Over recent years, large scale energy storage applications have been proposed in order to increase the solar energy penetration into the electricity grid with a view to limit the fossil fuels utilization in the energy sector. Among renewable energy technologies, Concentrated Solar Power (CSP) plants have a great potential for integration with Thermal Energy Storage (TES) systems. Thermochemical energy storage (TCES) is a less mature and considerably higher energy density among TES technologies and potentially capable of decoupling energy production and demand both for short and long term. In this framework, the TCSE at large scale investigated in this work is based on the Calcium Looping (CaL) process, which exploits the reversible calcination -carbonation reactions of calcium carbonate and calcium oxide.