A wind turbine works by letting moving air push on specially shaped blades, which spin a shaft connected to a generator that makes electricity. The blades work more like an airplane wing than a pinwheel: wind flowing over them creates lift that turns the rotor. Because the energy in wind rises steeply with speed, turbines are built tall and placed carefully, and a small difference in average wind speed makes a big difference in output.
Key takeaways
- Blades use lift, like an airplane wing, to turn the rotor.
- A generator in the nacelle (the housing at the top) converts rotation into electricity, sometimes through a gearbox.
- Power in the wind rises with the cube of wind speed: double the speed and you get about eight times the power.
- Turbines start generating around 3 to 4 metres per second, reach full power around 11 to 14 m/s, and shut down in very high winds for safety.
- Modern onshore turbines in Canada are huge, with towers often over 100 metres tall.
The main parts of a wind turbine
| Part | What it does |
|---|---|
| Blades (usually three) | Capture energy from the wind using lift |
| Hub and rotor | Connect the blades to the main shaft |
| Nacelle | Housing at the top that holds the drivetrain and controls |
| Gearbox (on many designs) | Speeds up slow rotor rotation for the generator |
| Generator | Converts mechanical rotation into electricity |
| Yaw system | Turns the nacelle to face into the wind |
| Pitch system | Twists each blade to control speed and power |
| Tower | Lifts the rotor into stronger, steadier winds |
| Transformer and cables | Step up voltage and carry power to the grid |
Step by step: from breeze to electricity
1. The wind meets the blades
Each blade has an airfoil shape. As air flows past, it moves faster over one side than the other, creating a pressure difference called lift. That lift pulls the blade around. Blades are also twisted along their length, because the tips travel much faster than the roots.
2. The rotor turns the shaft
Large turbine rotors turn slowly, often somewhere around 5 to 15 revolutions per minute. That's slow enough to watch, but the blade tips can travel well over 250 km/h.
3. The gearbox or direct drive
Generators work best spinning fast. Many turbines use a gearbox to increase the shaft speed. Others use a direct-drive design with a large generator that works at low speed, removing the gearbox and some maintenance needs.
4. The generator makes electricity
Inside the generator, magnets and copper coils move relative to each other, inducing electric current. Power electronics then condition it to match the grid's frequency.
5. Power goes to the grid
A transformer at the base or nearby raises the voltage. Underground cables gather power from all the turbines in a wind farm to a substation, where it joins the transmission grid. Learn more on our wind energy page.
Why wind speed matters so much
The power available in wind depends on the cube of wind speed. That's why developers spend a year or more measuring wind before building.
| Wind speed | Relative power available |
|---|---|
| 4 m/s | 1x |
| 6 m/s | ~3.4x |
| 8 m/s | 8x |
| 10 m/s | ~15.6x |
That's also why towers are tall. Winds are generally stronger and less turbulent higher above the ground, where trees, buildings and hills have less effect.
There's a ceiling: the Betz limit
No turbine can capture all the wind's energy, because air has to keep flowing through the rotor. Physics sets a theoretical maximum of about 59% (the Betz limit). Real modern turbines capture somewhat less than that at their best operating points.
How turbines control themselves
A turbine is constantly adjusting.
- Cut-in speed: at roughly 3 to 4 m/s, there's enough wind to start generating.
- Rated speed: around 11 to 14 m/s, the turbine reaches its maximum (rated) power. Above this, blades pitch to spill extra wind and hold output steady.
- Cut-out speed: around 25 m/s (about 90 km/h), many turbines feather their blades and stop to protect themselves.
- Yawing: sensors on the nacelle measure wind direction, and motors turn the rotor to face it.
Because the wind varies, a turbine rarely runs at full power all the time. Read capacity factor explained to see what that means for annual output.
Cold-climate turbines
Canada adds its own challenges. Cold-climate packages can include:
- Blade heating or ice detection, since ice changes blade shape and reduces output.
- Low-temperature steel and lubricants rated for very cold conditions.
- Heated nacelles to protect electronics.
How big are modern turbines?
Turbines have grown dramatically. New onshore projects in Canada commonly use machines rated around 3 to 6 megawatts, with rotors well over 100 metres across. Offshore turbines are larger still. Bigger rotors sweep more area and reach steadier winds, which is a large part of why wind power has become cheaper over time. Curious about the sea-based version? See offshore wind in Atlantic Canada.
Frequently asked questions
Why do most wind turbines have three blades?
Three blades offer a good balance of efficiency, smooth operation and cost. Two-bladed rotors wobble more as they turn, and adding more blades adds cost and weight with little gain.
Do wind turbines use electricity when they're not spinning?
Yes, a small amount, for controls, heating, lights and yaw motors. It's tiny compared to what they generate over a year.
How long does a wind turbine last?
Most are designed for about 20 to 25 years, and many projects are extended or "repowered" with new, larger turbines on the same site.
The bottom line
Wind turbines are elegant machines: blades shaped like wings, a generator high above the ground, and smart controls that keep them facing the wind and safe in storms. Understanding the cube rule for wind speed explains almost everything about where they're built and how they perform. For more terms, browse our glossary.
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