Wind Power
What causes the wind to blow? The earth’ s daily wind cycle is created by air above land heating up faster than the air over water. The warm air expands and rises and the heavier, cooler air rushes in to take its place— which creates wind.
Giant wind turbines can be used to collect the wind’ s kinetic energy, or energy of motion. The wind flows over the blades of the turbine, which causes them to lift and turn. The blades are connected to a drive shaft inside the turbine that turns an electric generator to produce electricity.
Before a wind farm is built, it takes careful planning to understand how fast and how much the wind blows at the site. Usually, wind speed increases at higher altitudes and over open areas.
Like solar energy, wind power has both benefits and limits. It’ s a clean source of energy and doesn’ t produce air pollution. One turbine can power hundreds of homes throughout the year.
However, wind turbines change the view of a landscape and can be a hazard to birds. They also can’ t provide power all the time— only when the wind is blowing. Sometimes the wind blows too hard and the turbines need to be shut off. Back-up power plants that are fueled by resources such as coal, oil and natural gas work along with wind power to ensure electricity is always available, every second of every day.
TRY IT! How windy is it outside your school? Make a class anemometer and find out!
Supplies & Tools:
• 4 small paper drinking cups
• scissors
• a marker
• 2 strips of stiff, corrugated cardboard about 18 inches x 3 inches
• stapler
• push pin
• sharpened pencil with an eraser on the end
• modeling clay
Directions
1. Make the paper cups lighter by cutting the rolled edges off the tops. 2. Color the outside of one cup with the marker.
3. Cross the cardboard strips so they make a plus sign. Staple them together.
4. Find and mark the exact center of the cardboard strips.
5. Staple the cups to the ends of the cardboard strips, making sure the cups all face the same direction.
6. Push the pin through the center of the cardboard and attach the cardboard cross with the cups on it to the eraser point of the pencil. Blow on the cups to make sure the carboard spins around freely on the pin.
7. Place the modeling clay on a surface outdoors. Stick the sharpened end of the pencil into the clay so it stands up straight. Using a watch with a second hand, count the number of times the marked cup spins around in one minute. You are measuring the wind speed in revolutions( turns) per minute. Weather forecasters’ anemometers convert the revolutions per minutes into miles per hour.
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