A ternary system exploiting the full solar spectrum to generate renewable hydrogen from a waste biomass feedstock

A solar-driven system is proposed capable of hydrogen production from waste biomass with low carbon and water footprints. The ternary system consists of a membrane-based waste biomass concentrator (WBC), a biomass preconditioning reactor (BPR) integrated with an array of hybrid PV-thermal (PVT) collectors, and a flow electrolysis cell (FEC) equipped with a custom, high-performance electrode – NiMo alloy deposited onto Ni foam. An innovative full-solar-spectrum hybrid PVT reflector-concentrator was constructed to confirm performance; this enabled a thermal efficiency of up to ∼50% to be achieved when operating the BPR at 120–150 °C, while also converting ∼8% of the solar flux to electricity for the FEC. The solar-thermal BPR can reform recovered waste biomass (i.e., a sugar-containing liquid feedstock) into a bio-alcohol (5-hydroxymethylfurfural) with a yield of 25 mol%, with the transformed biomass then used to feed the anodic compartment of the FEC. Within the FEC, biomass electrolysis using the NiMo catalyst facilitated hydrogen production, offering a low energy consumption of 40–53 kW h kg−1, which is 16–28% more efficient than alkaline water splitting using Ni foam electrodes. The ternary system achieved a 7.5% overall solar-to-hydrogen efficiency, additional revenue from clean water production (with >80% water reclaimed), and a value-added chemical by-product (2,5-furandicarboxylic acid at a 3–10% yield from the waste sugar stream). This work presents a new route towards efficient and economically feasible renewable hydrogen production—a system which can underpin a circular economy.

University of New South Wales (UNSW), Department of Chemical Engineering, Imperial College London, UK, Karlsruhe Institute of Technology, Karlsruhe, Germany

Qiyuan Li and Lixue Jiang and Gan Huang and Da Wei Wang and Jack Shepherd and Rahman Daiyan and Christos N. Markides and Robert A. Taylor and Jason Scott

Energy & Environmental Science

2023

8

10.1039/D3EE00603D

1754-5706

8

3497-3513

The Royal Society of Chemistry

16