Investigating emerging hydrogen technology topics and comparing national level technological focus: Patent analysis using a structural topic model

Abstract

Hydrogen technology has recently attracted great attention as a new energy technology with a potential to transform existing energy systems. However, since hydrogen technology is based on a concept encompassing a broad range of topics, such as hydrogen production, storage, distribution, and utilization, it is difficult for individual field experts to analyze it from an integrated viewpoint. In this study, we used a semiautomated, unsupervised learning approach for patent data analysis to identify specific technology topics in various fields of hydrogen technology and to analyze the technological focus of key countries. Thus, we collected 17 281 hydrogen technology patents from the last decade (2010-2019) from the United States Patent and Trademark Office (USPTO) and input the text in the title and abstract of the collected patents along with their metadata to a structural topic model. Consequently, we identified various hydrogen technology topics estimated based on the co-occurrence pattern of words within patents and represented as probabilistic word distribution. Furthermore, the metadata of the collected patents were used to identify topics that were newer or more impactful and appeared more frequently in patents from a certain country. After identifying technology topics, we also estimated the technology maturity rate (TMR) of each topic to measure its remaining potential. Among the 40 latent technology topics identified from the collected patents, 11 topics showed increasing proportion over time (new and trending) and five topics were highly cited by other patents (impactful). Furthermore, based on the analysis results, implications were presented for hydrogen research and development (R&D) strategy by (1) comparing the technology portfolios of key countries, (2) performing a technology correlation analysis of the identified hydrogen technology topics, and (3) proposing a decision framework for policymakers to categorize identified topics. We found that the primary technological focus was on fuel cell technologies for South Korea and Japan whereas hydrogen production technologies for France and the United States. Furthermore, technological rivalry patterns between key countries may differ notably depending on their specific technology topics or fields, highlighting the need for considering such aspects in developing R&D strategies. Finally, based on the proposed decision framework, we identified which technology topic to continue to focus on and consider easier expansion.