Reversible Solid Oxide Cell Systems for Grid Energy Management

The present study summarizes optimization studies aimed at identifying the most effective techno-economic pathways of deploying reversible solid oxide cell (ReSOC) based systems for energy storage. Carbon dioxide and water are co-electrolyzed in the stack to produce methane and hydrogen, which can be injected directly into a natural gas pipeline or further refined into a purer stream of methane. We explore performance and cost of a 50 MWe ReSOC system for system design concepts that evaluate different levels of methane purification. Results indicate that without external methanation, the system can produce a synthetic gas mixture of roughly 42% H2 and 55% CH4 at a cost of 72 $/MWh (20 $/GJ) and an 82.7%-LHV efficiency. Adding both a methanation reactor and a membrane increases methane purity to 92%, while only increasing cost by about 5% to 77 $/MWh (21.4 $/GJ). Over half of this cost is associated with the cost of carbon dioxide and electricity.