Degradation Analysis of SOFC Performance (1) — Severe Operation with High Fuel Utilization

Abstract

Central Research Institute of Electric Power Industry (CRIEPI) has operated four types of SOFC stacks, which are developed by Kyocera, NGK SPARK PLUG (NTK), NGK INSULATORS (NGK), and Denso in a NEDO’s project since FY2018 to FY2019 in order to clarify the technical issues for high-efficiency and toughness of SOFC stacks or make a concept for the high-efficient stacks. Each SOFC stack has been operated with the high fuel utilization (Uf = 80%) as a severe condition for high-efficiency for more than 3,000 hours, 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 of the SOFC stacks which were modified for improving long-term durability in the previous term.

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

“…Figure 2 shows degradation analysis results of the 2018 model obtained by using our electrode polarization model. Transitions of the change rate of the anode overvoltage, cathode overvoltage or IR loss have been similar to those of the 2016 model, respectively (1). The dominant degradation factors for the 2018 model were the cathode overvoltage and IR loss same as that for the 2016 model.…”

“…For more than 10,000 hours after the beginning of the test, the cathode overvoltage and the IR loss have slightly increased and the anode overvoltage has little changed. The dominant degradation factors for the 2014 model adv.2 were the cathode overvoltage and IR loss same as that for the 2014 model adv.1 (1). In the 2014 model adv.2, remarkable increase of the anode overvoltage has not been confirmed compared with the previous model.…”

“…The degradation factors were determined by the changes in the output voltage when the gas compositions were changed. The output voltage (V) of the SOFC single cell was expressed by equation [1] using the open circuit voltage (E), Nernst loss (η ne ), anode overvoltage (η a ), cathode overvoltage (η c ), and internal resistance (IR) loss (η ir ). Furthermore, the anode and cathode overvoltages are approximately considered as values of resistance as shown in equation…”

Multiscale modelling potentialities for solid oxide fuel cell performance and degradation analysis

“…Aer 5000 h at 1023 K and 0.2 A cm −2 , a lower degradation rate was reported resulting in 0.75 V% kh −1 . 25 Whereas the Ni-YSZ/YSZ/LSCF-CGO system showed a more stable performance with an overall value of 0.5 V% kh −1 aer 100 000 h of operation working at 973 K and 0.5 A cm −2 . 26 Referring to modelling activity, a multiscale analysis well ts the challenge to study SOFCs at nominal and aged states.…”

Electrical Efficiency of Two-Stage Solid Oxide Fuel Cell Stacks with a Fuel Regenerator

“…The durability of a tubular-type SOFC was demonstrated for 69,000 h by the Westinghouse Electric Corporation (later Siemens Westinghouse Power Corporation) in the 1990 s, 1 and the durability of various SOFCs has been confirmed. 2,3 Using the SOFC stacks, many types of SOFC modules and systems have been studied. For example, residential SOFC cogeneration systems have been developed by many manufacturers, and they have been installed on a large scale.…”