Hydrodynamic Performance of an Innovative Semisubmersible Platform With Twin Wind Turbines

Abstract

The deployment of offshore wind turbines has focused primarily on shallow seas (such as the North Sea, Chinese coastal waters, and the New England coast) using bottom fixed foundations. However, much of the world’s offshore wind resource lies in deeper waters where bottom-fixed foundations are not suitable, and floating platforms must be utilised. To date, the majority of floating concepts have been developed to support a single wind turbine. This leads to a high capital cost for each individual platform and consequently a high levelised cost of energy. The W2Power platform (developed by EnerOcean S.L, Spain) currently supports a pair of 6 MW wind turbines on outward-leaning towers. The design significantly reduces the cost per installed MW, increases the structure’s natural period, added mass, and radiation damping. The platform, patented in 2009, was the world’s first twin-turbine platform and the first to be demonstrated at sea (2019). This paper presents the hydrodynamics of a 1:40 scale model of the W2Power platform using the well-known OrcaFlex software. The analysis has been carried out under extreme and operational conditions, and the resulting hydrodynamic loads and motion response are presented. The mooring system was found to be sensitive to wave direction, particularly when propagating along the current direction. Furthermore, the results showed advantages in the hydrodynamic responses for the W2Power platform as an innovative floating system.