Fig. 6. Detail of WINFLO design. (The figures were reproduced according to the description provided in literature.).
The prototype wind turbine employed in the WINFLO project is 80 m in heights (from the foundation to the hub). Two 30 m blades are mounted on the hub to generate 1 MW electric power under routine operational condition. According to the plan, the currently installed wind turbine will be replaced by a lightweight turbine of 2.5 MW or 3 MW in the near future. It should be noted that the turbine employed in the project is adapted from the commonly used commercial wind turbines according to the specific marine conditions [41]. In other words, the floater introduced in the project is not compatible with the commonly used commercial wind turbines.
After two phases of successful basin experiments conducted in 2010 and 2011, the prototype was launched in real-world in the spring of 2014 at the SemRev marine experimentation site, which locates off the coast at Le Croisic. After the built of the prototype turbine, a pilot farm has been scheduled to be under operation in 2016. The pilot farm will be connected to the commercial grid and the electric powers generated by the pilot farm will be put into the market in 2016 onwards [42].
3.2. Ring-shaped floating foundation
In late 2013, a custom-designed floating square platform was developed by French wind farm developer Quadran and foundation specialist Ideol. The platform provides sufficient space at the base of the wind turbine for the operation and maintenance work, which usually requires tugboats anchored alongside with the turbine to provide space [43]. A sketch showing the main features of the foundation is presented in Fig. 7. An additional Damping Pool system, which essentially is a moon pool constructed inside the ring, was introduced by Ideol [41]. Such a pool is designed to have specific natural frequencies making the water entrapped into the damping tool act as a damper to reduce some of the floater's motions. Thanks to the damping pool, the ring-shaped foundation is acknowledged to be compatible with commonly used commercial wind turbines. In other words, the modifications of the turbine structure are no longer necessary.
In addition to the ring-shaped geometry, another innovation introduced by the project is the use of concrete to build the