Ever since man found out that energy from the natural forces could be harnessed to produce power, there was no looking back. Water, wind, sunlight, and even our own bodies were no impediment to sourcing enough electricty to power towns and villages, even cities.
Modern engineering has achieved feats which were unfathomable even 10 years ago. And now there are very impressive standards for everything. Same goes for wind turbines. These huge three-bladed marvels of engineering are fabulous and powerful in all their wind-to-power glory.
But wait, why do they only have three blades? Let’s investigate.
The blades of the wind turbine need special materials and very specific engines and rotors to be value-for-money.
If we consider a four-blade turbine, the extra blade and custom-made rotor will increase the cost to a very high level, but will not give a lot of output as compared to a three-blade turbine. Hence, the cost-to-production ratio is undesirable. So more blades is out of the question.
But costs can be saved using lesser blades, right? So why not use a two-blade turbine? Let us tell you why.
• For delivering the optimum performance equal to that of a three-blade turbine, we can increase the blade size of a two-blade turbine by 50%.
• Another option is to increase the rotational speed by 22.5%.
• Increasing the speed will result in a lot of noise, which is not something you’d want around when there are residential areas nearby.
• Increased speed or blade sized would also result in a lot of stress on the central rotor because the centrifugal force will increase the apparent weight of the blades. This would increase the cost again if you want to make a stronger and more durable hub.
Hence, a three-blade turbine design is the sweet spot for having optimum power generation, while at the same time keeping cost in check.