Thermodynamic analysis and optimal design of an innovative CaC₂ and electricity co-production system through air separation and energy storage

Large-scale liquid air energy storage is a solution to achieve the goal of net zero carbon emission. However, there is currently no mature application and more research in realistic application cases is needed. Facing the application in future industrial scenarios with high levels of renewable energy penetration, this study couples the liquid air energy storage to oxygen-thermal calcium carbide manufacturing industry by sharing an air separation unit. It is a chemical material and electricity co-production concept to reduce the specific energy consumption of calcium carbide and manage the uncertainties of power supply and demand. Thermodynamic and sensitivity analyses are conducted to understand the system performance and interactions between each process. In the chemical process, the production and purity of calcium carbide are 28.56 kg/s and 66.6 % respectively, and the specific energy consumption is 246.2 kWh/t-CaC₂. Material matching, equipment sharing, and thermal integration make the round-trip efficiency of the proposed system reach 56.8 %. An artificial neural network-based process optimization is performed to establish the optimal design. The proposed system presents 11 % higher round-trip efficiency and 2–3 times the energy storage density in comparison to stand-alone liquid air energy storage systems.