Posters

Abstract

INTRODUCTION The 200-meter resolution maps of estimated mean annual wind speed included in UL Solutions's digital platforms are designed for preliminary wind resource assessments and created with the Mesomap system, a coupled mesoscale-microscale modeling system based on the WRF and WindMap models. This work presents an updated validation of Europe's wind speed map, including a comparison against two of the most used public sources of wind resource data, the Global Wind Atlas (GWA) and the New European Wind Atlas (NEWA). METHODOLOGY The data used in the validation was first filtered and long-term adjusted at the top measurement height. However, before proceeding to map adjustment and validation, it's necessary to select the met stations carefully: * Masts with less than one year of measurements are removed from the sample to avoid seasonal biases. * When more than one masts are found within the same wind development project or area, as is often the case for a wind project in the pre-construction phase, a single met mast will be chosen as the most representative of the site. Typically, we select the met mast with the longest period of records and tallest measurement heights, assuming everything else equal. The rationale behind this filtering is to even out as much as possible the weighting given to all the areas of the map with met masts when performing the map adjustment. Otherwise, our map adjustment procedure intended to reduce the overall bias of the map would give too much weight to areas with a high density of met masts. Also, if there are met masts in different terrain conditions (e.g. hilltop vs. valley) or land use conditions (e.g. cultivation vs. forest) within the same wind development project or area, it is more appropriate to select the most representative mast than take the average of all the masts. RESULTS The validation was conducted with an initial sample of 315 tall met masts spread over 18 countries in Europe. After filtering the station list to account for minimum measurement period, one (representative) mast per project and reliability of the coordinates, 176 measurements remained available. The performance of the 200 m resolution wind map is compared to the one of the GWA and NEWA maps and is summarized in the following table: Average bias (m/s) Uncertainty (m/s) RMSE (%) UL Solutions 0.22 0.58 9.9 % NEWA 0.51 0.62 12.8 % GWA 0.65 0.61 14.3% The new validation yields a low mean bias of 0.22 m/s and an uncertainty, estimated as the standard deviation of the biases, of 0.58 m/s. Errors tend to be larger in more complex terrain and land cover. The comparison with the reference models shows a better performance of UL Solutions' map in all three statistical indexes: the bias, uncertainty and root mean square error (RMSE) are lower than GWA and NEWA. It's worth mentioning that the three models show a positive mean bias, so at least for the sample used in this exercise, all models overestimate the average the wind speed.