Lesson Plan: Ride the Wind!^TM
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Energy Transformations

This activity investigates the nature of several important energy transformations that can be observed as wind energy is captured and converted to electricity for the commercial market. It assumes that you have introduced the concept of energy transformations, but extends and applies this concept to renewable energy and public transit.

Curriculum Ties

This activity addresses learning outcomes in:

• Science 8 (2001 vers.) Unit D: Mechanical Systems
• Science 9 (1990 vers.) Unit 3: Heat Energy: Transfer and Conservation
• Science 9 (1990 vers.) Unit 4: Electromagnetism

Concepts

• Energy is easily converted from one form to another.
• Earth's surface winds are a viable source of electrical energy.
• Renewable energy from sources such as wind can help reduce air pollution.

Learning Outcomes

On the completion of this activity, students will:

• Describe several transformations of energy as wind is converted to electricity for use in powering Calgary's light rail transit system;
• Use the analysis of energy transformations to identify ways to improve the efficiency of mechanical / electrical systems.

Instructional Methodology

In this exercise, your students will be shown a series of important energy transformations common to many electrical and mechanical systems, and asked to identify points in an important energy system where these transformations occur. The example provided here is that of the City of Calgary's Ride the Wind!^TM program, which utilizes wind energy to supply electricity to the C-train system of Calgary Transit.

Timeline

• Homework assignment: Read the Ride the Wind!^TM Backgrounder
• 1 class period (40 Minutes)

Materials

 Ride the Wind!^TM Backgrounder (class set) [299 Kb]
 Ride the Wind!^TM Worksheet (class set) [236 Kb]

Preparation

In advance of the class, prepare a class set of the Ride the Wind!^TM Backgrounders, and the Ride the Wind!^TM Worksheet.

Plan

Ride the Wind!^TM Backgrounder Reading

Pass out copies of the Ride the Wind!^TM backgrounder, and have your students read it as a homework assignment. Alternately, you may have your students work on written answers to the questions at the end of the backgrounder, or be prepared to answer and discuss these questions at the beginning of the next class.

 Ride the Wind!^TM Backgrounder (class set) [299 Kb]

Ride the Wind!^TM Worksheet on Energy Transformations

Explain the major energy transformations that take place during the production of wind-source electricity, and the use of that electricity to turn electric motors such as those of the Calgary C-train:

• Mechanical (wind) to Mechanical (rotation): Wind energy is simply the energy of moving air. Wind energy is a form of kinetic energy (energy of motion). When air flows over an airfoil such as on an aircraft wing or wind turbine blade, lift is generated. In the case of the airplane, the wing carries the plane aloft. In the case of the wind turbine, the airfoil is fixed to a rotating shaft at one end, which turns as lift is generated on the blades of the turbine.

• Mechanical (rotation) to Electrical: Inside the wind turbine's housing is found an electrical generator that converts the energy of a spinning shaft into electricity. The spinning shaft turns a set of magnets (either permanent magnets, or electromagnets) mounted on a rotor. These magnets in turn cause an electrical current to flow in a set of tightly wound coils of wire, located close to the moving magnets.

• Electrical to Mechanical (rotation): This occurs inside all electric motors, and is the reverse of what happens inside an electrical generator. In this case, an electric current is passed through coils of wire wrapped around an iron core, causing it to become an electromagnet. Several of these magnets inside the motor act on other magnets attached to a rotating shaft, which spin rapidly when a current is flowing through the coils.

• Electrical to Heat: Almost all materials that are used to conduct electricity (copper wire, for instance) are not perfect conductors, and resist the flow of electricity to some degree. How much resistance there is depends on what the conductor is made of, how long the conductor is, and how large the current is. When electricity moves through a conductor with any degree of resistance, heat is always produced, which is absorbed by the air or other nearby materials. The conversion of electricity to heat is usually seen as a loss of useful energy, and steps are taken to reduce the losses, especially in long-distance transmission of electricity.

• Mechanical (rotation) to Heat: In mechanical systems, moving parts are frequently in contact with non-moving parts. The result is friction, which absorbs some of the energy of motion and converts it to heat. Friction in most mechanical systems is seen as a waste of energy, and elaborate measures are taken to reduce friction.

