When a boat lifts a sail, it is using wind energy to push it through the water. This is one form of work.Farmers have been using wind energy for many years to pump water from wells using windmills like the one on the right.In Holland, windmills have been used for centuries to pump water from low-lying areas.Wind is also used to turn large grinding stones to grind wheat or corn, just like a water wheel is turned by water power.Today, the wind is also used to make electricity.
Blowing wind spins the blades on a wind turbine -- just like a large toy pinwheel. This device is called a wind turbine and not a windmill. A windmill grinds or mills grain, or is used to pump water.The blades of the turbine are attached to a hub that is mounted on a turning shaft. The shaft goes through a gear transmission box where the turning speed is increased. The transmission is attached to a high speed shaft which turns a generator that makes electricity.If the wind gets too high, the turbine has a brake that will keep the blades from turning too fast and being damaged.You can use a single smaller wind turbine to power a home or a school. The small turbine on the right makes enough energy for a house. In the picture on the left, the children at this Iowa school are playing beneath a wind turbine that makes enough electricity to power their entire school.We have many windy areas in California. And wind is blowing in many places all over the earth. The only problem with wind is that it is not windy all the time. In California, it is usually windier during the summer months when wind rushes inland from cooler areas, like the ocean to replace hot rising air in California's warm central valleys and deserts.In order for a wind turbine to work efficiently, wind speeds usually must be above 12 to 14 miles per hour. Wind has to be this speed to turn the turbines fast enough to generate electricity. The turbines usually produce about 50 to 300 kilowatts of electricity each. A kilowatt is 1,000 watts (kilo means 1,000). You can light ten 100 watt light bulbs with 1,000 watts. So, a 300 kilowatt (300,000 watts) wind turbine could light up 3,000 light bulbs that use 100 watts!
As of 1999, there were 11,368 wind turbines in California. These turbines are grouped together in what are called wind "farms," like those in Palm Springs in the picture on the right. These wind farms are located mostly in the three windiest areas of the state: Altamont Pass, east of San Francisco San Gorgonio Pass, near Palm Springs Tehachapi, south of Bakersfield Together these three places in California make enough electricity to supply an entire city the size of San Francisco! About 11 percent of the entire world's wind-generated electricity is found in California. Other countries that use a lot of wind energy are Denmark and Germany.Once electricity is made by the turbine, the electricity from the entire wind farm is collected together and sent through a transformer. There the voltage is increase to send it long distances over high power lines.