Why do wind turbines have 3 blades? And why do they turn clockwise?

On June 15, it is the International Day of the Wind. Wind energy remains one of the most important technologies in switching from fossil fuels to renewable energy. But did you know that the blades of wind turbines always turn clockwise? And why does a wind turbine have three blades, while traditional wind mills have four?

Every year, more and more wind turbines are added, and they work increasingly efficiently, both on land and at sea. The turbines are, therefore, essential to limit global warming and switch to green energy production.

It is well known that wind turbines have three blades. It is less known why that is so. The reason for this is power distribution.

Wind turbine with four blades
Wind turbine with four blades

In a wind turbine with three blades, the forces are better distributed, making it firmer and more stable. You could correctly make a wind turbine with four or five blades, but that would make the turbine unnecessarily heavy and expensive.

The rotation speed is higher with one or two blades, and that leads to more noise. With one wick, you also need a compensation weight. This requires extra material and is detrimental to air resistance.

Two or three blades are the best compromise between high rotation speed and not too much noise. In addition, most think that a wind turbine with three blades is simply the most beautiful.

Shape of the blades

The shape of the blades is also more substantial than meets the eye. This shape determines how much electricity the turbine generates and how much noise the mill makes.

Why do wind turbines have 3 blades? And why do they turn clockwise?
Shape of the blades

Badly shaped blades have low efficiency and make a lot of noise. Windmill designers strive for the windmill to turn at its ideal speed at every wind speed. That is the so-called ideal fast running.

Along with the clock

Originally, the wind turbines turned counterclockwise, until a Danish sheet manufacturer decided in 1978 to turn its blades the other way around to distinguish itself. The manufacturer supplied blades to large companies, and the standard was then retained to avoid chaos when wind turbines from different manufacturers were placed together.

The decision to turn the blades clockwise also had economies of scale. Manufacturers could use the same production techniques and molds. In the past, of course, the direction of rotation of the windmills has already been looked at, but no one has ever determined which direction was the best.

Rotate along with the clock (clockwise direction)
Rotate along with the clock (clockwise direction)

Although researchers at the University of Colorado and the National Renewable Energy Laboratory in Colorado now think that it does indeed play a role in whether a turbine is rotating clockwise or counterclockwise.

Especially when they are on a wind farm, especially at night, and in the northern hemisphere, this is partly due to the rotation of the wind direction. This rotation can have a favorable or unfavorable influence on the blades and the efficiency of a mill.

Wind turbine is cheapest

Wind turbines initially received high subsidies, because it was a new and expensive technology. This also happened with nuclear energy. These subsidies for wind have fallen year after year, and meanwhile, onshore windmills have become the cheapest way to produce electricity.

A windmill, therefore, does not need fuel. Offshore wind turbines remain more expensive, but their cost has fallen by 60 percent in 3 years.

Wind turbines used to be difficult to recycle. Although the industry is taking steps forward, meanwhile 85 to 90 percent of the material of a wind turbine can be recycled.

Why do wind turbines have 3 blades? And why do they turn clockwise?

The steel of the mast can be fully reused without compromising on quality. The concrete foundations can be processed into new building material to build roads. The blades are slightly more difficult to recycle. That’s because they consist of composite materials such as fiberglass, carbon, polyester, PVC to polyurethane.

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