Thermal and environmental durability of novel particles for Concentrated solar thermal technologies

Bauxite-based proppants, commonly used in the fracking industry, are also employed in solid particle receiver types of Concentrated Solar Thermal (CST) technologies. However, fracking has been banned in many countries due to its environmental impact, leading to a decline in demand for proppants. As a result, the current proppant price of 1 €/kg is expected to rise due to reduced production capacities. Therefore, alternative particle types need to be developed for Concentrated Solar Thermal applications. Cost-effective particle production compared to traditional bauxite sintering has been explored. In this study, we conduct long-term isothermal aging tests at 1000 °C up to 4000 h to assess the optical degradation of novel cost-effective particles, which are composed almost entirely of recycled waste products. The performance of these novel particles is compared to traditional proppants. Additionally, we examine the durability of three types of coatings designed to enhance the solar absorptance of the particles from approximately 83 %–97.5 %. These coated particles are also subjected to climate chamber tests under controlled humidity and freezing conditions to determine if environmental factors will degrade the coatings. • Novel particles have been qualified for CST applications. • Optical data of the particles has been recorded during long-term testing at 1000 °C up to 4000 h • Environmental testing has been conducted on the particles in climate chambers. • Three types of novel coatings to enhance the particle's optical properties have been evaluated. • The coatings improve the optical efficiency of the particles and are stable under the tested conditions.