1 Department of Energy Technology, The Faculty of Engineering and Science, Aalborg University, VBN2 The Faculty of Engineering and Science (ENG), Aalborg University, VBN3 Fluid Mechanics and Combustion, The Faculty of Engineering and Science, Aalborg University, VBN4 Esbjerg Energy Section, The Faculty of Engineering and Science, Aalborg University, VBN5 Flemish Institute of Technological Research (VITO)6 Flensburg University of Applied Sciences
Thermodynamic and dynamic process simulation
This study aimed to investigate the feasibility of substitute natural gas (SNG) generation using biogas from anaerobic digestion and hydrogen from renewable energy systems. Using thermodynamic equilibrium analysis, kinetic reactor modeling and transient simulation, an integrated approach for the operation of a biogas-based Sabatier process was put forward, which was then verified using a lab scale heterogenous methanation reactor. The process simulation using a kinetic reactor model demonstrated the feasibility of the production of SNG at gas grid standards using a single reactor setup. The Wobbe index, CO2 content and calorific value were found to be controllable by the H2/CO2 ratio fed the methanation reactor. An optimal H2/CO2 ratio of 3.45–3.7 was seen to result in a product gas with high calorific value and Wobbe index. The dynamic reactor simulation verified that the process start-up was feasible within several minutes to facilitate surplus electricity use from renewable energy systems.