A comprehensive review of hydrogen safety through a metadata analysis framework

Hydrogen is widely recognized as a promising clean energy carrier, but its highly flammable and explosive nature presents significant safety challenges in its production, storage, transportation, and usage. Addressing these challenges is critical for the successful integration of hydrogen into global energy systems, aligning with the United Nations' sustainable development goals, to support the transition to a low-carbon future. This study aims to provide a comprehensive review of hydrogen safety through a metadata analysis framework, focusing on risks, challenges, mitigation strategies, and regulations for safe handling. Previous reviews have largely addressed general hydrogen safety concerns, but none have systematically evaluated the issue from a data-driven perspective. This review fills that gap by analyzing research trends, root causes of hydrogen's unsafe handling such as its low molecular density, broad flammability range, and high permeability, and exploring solutions such as chemical additives and gaseous inhibitors to improve safety. Utilizing bibliometric techniques and scientific mapping tools, this study synthesizes extensive research spanning from 2000 to 2024, visualizing the evolution of hydrogen safety research and identifying critical areas for future inquiry. The findings contribute valuable insights into the safe deployment of hydrogen technologies, offering recommendations for future research and regulatory advancements to mitigate risks and ensure hydrogen's role in a sustainable energy future.