Pilot-scale SOE-MCFC hybrid system for Co2/H2 mixture production - First experiences in the "Tennessee" project

In order to improve the energy efficiency of the Sabatier reactor-based power-to-gas process, molten carbonate fuel cells and solid oxide electrolyzers were installed instead of a conventional amine CO2 capture system and a classical alkaline electrolyzer. The plant is a multi-module prototype with a nominal capacity of 50 kW consisting of two SOE-MCFC units. The system was commissioned in 2022. The article describes the theoretical basis. The initial assumptions that were formulated at the stage of preparing for the research investment, as well as the deviations from them that became the result of detailed design were presented. The developed startup and shutdown procedures, as well as the first results of pioneering research were shown. The trial operation of the system was intended to provide information on integrated SOE-MCFC module and its performance and efficiency. The basic barriers for market implementation and recommendations for future research were discussed. The optimal operating point for hydrogen production needed 35.8 kWh/kgH2. Thus, electrical energy conversion to chemical energy efficiency is 93.9%. Flow preheating and electrical auxiliary heater power are not included. An MCFC at its ideal functioning point (around 4 kWel) outputs 5.4 kg/h of CO2 separated.