Technological opportunity identification for green marine fuels: a BERTopic-based patent mining study

Abstract

Introduction As shipping decarbonization research shifts from evaluating fuel emission-reduction potential to identifying deployment bottlenecks, more robust empirical evidence is urgently needed to characterize ship-level industrial innovation. This study takes patent mining as the core analytical basis to identify innovation clusters and compare five green marine alternative fuel pathways: hydrogen, ammonia, liquefied natural gas (LNG), methanol, and biofuels. Methods Based on 4,471 Derwent Innovations Index patent families covering 2000–2025, we employ BERTopic-based semantic mining to extract patent topics, fuel-specific innovation directions, and cross-fuel engineering modules. Meanwhile, 955 Web of Science core publications are utilized to construct the literature-frontier dimension of the analytical framework via keyword timeline and burst analyses, which lays a foundation for the subsequent literature–patent positioning of fuel development patterns. Results Hydrogen exhibits the strongest consistency between frontier research attention and sustained patent activity. Ammonia and methanol present remarkable recent frontier signals and late-stage patent growth, while LNG and biofuels mainly reflect transitional or continuity-oriented technological accumulation. Further patent-mining findings demonstrate that hydrogen innovation concentrates on fuel-cell conversion, energy management, and hybrid-power integration; ammonia and methanol technological opportunities focus on storage, supply, safety, and ship–fuel interfaces; LNG innovation centers on cryogenic storage and pressure management; and biofuel patents prioritize upstream feedstocks and renewable liquid-fuel production. Discussion Overall, technological opportunities are concentrated in both fuel-specific pathways and cross-fuel generic modules, especially onboard storage, fuel supply, emissions control, and ship-wide energy management. This study establishes a patent-validated approach to identifying differentiated technological opportunities, providing empirical support for targeted and efficient maritime decarbonization innovation strategies.