Italy’s Wind Atlas: Offshore Resource Assessment Through On-The-Spot Measurements

The Wind Atlas of Italy, first developed in 2002, was refined by CESI RICERCA in 2006, when it was also enlarged to offshore areas up to 40 km from the coastline. It displays maps of annual average wind speed (m/s) and specific energy production (MWh/MW) up to 100 m above ground or sea. This Atlas is published in an interactive version (named ATLAEOLICO). The Italian Wind Atlas is based on maps calculated using the WINDS model developed by the Department of Physics of the University of Genoa and has then been fine-tuned by comparison with measuring data from over 400 stations scattered all over Italy. Concerning offshore areas, the calibration of maps resulted more difficult because of the lack of direct measurements. The resulting uncertainty of wind maps over offshore areas has been estimated from a minimum of 2 m/s to a maximum of more than 3 m/s, which results in an uncertainty of no less than 1000 MWh/MW in specific energy production, too high for purposes of energy production evaluation. To reduce this uncertainty, a new wind measurement station has recently been installed at Pianosa, a small uninhabited and flattish island located in the Adriatic Sea off the Gargano promontory, one of the offshore areas with higher discordance of wind speed values among the various maps published so far. This island could also be taken as representative of the transition from the southern zone with better resources to the less promising northern part of the Adriatic Sea. This paper presents the results of the first five months of measurements at this station. These results have been analyzed with commercial codes for wind resource assessment and have then been compared with available information on wind resources in the same area, mostly measurements from satellites and coastal stations, and other published wind atlases