The Impact and Mitigation of Carbon Formation on Ni-YSZ Anodes from Biomass Gasification Tars

The combination of Solid Oxide Fuel Cells (SOFCs) and biomass gasification has the potential to become an attractive technology for the production of clean renewable energy. However the impact of tars, formed during biomass gasification, on the performance and durability of SOFC anodes has not been well established experimentally. This paper reports on an experimental study assessment of the performance and mitigation of carbon formation on the anodes of SOFC button cells from synthetic model tars arising from the gasification of biomass material. The anode material was a 60:40 wt.% NiO/YSZ cermet, which was tested in a synthetically generated syngas containing a concentration of up to 15 g/Nm3 biomass gasification tars. It was found that carbon formation in dry conditions significantly damaged the anode of the fuel cell resulting in decreased cell performance and excessive anode polarization resistances. These effects were reduced by applying a load to the cell, and were essentially inhibited once the steam content of the input fuel was > 2%.