Power to gas(PtG) has been payed attention as one of the ways to promote introduction of renewable energy. Solid oxide electrolysis cells(SOECs) are one of the electrolysis devices in the PtG. Because of its low electrolysis voltage and high utilization of generated heat, SOECs are expected to be the most attractive electrolysis cell from the viewpoint of energy conversion efficiency. In addition, since SOECs can electrolyze CO₂ into CO, which is used as a raw material of alkane, it attracts attention as technique of the recycling of CO₂. Thus, in recent years there has been growing interest in developing a co-electrolysis system. Because SOECs are constructed mainly on brittleness ceramics, a detailed understanding of temperature distribution in the cell is important for reducing thermal stress. Although the electrolysis reaction is endothermic, overpotentials and electrical resistivity of cell are factors of heat generation in the cell. Thus, the temperature distribution in SOECs is very complicated.

In this study, the temperature distribution in the micro-tubular cell was measured by thermocouples and a thermal imaging camera. The micro-tubular cell consists of (ZrO₂)_0.92(Y₂O₃)_0.08 (YSZ)/ YSZ / La_0.8Sr_0.2MnO₃ (LSM). The current collection of air electrode area was performed using Pt paste and wires. During the electrolysis process, the temperature change in the cell was small around gas inlet, and the difference of temperature along a tube length direction to gas outlet increased. Around Pt wire on the surface of the air electrode, the temperature change was maximum. Furthermore, the temperature change around gas outlet increased because of current collector was attached to the edge of fuel electrode at the side of gas outlet. Compared to steam electrolysis, the temperature change during the co-electrolysis process was smaller.