Wave energy resource assessment near Guanabara bay, Rio de Janeiro, Brazil

Abstract

Having the 1973 oil crisis as a warning, the developments in technologies related to renewable energy have increased significantly over the years. Wind-generated waves in the ocean offer a renewable energy resource and can be predicted several days in advance. However, they must be well-evaluated to optimize their exploitation. The present study uses numerical modeling to assess wave energy resources near Guanabara Bay in Rio de Janeiro. We developed a hindcast system consisting of two spectral wave models to simulate two years of wave scenarios, 2017 and 2018. The global wave model WAVEWATCH III was run with four nested computation grids. The lower grid provided boundary conditions for the regional wave model SWAN, which has a computational grid of 100 meters of resolution. The spatial and temporal wave energy distribution was studied considering the monthly, seasonal, and annual averages. The results were evaluated based on measured data from two meteoceanographic buoys. Furthermore, the root mean square error (RMSE), bias, scatter index (SI), symmetric slope (sym r), and correlation coefficient (corr) were applied as evaluation methods. The average wave energy for the annual time scale was similar between 2017 and 2018, reaching 8 kW / m near the Ilha Redonda island and 5 kW/m at the bay entrance. However, the results of the SV index suggest a significant difference between the seasonal variability of both years. The validation results show values for the bias equal to -0.20224 for the RJ-3 buoy and -0.08948 for the RJ-4 buoy. Therefore, the study area presents itself as promising in wave energy generation. However, seasonal variability should be a concern when selecting wave energy converters.