Electrical and thermal analysis of an intermediate temperature IIR-SOFC system fed by biogas

An Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC) system fed by not conventional fuels such as biogas can produce electric energy with high conversion efficiency and thermal energy. Inside the energy system, the methane in the biogas is mixed with steam, and then it is converted into carbon monoxide, hydrogen and carbon dioxide through steam reforming and water gas shift chemical reactions in an indirect internal reformer (IIR) mostly and in the SOFC anode minimally. The chemical energy of the electro-oxidation of hydrogen and carbon monoxide produced is directly converted into electric energy in the fuel cell anode. A part of the anode exhaust gas can be recirculated at the IIR inlet and the percentage of this recirculated anode exhaust gas together to the fuel utilization factor influence the performances (electric and thermal powers and efficiencies, primary energy saving and first law efficiency) of the SOFC system in a cogenerative arrangement. Through the simulation model of an IT-SOFC system fed by biogas in cogenerative arrangement, which was formulated ad hoc and implemented in a Matlab environment, the influence of the above-mentioned variables on the IT-SOFC system performances was evaluated. The verification of carbon formation at the anode was made.