Solar energy scenarios in Brazil, Part one: Resource ... - LEPTEN

ARTICLE IN PRESSF.R. Martins et al. / Energy Policy 36 (2008) 2843–2854 2853winter). One hypothesis may be the increase of aerosol particlenumber concentrations emitted to the atmosphere by the burningof biomass typical during this time of the year in these regions.3.3. Solar irradiation over a tilted planFig. 7 presents the maps for annual and seasonal means ofglobal solar irradiation over a plan tilted to an angle equal to thecell latitude. The assessment of the ‘‘tilted’’ component is veryimportant information for the development of PV applications andsolar heating systems. Disregarding the local topography, the solarirradiation over a surface tilted to a latitude angle is theconfiguration that allows capturing the maximum solar energythroughout 1 year.All maps in Fig. 7 present similar patterns as discussed forglobal solar irradiation. The furthermost levels of irradiation onthe tilted plane occur in the range that goes from the Northeast tothe Southwest during the spring and the smallest values in allBrazilian regions occur during the winter months.3.4. Diffuse solar irradiationFig. 8 exhibits the maps for annual and seasonal averages of thedaily total of diffuse solar irradiation. On the annual average onecan observe that the Northern region receives greater diffuseirradiation mainly in the estuary of the Amazon River. This is dueto the larger nebulosity in the region as a result of the ITCZinfluence. Seasonally the greatest diffuse irradiation occurs duringthe summer throughout the Amazon region. The smallest valueshappen during the dry season (fall and winter) in the Southeasternand Southern regions.4. ConclusionsThis paper describes the satellite-derived assessment of solarenergy resource prepared during the SWERA project. The projectSWERA had financial support from UNEP and GEF and it aimed atproviding reliable and high-quality information to decisionmakers, politicians, investors and stakeholders in order to fosterclean energy applications in developing countries. The solarirradiation maps for Brazil were prepared by using a radiativetransfer model BRASIL-SR fed by climate data and satellitederivedcloud cover data. The reliability of solar resourceestimates and model BRASIL-SR performance were checked outthrough comparisons with solar estimates provided by numericalmodels adopted in SWERA to map solar resources in otherparticipating countries and comparison with ground data acquiredin all Brazilian regions. Concisely, the model BRASIL-SRpresented a similar performance as other core models adopted bythe SWERA project for solar assessment in other regions, but itusually overestimates solar irradiation—MBE around 6% andRMSE about 13%.The larger values of global solar irradiation were found for thesemi-arid area in the Brazilian Northeast region. The extremelydry environment (semi-desertic) and the high number of sunshinehours all year round resulted in mean solar irradiation around6.5 kWh/m 2 day. Slight smaller values were obtained for theSouthern region during spring and summer seasons. However,the solar irradiation there presents higher variability through theyear due to the incursions of cold fronts originating from the deepcyclonic systems in the Antarctic region, mainly during fall andwinter seasons.The maps for solar irradiation over a plane tilted in a angleequal to the local latitude point toward the great potentialavailable for solar energy applications in Brazil, even in the semitemperateclimate in the Southern region where annual mean ofsolar irradiation is comparable to that estimated for the equatorialAmazonian region. It was also verified that all Brazilian territoriesreceive larger solar irradiance than many of the Europeancountries where a large number of solar energy projects are beingimplemented mainly as a result of good energy regulation forrenewables and valuable government incentives.The scenarios for solar thermal and PV applications, preparedby using the GIS database acquired during SWERA together withthe solar resource maps presented here, will be discussed in twoother papers to be published in the near future.AcknowledgmentsThis work was possible thanks to the financial support ofUNEP/GEF (GFL-232827214364–SWERA) and FINEP(22.01.0569.00). This work was prepared with the fundamentalcontribution of the following colleagues: Silvia V. Pereira, CristinaYamashita, Sheila A.B. Silva, Hugo Corrá and Rafael Chagas. Thefollowing institutional acknowledgment is due to Centre forWeather Forecast and Climatic Studies (CPTEC) and, in particular,for the people from the Environmental Satellite Division (CPTEC-DSA) for the continuous support in satellite data and ancillarysatellite products and from the Laboratory of MeteorologicalInstrumentation (CPTEC-LIM) for the support in operation andmaintenance of ground measurement sites. Thanks are due toDave Renné (NREL/USA), Richard Perez (SUNY/Albany) and TomHamlin (UNEP) for help and scientific contributions to thedevelopment of the SWERA project. Thanks are also due to CNPqfor the scholarships to researchers and technicians involved in theSWERA tasks.ReferencesBeyer, H.G., Pereira, E.B., Martins, F.R., Abreu, S.L., Colle, S., Perez, R., Schillings, C.,Mannstein, H., Meyer, R., 2004. 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