Wind Energy 101 Focus: This lesson will provide a basic overview of wind energy and wind turbines. Grade Level: 9 th Grade to 12 th Grade Time: 50 minutes 1. Have students brainstorm a list of ways we can generate electricity. List the ideas where students can see them. Then ask students to examine the list and decide: Which way do they think most of the power is generated in our area? Which ways do they think are the most damaging to the environment (including ecosystems etc)? Which ways might be the least damaging? Which ways could be considered renewable, or inexhaustible? Which ways cost the most money? 2. Define Renewable Energy Renewable Energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable (naturally replenished). Tell the students that they will be concentrating on only one renewable energy source today Wind Energy. Ask students and let them give responses: Question: What is wind? Ans: Wind is simply air in motion. Question: How do we know how fast the wind is blowing? Ans: Anemometer. An anemometer is typically a small cup device that measures wind speed, and is commonly found on the top of wind turbines to gage wind speed. See one here: Author: Jim Carlin Page 1
Question: What causes wind? Explain: Because the earth s surface is made of very different types of land and water, it absorbs the sun s heat at different rates. This causes uneven heating of the earth's surface which creates a difference in temperature between two regions. A difference in temperature between two regions directly creates a difference in pressure between them as well. This difference in pressure actually causes the air to move (from high pressure to low pressure). [So then, wind is simply air in motion as a result of a pressure difference between two regions.] Wind Facts An analogy to pressure difference can be shown using a clear tube with a marble inside. When the ends of the tube are equal in height, the marble does not roll. When one side of the tube is elevated, the marble rolls. Each end of the tube represents a pressure P1 and P2. If the marble rolls from P1 to P2, which is the higher pressure? (Ans: P1) Wind is affected by the rotation of the earth and causes it to flow in a curved line. This is known as the Coriolus Effect. The type of landscape can affect the wind. For example, heavily forested areas or even city skyscrapers tend to slow wind down while open prairies or water expanses allow for unobstructed faster wind speeds. Wind speeds above the ground are higher than wind speeds near the ground 3. Introduce the concept of Kinetic Energy Kinetic Energy is the energy something possesses due to its movement. Anything that moves has Kinetic Energy, therefore wind has Kinetic Energy. This energy can be expressed in a mathematical equation: at which the something is traveling. where m is the mass of something and v is the velocity Mass has units of kilograms (kg) and velocity has units of meters per second (m/s). Author: Jim Carlin Page 2
Question: What are the units for Kinetic Energy? * Have students figure out what this would be using the above mathematical equation. Ans: kilograms meters squared per second squared ( known as a Joule. ) which is also (Pronounced: jewel ) So, = 1 Joule, and is about the amount of energy it takes to lift an apple one meter off the ground. Explain to students that Kinetic Energy can be applied to Wind Energy because wind is moving. It is the Kinetic Energy of the wind that is converted by a wind turbine, into Electrical Energy. *Have students work the following exercise: (sketch on a board) Let s say that you have a block of air that is 1 cubic meter and has a mass of 1.18 kg. This block of air is traveling at 12 m/s. What is the Kinetic Energy of the block of air in Joules? Ans: (.5 * 1.18 * 12 2 ) = 85 Joules Now let s say you have a block of air that is 100 cubic meters with a mass of 118.4 kg traveling at 12 m/s. What is its Kinetic Energy? Ans: (.5 * 118.4 * 12 2 ) = 8524.8 Joules Explain that this shows the difference in scale between the wind on a model wind turbine (the size of a house fan) and the wind on a large wind turbine. Author: Jim Carlin Page 3
4. Describe to students the main components of a Horizontal Axis Wind Turbine (HAWT): [Sketch the following where students can see] Tower structural support of the wind turbine (around the length of a football field high). Blades usually 3 blades each approximately 45 meters in length, capture the wind energy. Hub rotating piece where blades are attached. Low Speed Shaft rotates at the same speed as the blades. Gear Box converts the low-speed-shaft rotation to a faster rotation shaft. High Speed Shaft turns the generator. Generator creates electricity. Nacelle houses the low/high speed shafts, gear box, and generator atop the tower. Author: Jim Carlin Page 4
5. Show the following video which gives a brief overview of how a wind turbine works. Before showing, make sure students are aware that they must answer questions following the video: http://www.youtube.com/watch?v=tszitseqfr0. Follow-Up Video Questions: a. Where are some ideal places for a lot of wind? b. How is wind speed measured on a wind turbine? c. About how fast does the Low Speed Shaft turn? d. How fast does the High Speed Shaft turn? e. What is the Coriolus effect? f. Why are wind turbines so tall? g. A small wind farm can produce power for how many homes? Author: Jim Carlin Page 5