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Generating Electricity: Wind Power

Wind turbine and electrical cord

Wind turbine and electrical cord (Mohamed Hassan, Pixabay) 

Wind turbine and electrical cord

Wind turbine and electrical cord (Mohamed Hassan, Pixabay) 

Let's Talk Science

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Learn how moving air can be used to generate electricity.

We can use moving air, or wind, to generate electricity. This is called wind power. At the end of 2019, Canada had the ability to generate 13 413 MW of wind power. This is enough to power about 3.4 million Canadian homes.

Did you know?
About 5% of the world's electricity comes from wind power.

Wind power is usually generated using a wind turbine. Wind turbines are mechanical systems that convert kinetic energy into electrical energy. Kinetic energy is energy that comes from movement. Wind is the movement of air. There are wind turbines on land and in water.

Wind turbine in action

Modern wind turbines are complex machines with three main subsystems. These are the rotor and its blades, the nacelle and the tower

Parts of a wind turbine
Parts of a wind turbine (Let’s Talk Science using an image by Ghrzuzudu via iStockphoto).
  1. When wind blows past the blades of the rotor, it makes them rotate. 
  2. The low-speed shaft is connected to the rotor. This shaft rotates when the rotor rotates. There is a brake on the low-speed shaft if the blades need to be stopped,
  3. A large gear is connected to the low-speed shaft. When the shaft rotates, so does this gear. 
  4. A smaller gear meshes with the large gear. The smaller gear turns faster than the large gear. This is because of the gear ratio.
  5. The small gear converts the slow rotation of the turbine blades to a speed of approximately 1500 revolutions per minute (rpm).
  6. The small gear is connected to another shaft. This is the high-speed shaft. This shaft is connected to the generator.
  7. The generator converts mechanical energy into electrical energy using a powerful magnet in motion near a wire
  8. A control box in the nacelle receives information from an anemometer and a wind vane. Controllers on the ground use this information to turn the nacelle or switch the turbine on and off.
Interior parts of a nacelle
Wind turbine showing the interior parts of the nacelle (© 2020 Let’s Talk Science. Derivative work of public domain image by the US Office of Energy Efficiency and Renewable Energy via Wikimedia Commons).



1. Direction of wind
2. Rotor blades
3. Low-speed shaft
4. Brake
5. Gears
6. High-speed shaft
7. Generator
8. Control box
9. Anemometer
10. Weather vane


How does a wind turbine work? (2016) by Acciona (2:46 min.).

That depends on its size. The larger the rotors, the more power the turbine can generate. So it’s probably not a surprise that wind turbines are getting bigger. 

The largest wind turbines on land in North America are about 111 m tall. Their rotor blades can stretch to a diameter of 135 m. That’s taller than the Peace Tower at the Parliament Buildings. And the rotor blades reach wider than a football field. Wind turbines found offshore in the ocean can be even larger.

Wind turbine sizes over time
Turbine sizes compared to some Canadian landmarks (©2020 Let’s Talk Science. Berkeley LAb).


Did you know?
The world’s biggest offshore wind turbine is the Haliade-X. Its rotor blades reach a diameter of 220m and it is 260m tall. 

You might see many wind turbines close together. This is called a wind farm. Wind farms can have a few turbines up to several hundred. Canada has a lot of wind farms. Some of these are very large!

Graph of the largest wind turbines in Canada by size
Largest wind farms in Canada (2019) (Source: Natural Resources Canada).


Wind power is called a renewable source of energy. This is because the energy from wind will not run out. Fossil fuels will run out. Wind power is also a clean form of electricity generation. It doesn’t produce greenhouse gases. But greenhouse gases are produced when we manufacture turbines and set them up. 

Wind turbines can only run when the wind is blowing. And they can’t run when the wind is too fast or too slow. To have reliable power when it's needed, this means other electricity sources or forms of electricity storage may be needed alongside wind power.

Some people are concerned that wind turbines may affect human health. They can definitely harm birds and bats, though turbine builders study animal habitats and migratory routes so they cause as little impact on wildlife as possible.


How do Wind Farms Affect Birds and Bats? (2019) 
This article by Let’s Talk Science explores several ways wind turbines can affect animals.

Weather: Wind (2020)
This backgrounder by Let’s Talk Science explains what causes wind and how we measure it. 

Let's Talk Energy - Wind 
This article by Ingenium traces the history of wind power and its challenges and opportunities in future.

Wind turbine (2019)
This essay with video (9:53 min.) illustrates the parts of a turbine.


American Institute of Physics. (2019 August 13). Growth of wind energy points to future challenges, promise.

Canadian Renewable Energy Association. Wind. Solar. Storage. 

Energy Education. (n. d.). Wind Turbine.

Natural Resources Canada. (2020 October 6). Renewable energy facts

Wiser, R., Hand, M., Seel, J., and Paulos, B. (2016 November). Reducing Wind Energy Costs through Increased Turbine Size: Is the Sky the Limit? Berkeley Lab Electricity Markets and Policy Group.