Research progress on application of hydrogen-mixed natural gas in terminal pipe network

Hydrogen energy is one of the important development directions of new energy towards the goal of carbon neutralization. Many researches have been conducted in China on the adaptability of hydrogen-mixed natural gas transportation in long-distance gas pipelines, but no comprehensive analysis has been performed for its application in terminal pipe network. In this study, the research status on the interchangeability of hydrogen-mixed natural gas in terminal application worldwide, the adaptability of equipment and material and their safety was surveyed. According to the results, the hydrogen-mixed natural gas has a good adaptability to civil gas appliances and terminal pipeline materials, but further research on interchangeability, medium stratification, leakage detection, odorization, and metering is required before supplying hydrogen-mixed natural gas to end users. Hence, suggestions were proposed in accordance with the characteristics of terminal pipe network and the demand on gas supply: (1) to conduct an interchangeability analysis based on the specific natural gas components and the working conditions of gas appliances, (2) to increase the transportation pressure to eliminate the influence of the additional pressure of high risers, and analyze the medium stratification under extreme working conditions, (3) to conduct a comprehensive analysis on the sealing performance of connectors, and optimize the layout of leakage detection equipment and odorants based on the leakage and diffusion characteristics of hydrogen, (4) to establish a hydrogen-mixed natural gas metering standard system urgently, and (5) to speed up the adaptive adjustment of hydrogen separation units and technologies of terminal pipe network. In general, the research results could provide reference for the application of hydrogen-mixed natural gas in terminal pipe network and the development of hydrogen energy industry chain.