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.

A Darrieus syle turbine generates less torque than a Savonius style turbine. This lack of torque makes it better suited for electricity generation than pumping or similar tasks requiring more torque. A Darrieus turbine generates less stress on the bearings and generator compared to a Savonius style turbine. Centrifugal forces are greater on the aerofoils of a Darrieus turbine. Aerofoils on a Darreius turbine must be built much stronger than on other types of turbines.

The largest Darrieus turbine was used in Cap Chat, Quebec, Canada. This turbine had a rotor diameter of 100 meters. This turbine is no longer in service. Larger Darrieus turbines need guy wires for support, this drawback makes them less desirable for farm applications. Another drawback is the turbine must be taken down to replace the bearings or perform similar maintenance.