Using an automotive alternator to construct a wind-powered electrical generator can reduce or eliminate dependency on "grid" power, even if the wind turbine is only used for lighting or recharging batteries. The average backyard engineer can construct a wind power plant in about two hours.
Create or purchase several propellers. A propeller will have a leading edge that is curved, so that passing air will force it away from the source. Tacking the ends together at a central focal point will keep this force constant, and push the propellers in a circular motion.
Fabricate a propeller/vane assembly. Mounting several propellers to a rotating surface (ball-bearing wheel), then mounting a directional vane to the rear of the rotating wheel's mount will turn wind energy into a mechanical force.
Attach the alternator to the propeller assembly. The inside of the propeller wheel will rotate, and this can be used to turn an alternator's pulley by welding a suitable automotive pulley to the wheel's surface, then driving the alternator with a belt. In some instances, welding the alternator directly to the rotating wheel makes sense, but an automotive belt setup can allow easier maintenance for the equipment. Mount the alternator onto the frame of the stand, below the propeller assembly. Adjust the height of the alternator until the belt is tight, then secure the alternator.
Place the entire turbine into a high-wind location. As the propellers turn, the pulley drives the belt, which turns the alternator and generates electricity. The rear vane will point the propeller assembly at the wind source.