ATMOSPHERIC ATTENUATION ON HELIOSTAT FIELD

摘要

Concentrating Solar Power design is highly dependent on local solar radiation, atmospheric variables (i.e. water vapor content, aerosols concentration, etc) and wind velocity. In the special case of central receiver power plants, the impact of atmospheric attenuation has to be taken into account to get more accurate designs. Atmospheric attenuation impacts both solar resource and heliostat field energy transmission and is neither measured nor estimated by main solar atlas. A common heliostat field design consists of overestimating heliostat number to ensure that the nominal energy is received at the receiver for all the range of attenuation values. Atmospheric attenuation is a physical process that does not impact all wavelengths in the same way and therefore it cannot be described as a single atmospheric attenuation without losing its physical meaning. This work is focused on deriving atmospheric attenuation values from ground data using a numerical model and describes step by step how it should be applied to estimate whole heliostat field attenuation. Atmospheric attenuation will first be described from the radiative transfer theory to be express for each heliostat. On a second part, numerical application will be shown using SMARTS radiative transfer model with satellite date from MERRA-Ⅱ. Variation in LCOE induced by atmospheric attenuation will be calculated to show importance of this parameter in site selection for tower power plant.