Optimal Design of a Novel Integrated Energy System Based on the CO2 Network and Reversible Solid Oxide Cell Technology

Integrated energy systems have emerged as a crucial solution for no carbon energy system transition towards carbon neutrality. This paper proposes a novel integrated energy systems that synergistically combines a reversible solid oxide cell with a gas-liquid two-phase CO2 network. The system integrates multiple technologies, including photovoltaics, solar thermal collectors, Organic Rankine Cycle, and hybrid energy storage (lithium-ion batteries, hydrogen tanks, and molten salt storage). Two key innovations are the utilization of the CO2 network to transfer energy to end-users for district heating and cooling with lower heat dissipation and passive cooling and the utilization of the reversible solid oxide cell to achieve multi-scale energy storage. Moreover, a novel planning methodology is introduced, which combines an extended Energy Hub structure with process synergy to define the optimal system design and its operational strategy. A case study of a community in Beijing is implemented to demonstrate its feasibility. The results indicate an optimal configuration with 100 MW PV and 1123 MWh hydrogen storage, achieving a total annual cost of 216 million CNY. The operational analysis reveals effective multi-time scale energy management, where batteries handle short-term fluctuations, while the reversible solid oxide cell and hydrogen storage facilitate long-term energy shifting. The CO2 network proves instrumental in enabling cross-sectoral synergy by simultaneously meeting heating and cooling demands, thereby reducing the terminal load and enhancing overall efficiency. This study provides a theoretical foundation and a viable technical pathway for designing efficient, low-carbon, and self-sufficient regional energy systems.