Dynamic Biogas Upgrading for Integration of Renewable Energy from Wind, Biomass and Solar

The Sabatier process is investigated as a storage scheme for renewable energy. Hydrogen derived from fluctuating renewable energy sources like wind and solar is converted to methane by the hydrogenation/methanation of carbon oxides. Biogas from anaerobic digestion is considered in this study as a high concentrated source of carbon dioxide. By using the Sabatier process, the CO2 content of the biogas is converted to CH4, which is a new upgrading process for biogas. By switching between (i) this upgrading process during periods of extensive electricity production from wind and solar, and (ii) combined heat and power production from biogas during periods of electricity demand, bioenergy utilization becomes a dynamic process. In such a process scheme, biomass, wind, and solar could be integrated in a local context.

This thesis aims to demonstrate the feasibility of the dynamic biogas upgrading as a sustainable process for electricity storage and system integration in Northern Germany, i. e. the state of Schleswig-Holstein. A feasibility study was conducted to analyze the energy system in this region and the potential for this process. Process simulation tools were used to prove the product gas properties and the degree of efficiency of the system. Lab-scale and bench-scale experiments where further applied to demonstrate the utilization of industrial waste water for biogas production and the general applicability of biogas in the Sabatier process.