Degradation Analysis of SOFC Performance for Long-Term Operation with High Fuel Utilization

In a NEDO's project from FY2020 to FY2024, Central Research Institute of Electric Power Industry (CRIEPI) has operated three types of SOFC stacks, which are developed by KYOCERA, MORIMURA SOFC TECHNOLOGY (MST), and DENSO in order to clarify the technical issues for high efficiency and toughness of SOFC stacks and establish the method for degradation diagnosis of SOFC stacks. Each SOFC stack has been operated with the high fuel utilization (Uf = 80 and 85%) as a severe condition for high-efficiency and degradation factors for SOFC durability have been analyzed by using the electrode polarization model which we have developed. Analysis results until now showed that dominant degradation factor was increase of cathode overvoltage or IR loss as same as that in the previous term. Moreover, thermal property testing has been conducted to apply the effect of temperature to our polarization model. It was clarified that internal resistance and electrode resistance coefficients can be expressed by Arrhenius equation.