China, People’s Republic

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.

Because of the pressure to meet carbon neutrality targets carbon reduction has become a challenge for fossil fuel resource-based regions. Even though China has become the most active country in carbon reduction its extensive energy supply and security demand make it difficult to turn away from its dependence on coal-based fossil energy. This paper analyzes the Chinese coal capital—Shanxi Province—to determine whether the green low-carbon energy transition should be focused on coal resource areas. In these locations the selection and effect of transition tools are key to ensuring that China meets its carbon reduction goal. Due to the time window of clean coal utilization the pressure of local governments and the survival demands of local high energy consuming enterprises Shanxi Province chose hydrogen as its important transition tool. A path for developing hydrogen resources has been established through lobbying and corporative influence on local and provincial governments. Based on such policy guidance Shanxi has realized hydrogen applications in large-scale industrial parks regional public transport and the iron and steel industry. This paper distinguishes between the development strategies of gray and green hydrogen. It shows that hydrogen can be an effective development model for resource-based regions as it balances economic stability and energy transition.

In the context of “dual carbon” restrictions on carbon emissions have aĴracted widespread aĴention from researchers. In order to solve the issue of the insufficient exploration of the synergistic emission reduction effects of various low-carbon policies and technologies applied to multiple microgrids we propose a multi-microgrid electricity cooperation optimization scheduling strategy based on stepped carbon trading a hydrogen-doped natural gas system and P2G–CCS coupled operation. Firstly a multi-energy microgrid model is developed coupled with hydrogendoped natural gas system and P2G–CCS and then carbon trading and a carbon emission restriction mechanism are introduced. Based on this a model for multi-microgrid electricity cooperation is established. Secondly design optimization strategies for solving the model are divided into the dayahead stage and the intraday stage. In the day-ahead stage an improved alternating direction multiplier method is used to distribute the model to minimize the cooperative costs of multiple microgrids. In the intraday stage based on the day-ahead scheduling results an intraday scheduling model is established and a rolling optimization strategy to adjust the output of microgrid equipment and energy purchases is adopted which reduces the impact of uncertainties in new energy output and load forecasting and improves the economic and low-carbon operation of multiple microgrids. SeĴing up different scenarios for experimental validation demonstrates the effectiveness of the introduced low-carbon policies and technologies as well as the effectiveness of their synergistic interaction

To solve the problems of low utilization of biomass and uncertainty and intermittency of wind power (WP) in rural winter an interval optimization model of a rural integrated energy system with biogas fermentation and electrolytic hydrogen production is constructed in this paper. Firstly a biogas fermentation kinetic model and a biogas hydrogen blending model are developed. Secondly the interval number is used to describe the uncertainty of WP and an interval optimization scheduling model is developed to minimize daily operating cost. Finally a rural integrated energy system in Northeast China is taken as an example and a sensitivity analysis of electricity price gas production and biomass price is conducted. The simulation results show that the proposed strategy can significantly reduce the wind abandonment rate and improve the economy by 3.8–22.3% compared with conventional energy storage under optimal dispatch.

A direct drive wave power generation system (DDWPGS) has the advantages of a simple structure and easy deployment and is the first choice to provide electricity for islands and operation platforms in the deep sea. However due to the off-grid the source and load cannot be matched so accommodation is an important issue. Hydrogen storage is the optimal choice for offshore wave energy accommodation. Therefore aiming at the source-load mismatch problem of the DDWPGS an electric-hydrogen hybrid energy storage system (HESS) for the DDWPGS is designed in this paper. Based on the characteristics of the devices in the electric-hydrogen HESS a new dynamic power allocation strategy and its control strategy are proposed. Firstly empirical mode decomposition (EMD) is utilized to allocate the power fluctuations that need to be stabilized. Secondly with the state of charge (SOC) of the battery and the operating characteristics of the alkaline electrolyzer being considered the power assignments of the battery and the electrolyzer are determined using the rule-based method. In addition model predictive control (MPC) with good tracking performance is used to adjust the output power of the battery and electrolyzer. Finally the supercapacitor (SC) is controlled to maintain the DC bus voltage while also balancing the system’s power. A simulation was established to verify the feasibility of the designed system. The results show that the electric-hydrogen HESS can stabilize the power fluctuations dynamically when the DDWPGS captures instantaneous power. Moreover its control strategy can not only reduce the start-stop times of the alkaline electrolyzer but also help the energy storage devices to maintain a good state and extend the service life.

