Nacelles vary in size, with some big enough “for a helicopter to land on,” according to the U.S. Department of Energy (DOE).

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They sit directly behind a turbine’s blades and are shell-like structures that contain crucial pieces of kit. These include the turbine’s gearbox, controller, generator and brake. Hall explained how a gearbox “takes that low speed rotational energy of a rotor and, through a series of gears, speeds it up … and turns it into high-speed rotational energy.”



So, as the blades spin, the gearbox increases rotational speeds from roughly 30 to 60 rotations per minute (rpm) to around 1,000 to 1,800 rpm, according to the DOE. At this speed, the turbine’s generator spins and starts to produce electricity.



Generators convert mechanical energy to electrical energy.

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According to the U.S. Energy Information Administration (EIA), they contain insulated coils of wire which form a cylinder, which in turn surrounds an electromagnetic shaft. As this shaft rotates a small electric current in each section of the wire coil is induced. “Each section of the wire coil becomes a small, separate electric conductor,” the EIA states. “The small currents of the individual sections combine to form one large current.”

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Once electricity is produced, it is sent to the grid. A transformer, located at the bottom of a turbine’s mast, or tower, connects it to the grid.

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As major French utility Engie explains, the electricity produced by the wind turbine is raised to the grid voltage. “It is then transferred via a substation before being injected into the distribution or transmission networks.”

The nacelle

As the blades spin, the gearbox increases rotational speeds from roughly 30 to 60 rotations per minute (rpm) to around 1,000 to 1,800 rpm.