H.B. Aditiya, T.M.I. Mahlia, Zhongyan Huang
Hydrogen has emerged as a key green energy carrier for deep decarbonisation, offering a viable pathway to reduce emissions from carbon-intensive industries while enabling greater integration of renewable energy source into the global energy system. This study provides a comprehensive review of green hydrogen production technologies, storage methods, and industrial applications, alongside the financial and regulatory landscape shaping its large-scale deployment. From techno-economic viewpoints, alkaline electrolysis offers cost advantages at approximately USD 270/kW compared with proton membrane exchange and solid oxide electrolysis. Storage technologies show levelised costs of USD 2.48–15.61/kg H 2 with scalability to gigawatt level, surpassing battery systems. Hydrogen adoption enables substantial decarbonisation in hard-to-abate sectors, with deployments estimated to cut more than 1 Mtonne CO 2 emissions annually in steelmaking and more than 100 ktonne in cement production. This study underscores the importance of international cooperation, outlining pathways for countries with abundant renewable resources (e.g., Canada, Australia) to emerge as major hydrogen producers, while nations with strong demand (e.g., Japan, South Korea) act as market catalysts. Finally, investment dynamics, government incentives, regulatory frameworks, and targeted policy recommendations are reviewed to provide a holistic perspective for building a resilient and sustainable hydrogen ecosystem.