Demonstration of decentralized high-purity hydrogen production from wood chips for PEM-FC application

Abstract

A 100 kWH2 demonstration plant for the production of high-purity hydrogen from wood chips, the BioH2Modul, and a proton exchange membrane fuel cell tractor, the FCTRAC, were developed and built to demonstrate a whole value chain for decentralized hydrogen production and on-site utilization. The circular economy approach proposes a holistic solution to the issue of defossilization in the agricultural and forestry sector. This work focuses on the hydrogen production process chain in which wood chips are converted by downdraft fixed-bed gasification into a product gas to be conditioned, cleaned, and upgraded to purified hydrogen. Commissioning of the fixed-bed gasifier, the water-gas shift unit, the water quench, the rapeseed methyl ester scrubber, the adsorber unit, and the compression unit was successfully completed, proving reliable operation. The two-staged water-gas shift unit converted about 93% of carbon monoxide, increasing the hydrogen content to 32.6 vol.-%db. In the downstream coarse gas cleaning units, 98% of ammonia and 90% of the tar compounds were separated. The separation efficiency for benzene amounted to 17%. The pressure swing adsorption unit was successfully coupled, but commissioning was not completed. However, previous pilot-scale test runs with a similar process chain proved the technical feasibility of high-purity hydrogen (= 99.97 vol.-% purity) production via downdraft fixed-bed gasification of wood chips.