Impact of Soiling Physicochemistry on Mirrors With CSP Applications at the Plataforma Solar Del Desierto De Atacama, Chile

Abstract

The context of global economic instability and armed conflicts has caused fossil fuels to reach unprecedented levels. In this sense, Concentrating Solar Power (CSP) technology has proven to be an excellent option to diversify the energy matrix dependent on fossil fuels, especially in places where there is a good quality solar resource, such as desert areas. These good qualities can be overshadowed by local phenomena such as soiling that can affect the viability of a project. In this paper, the effect of soiling on CSP mirrors installed in a cold desert climate in the Atacama Desert, Chile, is presented. During the 202 days (continuous) of outdoor exposure, atmospheric parameters such as humidity and temperature, as well as reflectance were evaluated daily. At the end of the experiment, the chemical composition of the material deposited on the mirror surface was analyzed by scanning electron microscopy (SEM) and elemental analysis (EDX). The characterization of the material detected the presence of Gypsum (soluble salt), which was shown to have the ability to cement the deposited material. The atmospheric parameters showed that the relative humidity at the site can exceed 60%, sufficient values to solubilize the Gypsum, producing the cementation process. The reflectance values showed that the effect of the cemented material, for 202 days of exposure, can reach a 47% loss of its reflective capacity. This means that the longer the exposure time, the greater the effect of the cementation and the more energy will be needed to clean the mirrors.