This study proposes a multitype electrolytic collaborative hydrogen production model for optimizing the capacity configuration of renewable energy off grid hydrogen production systems. The electrolytic hydrogen production process utilizes the synergistic electrolysis of an alkaline electrolyzer (AEL) and proton exchange membrane electrolyzer (PEMEL) fully leveraging the advantages of the low cost of the AEL and strong regulation characteristics of the PEMEL. For the convenience of the optimization solution the article constructs a mixed linear optimization model that considers the constraints during system operation with the objective function of minimizing total costs while meeting industrial production requirements. Gurobi is used for the optimal solution to obtain the optimal configuration of a renewable energy off grid hydrogen production system. By comparing and analyzing the optimal configuration under conventional load and high-load conditions it is concluded that collaborative electrolysis has advantages in improving resource consumption and reducing hydrogen production costs. This is of great significance for optimizing the capacity configuration of off grid hydrogen production systems and improving the overall economic benefits of the system.

Utilizing renewable energy sources (RESs) such as wind and solar to convert electrical energy into hydrogen energy can promote the accommodation of green electricity. This paper proposes an optimal capacity planning approach for an industrial electricity-hydrogen multi-energy system (EHMES) aimed to achieve the local utilization of RES and facilitate the transition to carbon reduction in industrial settings. The proposed approach models the EHMES equipment in detail and divides the system’s investment and operation into producer and consumer sides with energy trading for effective integration. Through this effort the specialized management for different operators and seamless incorporation of RES into industrial users can be achieved. In addition the variations in investment and operating costs of equipment across different installed capacities are considered to ensure a practical alignment with real-world scenarios. By conducting a detailed case study the influence of various factors on the capacity configuration outcomes within an EHMES is analyzed. The results demonstrate that the proposed method can effectively address the capacity configuration of equipment within EHMES based on the local accommodation of RES and variable unit cost sequence. Wind power serves as the primary source of green electricity in the system. Energy storage acts as crucial equipment for enhancing the utilization rate of RES.

In the process of building a new power system with new energy sources as the mainstay wind power and photovoltaic energy enter the multiplication stage with randomness and uncertainty and the foundation and support role of large-scale long-time energy storage is highlighted. Considering the advantages of hydrogen energy storage in large-scale cross-seasonal and cross-regional aspects the necessity feasibility and economy of hydrogen energy participation in long-time energy storage under the new power system are discussed. Firstly power supply and demand production simulations were carried out based on the characteristics of new energy generation in China. When the penetration of new energy sources in the new power system reaches 45% long-term energy storage becomes an essential regulation tool. Secondly by comparing the storage duration storage scale and application scenarios of various energy storage technologies it was determined that hydrogen storage is the most preferable choice to participate in large-scale and long-term energy storage. Three long-time hydrogen storage methods are screened out from numerous hydrogen storage technologies including salt-cavern hydrogen storage natural gas blending and solid-state hydrogen storage. Finally by analyzing the development status and economy of the above three types of hydrogen storage technologies and based on the geographical characteristics and resource endowment of China it is pointed out that China will form a hydrogen storage system of “solid state hydrogen storage above ground and salt cavern storage underground” in the future.

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.

With the goal of achieving “carbon peak in 2030 and carbon neutrality in 2060” as clearly proposed by China the transportation sector will face long–term pressure on carbon emissions and the application of hydrogen fuel cell vehicles will usher in a rapid growth period. However true “zero carbon” emissions cannot be separated from “green hydrogen”. Therefore it is of practical significance to explore the feasibility of renewable energy hydrogen production in the context of hydrogen refueling stations especially photovoltaic hydrogen production which is applied to hydrogen refueling stations (hereinafter referred to “photovoltaic hydrogen refueling stations”). This paper takes a hydrogen refueling station in Shanghai with a supply capacity of 500 kg/day as the research object. Based on a characteristic analysis of the hydrogen demand of the hydrogen refueling station throughout the day this paper studies and analyzes the system configuration operation strategy environmental effects and economics of the photovoltaic hydrogen refueling station. It is estimated that when the hydrogen price is no less than 6.23 USD the photovoltaic hydrogen refueling station has good economic benefits. Additionally compared with the conventional hydrogen refueling station it can reduce carbon emissions by approximately 1237.28 tons per year with good environmental benefits.