Thermal characterization and cost analysis of cement-based composite materials for thermochemical energy storage

The objective of this study is the synthesis and thermal characterization of cement-based composites for thermochemical energy storage (TES), focusing on three cement families: Portland Cement (PC), Calcium Aluminate Cement (CAC), and Calcium Sulfoaluminate Cement (CSA). We explore the potential of those composites in enhancing energy storage capabilities, while being cost-effective and robust. The research has involved composites with varying proportions of sepiolite to enhance porosity and reduce costs. An in-situ synthesis technique was conveniently employed allowing promising results on control over salt content. Water vapor-sorption analyses were conducted on six selected samples at two temperatures (30 °C and 50 °C) and across five relative humidity points. The Polanyi adsorption potential theory was employed to extend the analysis and model realistic operating cycles. We found that the top-performing composite exhibited an energy density of 85 MJ/m3 with a storage cost of 9.30 €/kWh, thus resulting comparable or superior to materials like Zeolite 13×/MgSO4 and silica gel/CaCl2, but lower than vermiculite/CaCl2 or LiCl. Nonetheless, the novel composites demonstrate lower costs and promising behavior with respect to important challenges as deliquescence or poor mass transport. The synthesized cement-based composites show significant potential in TES technology, though further optimization is still requited in terms of energy density and material cost. This research also suggests that cost reductions for CAC and CSA cements through scale economies and material mixing strategies, like combining CAC with PC might be feasible to further enhance the viability of these composites in TES applications.