Hydrogen economy research using Latent Dirichlet Allocation topic modeling: Review, trends and future directions

The hydrogen economy has recently gained significant importance as a critical component of energy systems, offering a way to reduce carbon emissions and pave the way to a sustainable, clean energy future. This review leverages Latent Dirichlet Allocation (LDA) topic modeling to comprehensively analyze the rapidly expanding body of literature on hydrogen economy. In this review paper, we identify research areas, track their evolution, and explore different topics in this field. We examine literature from various perspectives on various subject areas and compare it before and after 2020 to highlight progress and shifting focuses. Our findings demonstrate a significant rise in research output on the hydrogen economy post-2020. Moreover, key trends include green hydrogen production, renewable energy integration, and the use of waste and biomass in hydrogen generation. We further discuss future research directions and map our findings to the current industry status and internationally announced hydrogen plans. Finally, we highlight the limitations and implications of our research for academia, industry, and policymakers. This review provides a comprehensive view of the hydrogen economy, using LDA to reveal in-depth insights into this emerging field. • LDA reveals key hydrogen economy research trends. • Post-2020 focus shifts to green hydrogen and sustainability. • Integration of hydrogen with renewable energy and circular economy. • Advanced materials enhance hydrogen storage and production. • Policy frameworks crucial for hydrogen economy growth.