Development of granular thermochemical heat storage composite based on calcium oxide.

Thermochemical heat storage is a promising technology for the efficient utilization of renewable energy. Among available thermochemical systems, the CaO/Ca(OH) 2 system is the most popular because of availability and cost. However, poor powder properties and low heat storage rates hinder the successful implementation of this system. This study presented a novel synthetic method of granular composites based on carboxymethyl cellulose sodium (CMC) and vermiculite in order to mitigate the drawbacks of natural materials and stabilize the size of materials for use in moving bed reactors. TGA and DSC experiments and some essential characterizations were done in order to evaluate the improvements on the basis of three objectives: the heat storage rate, heat storage density, and mechanical properties, compared with natural materials. Results showed that the granular composite still had great structural integrity after several dehydration/hydration cycles, whereas compacted natural materials had fragmented. Additionally, composite had a higher heat storage rate than natural materials. The gravimetric storage density of granular composite was slightly reduced while the volumetric storage density was enhanced up to approximately 124% as compared to the powdery Ca(OH) 2 material. It was concluded that present synthetic method is a promising route for the development of Ca-based composite materials. • A novel synthetic method of granular composites based on CMC and vermiculite is developed. • Granular composites still have great structural integrity after several cycles. • The heat storage rate of composite is improved compared with natural materials. • The volumetric storage density of composite materials is slightly enhanced. [ABSTRACT FROM AUTHOR]