A Darrieus rotor supported by a bearing system to rotate about a vertical axis for capturing wind energy has an alternator that is directly-driven by the rotor and converts rotational power from the rotor into electrical power. An electronic controller controls the electrical load applied to the alternator and the power output from the alternator to an output. The alternator is constructed having a substantially constant reluctance torque for all angular positions of rotation of the rotor. The bearing system includes upper and lower rolling element mechanical bearings that provide radial support of the rotor against wind load and axial support of the rotor, and a magnetic bearing that provides axial lift that reduces the axial load on the mechanical bearings and reduces the starting torque for rotating the rotor. The electronic controller applies minimal electrical load to the alternator until the rotor is at a rotational speed greater than a deadband for the rotor in the instantaneous wind speed, whereby the electronic controller, the alternator and the bearing system together avoid retarding forces that would otherwise prevent passive self-starting.
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