By Renewable Energy Focus staff

The guidelines furthermore specify the principles of structural design, load cases for the platform and mooring system, stability and the structural division and design criteria for the top structure for floating offshore wind turbines.

The Guidance Note NI 572 covers floating platforms supporting single or multiple wind turbines with horizontal or vertical axes.

Maxime Pachot, Offshore Wind Turbine Manager, Bureau Veritas, says: “There is growing demand for offshore wind turbines which can be safely installed in very deep water locations. They will use one or more types of floating platform to mount the turbine and may need a service life equivalent to offshore oil and gas projects.”

Three categories of floating wind turbine platforms are covered:

  • Ballast floating wind turbine platforms that achieve stability by using ballast weights placed below a global buoyancy centre;
  • Tension Leg Platforms (TLP), that achieve stability through the use of tendons; and
  • Buoyancy floating wind turbine platforms that achieve stability by the use of distributed buoyancy.

The top structure with the rotor-nacelle and tower will be certified in accordance with International Standard IEC 61400-3 and/or national regulations. The floating wind turbine platform on which the generating assembly is mounted will be classified by Bureau Veritas under its Rules for the Classification of Offshore Units (Offshore Rules), which also extend to cover the mooring system.