Experimental investigation of hydrogen-intensified synthetic natural gas production via biomass gasification: a technical comparison of different production pathways

Abstract

AbstractA sustainable and secure energy supply requires alternative concepts for energy generation. Utilizing biomass to produce synthetic natural gas (SNG) allows the synthesis of a currently widely used energy carrier on a renewable basis. The additional integration of hydrogen increases the carbon utilization of the biomass. This study experimentally investigates and compares the production of raw-SNG in three novel process chain configurations combining the advanced dual fluidized bed (DFB) gasification technology, gas cleaning units, and a fluidized bed methanation reactor. The three process chains comprise the direct methanation of DFB product gas, a hybrid route with hydrogen addition to the DFB product gas, and the methanation of a hydrogen-enriched product gas generated through DFB gasification with in situ CO2 removal (SER process). The direct methanation of the DFB product gas yielded a raw-SNG CH4 content of 40 vol.-%db at 360 °C and atmospheric pressure conditions. Through the integration of external hydrogen in a hybrid process, the carbon utilization of the biomass could be increased from 37% to around 70% at an unchanged cold gas efficiency of 58–59%. Via the SER process, a high raw-SNG CH4 content of 70 vol.-%db was achieved at an increased cold gas efficiency of 66% without the need for external hydrogen. Finally, a comparison points out the main advantages of the process configurations and provides a decision basis for novel SNG production pathways.