The Energy CycleTM
Environmental Education Lesson
Edwards YMCA Camp and Conference Center
Summary
Students will become a "power plant" which will create electricity by pedaling a bicycle-powered generator. Students have an opportunity to discuss what energy is, different forms and sources of energy, and to find out if energy is renewable or non-renewable resource.
Usage
Teachers need special training to use the Energy CycleTM. This class is for 5th - 8th grades. Advanced activities for older students can be found in the Energy CycleTM manual. Ask the Environmental Education Director for more information.
Objectives
Upon completion of this lesson students will be able to:
- Define the term energy.
- Differentiate between renewable and non-renewable energy sources.
- Describe energy use differences between incandescent and fluorescent light bulbs.
- List ways of conserving energy in their home and school.
Materials
Markerboard
Dry Erase Markers
Energy CycleTM setup (bike, generator, display board, and accessories)
Light bulb game board and pieces
Proper Way to Use the Energy CycleTM
- When a student comes up to get onto the bike he/she should get on by bringing his/her leg in front of them. NOT BEHIND THE BIKE! The reason is that the person could rip out the wires.
- Once the student is on he/she should stay seated while he/she is pedaling, standing could cause the bike to tip over. The seat can be adjusted for the proper height.
- Pedal at a steady pace. Do not allow the student to pedal fast to the point where the needle on the meters is past the numbers. You want the student to pedal between 12 and 14 on the voltmeter.
Introduction
All activity involves the use of energy. Here are some of the many ways we need and use energy every day:
to make our food
to maintain our body functions and mobility
to heat and light our homes and schools
to fuel our cars, buses, airplanes, and ships
to maintain/drive the cycles on our planet (water cycle)
Most of us have some intuitive idea of what "energy" means. Although we might be not able to formulate a definition of the word, we use it often and in various contexts. The definition of energy used most often in physical science is "ability to do work". What does "work" mean? Work can perhaps most easily be defined as a change in the position, speed, state or form of matter. Therefore, energy is the capacity for changing matter.
Perhaps it is easier to think in terms of what energy does, rather than what it is. We can detect energy when is it displayed. Energy is displayed when heat or light is given off, objects move, and sound is produced. These are some of the many ways in which we detect that energy is changing matter.
Where Does Energy Come From? (Warm-up) (15 minutes)
Ask the students some questions to get their mind on energy:
- Where did you get the energy in your body that allowed you to walk in here? (Food)
- That allows you to breathe while you're sitting here? (Air)
- What did you have to eat today? Where did the energy in the food come from? (Sun)
Sun is the Power
Have the students try to trace any food that is mentioned back to the sun as the original source of its energy. Our ultimate source of energy is the sun. We can say we are (indirectly through plants) solar powered! Depending on the students' grade level, you might ask them to name the biochemical process (photosynthesis) that allows plants to use light energy for growth.
Sources vs. Forms
On a dry erase board, have the students' name and write different sources and forms of energy.
A source of energy is where energy comes from. Examples of sources of energy are:
| Sun: | the earth's primary energy source. | | Fossil fuels: | (petroleum, coal, natural gas) a non-renewable source. |
| Food: | energy sources that we directly use to power our bodies. |
Others would included wind and water.
A form of energy is when a source of energy is changed into a useable energy. Examples of forms of energy are:
| Source of energy = | Sun | Form of energy = | Solar or radiant energy |
| | Uranium | | nuclear energy |
| | Earth's core | | Geothermal |
Brainstorm ideas for other sources of energy. Where did the bus you came on get it's energy from? (Gasoline, oil, fossil fuel, etc.) Walk over and flip the lights in the room off and on. Ask the students where the energy that powers the lights in this room comes from (coal fired plant). What are other ways electrical energy is supplied in Wisconsin and Illinois (hydroelectric power plant, nuclear power plant)? What are the sources of the energy used to produce electricity in these power plants? (water and uranium)
Renewable vs. Non-renewable
Looking at the list of energy sources, ask the students the difference between a renewable resource (something that can be used over again; recurring or continuous) and a non-renewable resource (sources that take a great deal of time to form and cannot be replenished in human life time). Have them give examples of each and explain why it is renewable or non-renewable. Discuss the primary sources of the electrical energy used in Wisconsin and Illinois (coal, nuclear, hydroelectric). Which of these are renewable energy resources? What are some sources of renewable energy that could be used to supply some of our energy needs (solar, wind, wood, biomass, etc.). Briefly discuss the environmental impact of the use of non-renewable vs. renewable energy sources.
Activities
How Efficient Is Your Light Bulb? (optional activity)(5 minutes)
Students don't realize that the light bulbs in their home are wasting energy. This activity is designed to get the students thinking about conservation practices that they could do in their own homes. The teacher will hand out cards with a description of a fluorescent or incandescent light bulb to the students. The student will read aloud what is on his/her card, then decide which bulb his/her card should go with by placing it under the right picture. Doing this activity, will give the students a better understanding of how the two light bulbs differ.
