Savonius turbines use rotors that typically have a “bucket” design. These rotors, studied by numerous investigators since the 1920s, have been used extensively in high-torque low-speed applications, i.e., water pumping and ventilation. These rotors cannot compete with other configurations on an aerodynamics performance basis, but their ease of fabrication has yielded many applications, particularly in developing countries and do-it-yourself projects. A 2-bucket design reaches maximum efficiencies in the mid-twenties percentage range and a 3-bucket design reaches efficiencies in the high-teens percentage range. These efficiencies are obtained at rotational velocities (at the outside edge of the rotor) that are significantly less than the inflow wind speed. Practically, the efficiency is, at the very best, thirty percent and is only obtained at very low rotation rates. At higher rotational rates, the efficiency of the rotor decreases dramatically