High Efficient Waste Biomass Conversion to Electricity and Heat

SOFC anodes contain nickel as composite with YSZ (yttria stabilised zirconia) or GCO (cerium gadolinium oxide). One of the significant advantages is the ability to catalyse internally reforming reactions which allows for using methane (carbon containing) fuels directly, because the anode fulfills two functions: a catalytic reforming and an electro-catalytic functionality. They have achieved a mature state for both, the anode supported (ASC) and electrolyte supported (ESC) concepts. A well-known challenge of these anodes is the poisoning by impurities, e.g., sulphur containing impurities or by carbon deposition. To avoid the degradation due to these mechanisms, a proper fuel gas cleaning can be employed or the development of tolerant anodes. The latter path has not yet been successful on the high TRL level due to the so far unmatched high electrochemical performances and the reforming activities of the Ni –SoA anodes. Comprehensive studies have looked at the sulfur tolerance of SoA anodes – mostly in the ASC concept, because sulphur is a typical impurity in many relevant SOFC fuels. Biogas contains additional impurities, with the potential of a poisoning effect on the catalytic reforming and/or the electro-catalytic activity. A complex mixture of impurities can amplify or attenuate the effect of the single impurity. Therefore, the project will investigate both, the effect of sulphur as a very well-defined representative and also the whole impurity mixture by using real biogas directly. From tests of such SOFCs in electrolysis mode, it was found that performance and durability were improved through infiltration of nano particles (like CGO) into the cells. Further, a performance improvement of degraded SOFC stacks was achieved by infiltration as well. This concept will be transferred to the cells/stacks in this project.