Impact of atmospheric aerosol loads on Concentrating Solar Power production in arid-desert sites

The accurate quantification of direct normal irradiance (DNI) and the production of time series of DNI have a key role during the planning and designing stages of CSP plants. Satellite derived data are frequently used for that purpose. One of the important sources of uncertainty for satellite derived DNI is the accuracy in the quantification of aerosol optical depth, one of the most important parameters that contribute to solar radiation attenuation at the Earth's surface. This topic can be extremely important in desert and arid places where sudden and large increase of aerosol optical depth can be eventually expected. This work presents an analysis of the uncertainty about the knowledge of aerosol optical depth in Sede Boqer and Tamanrasset, its contribution to the uncertainty of DNI values estimated from Meteosat imagery, and finally the impact on the CSP plant energy dispatched. Reference plants for CSP parabolic trough and CSP tower technologies have been modelled with SAM with no thermal storage system, and a GEMASOLAR plant-type has been also modelled as an example of tower plant with large thermal storage system. The results have shown that in Tamanrasset the sudden and eventual high peaks of aerosol optical depth resulted in an important decrease of the daily energy produced by the plant; this reduction is not always observed when satellite derived DNI is used to input meteorological conditions in SAM due to the underestimation of the aerosol optical depth. The use of large thermal storage system notably reduces the impact of these phenomena on the CSP power plant output.