Hydrogen production from woody biomass via fixed-bed gasification at pilot-scale

Sustainable energy carriers are needed to reduce greenhouse gas emissions and tackle the climate crisis. Low-emissions hydrogen is one of many conceivable energy carriers. In this study, hydrogen production via air gasification of wood chips is experimentally investigated with the aim of achieving a hydrogen purity suitable for proton exchange membrane fuel cells. A 50 kW th fixed-bed gasifier is coupled with a pilot-scale process chain for product gas cleaning, conditioning, and hydrogen purification. Test runs are carried out in which the inlet temperatures of the water-gas shift unit and the adsorption time of the pressure swing adsorption unit are varied. Tar compounds are converted in the water-gas shift unit, resulting in a less complex tar composition and potentially simplifying the downstream gas cleaning processes. The obtained hydrogen purity is ≥ 99.977 vol.-% and ≥ 99.964 vol.-% with a hydrogen recovery of 70.3% (55.1 g H2 kg −1 BM.db ) and 75.1% (58.9 g H2 kg −1 BM.db ) at adsorption times of 450 and 470 s, respectively, an adsorption pressure of 6.4 bar a and an equalization pressure of 5.0 bar a . The process proves to be technically feasible and offers room for optimization. • High-purity H 2 production via air gasification of wood chips is technically feasible. • > 94% CO conversion by the WGS reaction over a commercial Fe/Cr-based catalyst downstream of the gasifier. • Phenols, cresols, styrene, and indene were converted to a large extent over the Fe/Cr-based catalyst. • The H 2 purity achieved (≥ 99.977 vol.-%) is in-line with the H 2 threshold of the ISO 14687:2019 standard (≥ 99.97 vol.-%). • N 2 and Ar proved to be the impurities with the fastest breakthrough in the PSA unit.