Comprehensive review of hydrogen energy systems: trends, technologies, and future applications

Green hydrogen, the renewable energy‐driven hydrogen produced through water electrolysis, has become one of the key decarbonization options across energy‐intensive industries. The present review describes the primary technologies of hydrogen which are mature alkaline, proton exchange membrane, solid oxide, and newer technologies like anion exchange membrane and photo electrochemical processes. Additionally, the current review covers the choice of hydrogen storage and distribution by alternatives as compression, liquefaction, ammonia, and liquid organic hydrogen carriers that have different energy and infrastructure requirements. The current review also discusses the large‐scale decarbonization efforts focus on the steel sector, the chemical industry, and transport use currently represented by fuel‐cell cars, ammonia‐fueled ships, or e‐kerosene‐powered flights. The review additionally covers the aspects related artificial intelligence and digitalization in hydrogen systems The constant issues of infrastructure, materials, and safety are still apparent but AI advances, the integration of systems, and the global collaboration of scientific entities are making green hydrogen one of the backbones of future sustainable energy systems.