Explain that Calgary's C-train system is not powered exclusively by wind power, but that the electricity comes from a variety of sources, including coal and natural gas-fired power plants, hydroelectric stations, and others. Note that the City of Calgary has agreed to purchase enough electricity from wind energy providers (21,000 megawatt-hours of power) to supply the C-Train's needs on an annual basis.

Pass out copies of the Ride the Wind!^TM worksheet and have the students identify and label as many energy transformations as they can find. They may work in groups or individually. When they are finished, discuss their answers with them. Go over the diagram and identify each energy transformation, discussing how and where each transformation occurs. See the "Ride the Wind!^TM Worksheet Notes".

Have your students answer the questions on the reverse side of the worksheet either as homework or in-class group or individual work. The questions may also be used as class discussion material. The questions and their suggested answers appear with the "Ride the Wind!^TM Worksheet Notes".

Ride the Wind!^TM Worksheet Notes

1. Wind Turbine:
   (M->M, M->H, M->E)
   At the wind turbine, the flow of air is converted to rotational mechanical energy. This is done as the blades of the turbine generate lift in the moving air. The turbine's gearbox and generator contain bearings that heat up due to friction when moving parts contact stationary parts. As the generator turns, some of the rotational mechanical energy is converted to electricity.
   
   
2. Transformer:
   (E->H)
   The transformer changes the electricity coming from the wind turbine into a form that can be sent via the high-voltage transmission lines. Electricity moving through the transformer must pass through several different electrical components, which means that some heat is also produced. Transformers contain special oil that absorbs this heat, preventing the transformer from getting too hot.
   
   
3. Transmission Lines:
   (E->H)
   Transmission lines always lose small amounts of electricity due to resistance. They lose this energy in the form of heat, which is absorbed by the air around the wire.
   
   
4. Transformer:
   (E->H)
   As above.
   
   
5. C-Train:
   (E->M, E->H)
   The C-Train is equipped with electric motors that convert electricity into useable mechanical energy. This energy drives the train down the tracks from station to station. Because the C-Train contains a lot of moving parts (motors, axles, wheels, and other parts), some friction is developed, which is converted to heat and absorbed by the air, the rails, and parts of the train.

Extension Activity: Build a Wind Turbine

The "Build Your Own Wind Turbine" project makes an excellent follow-up activity, and graphically demonstrates the principles of energy transformations. Students will construct a mechanical / electrical system that generates measurable amounts of electricity by converting the energy of moving air first to rotating mechanical energy, then to electricity through the physical process of induction. This wind turbine is designed with a brushless alternator that incorporates magnets and coils of wire to conduct the charge. The turbine produces alternating current at voltages high enough to light an LED or 1.5 volt incandescent flashlight bulb.

Instructional Methodology

The wind turbine can be incorporated into your unit plan in several ways, including:

• In-class individual or group project.
• Teacher-built demonstration model.
• Take-home term project.

Timeline

If used as an in-class project, the construction of the Savonius wind turbine requires between 3 and 5 class periods, depending on the skill of the students.

Materials

Most of the tools and materials for the wind turbine construction can be found at school, at home or at your local hardware store. Two special items you may need to purchase are magnets and copper wire.

Magnets:
Any strong face-polarized ceramic magnet will do as long as its dimensions do not exceed 1.5 by 4 cm. The plans call for circular ¾" rare-earth magnets. They are available at:

• Lee Valley Tools
  7261 - 11th Street SE
  Calgary, AB T2H 2S1
  Tel: 403-253-2066

Wire:
Ask for 24-gauge enameled magnet wire. A ½-pound spool will make 5 coils. Also available in 10-pound spools, from which about 100 coils can be constructed.

Sources:

• B & E Industrial Electronics
  444 Manitou Rd SE
  Calgary, AB T2G 4C4
  Tel: 1-800-661-5619 or 403- 243-7211
  info@beelectronics.ca
  (they have a courier service available)

• Active Components
  2015 32 Ave NE Unit 1
  Calgary, AB
  Tel: 403-291-5626
  (They have 22 and 26 gauge wire)
  

• Winford Insullations
  Bay C 4415 58th Ave SE
  Calgary, AB
  Tel. 403-236-3667