Pressurized electrolysis and co-electrolysis in solid oxide cells – preliminary experimental results

• Gastight and stable operation of a novel test stand up to 10 bar(a) was achieved. • Pressurized operation of solid oxide cells up to 5 bar(a) under 700 °C is shown. • Performance in co-electrolysis in a wide range of operating conditions is shown and discussed. Solid oxide electrolyzers (SOE) offer the possibility of simultaneous electrochemical reduction of steam and carbon dioxide in a single-step process, known as co-electrolysis (co-SOE). The composition of synthetic gas produced in co-SOE (including mostly H 2 and CO) can be precisely adjusted to specific downstream processes. Thus, SOE operated in co-electrolysis mode can be coupled with reactors such as Fisher-Tropsch or Sabatier, to produce liquid or gaseous hydrocarbonaceous fuels, respectively, in a Power-to-X processes. This not only enables energy storage in a form easily handled by existing infrastructure but also efficiently utilizes carbon dioxide, closing the loop and making it possible to recycle and reuse the gas. Converting both H 2 O and CO 2 in a single reactor can simplify and improve the efficiency of the syngas production process. Moreover, thermal integration of co-SOE with these reactors additionally boost the efficiency of Power-to-X systems. The results of an experimental investigation are presented in this paper. The research assessed the possibility of utilizing SOE/co-SOE cells for the highly efficient production of substrate for the synthesis of e-fuels. Electrochemical measurements were conducted for two types of cells in a temperature range between 660 °C and 700 °C. Four alternative compositions of feeding mixture were used at ambient pressure with additional experiments at elevated pressure in steam electrolysis mode. The impact of operating parameters on SOC performance, in the context of synthetic fuel production, is discussed.