From Biomass to Hydrogen: The Triple-Pathway Blueprint of AB2H for Low-Carbon Bio-Syn/Hydrogen

This paper presents the dissemination and technical development path of the project Advanced Biomass to Hydrogen: Pathways for Eco-Efficient Energy Conversion (AB2H), conducted within the NEST (Network for Energy Sustainable Transition) framework. The AB2H initiative focuses on the sustainable production of hydrogen from biomass-derived resources, targeting the exploitation of both thermochemical and biochemical pathways to generate low-emission, renewable hydrogen. The project is structured around three core technological directions: (i) generation/enrichment of hydrogen through a Water-Gas Shift (WGS) reactor that upgrades syngas, typically generated from biomass gasification; (ii) the use of Microbial Electrolysis Cells (MECs), which integrate electrochemical conversion with microbial metabolism to extract hydrogen from organic waste under the application of a low external voltage, and (iii) photo- and dark-fermentation processes converting humid organic waste into biohydrogen via microbial activity. A literature review has been carried out to examine the current state of play, with specific attention to recent technological developments. This has served as planning the construction of prototypes functional to the project objectives. These insights have also guided the construction of numerical models for evaluating the hydrogen production performance of each pathway. The results section presents simulation outputs focused on a specific case study, providing quantitative assessments of hydrogen yields, various system performance indicators and efficiencies regarding the hydrogen generation via the WGS. A syngas obtained from the gasification of wet biomass is considered for processing in a WGS system. Simulations are performed to identify the most favorable conditions for maximizing both hydrogen production efficiency and carbon monoxide conversion. For the assessed case, the highest hydrogen production efficiency achieved is approximately 62.3%.