Wind turbine blades range from under 1 meter to 107 meters (under 3 to 351 feet) long.
For example, the world’s largest turbine, GE’s Haliade-X offshore wind turbine, has blades up to (107 meters (351 feet) long! On the other hand, small commercial windmills can only be a few meters long.
Wind turbine blades can vary considerably in shape and length, and there is no one “perfect” blade length. The blade length depends on the size of the wind turbine, wind speed in the area, and other factors such as local regulations or restrictions.
This article takes a closer look at the relationship between wind turbine blade length and efficiency.
The importance of wind turbine blade length
Wind turbine blades are shaped like an airplane wing. When wind pushes on the blade, it causes two powers: lift and drag.
The lift force is performed perpendicular to the wind flow (the blade), causing it to rotate.
The drag force is parallel to the wind flow and acts as a resistance force that slows down the blade’s spinning speed.
When designing a wind turbine blade, you must consider both the lift and drag forces to determine how long your blade must be:
- Too much drag, and the blade won’t be able to spin.
- Too much lift and the blade will spin too fast and could break.
How do wind conditions affect the length of wind turbine blades?
The ideal length of wind turbine blades is heavily influenced by the wind conditions in the wind farm area.
In high-wind areas, longer blades can capture more energy and generate electricity faster, so it makes sense to invest millions of dollars in building them.
However, one problem is that higher wind will cause the blades to spin faster, which puts a lot of stress on the shaft and bearings. This is why in some cases, you might want to design a thicker, shorter blade with a relatively high drag to prevent the blades from spinning too fast.
In low-wind areas, longer blades are not very common because less wind is available to generate electricity and are, therefore, less likely to be worth the investment.
How heavy is a wind turbine blade?
Modern wind turbine blades are typically made from fiberglass or carbon fiber, making them light and robust but expensive to produce.
The average weight of one blade can range anywhere between 20 metric tonnes for smaller turbines, up to 55 metric tonnes for large offshore turbines.