Introduction to Hydroelectric Power. This lesson provides an overview of hydroelectric power (also called

Transcription

1 Overview This lesson provides an overview of hydroelectric power (also called hydropower), with an emphasis on low-head and low impact hydropower. Students view an audiovisual presentation, Introduction to Hydroelectric Power, which introduces them to key vocabulary and science concepts related to hydropower. A study guide is provided for students to use during the presentation to help focus their attention and reinforce their understanding. Teacher note: This same lesson appears here as well as in Unit 3. This allows Unit 2 to provide a complete survey of renewable energy sources important in Arizona and Unit 3 to provide a complete overview of hydroelectric power, the renewable source we most use. 8

2 Core Concepts Hydropower energy is ultimately derived from sunlight, which drives the water cycle, and gravity, which causes water to flow downward. A hydropower (hydroelectric power) plant uses the energy of motion in flowing water to rotate a turbine which activates a generator to produce electricity. Magnetism produces electricity: Whenever an electrical conductor (such as a copper wire) is moved through a magnetic field, an electric current is produced. An electrical generator is a device that converts mechanical energy into electrical energy by moving a wire through a magnetic field. Most power plants use the energy of heat or flowing water to spin a turbine, which has a shaft connected to a generator that changes the kinetic spinning energy into electric energy. The amount of electricity that can be generated by a hydropower plant is dependent on the flow rate (the quantity of water flow in a given time) and the head (the height from which the water falls and the pressure behind that water). High-head hydropower plants are the most common type of hydropower plant and generally utilize a dam to store water at a significant elevation. Low-head hydropower plants are hydropower plants that utilize heads of several meters or less. Low-head hydropower technology expands the opportunity to capture energy from water sources by including such systems as small creeks, irrigation and water delivery canals, or small systems on otherwise sizeable dams. These concepts are from the Powering Our Future Energy Education Conceptual Framework (Appendix A). 9

3 Learning Objectives ARIZONA DEPARTMENT OF EDUCATION ACADEMIC STANDARDS See Appendix B for the full text of these ADE Standards. Science TIME NEEDED Part One 45 minutes Part Two 45 minutes TEACHER BACKGROUND INFORMATION Review these sections of the Energy Primer: Renewable Energy Sources SC06-S2C-03; SC06-S5C3-0; SC06-S5C3-02; SC06-S6C-04; SC07-S2C-03; SC08-S2C-03 subsection on Hydropower Also review Parts One and Two of the presentation, Introduction to Hydroelectric Power. After completing this lesson, students will be able to do the following: State why hydropower is considered a renewable energy source. Define and describe the functions of waterwheels and turbines. Describe how electricity is generated from flowing water. List and describe at least two different kinds and sizes of hydropower systems. Define and describe the concepts of flow and head in relation to a hydropower system. Calculate the amount of electricity generated at a hydropower facility given flow rate and head. List several hydroelectric facilities in Arizona and state the rivers on which they are located. Define low-head hydropower and give one example of a low-head hydro system in the Phoenix area. 0

4 Advance Preparation MATERIALS Student Study Guide: Understanding Hydroelectric Power photocopy one per student CD-ROM PowerPoint Presentation: Digital (PowerPoint) projector or Television Computer or laptop with PowerPoint program and CD-ROM drive GENERAL PREP View the PowerPoint presentation in advance of your students, testing your computer projection equiptment if necessary.

5 Suggested Procedure Explain to students that in this lesson the class will be studying about hydroelectric power. (Explain to the class that the term hydroelectric power is often shortened to hydropower.) You might ask students several leading questions such as: Can anyone tell the class what hydropower is? or Do we get any of our energy from hydropower? Explain that the presentation they are about to see will answer these kinds of questions and help them understand the basics of hydropower and the key terms and concepts they will be using throughout this unit of study. 2 Pass out the student study guideunderstanding Hydroelectric Power and briefly review the kinds of questions and key terms they should be listening for during the presentation. Point out that all of the information they need to complete their study guides will be clearly presented in the presentation. They will just need to pay careful attention. (Note: It is suggested that Part One be viewed and the study guide completed before presenting Part Two.) 3 Present Part One, using a PowerPoint program and projector. The program is intended to be presented manually so you will have time to answer questions or allow students time to fill in the blanks on their study guides. 4After completing the presentation of Part One,, you may want to review the student study guide and have students help each other complete parts they missed. You may also review the entire study guide as a class to further encourage student learning. (Note: This is intended as an introduction and overview of terms, most of which will be reiterated in later lessons of Unit 3. It is not expected that students will completely comprehend all the concepts upon viewing this presentation.) 2

6 5Present Part Two, Hydroelectric Power in Arizona, using the PowerPoint program. Again, have students follow along and fill in the blanks of Part Two of their study guides. As with Part One, review the study guides as a class following the presentation. 6 Highlight important science concepts and link the presentation to earlier lessons by discussing the following: Review the water cycle as needed and analyze how hydropower generation is dependent on the water cycle. Review the concept of renewable and nonrenewable natural resources. Because the water cycle is ongoing, water was traditionally considered a renewable resource. Now it is increasingly recognized as a global concern that the total amount of fresh water on Earth is limited. Analyze how the energy transformations involved in generating hydropower are similar to or different than those involved in generating electricity in other ways. Analyze energy transformations that may take place after the electricity reaches its point of use to light energy, heat (thermal) energy, or motion (kinetic) energy. In the U.S., additional large-scale hydropower facilities are unlikely to be built. This is due to a combination of scientific understandings of the impacts of new dams, federal environmental protections, and availability of sites. New hydropower plants are likely to be low-head and low-impact facilities. 3

7 ASSESSMENT IDEAS The provided student study guides and discussion of them could serve as an assessment. See also the mathematics extension idea that follows. In general, however, this lesson was developed as the opening lesson for Unit 3 and was expected primarily to lay the foundation on which students would build their understanding through later lessons of Unit 3. EXTENSION IDEAS Electric energy transformations: Discuss examples of how the electrical energy produced by a hydropower or other generating plant is used. This could serve as a review if you conducted Unit Lesson 3 and/or Unit Lesson 4, but now would also be a valid time to introduce this topic. At the point of use, we transform electric energy into other forms of energy specifically to thermal (heat), motion, light, or sound energy. Ask students to work in pairs to brainstorm as many examples of each as they are able (for example, electric energy is transformed to thermal energy in an electric stove, oven, hair dryer, heater, etc.). Contrast the transformations involved in generating electricity (typically mechanical or motion to electrical) with energy transformations at the point of use. [ADE Science Standards SC06-S5C3-0; SC06-S5C3-03.] Hydropower math class: Use some of the data about specific dams provided in the Introduction to Hydropower PowerPoint presentation (with creative variations by the teacher) to develop a series of mathematics word problems involving calculations related to power, head, and flow. Allow the students refer to the notes they took on their student study guides as reference sources for checking definitions and the equation. 4

8 5