Dynamic and steady state analysis of a power to methane system using a commercial solid oxide cell (SOC) electrochemical reactor

Higher penetration of renewable energy sources in the energy mix and increasing pressure to decarbonize society introduces new challenges. Energy storage and grid stabilization systems are necessary to address the intermittent nature of renewable energy sources (wind, solar etc.). Apart from the aforementioned challenges, moving towards a decarbonized economy, where electrical energy becomes the prime mover, new pathways to produce valuable and important chemicals (hydrocarbons etc.) should be established. Storing electricity in form of chemical energy is advantageous due to its long storage duration and its flexibility in use [1]. Methane is an important energy carrier and also an important raw material for various other process industries. Hence, converting renewable electricity to synthetic natural gas can address the issue of renewable energy storage and provide an alternate route for chemical energy required by process industries. In this paper, a Power to Methane energy storage system based on the experimental study of a commercially available 10 layer SOC reactor is presented. Thermal management of the electrolysis process is addressed by considering different possibilities for heat integration. Pressurized operation of the system is considered to study the effect of internal methanation within the SOC reactor on the system performance. For the proposed system an electric to chemical energy conversion efficiency of 91 % is feasible under nominal steady state operation conditions. The effect of heat loss from SOC the reactor on the system performance is considered. A dynamic study of the system is performed to study the impact of transient behavior on system performance and methane production. Additionally, strategies for transient operation are proposed to prevent hot spots, cold spots or sharp temporal and spatial temperature gradients in the SOC reactor that lead to eventual failure of the system are presented. For the above analysis an experimentally validated 1-D model of a reversible SOC reactor is used to study the temperature distribution in the SOC reactor during system operation 13 th European SOFC & SOE Forum 2018 3 – 6 July 2018, Lucerne Switzerland