Hydrogen Production via Water Electrolysis: A Bibliometric and Systematic Review of LCA Methodologies and Electricity Supply Impacts

Hydrogen production via water electrolysis (WE) has emerged as one of the key pathways for decarbonizing hydrogen supply, leading to a rapid increase in Life Cycle Assessment (LCA) studies evaluating its environmental performance. The primary objective of this work is to characterize the evolution of the scientific literature and examine the methodological approaches adopted in these LCA studies addressing hydrogen production via water electrolysis. Accordingly, this article combines a bibliometric analysis of 386 publications retrieved from Scopus and Web of Science with a PRISMA-based systematic review of selected studies. It revealed a considerable increase in articles published on the topic in the last 10 years, with major contributions coming mainly from China, Germany, and North America. Keyword co-occurrence analysis indicated that WE has developed into a well-established research topic in the LCA literature and highlighted “life cycle assessment”, “hydrogen production”, and “water electrolysis” as the main searched keywords. Additionally, a systematic assessment of 23 selected articles indicated that most publications adopted a functional unit of 1 kg H2 and system boundaries of cradle-to-gate, with cradle-to-grave also being frequent. ReCiPe 2016 emerged as the most widely adopted life cycle impact assessment (LCIA) methodology, while climate-related indicators such as Global Warming Potential (GWP), greenhouse gas emissions (GHG), and carbon intensity (CI) were the most applied impacts, being addressed by all reviewed studies. The main contributor for these global emissions was the different types of electricity supplies, showing that electricity grids composed mainly of fossil fuels contributed largely to the increase in emissions, while renewable energy, in particular wind and solar power, were often associated with substantially lower emissions.