This is a Darrieus vertical axis wind turbine. (VAWT) It was patented in 1931 by a French aeronautical engineer named Georges Jean Marie Darrieus. It is a lift style turbine. It usually has 2 or 3 aerofoils. The aerofoils are designed to create lift to turn the rotor. It can spin at many times the speed of the wind striking it.

Darrieus turbines are not self starting. One method used to start the turbine is a small powered motor. This is a good method when the turbine is grid-tied, as power for the motor is readily available. Another method to use is 2 or 3 small Savonius style rotors mounted on the main shaft. These rotors slow down the turbine, but make up for this shortfall by making the turbine more simplistic in design and easier to maintain.