Wind Energy Assessments in the Northern Romanian Coastal Environment Based on 20 Years of Data Coming from Different Sources

Abstract

Based on the fact that the wind speed tends to increase as we go from onshore to offshore, the aim of this work is to perform an analysis of a Romanian coastal sector located near the Danube Delta. Over the course of 20 years (2001–2020), in situ observations and reanalysis data (ERA5 and MERRA-2) of the local wind conditions were evaluated from a meteorological and renewable point of view. This evaluation includes two onshore sites (Galati and Tulcea), one site located near the shoreline (Sulina) and also two offshore sites defined at 64 and 126 km from the coastline. From the comparison with in situ measurements, it was found that ERA5 shows a better agreement with the onshore sites, while for the Sulina site the MERRA-2 is more accurate. Additionally, it was highlighted that by using only four values per day of reanalysis data (00:06:12:18 UTC), the average wind speed is similar with the one from the hourly data. As for a wind turbine performance (hub height of 100 m), in the case of the onshore sites the downtime period is much higher during the night (up to 63%) compared to only 23% indicated by the offshore ones during the entire day.