This study explores the conversion of Sargassum seaweed into hydrogen through alkaline thermal treatment (ATT), an integrated process that simultaneously enables biomass conversion and carbon capture in the solid state. ATT provides a promising route for utilizing wet, salty biomass such as Sargassum seaweed without the need for extensive drying or desalination. By employing metal hydroxides (e.g., NaOH) in the presence of a gas-reforming catalyst, the degradation and gasification behaviors of Sargassum seaweed are studied with the goal of optimizing hydrogen production efficiency under carbon-free conditions. This research further investigates the comparative performance of terrestrial and aquatic biomass feedstocks in ATT. Preliminary results suggest that aquatic biomass may exhibit higher conversion efficiency with wet ATT process, which could result from the compositional factors of each biomass. In particular, the role of water in the reaction pathway is re-evaluated to clarify the contribution of H₂O and alkali hydroxides in hydrogen formation. Additionally, the study addresses the solid residue generated from the ATT process, focusing on both pre-treatment and post-treatment strategies. These include examining how acid/base pre-treatment affects biomass degradation and ATT efficiency, as well as evaluating post-treatment methods for mineral recovery and residue utilization. These efforts aim to improve process sustainability, broaden feedstock applicability, and enhance the overall value chain of marine biomass-to-hydrogen technologies.
