Wind turbines have been used to generate power for centuries. There have been steady improvements to their designs over the years and nowhere is this more apparent than the changes made to the blades these wind turbines use to spin their rotors. These improvements in blade design allow modern wind turbines to generate more power from less wind, do so much more quietly and in some cases allows the turbine to be smaller as well.
Early versions of wind turbines used blades that were made from mats of reeds. These were a crude but effective way of harnessing the wind, but were not very durable. They worked well, but required constant replacement and were easily damaged in high winds.
These early reed blades were eventually replaced by cloth sails that offered a lighter blade and also a much improved durability. Many of the early windmills that used these sail-based blades were vertical axis designs and did a pretty efficient job of converting wind into power for processing grain.
As these improvements continued, wind turbines eventually matured into a horizontal axis design with blades built from wood. Many of these early wood designs followed improvements in early airplane blade design since they shared some of the same aerodynamical requirements. These newer wooden blades offered the advantage of improved strength and a lighter weight, which allowed the rotor to spin faster and provide more power from the wind turbine.
During this time of development, some of the first wind turbines were being used to generate electricity as a result of their rotation. Even though these early models were smaller in size, they would eventually be scaled to larger sizes and used for commercial applications.
Development of wind turbine blades designs continued along two distinct tracks from this point forward and the blades being designed for horizontal axis turbines were dramatically different from the requirements of vertical axis turbines. The improvements in horizontal axis blade design came from changes in blade shape and pitch, materials and number of blades used on the rotor.
Most horizontal wind turbines settled on a 3-blade design, which gives the best balance of stability and rotor speed. Many of the blades being used in these modern turbines are made of a composite material that provides tremendous strength, flexibility and is very lightweight as well to provide the perfect blade for both residential and commercial applications. This allows wind turbines that use these new blades to both spin faster and capture winds of lower velocity that would have been missed by older wind turbines.
The blades being used for the vertical axis wind turbines have also gone through dramatic changes and there are a wide variety of radical designs available today for all applications. These blade designs are either based on wind drag or wind lift and both of these principles will provide a good amount of rotation for these units.
The advantage that the vertical axis wind turbine designs provide is that they can turn in a wind blowing in any direction and immediately convert this wind into a rotation. This means that they are actually turning more consistently than most of the horizontal axis designs and provide a more consistent output of power. They are also very popular for use in residential environments because they don’t usually require a tower and so can be utilized lower to the ground than most horizontal designs.