WindFloat is a floating foundation for offshore wind turbines with a simple, economic and patented design. The innovative features of the WindFloat dampen wave and turbine induced motion, enabling wind turbines to be sited in previously inaccessible locations where water depth exceeds 40m and wind resources are superior. Further, economic efficiency is maximized by reducing the need for offshore heavy lift operations during final assembly deployment and commissioning.
In October, 2011, Principle Power deployed a full-scale 2 MW WindFloat prototype (WF1) 5km off the coast of Aguçadoura, Portugal. The structure was completely assembled and commissioned onshore before being towed some 400km along the Portuguese coast (from it's assembly facility near Setubal, Portugal). Additionally, certification (or class) was an area of focus in the prototype design as it will be a future requirement for commercial projects. To date the system has produced in excess of 16 GWh of electricity, delivered by sub-sea cable, to the local grid. Principle Power gained priceless operational data and experience for use in future WindFloat systems world-wide.
The WindFloat’s very successful 5-year deployment, in the open ocean of the Atlantic, has proven that the technology can meet its promise and is ready for commercialization. In July 2016, having completed all of its project objectives, Principle Power initiated the WindFloat decommissioning process. The WindFloat foundation was detached from its mooring lines and electrical cable, and then towed back to Southern Portugal’s to the Port of Sines, where the wind turbine was dissembled. This was the first time an offshore wind turbine had been dismounted from a floating structure and it demonstrated the procedures to be used in commercial projects in the event of unanticipated major component failure. The turbine has now been transferred to another project and the inspections reveal that the WindFloat foundation itself is in excellent condition.
Multiple follow-on projects are under development for the installation of the next generation WindFloat units. These demo-scale commercial projects will aim to deploy multiple WindFloat systems in an array layout, test the quick disconnect O&M philosophy of the technology (for large corrective actions), and further prove the bankability of floating offshore wind technology.
The next generation WindFloat systems will make use of all the learnings from the WF1 prototype deployment as well as integrate other innovations developed by Principle Power's design team throughout the WindFloat technology development process. These WindFloat designs will be optimized, both with respect to size and performance, for today's 9.4 MW offshore wind turbines. The result will be significant cost savings to the customer on a levelised cost of energy basis. Furthermore, Principle Power anticipates reduced O&M downtime, decreased annual operational costs and significantly less risk in the operations of a WindFloat equipped windfarm.
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There are three primary advantages to the WindFloat foundation: first, its static and dynamic stability provides sufficiently low pitch performance enabling use of commercial offshore wind turbines; second, its design and fabrication methodology allow for onshore assembly of the complete system including the turbine; third, its shallow draft allows for depth independent siting and wet tow (fully assembled and commissioned) to installation site.
The WindFloat is fitted with patented water entrapment (heave) plates at the base of each column. The plates “entrain” water resulting in a large added-mass component and the sharp edges of the plates increase the viscous damping due to vortex shedding. In addition, The WindFloat’s patented hull-trim system (also known as active ballast) distributes water ballast between the three columns of the WindFloat to compensate for variable turbine thrust due to low frequency changes in wind velocity and direction. The system is closed-loop (no water moves in or out of the system), fail-safe, and comprises only a small fraction of the total WindFloat ballast water.
The design of the WindFloat enables the structure to be fully assembled onshore and towed to its final location. All fabrication and qualification is completed at quayside in a controlled environment. Deployment cost savings are significant when compared with bottom-fixed foundations such as monopile or jacket type structures which require offshore heavylift operations and significant vessel capabilities for installation.
The WindFloat’s conventional mooring system only includes components that are relatively inexpensive, readily available globally, and simple to install. The mooring configuration is similar to those on Oil and Gas platforms and permanently moored maritime structures. Drag embedment anchors permit installation in various soil conditions including mud, clay, sand and layered soils. Their installation is less weather-dependent than other alternatives, and installation does not require full geotechnical surveys of the sea bed prior to design. Further, the incremental cost increase, due to water depth, associated with a WindFloat mooring is minimal. This permits greater flexibility in site location and turbine placement to customers.
Turbine Hub Height
Operational Water Depth