An Ounce of History of the Wind Turbine

There are several different variations of the windmill, those made specifically for pumping water, those made for decoration and those made for generating electricity. There are two distinct categories of windmills, or as I will call them, Wind Turbines. Generally, the wind generators used for electricity production are Horizontal Axis Wind Turbines - HAWTs. The most common, are the large 3 blade turbine towers (see below). The other category is the Vertical Axis Wind Turbine or VAWT. These turbines derive their names from the direction in which their axis is mounted, i.e. horizontal or vertical.

Figure 1 : 3 Blade HAWT


Figure 2 : 3 Blade VAWT

Another big characteristic of these two turbines causes a considerable difference in their efficiency. The “blades” which catch the wind can either be lift or drag devices. A lift blade (mostly used on HAWTs) uses the same principal as an airplane wing or airfoil to “lift” or turn the blade. On the other hand, a drag blade (like those used in a conventional windmill) only gets pushed by the wind, which makes it the less efficient of the two when it comes to catching the wind.

Figure 3 : Lift device

The VAWT is the older one of the two turbine technologies and has its origins way back to about 500BC. You may find many patents on this type of rotor, it is the most often re-patented design. Apparently this design is still illusive enough to slip through the patent office again and again. The Savonius variation in particular is about 100 years old.

Figure 4 : VAWT; Darrieus, Savonius and H-Rotor respectively

In both the Savonius Wind Turbine and Pringles Wind Turbine DIY projects, I focus on the Savonius turbine (a VAWT) that stands on the ground and can accept wind from any direction. Both are drag devices, with lower efficiencies than the lift ones, but they are considerably easier to build.