ABSTRACT:

Following the most recent European directives, issued to limit dioxide emission and to increase the proportion of renewable energy in the global energy balance, and in accordance with the tendency to research renewable energy sources in the offshore environment, a number of offshore wind farms have been installed in the north sea area. At the moment, most of these offshore wind farms are very close to the coast in very shallow waters. The foundation structures are normally composed of a gravity base made of concrete or a monopile driven into the seabed. The tendency of the wind turbine manufacturer is to create specific products for offshore use of greater dimensions and power production. The gravity base solution is applicable only for small turbines in very shallow waters (up to 8 m.) and the cohesion of the sea bed should be evaluated extremely well to avoid foundation subsidence the monopile solution is applicable in deeper waters and suitable for greater turbines, but only in the case of particular seabed conditions. As it is necessary to install offshore wind farms at a minimum distance from the coast of 3 miles in order to minimise the visual impact of the turbines, and with the presence of medium to low seabed cohesion, a new foundation structure project and development will be imperative. The Department of Civil Engineering (DIC) at the University of Florence has been involved in the study to design an offshore support suitable for greater offshore turbines (up to 5 mw) at a water depth up to -20 m and with a low seabed cohesion. The specification also required simplification of installation operations, with a floating asset during transportation of the structure to the offshore site.

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