Wind power has been used for centuries to help humans move machines that act as labor saving tools, taking the effort out of an otherwise exhausting task. One set of such machinery has not only existed for a long time but has also worked well. Deep in the desert of Iran, a small town called Nashtifan is home to the world's oldest windmills, dating back over a thousand years.
Harnessing the Power of Wind
Nashtifan is an old town in northeastern Iran near Khaf in Khorasan Razavi Province. Its name means "storm's string" and is known for its uniquely powerful winds.
In the middle of spring and summer, the eastern region of Iran experiences monsoon and dominant wind. The high winds reach up to 62 to 75 miles (100 to 120 kilometers) per hour, and ancient Persians harnessed the roaring winds with their unique version of windmills (Asbad). They used the brilliant system of windmills to satisfy their need for food and produce specific flour products.
Windmill construction has been practiced in Iran since A.D. 633, with windmill systems used to pump water to the surface around 5,000 years ago. The windmills in Nashtifan serve dual purposes. Locals use them to utilize the threat of vigorous winds as kinetic power and a protection wall for the town from strong winds.
Made of straw, natural clay, and wood, the lofty muddy towers stand upright and have been milling grain for flour for an estimated 1,000 years. Each windmill is made of eight chambers, which house six blades. The blades become grindstones as the strong, steady wind enters the chambers.
The windmills are erected on two parallel adobe walls on the southern edge of Nashtifan. These towers comprise the windcatcher tower and the lower room where the stone mills were spinning. The windcatcher at the topmost part of the tower has a vertical opening face to the northern part of the region. This way, the wind is easily trapped and directed to the vertical wooden vanes in the middle of the structure. The handmade wooden blades move with the wind, and by their rapid whirl, energy is transferred to move the big grindstone under the tower.
If the wind blows, this simple but efficient system can produce up to 331 pounds (150 kilograms) of wheat bags. A tank above the stones put the wheat seeds in. Meanwhile, the amount of wheat being poured from the tank to the stone hole is controlled by the pressure and speed of the wind. Because of this, there is no need for an operator to control the whole process of graining.
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Vertical Axis Design
It is believed that the knowledge of building wind-driven mills spread throughout the globe through Iran, with the system being adapted differently in other places. What makes Nashtifan's windmills different from those in other parts of the world, especially in Europe, is the axis of the wooden turbines.
Unlike other windmill designs, the Persian version has the blades arrayed in the vertical direction, so there is no need for any other median part. This way, wind power is directed right into the grindstones, generating energy at the highest level.
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