Biomass integrated gasifier-fuel cells: Experimental investigation on wood syngas tars impact on NiYSZ-anode Solid Oxide Fuel Cells

The aim of this work is to assess the feasibility of a Biomass Integrated Gasifier Fuel Cell (B-IGFC) plant. High temperature Solid Oxide Fuel Cells (SOFC) are the most efficient energy systems currently being developed and they show good fuel flexibility thanks to their high operational temperature. For the application here discussed, the fuel major active species are H2,CO and CH4; yet, in wood-derived syngas small amounts of higher hydrocarbons are produced too. Among them, tars are claimed to be biomass Achille's heel, causing severe issues in internal combustion engines and turbines. Conversely, SOFCs might be able to decompose tars with a gain on cell performance. However, in order to avoid fast degradation, tars concentrations have to be below a critical threshold. In this work, SOFC operation with real wood syngas from a pilot batch gasifier is firstly demonstrated. Then, longer tests are repeated under controlled conditions, artificially reproducing wood syngas with and without tars. Tests demonstrated that commercial NiYSZ-anode cells are able to work on syngas with a model tar (toluene) concentration up to 10 g/N m3, exhibiting a voltage gain with regard to performances on syngas without model tar. No material degradation was observed after the experiments. As a final result, this paper aims at providing a proof of concept of a simplified B-IGFC system design, in order to reach its cost-effectiveness on small-scale installations.