 ) emissions have been less than those in the same period of gasoline internal combustion engine vehicles (GICEV). However EV and hybrid electric vehicle production CO2 emissions have been greater than those during the same period of GICEV and the total CO2 emissions of EV have been less than during the same period of GICEV.

During the 13th Five-Year Plan China's natural gas industry developed rapidly and a diversified supply and marketing pattern was formed including domestic conventional gas unconventional gas (shale gas tight sandstone gas coalbed methane etc.) coal-based synthetic natural gas imported LNG and imported pipeline gas. The gross calorific value of gas sources ranged from 34 MJ/m3 to 43 MJ/m3 and the maximum difference of calorific value between different gas sources exceeded 20%. On May 24th 2019 the National Development and Reform Commission and other three ministries/commissions jointly issued the Supervision Regulation on the Fair Access of Oil and Gas Pipeline Network Facilities and required that a natural gas energy measuring and pricing system shall be established within 24 months from the implementation date of this Regulation. In order to speed up the construction of China's natural gas energy measuring system this paper summarizes domestic achievements in the construction of natural gas energy measuring system from the aspects of value traceability and energy measurement standard and analyzes natural gas flowrate measurement technology calorific value determination technology value traceability localization intelligentization and application technology of key energy measurement equipment natural gas pipeline network energy balancing technology based on big data analysis multi-source quality tracking and monitoring technology and energy measurement standard system the need of new energy detection and measurement technology and put forward strategy for the development of natural gas measuring in China. And the following research results are obtained. First China's natural gas energy measuring system can basically meet the requirements of implementing natural gas energy measurement but it still falls behind the international leading level in terms of calibration and application of high-level flowmeter (such as 0.5 class) high-accuracy gas reference material level of calorific value reference equipment and measurement standard system and needs to be further improved. Second it is necessary for China to speed up the research and application of the localization and intelligentization technologies of key energy measurement equipment. Third natural gas pipeline network shall be equipped with measurement check method energy balancing system based on big data analysis and multi-source quality tracking and monitoring system so that the energy transmission loss index of natural gas pipeline network can be superior to the international leading level (0.10%). Fourth to realize the large-scale application of hydrogen energy and bio-energy and the mixed transportation of hydrogen bio-methane and natural gas it is necessary to carry out research on new technology and standardization of hydrogen/bio-methane blended natural gas detection and measurement.

A steam methane reforming reactor is a key equipment in hydrogen production and numerical analysis and process control can provide a critical insight into its reforming mechanisms and flexible operation in real engineering applications. The present paper firstly studies the transport phenomena in an industrial-scale steam methane reforming reactor by transient numerical simulations. Wall effect and local non thermal equilibrium is considered in the simulations. A temperature profile of the tube outer wall is given by user defined functions integrated into the ANSYS FLUENT software. Dynamic simulations show that the species distribution is closely related to the temperature distribution which makes the temperature of the reactor tube wall an important factor for the hydrogen production of the reformer and the thermal conductivity of the catalyst network is crucial in the heat transfer in the reactor. Besides there exists a delay of the reformer's hydrogen production when the temperature profile of the tube wall changes. Among inlet temperature inlet mass flow rate and inlet steam-to-carbon (S/C) ratio the mass flow rate is the most influencing factor for the hydrogen production. The dynamic matrix control (DMC) scheme is subsequently designed to manipulate the mole fraction of hydrogen of the outlet to the target value by setting the temperature profile trajectory of the reforming tube with time. The proportional-integral control strategy is also studied for comparison. The closed-loop simulation results show that the proposed DMC control strategy can reduce the overshoot and have a small change of the input variable. In addition the disturbances of feed disturbance can also be well rejected to assure the tracking performance indicating the superiority of the DMC controller. All the results give insight to the theoretical analysis and controller design of a steam methane reformer and demonstrate the potential of the CFD modeling in study the transport mechanism and the idea of combining CFD modelling with controller design for the real application.