Thermochemical energy storage (TCES) basically consists of using the high temperatures attainable in a Concentrating Solar Power (CSP) plant to drive an endothermic chemical reaction, and when energy is needed, the stored reaction products are brought together at the necessary conditions to drive the exothermic reverse reaction. The calcium looping (CaL) process, based on the cyclic carbonation-calcination reaction of CaO, is a recently emerging promising choice for TCES mainly due to the low cost of natural geological CaO precursors such as limestone and marble wastes and to the high energy density that can be achieved (e.g., 1790 kJ/kg for CaCO₃). These materials can be stored at ambient temperature without heat loss for long periods.

This project aims to develop, test and model a potentially low-cost and efficient TCES system based on the integration of the CaL process in CSP plants using cheap viable Portuguese CaO solid precursors (wastes of marble powder, water treatment sludge and natural geological resources such as dolomite and limestone). Moreover, the project will evaluate for the first time the sustainability of an optimised solar-driven CaL process for CO₂ capture and TCES integrated in an industrial cement plant with water and heat integration. Based on experimental and modelling studies, this project seeks to advance the proposed TCES process from TRL-2 to TRL-4 by demonstrating the system’s key advantages and its high exergetic and energetic efficiencies.