Dealing with exergetic analysis of solid oxide electrolyzer

Green hydrogen has emerged as a promising energy vector to mitigate global warming. Among the most widespread electrolyzer technologies globally, the Solid Oxide Electrolysis Cell (SOEC) offers the highest efficiency. These cells operate in a temperature range of 600 to 1200°C, reducing electricity demand and increasing the required thermal energy. This study aims to compute the exergetic efficiency of the SOEC, defined as the ratio of output to input exergy rates. Alternatively, using the SPECO method, efficiency is determined by the ratio of product exergy to fuel exergy. The input-output exergetic efficiency was also evaluated, and SOEC electricity consumption was modeled. Three performance scenarios regarding the utilization factor and the steam fraction ratio at the cathode inlet were analyzed. Results indicate that SOEC exergetic efficiency can exceed 100%, varying with the assumed water dead state and operational temperature (electrolyzer operation modes). Comparisons with literature data are also provided.