2- vs 3-bladed wind turbines
Did you know that 3-bladed wind turbine (with a specific power) spins at a lower speed than 2-bladed wind turbines (with the same power). Therefore, the force output on a 3-bladed turbine to the structure (blades, nacelle, tower and foundation) is larger. As a result of that, the strength of 3 bladed wind turbines and foundation has to be higher. More material is required for 3-bladed wind turbines. On top of that there are more reasons why 3-bladed wind turbines are larger and need more strength:
– 3-bladed turbines produce a lot of vibrations at higher wind speeds and need stronger structures to deal with these vibrations.
– 3-bladed wind turbines have a much bigger and much heavier rotor, the rest of the turbines structure is also heavier and stronger because of this.
– Because the rotor frequency of a midsize wind turbine is lower compared with a 2-bladed turbine the torque on the gearbox is higher. Therefore the gearbox needs to be heavier.
-The total amount of materials used for 3-bladed midsize wind turbines (with a specific power) often exceed the amount of materials for a 2-bladed turbine (with the same specific power) twice or more.
– Foundations required for 3-bladed midsize wind turbines can require up to 4 times the amount of concrete.
Two-bladed wind turbines do not have the technical shortcomings of 3-bladed wind turbines. 2-bladed structures (blades, nacelle, tower and foundations) are more efficient and much lighter. Because rotation speed is higher, the blades are slimmer, lighter and have less visual impact compared with three bladed wind turbines.
In addition, and in support of 2-bladed designs, support roads can be lighter and less hoisting capacity is needed per installed kW.