Pulsed electrolysis of carbon dioxide by large-scale solid oxide electrolytic cells for intermittent renewable energy storage

Abstract

CO2 electrolysis with solid oxide electrolytic cells (SOECs) using intermittently available renewable energy has potential applications for carbon neutrality and energy storage. In this study, a pulsed current strategy is used to replicate intermittent energy availability, and the stability and conversion rate of the cyclic operation by a large-scale flat-tube SOEC are studied. One hundred cycles under pulsed current ranging from −100 to −300 mA/cm2 with a total operating time of about 800 h were carried out. The results show that after 100 cycles, the cell voltage attenuates by 0.041%/cycle in the high current stage of −300 mA/cm2, indicating that the lifetime of the cell can reach up to about 500 cycles. The total CO2 conversion rate reached 52%, which is close to the theoretical value of 54.3% at −300 mA/cm2, and the calculated efficiency approached 98.2%, assuming heat recycling. This study illustrates the significant advantages of SOEC in efficient electrochemical energy conversion, carbon emission mitigation, and seasonal energy storage.