Operation experience with a novel highly efficient micro-scale CHP system based on fuel-flexible gasification and a SOFC

An efficient and fuel flexible micro-scale biomass CHP technology based on the combination of a small-scale updraft gasifier with a SOFC system is developed within the project FlexiFuel-SOFC. High load flexibility and a maximum of full load operating hours of the CHP system is achieved by operating the CHP part of the plant with a side stream (product gas extracted from the gasifier) of a heat controlled system (gas burner and boiler as well as heat recovery). A gas cleaning unit (GCU) for the treatment of the side stream according to the requirements for the operation of the SOFC regarding contaminant (H2S, HCl) and TSP removal as well as tar content reduction was designed, constructed and successfully evaluated. A considerable reduction of the gravimetric tar content down to a suitable tar content for the operation of the SOFC stack module is achieved by gasifier internal tar reformation and a further reformation step in the tar reformer of the GCU. Comprehensive tests have been successfully performed with a broad spectrum of solid biomass fuels at a testing plant at BIOS in Graz. Promising test run results showing a basic proof of concept for the new technology could be gained.