Direct Methanation and Storage Concepts for the Flexibilization of Biogas Plants

Abstract

Enrichment of the methane fraction in a biogas mixture is an innovative possibility to make existing biogas plants more flexible by using excess power. In the described concept, the CO2 in the biogas is directly catalytically converted into CH4 with H2. The CH4-enriched biogas is again fed into the digester to save energy for later use in the combined heat-and-power unit. Additionally, the fed heat gas can mix and heat the substrate. A heat pipe injector system was therefore developed for cooling the hot biogas stream after methanation and to prevent damage to the microbial consortia during the biomass mixing. The concept was proven at a laboratory-scale biogas plant.