Recent progress in bio-hydrogen production for sustainable energy and chemical production

Openshaw, D. and Bagnato, G. (2026) Recent progress in bio-hydrogen production for sustainable energy and chemical production. Renewable and Sustainable Energy Reviews, 226: 116307. ISSN 1364-0321

Abstract

To combat global warming, the decarbonisation of energy systems is essential. Hydrogen (H2) is an established chemical feedstock in many industries (fertiliser production, steel manufacturing etc.) and has emerged as a promising clean energy carrier due to its high energy density and carbon-free usage. However, most H2 is currently produced from fossil fuels, undermining its sustainability. Biomass offers a renewable, carbon-neutral feedstock for H2 production, potentially reducing its environmental impact. This review examines thermochemical, biological, and electrochemical methods of bio-H2 generation. Thermochemical processes - including gasification, fast pyrolysis, and steam reforming - are the most technologically advanced, offering high H2 yields. However, challenges such as catalyst deactivation, tar formation, and pre- and post-processing limit efficiency. Advanced strategies like chemical looping, sorption enhancement, and membrane reactors are being developed to address these issues. Biological methods, including dark and photo fermentation, operate under mild conditions and can process diverse waste feedstocks. Despite their potential, low H2 yields and difficulties in microbial inhibitors hinder scalability. Ensuring that microbial populations remain stable through the use of additives and optimising the bioreactors hydraulic retention rate also remain a challenge Combined fermentation systems and valorising by-products could enhance performance and commercial viability. Electrochemical reforming of biomass-derived compounds is an emerging method that may enhance water electrolysis by co-producing value-added by-products. However, current studies focus on biomass-derived compounds rather than complex biomass feedstocks, limiting commercial relevance. Future research should focus on feedstock complexity, electrocatalyst development, and system scaling. A technology readiness comparison shows that thermochemical methods are the most commercially mature, followed by biological and electrochemical approaches. Each method holds promise within specific niches, warranting continued innovation and interdisciplinary development.