This vertical axis wind turbine is of the Savonius or drag type invented by the Finnish engineer Sigurd Savonius in 1922 for the purpose of converting the power of the wind into torque on a rotating shaft.
Because of the curvature of the blade, it experiences less drag when moving against the wind than when moving with the wind and the differential between the two causes the turbine to spin. Being a helical design, the blade is always facing the wind regardless of its direction and works well in turbulent wind conditions.
When the wind blows, the blade stops a percentage of the wind which is converted into energy. That energy is connected mechanically via a series of pulleys and a drive belt to a generator, wired via a control box to an inverter and then connected to the electricity grid.