Impactos das mudanças climáticas futuras sobre a geração de energia renovável no Nordeste brasileiro

Abstract

The use of renewable sources for power generation is essential to the balance of the Brazilian energy system. The highest energy potential from wind and solar sources is concentrated in the Northeast region of the country, and yet these generation sources are still little explored, corresponding to approximately 7% of the electricity generated in Brazil. In recent years, several mapping studies of the potential energy generation have been carried out for the Brazilian territory, but few evaluate possible impacts of future changes in climate on wind intensity and solar irradiation. In addition, the importance of consistent climate studies for the formulation of more effective public energy policies and how they can contribute to regional development is rarely addressed. In this context, the general objective of this study is to better understand the behavior of wind intensities and solar irradiance in scenarios of future climate change in the Northeast region of Brazil, since this can be a valuable tool for decision making and adequate medium/long term energy planning. For this, wind intensity and solar irradiance projections were performed using the regional climate model RegCM4.7.1 and the dynamic downscaling used the output of the global model Hadley Global Environment Model 2-Earth System model (HadGEM2-ES). The recent past experiments were carried out for the period from 1995 to 2005. For future climate projections, the RCP8.5 emissions scenario were considered, with projections from 2005 to 2015 for the beginning of the century, from 2040 to 2050 for the middle of the century and from 2090 to 2100 for the end of the century. The results were compared to daily and monthly interpolation data produced by Xavier et al. (2015) over the Brazilian territory and the performance of the simulations evaluated through the Mean Absolute Error (MAE), Deviation or Uncertainty (BIAS), Root Mean Squared Error (RMSE). In general, the results showed that the regional model REGCM4.7.1 is able to adequately capture the patterns of both wind intensity and solar irradiance on the surface. The numerical experiments show that both the intensity of the wind and the solar irradiance can vary spatially and seasonally, with differences up to 40% in certain months of the year and in some specific regions. Considering the average variations for each of the studied periods, it can be observed that the solar irradiance on the surface showed little variation (less than 2%) for the future, indicating a greater tendency of stability while the wind intensity presented more significant variations, with increments close to 6% for the middle of the century. Although no large percentage changes are projected, there is an increase over the century in the number of months with values above the average for the current period, reinforcing NEB as a promising region for the expansion of energy production in the country. Thus, the results produced aimed to contribute to a scientifically consistent database for the Northeast that could serve as an initial subsidy for decision makers in the planning of public energy policies.