Browsing by Author "Rakuoane, Molibeli"

Now showing 1 - 1 of 1
  • Thumbnail Image
    ItemOpen Access
    Wind measurements using SODAR: Hirundo wind farms case study
    (National University of Lesotho, 2024) Rakuoane, Molibeli; Mpholo, Moeketsi
    This study compares the wind data of the European Centre for Medium-Range Weather Forecasts Reanalysis Version 5 (ERA 5) to that obtained from the sound detection and ranging (SODAR) at the Rothe Plateau. It utilizes industry-standard software, Wind Atlas Analysis and Application Program (WAsP), to undertake the analysis. WAsP was employed to generate wind resource maps, to model the wind flow over complex topography and to forecast the yearly wind conditions. The availability of SODAR data, obtained from 23 January 2024, to 31 July 2024, after eliminating inaccurate and suspicious data, was 57.36%. It is commonly perceived as being of inferior quality due to its failure to meet the 90% threshold. The precision of wind resource validation is determined by the degree of accuracy and availability of the relevant data. The findings of this study show that the forecast errors of ERA 5 represent about 12.2% of the range of SODAR wind speed data, indicating a moderate level of accuracy. The normalized root mean square error (NRMSE) for wind speed and direction were found to be 0.122 and 0.359, respectively. The ERA 5 provided inaccurate wind direction. Furthermore, the mean bias error (MBE) of -1.51 m/s and -7.840, respectively, for wind speed and direction were discovered, indicating an under prediction by the ERA 5 model. The correlation coefficient (R) between the two datasets was determined to be 0.725 (72.5%). Demonstrating a robust and reliable connection between SODAR and ERA 5. However, the wind direction correlation indicated a relatively poor connection of 27.7%. With a determination coefficient (R2) of 0.525, ERA 5 is not able to capture and represent the complexity and dynamics influencing fluctuations in wind speed variations. The chosen turbine generator for the Hirundo Energy wind farm is the Vestas V162-6.0 MW, with a maximum rated power of 6.0 MW. The wind farm contributes significantly to the generation of renewable energy, with an anticipated net annual production of 75.5 GWh, about 8.9% compared to the country’s consumption of 848 GWh per annum in 2022. This proves that wind energy technology can be effectively harnessed in Lesotho and highlights the significance of data validation and farm planning for optimizing energy output and efficiency. However, due to the lack of continuous onsite measurements, the capacity factor was found to be 17.95%, compared to a global average of 30% for grid-connected wind farms.