Waste-to-hydrogen pathways: A cross-sectoral review of feedstock potentials, process integration, and sustainability metrics

Abstract

Biohydrogen production from waste offers a dual solution to mounting waste management pressures and fossil fuel dependence. This review addresses the gap through a cross-sectoral analysis of waste categories: agricultural residues, municipal solid waste, and wastewater, synthesised across classification tables and a review on a comparative framework encompassing hydrogen yield, energy output, environmental impact, economic feasibility, technology readiness, grid integration potential, scalability, and regional relevance. Dark fermentation of sugar-rich agro-industrial wastes achieves the highest near-term viability, with pineapple peel juice yielding up to 2.3 mol H2/mol sugar and POME reaching 1.88 mol H2/mol sugar under thermophilic conditions, both requiring minimal pretreatment. However, Technology Readiness Level mapping reveals that no reviewed pathway has surpassed TRL 7, and the levelized cost of biohydrogen spans $2.50–48.96/kg H2, with pathway selection, not feedstock alone, as the primary cost driver. Life cycle assessment integration remains critically absent from most studies, motivating the standardised cradle-to-grave LCA–TEA framework proposed herein. The review aligns these findings with Malaysia's National Energy Transition Roadmap (NETR), Sarawak Hydrogen Economy Roadmap (SHER), and Post-COVID Development Strategy (PCDS) 2030, identifying waste-to-biohydrogen as a priority deployment pathway for the circular bioeconomy.