Biogas fueled solid oxide fuel cells - from cell to system level

The use of biogas fueled solid oxide fuel cells (SOFC’s) could be a promising option in order to reduce greenhouse gas emissions and to get one step further in the direction of a circular economy. The main components of biogas are CH4 and CO2. Furthermore, other impurities are present in the biogas. A SOFC can convert hydrocarbon fuels like biogas directly into heat and electricity without producing NOx or small particles like in combustion engines. Additionally, different kinds of biogas compositions are feasible for a SOFC. In this thesis, different aspects of biogas fueled SOFC’s are investigated from both a theoretical and experimental point of view. SOFC operation modes and poisoning effects are analyzed considering real biogas. Biogas is used from the biggest dump site of Denmark and from a wastewater plant located in Italy. Additionally, anode-off gas operation parameters for avoiding carbon formation during biogas SOFC operation are investigated. Finally, an efficiency study of biogas fueled industrial sized SOFC systems is conducted. In general, the results of this thesis show that operation of biogas fueled SOFC’s is possible and high efficiencies can be achieved. Moreover, different approaches and strategies are successfully investigated in order to achieve a stable operation during real biogas fueled SOFC’s operation. Thereby, the system complexity could also be reduced.