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Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

Hanrieder, Natalie and Wilbert, Stefan and Pitz-Paal, Robert and Emde, Claudia and Gasteiger, Josef and Mayer, Bernhard and Polo, Jesus (2015) Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements. Atmospheric Measurement Techniques, 8, pp. 3467-3480. Copernicus Publications. DOI: 10.5194/amt-8-3467-2015 ISSN 1867-1381

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Official URL: http://www.atmos-meas-tech.net/8/3467/2015/amt-8-3467-2015.pdf

Abstract

Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrated solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in raytracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested, and more than 19 months of measurements were collected and compared at the Plataforma Solar de Almería. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the nochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for concentrated solar power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the time-dependent solar spectrum which is reflected by the collector. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the absorption and broadband correction (ABC) procedure, additional measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from 1-year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.57 %. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8 %. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.8 %. Additionally, a simulation approach which just uses sun photometer and common meteorological data to determine the on-site atmospheric extinction at surface is presented and corrected FS11 and LPV4 measurements are validated with the simulation results. For T1 km equal to 0.9 and a 10 min time resolution, an uncertainty analysis showed that an absolute uncertainty of about 0.038 is expected for the FS11 and about 0.057 for the LPV4. Combining both uncertainties results in an overall absolute uncertainty of 0.068 which justifies quite well the mean RMSE between both corrected data sets. For yearly averages several error influences average out and absolute uncertainties of 0.020 and 0.054 can be expected for the FS11 and the LPV4, respectively. Therefore, applying this new correction method, both instruments can now be utilized to sufficiently accurately determine the solar broadband extinction in tower plants.

Item URL in elib:https://elib.dlr.de/99907/
Document Type:Article
Title:Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Hanrieder, Natalienatalie.hanrieder (at) dlr.deUNSPECIFIED
Wilbert, Stefanstefan.wilbert (at) dlr.deUNSPECIFIED
Pitz-Paal, Robertrobert.pitz-paal (at) dlr.deUNSPECIFIED
Emde, ClaudiaLMU, MIMUNSPECIFIED
Gasteiger, JosefLMU, MIMUNSPECIFIED
Mayer, BernhardLMU, MIM & DLR, IPAUNSPECIFIED
Polo, JesusCIEMATUNSPECIFIED
Date:25 August 2015
Journal or Publication Title:Atmospheric Measurement Techniques
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:8
DOI :10.5194/amt-8-3467-2015
Page Range:pp. 3467-3480
Publisher:Copernicus Publications
ISSN:1867-1381
Status:Published
Keywords:atmospheric extinction, direct normal irradiance, radiation loss
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:Concentrating Solar Systems (old)
DLR - Research area:Energy
DLR - Program:E SF - Solar research
DLR - Research theme (Project):E - Qualification (old)
Location: Köln-Porz , Oberpfaffenhofen
Institutes and Institutions:Institute of Solar Research > Qualifizierung
Institute of Atmospheric Physics > Atmospheric Remote Sensing
Deposited By: Kruschinski, Anja
Deposited On:30 Nov 2015 11:54
Last Modified:02 May 2019 14:13

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