The Savonius turbine is one of two main types of vertical-axis wind turbine (VAWT); the other is the Darrieus turbine. Invented in Finland in the 1922 by Sigurd J. Savonius, the Savonius turbine is S-shaped if viewed from above, and has two, three, or more scoops to catch the wind. Although, unlike the Darrieus turbine (which uses airfoils and aerodynamic lift to turn the blades), the Savonius turbine can't rotate faster than the speed of the wind, it does yield a high torque.

 

It is useful for grinding grain, pumping water, and many other tasks, but its slow rotational speeds make it unsuitable for generating electricity on a large-scale. Small electricity-producing Savonius turbines for domestic use, however, such as the one shown here, have been developed.

 

Advantages

 

Having a vertical axis, the Savonius turbine continues to work effectively even if the wind changes direction.

Because the Savonius design works well even at low wind speeds, there's no need for a tower or other expensive structure to hold it in place, greatly reducing the initial setup cost.

The device is quiet, easy to build, and relatively small.

Because the turbine is close to the ground, maintenance is easy.

 

Disadvantage

 

The scoop system used to capture the wind's energy is half as efficient as a conventional turbine, resulting in less power generation.