China, People’s Republic

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.