Design and modeling of an energy storage system based on solid oxide reversible cells with syngas as fuel and co-electrolysis of CO2 and H2O

The intermittent nature of renewable energy sources makes it difficult for electric utility companies to effectively implement these technologies in the power grid due to mismatches between supply and demand. Solid oxide cells are electrochemical devices that are receiving a lot attention as an effective power grid balancing technology, given their ability to operate as Solid Oxide Fuel Cells (SOFC) for electric power generation, and as Solid Oxide Electrolysis Cells (SOEC) for chemical fuel production. Solid Oxide Reversible Cells (SORC) are capable of working alternately in these two modes, thus can be used to store electricity in the form of fuel when energy supply in the grid exceeds the energy demand and can release this energy when demand exceeds the supply from generation systems.The purpose of this project was to design an energy storage system that uses solid oxide reversible cells and syngas as fuel, consuming it to produce electricity during operation as a fuel cell and producing it back to store electric power through the co-electrolysis of water and CO2 when working as an electrolysis cell. The design and steady-state simulation of the system was performed using the process simulation software Aspen Plus, where a base configuration of the plant was constructed and improved using as main criteria the roundtrip efficiency and exergy efficiency achieved. This approach allowed to locate the main sources of energy and exergy losses, therefore strategies could be implemented to reduce them, finally achieving a more advanced and efficient system. Overall, it was possible to attain improvements in system roundtrip efficiency from 29% to 44%; in SOFC exergy efficiency from 44% to 64%; and in SOEC exergy efficiency from 66% to 68%.Electrical Engineering | Sustainable Energy Technolog