By Kendra Rand

According to most records, the first windmill started turning in Persia around 200 BC. Life was a little different then…think invention of the horseshoe and the first calculation of the Earth’s circumference. But if you type “windmill” into Google, Bing, or your search engine of choice today, you will still get millions of hits. That is not too bad for a piece of 2,200-year-old technology.

The Pitstone Windmill, located in Buckinghamshire, England, dates back to at least 1627.
Photo by Michael Reeve
Creative Commons

At fourteen, William Kamkwamba used a library book, bicycle parts, trees, pvc pipe, and a few scrap parts to build the first windmill he had ever seen. His work set off a chain of events that have dramatically improved his community and the entire country of Malawi. Read more on his website, www.williamkamkwamba.com.
Photo by Tom Rielly, Creative Commons

The Brazos Wind Farm in the plains of West Texas.
Public domain

The designs and infrastructure have evolved, but the motivation for using windmills is still about the same. Early windmills were primarily used to automate pumping water and grinding grain. Today, people use the electricity produced by windmills (or wind turbines) to power hot water heaters and coffee grinders.

Wind energy is attractive because it is renewable—putting up a farm of windmills doesn’t use up a limited supply of wind like mining does to coal.

Flying kites and tumbling plastic bags show that wind carries kinetic energy. The purpose of a windmill is to harness that energy and transform it into mechanical or electrical energy—energy that can be used to do work. Wind turbines, which are getting most of the attention these days, are windmills that harness wind energy and turn it into electrical energy for homes and businesses.

How do wind turbines work?

As wind blows through a windmill, the blades catch the wind and lift up, like a kite.

Unlike a kite, the blades on a windmill are fixed on one end and so they rotate in the wind. The fixed end is connected to a long rod, or drive shaft. As the blades rotate, the shaft spins. 

The mechanical energy from the spinning drive shaft powers a generator, which turns the mechanical energy into electrical energy. The electricity is then run out through power lines and into to the electrical grid.

In 2008, wind turbines generated 1.26% of all of the electricity generated in the United States, and about 1.5% of all of the electricity generated in the world.

Many people would like to see wind energy play a larger role in energy production, because it is a renewable and clean source of energy. However, wind turbines are still only about 20-35% efficient. Continue reading to find out how scientists are trying to increase the efficiency of turbines so they can play a larger role in energy production.