Hydrogen, which has been seen as a kind of significant industrial source, has been increasingly focused as the clean energy in anet-zero carbon emission future, with broad application prospects in the fields of transportation, energy supply, metallurgy and chemicalindustry. Nevertheless, the development and application of hydrogen, especially green hydrogen, have been restricted with technologiesand costs in its production, storage and transport process. It should be confirmed that quite a bit of the energy will be lost in the transformation and transportation process whether in high-pressure compressed form, liquid form or other Power-to-X strategies. Furthermore, itwas easy to understand more reliable life cycle economic analysis of hydrogen would be estimated while energy efficiency was considered.By comparison, liquid hydrogen and ammonia were regard as the better methods for large-scale power or heat supply under different periods. Herein, based on the consideration of the energy efficiency of hydrogen, technologies and costs of its production, storage and transport were summarized in this work, together with the large-scale power supply by green hydrogen and ammonia. Comprehending the worldwide green hydrogen outlook would make benefits for China′s transition towards a future where hydrogen will be a major energy player.