Although the popular image of a wind turbine is of a huge, white machine towering over farmers' fields, that is by no means the only type. The simple principle of a wind turbine -- using the wind to push blades that turn a generator shaft -- works at any scale and is simple enough to build at home. The most complex part of building a wind turbine is shaping the blades to extract the maximum energy from the wind. Building a vertical wind turbine -- known as a Savonius wind turbine -- solves this problem with a very simple design.
Buy a DC electric motor. The best ones for wind turbines come from old computer tape drives, which can be bought second-hand from electronics stores or online auctions. As these motors have the same internal components as a generator, applying rotational force to the shaft will generate a current in the wires coming out of the motor.
Slice the 24-inch piece of storm water pipe into two 12-inch sections, then slice each one in half lengthwise to make two semicircular pieces. The result will be four 12-inch sections of half pipe that will work as blades for the turbine.
Cut out three circular pieces of aluminium, each with a diameter of 12 inches. Drill a 1.5 inch diameter hole through the centre of two of the disks.
Place the disk without a hole flat on the ground, then stand the 25-inch piece of 1.5-inch PVC on its end in the centre of the disk. Attach it there with two small angle brackets, screwed into the disk and the PVC pipe . This pipe will be the central shaft of the vertical turbine.
Stand two of your blade pieces on their semicircular ends on opposite sides of the shaft, with the concave side of one blade facing forward and that of the other blade facing backwards. Attach their 12-inch long straight sides to the shaft by screwing them to small 90 degree angle brackets, then screwing the brackets into the shaft.
Slide another aluminium disk over the top of the shaft and down onto the blades. Secure it to them and to the shaft with angle brackets and screws.
Attach the other two blades in the same way as the first, but rotated 90 degrees relative to the first set. When looking from above, the four blades should make a cross shape.
Cap the blade assembly with your third aluminium disk, held in place by angle brackets and screws and slide over the end of the PVC pipe. There should be about one inch of PVC exposed above the metal disk.
Buy an aluminium bushing that fits into the end of the 1.5-inch PVC and snugly fits over the shaft of your DC motor. Hammer the bushing into the pipe.
Buy a 6-inch storm water pipe end cap and drill a hole in the centre for the generator shaft. Drill smaller holes to match the threaded holes in the faceplate of the DC motor.
Slide the end cap over the shaft and attach it to the motor by passing screws through the small holes into the threaded holes in the motor's faceplate.
Slide the shaft of the motor through the aluminium bushing at the end of the pipe serving as your blade assembly shaft. This attaches the blades to the motor and finishes the turbine. Before use, it must be mounted and connected to a voltage adjuster.
Bury the bottom 16 inches of an 80-inch piece of 6-inch diameter storm water pipe in the ground, and secure it in place with concrete. To do this, dig a hole a few inches wider than the pipe, then pour in premixed concrete (available from any home improvement store) and add water according to the directions on the bag. Wait 24 hours for it to dry.
Cut a small hole in the mounting pipe at ground level for the wires running from the motor.
Attach three pieces of angle bracket to the bottom of the motor with screws, extending out beyond the bottom of the motor as far as the plastic cap extends out from the top. These will press against the walls of the mounting pipe and hold the motor/generator stable.
Slide the motor down into the mounting pipe. The plastic end cap attached to the motor's faceplate will seal the end of the mounting pipe, with the blades of the windmill above it.
Run the wires from the motor out the bottom of the mounting pipe and to a voltage adjuster. This will bump up the five volts or so coming from the turbine to the 12 volts necessary to charge a battery. These adjusters are available from electronics suppliers.
Connect the voltage adjuster with two wires to the terminals of a 12-volt battery. The turbine is now complete. When wind hits the vertical pieces of half pipe, it will turn the shaft of the motor, which will induce a current that flows into the voltage adjuster and charges the battery, which you can then use to power household devices.