Thursday, March 12, 2009
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.
How Wind Turbines Work
Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetation. Humans use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity.
The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity.
So how do wind turbines make electricity? Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. Take a look inside a wind turbine to see the various parts. View the wind turbine animation to see how a wind turbine works.
This aerial view of a wind power plant shows how a group of wind turbines can make electricity for the utility grid. The electricity is sent through transmission and distribution lines to homes, business, schools, and so on.
Wednesday, March 11, 2009
A wind turbine is a machine made up of two or three propeller-like blades called the rotor. The rotor is attached to the top of a tall tower. As the wind blows it spins the rotor. As the rotor spins the energy of the movement of the propellers gives power to a generator. There are some magnets and a lot of copper wire inside the generator that makes electricity. Because winds are stronger higher up off the ground, wind turbine towers are about 30 metres tall to allow the rotor to catch more wind energy. The turbines are built with a device that turns the rotor so that it always faces into the wind. Just one wind turbine can generate electricity for a single house or the electrical energy to pump water or to power a mill which grinds grain. The electricity can be used to charge batteries which store the electrical energy.