Wood Gas Processing To Generate Pure Hydrogen Suitable for PEM Fuel Cells

A test campaign was carried out to generate renewable hydrogen based on wood gas derived from the commercial biomass steam gasification plant in Oberwart, Austria. The implemented process consisted of four operation units: (I) catalyzed water–gas shift (WGS) reaction, (II) gas drying and cleaning in a wet scrubber, (III) hydrogen purification by pressure swing adsorption, and (IV) use of the generated biohydrogen (BioH₂) in a proton exchange membrane (PEM) fuel cell. For almost 250 h, a reliable and continuous operation was achieved. A total of 560 (L_{<i>n</i> dry basis (db)})/h of wood gas were extracted to produce 280 (L_{<i>n</i> db})/h of BioH₂ with a purity of 99.97 vol %_db. The catalyzed WGS reaction enabled a hydrogen recovery of 128% (<i>ṅ</i>_BioH₂)/(<i>ṅ</i>_{H₂,wood gas}) over the whole process chain. An extensive chemical analysis of the main gas components and trace components (sulfur, C_<i>x</i>H_<i>y</i>, and ammonia) was carried out. No PEM fuel cell poisons were measured in the generated BioH₂. The only detectable impurities in the product were 0.02 vol %_db of O₂ and 0.01 vol %_db of N<sub>2