Biohydrogen from waste through biomass electrolysis: challenges and opportunities

Abstract

Electrolysis of biomass is a promising process for hydrogen generation from waste biomass that is still unexplored. This work investigated hydrogen production from food waste, poultry litter and pure biomass components (glucose, starch, cellulose, hemicellulose and lignin) using an H-type proton exchange membrane electrolytic cell (H-PEMEC). The process involves two steps: first, the biomass undergoes chemical oxidation (pretreatment), followed by hydrogen production during electrolysis. Lewis acid (FeCl3) and polyoxometalate (POM) were employed as redox reagents for depolymerising/oxidising biomass. Biomass electrolysis, at technology readiness level 2/3, offers advantages such as lower temperatures than thermochemical processes, minimal energy consumption, high hydrogen production potential, and reduced carbon footprints. Preliminary research used FeCl3 to pretreat pure biomass components (cellulose, starch, lignin, and glucose) for hydrogen production in an H-PEMEC. Electrolysis at 1.20 V yielded hydrogen volumes ranging from 6.3 mL to 12.1 mL. When POM was used as a redox catalyst for depolymerising pure biomass components, hydrogen production increased by 23 % due to its dual Lewis and Bronsted acid sites, enhancing biomass degradation. Food waste (banana and cucumber peels) pretreated with POM and electrolysed at 1.20 V yielded 49.2 mL and 39.6 mL of hydrogen, achieving 10-17 % H-content conversion efficiency. Optimisation of pretreatment conditions using central composite design (CCD) and response surface methodology (RSM) identified ideal conditions for poultry litter: 20 g/L biomass, 101 ℃, 0.197 mol/L POM, and 3 hours, yielding a maximum hydrogen output of 24.3 mL, representing 11 % H-content extraction. Further, solar-assisted POM degradation of banana peel using a Xenon lamp yielded 26.7 mL of hydrogen, achieving ~10 % H-content conversion. Finally, the global warming potential (GWP) for the biogenic electrolysis process was assessed at 6.58 kg CO2 equivalent, significantly lower than the GWP of steam reforming of methane of value 11.20 kg CO2 equivalent.

Thesis is embargoed until 31 March 2026.

Date of Award	Mar 2025
Original language	English
Supervisor	Neil Hewitt (Supervisor), Caterina Brandoni (Supervisor) & Ye Huang (Supervisor)