Quick summary

The wind turbine generator, otherwise known as the WTG for short is the most expensive component in the wind farm and will typically cost upwards of 50% of the total cost of the wind farm.  The WTG consists of:

  • The tower section (usually painted white) is typically more than 90 metres long, with a diameter of over 6 metres
  • The nacelle (the enclosure at the top of the tower, containing the gearbox and/or major electrical components and converters)
  • The hub, connecting the blades to the nacelle
  • The blades, typically made of fibre-glass and optimised for aerodynamic performance

A large WTG installation vessel is required to lift these components onto the foundation (the yellow section below).  We cover these components in more detail in later sections and in the online training videos.

offshore wind turbines WTG

1. Wind turbine key characteristics

We need some basic information to get started in working out which wind turbine (WTG) will be best for your wind farm:

  • WTG rated power output in Mega Watts (MW).  For modern offshore WTG’s this will be in the range from 6MW all the way up to 10MW.  There are plans for even larger WTG’s with power ratings of 12MW and beyond.
  • Power curve – this illustrates how the wind turbine will perform at different wind speeds, at what wind speed it starts to produce power and what wind speed it reaches maximum power.
  • WTG component weights, dimensions and a typical hub height (hh).  The hub height is the vertical distance from sea level to the centre of the hub (attached to the nacelle). All these variables are important for wind farm design (the layout and spacing of the turbines), and also for installation.  If the components are too heavy or the hub height is too high for the average installation vessel then this can push up costs prohibitively.
  • WTG cost, or cost per MW of installed capacity. This is sometimes difficult to guess in the early stages because prices are constantly falling and price negotiations typically come later in the project development process, so only estimates can be used.  When designing a wind farm it is desirable to keep at least two scenarios running with two different WTG manufacturers for as long as possible.