Hydrogen,as a clean,zero-carbon,efficient and sustainable energy carrier,provides an alternative solution for deepening the clean energy transition and fully achieving Two Replacements. At present,most hydrogen is produced by fossil fuels,and direct use of hydrogen as energy cannot achieve the goal of de-carbonization. Renewable energy such as wind energy and solar energy is used to produce green hydrogen to achieve the de-carbonization of the whole process from supply to consumption,so that the energy de-carbonization can be achieved by hydrogen energy.Green hydrogen comes from renewable energy. Green hydrogen is an important zero-carbonsolution in the final energy consumption fields where it is difficult to directly use electricity. It becomes the link between renewable energy such as wind energy and solar energy and final energy consumption,to achieve indirect electricity replacement or even non-energy application of electricity,thus promoting comprehensive electrification on the energy consumption side. Compared with electricity,hydrogen is easier to be stored on a large scale.The mutual conversion of electricity and hydrogen will provide important long-term flexible adjustment capabilities for new power systems with renewable energy as the mainstay,to promote the development and consumption of renewable energy,thus facilitating clean replacement of energy supply. The close connection between electricity and hydrogen will become an important feature of the new energy system in the carbon neutrality scenario,and an interconnected modern energy network will be built in combination with various energy forms such as biomass energy,geothermal energy,and natural gas. Hydrogen energy is expected to become one of the important roles in the third energy transition,and it will be used with electricity to achieve the clean,low-carbon and sustainable development of the future energy system.In this report,from the perspectives of demand,production,and allocation and in combination with different links in the hydrogen industry chain,the technical statuses of hydrogen application,hydrogen production,hydrogen storage,and hydrogen transportation are sorted out,the cost-effectiveness of different technical routes is compared,and the R&D directions of key technologies in the future are proposed. Based on the analysis of carbon neutrality energy scenarios and technology development trends,the scale of hydrogen energy demand in the future is judged. Based on the assessment results of clean energy resources,the potential and cost-effectiveness of green hydrogen production are studied. On this basis,an overall optimization analysis model for the electricity-hydrogen zero-carbon energy system is built,and the long-distance and large-scale hydrogen energy allocation scheme in China is proposed with the optimization goal of minimizing the energy consumption cost of the whole system in this report.In this report,the relevant research results of the Global Energy Interconnection Development and Cooperation Organization (GEIDCO) on hydrogen energy are collected,aiming at enabling readers to master the technical statuses and development trends of the application,production,storage,and transportation of green hydrogen industry,and providing a reference for policy makers to fully understand the development prospects of hydrogen energy,formulate relevant policies and plan development paths. However,there might be inadequacies as data and time for preparation are limited.