Why Do Wind Turbines (Usually) Have 3 Blades?
For the last eight years I have been working in the wind energy industry, designing wind turbine blades. A lot of people I talk to ask me questions about wind energy, and by far the most common of these is: “why do wind turbines have three blades?”
It is an interesting question because there is actually a lot of disagreement amongst engineers about what the reason is. If you ask five engineers in the wind industry, you’ll probably get five different answers. And the reason for that is that there is no single reason why wind turbines have three blades. It’s a tradeoff between a whole bunch of different factors.
So let’s look into some of those factors and find the answer to the question: “Why do wind turbines have three blades?”
I want to start by talking about aerodynamic efficiency, because sometimes people ask “what is the most efficient number of blades for a turbine to have?”
And the answer to that question is that there is no answer.
You can have an aerodynamically optimised wind turbine with any number of blades. You can design a turbine with 1 blade, 3 blades, 6 blades, even 100 blades. And they can all have the same efficiency if you change the width of the blade or the speed that they rotate.
