Exploration of Kgalagadi Sand as a High-Temperature Heat Storage Material for the Growing Renewable Energy Market in Botswana

Abstract

This study presents an investigation of Botswana’s Kgalagadi Desert sand for its feasibility as a high-temperature sensible thermal energy storage material. The main objective of the study is to thermally characterise the sand by investigating its decomposition under thermal stress, the variation of its thermo-physical properties, agglomeration effects, phase transitions, and many others. The study used a differential scanning calorimeter (DSC) for heat flow analysis, a thermogravimetric analyser (TGA) for thermal stability and mass loss determination, an X-ray Diffractometer (XRD) to determine the mineralogy of the sand, and an X-ray fluorescence (XRF) analyser for the elemental composition. Results from the aforementioned tests showed that Kgalagadi sand is pure and silica-rich with relatively good thermo-physical properties, thus the sand is ideal for high-temperature thermal storage applications. The sand also maintains weight stability after cyclic high-temperature heat stresses, and it also does not suffer from agglomeration, likely due to its purity.