Sustainable Energy

From top to bottom: How a wind turbine actually works

From top to bottom: How a wind turbine actually works

From top to bottom:
How a wind turbine actually works

From the deep, cold waters of the Irish Sea to Scurry County, Texas, wind turbines are being built all over the world.
With the hypnotic rotation of their blades and imposing height, these feats of engineering have become an iconic symbol of renewable power in the 21st century, with 51.3 gigawatts (GW) of new capacity installed last year.

Here, CNBC’s “Sustainable Energy” delves into the nuts of bolts of wind turbines, from top to bottom, to better understand how they work and the technology that underpins them.

The blades

Wind turbines take the wind’s kinetic energy and turn it into mechanical power. Perhaps the most recognizable parts of a turbine are its blades. Many turbines today have three blades, while some have two. Blades, according to Anders Bach Andersen, senior product manager at MHI Vestas Offshore Wind, are designed to “capture” the wind, with the shape of a blade generating lift.

GE Renewable Energy’s Ed Hall told CNBC that the blades on a turbine are very much like the wings on an aircraft. “They utilize the movement of air and create lift, or a force, on that blade,” Hall added. “In the case of an airplane, that lift holds the airplane up in the air. In the case of a wind turbine, we use that lift to turn the rotor.”

The turbine’s rotor is connected to its generator, which is located in the nacelle.
The blades on a turbine are very much like the wings on an aircraft, utilizing the movement of air and creating lift.
Nacelles vary in size, with some big enough “for a helicopter to land on,” according to the U.S. Department of Energy (DOE).

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.

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.”

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.

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.
Source: UK regulator Ofgem

The tower

Both the nacelle and blades rest on top of a turbine’s tower, which can be made from concrete, steel lattice, or tubular steel.  Their main function, Hall told CNBC, is “to provide the supporting structure for the nacelle and the blades.”

The American Wind Energy Association (AWEA) says that turbines typically reach “at least 80 meters tall” which equates to just over 260 feet.

The height of a tower has a direct effect on the amount of power that can be produced.

“Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity,” according to the DOE.

Given the significance of height in relation to power, it goes without saying that wind speed is hugely important too. As the AWEA notes, modern turbines start producing electricity when wind speeds hit 6 to 9 miles per hour.
Just a single rotation of one 8 MW offshore turbine can, according to Danish energy firm Orsted, power 122 hours of television watching.


The foundations of turbines are crucial to their safe operation.

Hall told CNBC that foundations could vary a lot depending on soil structure, adding that it was “not unusual to see one 10 meters deep with a heavy concrete and reinforced steel cage kind of construction.”

In the offshore sector, developments in technology have led to significant changes.

“When offshore was born it was basically onshore turbines that were put in the sea and what we can see now is … bespoke offshore turbines,” MHI Vestas Offshore Wind’s Bach Andersen said.

Offshore foundations can differ depending on conditions, with monopile, gravity and jacket foundations used.

Major Spanish utility Iberdrola describes monopile foundations as being “quite simple structures” that are made from a steel cylinder that gets “anchored directly to the sea bed.”

Gravity foundations are made up of either concrete or steel platforms with diameters of roughly 15 meters, while jacket foundations, according to Iberdrola, have a lattice framework with three to four “sea bed anchoring points.”