Sustainable Ceramic Particles for CSP Applications

Abstract

High-temperature-resistant ceramic particles are developed as solar heat absorbers and storage media in point-focused concentrated solar power (CSP) technology [1]. A promising secondary source of raw materials for ceramic particles are metallurgical by-products, frequently referred to as metallurgical slags. The chemical composition of many metallurgical by make them attractive materials for CSP technologies. In particular, by-products varieties with high contents of darkening, transitional metals such as Fe, Mn, Co, and Cu are attractive to solar absorbers requiring high absorptance of solar light. A suitable chemical composition, in particular with low free SiO2 is beneficial for use as filler materials in molten-salt thermal energy-storage (TES) systems. In a pilot study copper-metallurgy-derived fayalite slags were characterized in terms of their material and solar thermal related thermo-physical and thermo-chemical properties. It turns out that solar absorptance and high-temperature stability make them attractive for solar particle absorbers whereas their relative chemical inertness to molten solar-salt, a mixture of NaNO3 and KNO3, makes them durable TES filler materials for operation up to 600°C. For application in CSP technology, fabrication of millimeter-sized, spherical ceramic particles is developed on the basis of oil-drop technology.