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Offshore Wind Chapter | 4 87

floating wind turbine technology is at the demonstration stage (similar to
the tidal energy industry). Much research is ongoing to test and assess the
performance of offshore floating wind turbines.

4.2 AN INTRODUCTION TO OFFSHORE WIND TURBINES

Horizontal axis wind turbines are commonly used for generating electricity
offshore. Fig. 4.4 shows an example of horizontal axis offshore wind turbines
(Haliade-150, with a capacity of 6 MW and diameter of 150 m) during instal-
lation. Fig. 4.5 shows a schematic of a horizontal axis wind turbine. In simple
terms, the wind exerts forces on the blades (lift and drag) and turns the rotor.
A low-speed shaft is connected to the rotor. The gearbox transmits the power
(rotation and torque) of the low-speed shaft to a high-speed shaft that spins
a generator. Functions of the individual components of a wind turbine are
explained briefly as follows: 1
Anemometer: Used to measure the wind speed. The collected data are trans-
mitted to the controller unit, for instance, to stop the wind turbine at very
high speeds (e.g. during hurricanes).

Blades: Harvest the wind energy. Wind exerts forces (lift and drag) on the
blades, causing the rotor to spin.

FIG. 4.5 Schematic of a wind turbine. (Courtesy of the US Department of Energy.)

1. See https://energy.gov/eere/wind/wind-energy-technologies-office.