An efficient and fuel flexible micro-scale biomass CHP technology based on the combination of a small-scale updraft gasifier with a SOFC system has been developed within the EU H2020 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. After successful test of the GCU comprehensive test runs with the SOFC followed. Overall more than 300 hours of GCU operation and 250 hours with SOFC operation could be achieved with different biomass fuels. The gas quality was satisfactory and the SOFC system achieved its nominal capacity (6 kWel). Following, the basic proof of concept for the new technology could be gained.

During recent years comprehensive work has been done on the development of small-scale solid biomass based combined heat and power generation technologies but still only few systems are available, their efficiencies are rather moderate, their fuel flexibility is restricted and their market penetration is poor. Against this background, the on-going Horizon 2020 project FlexiFuel-SOFC aims at the development of a new, highly efficient and fuel-flexible micro-scale biomass CHP technology for a capacity range of 25 to 150 kW (fuel power). The technology consists of an updraft gasifier, a gas cleaning system and a solid oxide fuel cell (SOFC). The new technology is developed with a main focus on (i) the further development of a small-scale fixed-bed updraft gasifier technology towards higher fuel flexibility and integration into the SOFC based CHP system, (ii) the development of a novel and compact gas cleaning unit and (iii) the further development of a SOFC system (stack efficiency of ~40 % with product gas from the updraft gasifier). A first testing plant has been designed, constructed and is presently taken into operation.