WORLD

Without regular attention, Iran’s centuries-old windmills may one day stop. (Nat Geo News)

How do windmills and wind turbines work? Use our resource to better understand wind energy.

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit, including a link to today’s easy locator map.

Discussion Ideas

• The windmills of Nashtifan, Iran, have been operating for between 500 and 1,000 years. What are they used for? Read the short Nat Geo News article or watch the great video above for some help.
  • The windmills, “made of natural clay, straw, and wood … have been milling grain for flour for an estimated 1,000 years.”
  • According to the video, “We put [in] the wheat, we get the powder (flour), we make naan, we enjoy it!”

• The Nashtifan windmills don’t look quite like the European-style windmills we’re most familiar with today. How are they different? Take a look at the orientation of both windmills, and read through the very first part of our encyclopedic entry for some help.
  • The Nashtifan windmills have a vertical axis, an arrangement in which the millstones are attached to the windmill’s vertical driveshaft. Nashtifan’s 120 mile-per-hour winds spin the blades, which spin the shaft, which spins the millstones, which grinds the grain.
    • The downside to this style of vertical axis windmill (called a panemone) is that because the wind panels rotate horizontally, only one side absorbs wind energy while the other half goes against the wind current. (For this reason, the Nashtifan windmills are shielded on one side.) As a result, the blades can never move faster than, or even at, the speed of the wind.
  • The Dutch-style windmills have a horizontal axis, in which the blades spin parallel to their towers.

• Do the Nashtifan windmills operate the same way as modern wind turbines?
  • No. Windmills are not the same as wind turbines. Wind turbines generate electricity. Windmills like those at Nashtifan were originally designed to grind (mill) grain and pump water.

• The design for vertical axis windmill stretches back about 1,000 years. Are there modern versions of this design?
  • Yes, there are definitely vertical axis wind turbines! The rotor blades of modern VAWTs drive a generator, which converts wind energy to electricity. Because the main rotor and generator are located near the ground, maintenance for VAWTs is easier and less expensive than it is for horizontal axis wind turbines. VAWTs also do not have to be upwind to generate electricity, and they can be much smaller than their horizontal counterparts.
  • Progressive Field, home of the Cleveland Indians, had a corkscrew-shaped vertical wind turbine for nearly a year. The turbine provided electricity to both the facility and the local electrical grid. It was removed in 2013 … due to wind damage.

• Could the Nashtifan windmills be converted to wind turbines and supply the area with clean electricity?
  • No, not efficiently. If the Nashtifan windmills were turbines, “they would produce only a small amount of electricity, possibly not even enough for a lightbulb.”

TEACHERS TOOLKIT

Nat Geo: Iran’s Centuries-Old Windmills May Soon Stop Turning

Nat Geo: What is wind energy?

Nat Geo: Where are the Nashtifan windmills? MapMaker Interactive map

Amusing Planet: The Ancient Windmills of Nashtifan