SOFC-CHP system operated on biogas

At Fraunhofer IKTS, the authors have built and tested an integrated biogas generator / SOFC system in the kW class, covering the whole process flow from biomass pre-treatment and anaerobic digestion to SOFC integration to by-product clean-up. The whole system is modular and has been operated onsite at the Rosswein wastewater treatment facility. SOFC and fermentation processes are interlinked to make use of excess heat from the SOFC in the bio-process. A SOFC system has been built featuring innovative ceramic components and has successfully been operated on biogas. Ultrahigh power density ESC cells have been combined with cost effective net shaped CFY alloy interconnectors to build compact, yet very robust, efficient and redox stable SOFC stacks. It has been demonstrated that biogas - in contrast to methane - can be converted in extremely simple POX reformers without offgas recirculation while gross system efficiency can still be well over 40 %.