Solid oxide fuel cells high flexibility on fuel typology allows to foresee their future use with a large spam of biogenous fuels. Coupled with their high efficiency in energy transformation, this characteristic could become a useful basis for plants devoted to the reduction of greenhouse gas emissions, and for the widespread use of residential renewable fuels.
An interesting feature is the use of biogas from anaerobic digestion of algae cultures. However some requirements have to be taken into account concerning the presence and the effect of gas trace compounds like sulphur, halides and others on the cells’ anodes.
This paper investigates the utilization of biogas from anaerobic digestion in solid oxide fuel cells. This is an high quality fuel in terms of permanent gas compounds and impurities consisting mainly of hydrogen (around 60%) and the rest CO2. The experiments consisted in testing single planar cells with the produced biogas. Planar solid oxide fuel cells with NiO/YSZ traditional anodes were tested in order to evaluate the electrochemical cell performance and eventually optimize the biogas production process for the specific purpose. The evaluation was achieved by taking current voltage measurements and impedance spectra at different temperatures. Also thermodynamic calculations were conducted to account for water gas shift and Boudouard reactions.
Results obtained with the biogas and humified hydrogen as reference were compared. The operation of solid oxide fuel cells was demonstrated with such biogas achieving high power density and without any appreciable degradation. Also microscopic analysis confirmed the integrity of the microstructures.