A Savonius wind turbine includes a rotor assembly that rotates about a longitudinal axis. The rotor assembly includes at least two curved turbine blades extending parallel to the longitudinal axis and at least two support discs connected to the at least two curved turbine blades. At least one of the at least two support discs has at least one relief vent defined therein for allowing air to pass through the at least one support disc. The wind turbine may be provided with two rotor assemblies having their curved turbine blades arranged so that the rotor assemblies are driven to rotate in opposing rotational directions.