Green-hydrogen research: What have we achieved, and where are we going? Bibliometrics analysis

In response to the global challenge of climate change, 136 countries accounting for 90% of global GDP and 85% of the population have now set net-zero targets. A transition to net-zero will require the decarbonization of all sectors of the economy. Green-hydrogen produced from renewable energy sources poses little to no threat to the environment and increasing its production will support net-zero targets Our study examined the evolution of green-hydrogen research themes since the UN Sustainable Development Goals were adopted in 2015 by utilizing bibliographic couplings, keyword co-occurrence, and keyphrase analysis of 642 articles from 2016 to 2021 in the Scopus database. We studied bibliometrics indicators and temporal evolution of publications and citations, patterns of open access, the effect of author collaboration, influential publications, and top contributing countries. We also consider new indicators like publication views, keyphrases, topics with prominence and field weighted citation impact, and Altmetrics to understand the research direction further. We find four major thematic distributions of green-hydrogen research based on keyword co-occurrence networks: hydrogen storage, hydrogen production, electrolysis, and the hydrogen economy. We also find networks of four research clusters that provide new information on the journal’s contributions to green-hydrogen research. These are materials chemistry, hydrogen energy and cleaner production, applied energy, and fuel cells. Most green-hydrogen research aligns with Affordable and Clean Energy (SDG 7) and Climate Action (SDG 13). The outcomes of policy decisions in the United States, Europe, India, and China will profoundly impact green-hydrogen production and storage over the next five years. If these policies are implemented, these countries will account for two-thirds of this growth. Asia will account for the most significant part and become the second-largest producer globally.