Electricity: What a Bright Idea! (10 Minutes)
Ask the students to tell you some of the ways they used energy today and list them on the board. Circle the ones that involved electricity. Talk with the students about what it would be like to live without electricity. Discuss ways that we use electricity every day without really thinking about it. Briefly discuss what electricity is. Electricity is the behavior of negative and positive charges (electrons and protons) due to their attraction and repulsion. Discuss how electricity is made in a typical power plant. Use the simplified diagram of electrical production and transmission. (See poster)
Ask for a volunteer to pedal the bike and discuss the relationship between the power plant diagram and the Energy CycleTM components. Explain to the group that the student is the energy source that runs the generator that is producing electricity that runs through electrical wire to the lights and various other appliances they see on the panel.
What Light to Light? (15 Minutes)
Ask for a different volunteer to come up and pedal the bike. Using the switches for the incandescent light panel on the left side of the display board, switch on the lights one at a time, asking the student after each one if it's OK to switch on another. When the student gets up to 4, they will probably be having some trouble keeping a constant current.
Ask for another volunteer to come up. This time use the fluorescent lights on the right side of the display board and repeat the previous procedure. The second student should have no difficulty keeping all four bulbs lit. Explain that the two sets of lights may look different, but actually they are giving off the same amount of light.
Ask the students why they think that it's easier to pedal when lighting up the fluorescent bulbs. Are the people in that group stronger? Discuss the comparative efficiency of the bulbs. Why was it easier to ride the bike with all 4 lights (fluorescent bulbs) compared to only a few for the incandescent? Less energy is needed for the fluorescent, which in turn saves money compared to the incandescent bulbs.
Efficiency can also be shown by comparing the amount of heat produced by each type of bulb. Have a student come up and hold one hand close to an incandescent bulb and the other close to a fluorescent bulb while another student pedals and you switch between the bulbs. Ask the student which feels warmer. Discuss the relative amount of energy that is converted to light and heat by each bulb. (90% of the energy used by an incandescent bulb is converted to heat, while only 10% is converted to light. A compact fluorescent bulb converts 40% of the energy into light and 60% into heat. Much more efficient since they give 4 times more light for the same amount of energy. But overall, both of the "light bulbs" are really "heat bulbs".)
Ask for a new student to come up to pedal. Switch between one 50-watt incandescent bulb and one 13-watt compact fluorescent. Ask which is easier. How about two compact fluorescent? How about three? Four? Switch back to the single incandescent bulb each time you add another compact fluorescent bulb. The student riding the bike can "feel" the efficiency of the energy conversion from mechanical energy to light energy. The other students will observe the same result. Four compact fluorescent bulbs use about the same amount of energy as one incandescent, but produce four times as much light.
What Runs Our Appliances? (15 Minutes)
Have students determine the wattage difference between the incandescent and fluorescent bulbs. Watts (power used) are calculated by multiplying volts (push) by amps (flow of electrons). As a student is riding the bike, turn on a single incandescent bulb. Have one student watch the voltmeter and the amp meter. Have the students multiply the readings together. The answer should roughly match the wattage written on the bulb. Repeat this for a fluorescent bulb. Ask the students the question "How much higher is the wattage of the incandescent bulb than the fluorescent bulb? (Four times, which matches the difference in their efficiencies). Remind them that each bulb gives off the same amount of light.
How much would it cost to run the appliance?
Have a student volunteer to get on the bike and pedal, lighting two 50 watt incandescent bulbs for a couple minutes or until they get tired. Tell him or her that if they pedaled for 10 hours, they would be producing the energy equivalent of 1,000 watt-hours or 1 kilowatt-hour (100 watts times 10 hours). In Wisconsin, the average cost for electricity is about 7 per kilowatt-hour. How about it, would you say that electricity is a good value?
Using compact fluorescent and incandescent light bulbs as an example, discuss the concept of lifecycle cost (how much it would cost to use during the life time of the bulb) of the bulbs, which includes initial purchase cost as well as energy use and expected lifetime of the bulbs. Which bulbs really cost the most? Would this be true of other appliances also? How can we compare the lifecycle cost of appliances? (See Appendix A)
Batteries and Capacitors (15 Minutes)
Energy is either in motion or it is being stored. Kinetic energy refers to motion. Potential energy refers to stored energy, so it may be thought of as captured or unreleased energy.
Ask the students if they know what a battery does. Explain that the capacitors on the display board are similar to batteries, they can store energy for later use. Ask for a volunteer to come up and charge the capacitors. Once they are charged, ask the group how long they think various appliances on the board will stay on relative to each other.
Start off by using the tape/radio to demonstrate how the capacitors work. Set the timer for four minutes. Hand the timer to a student to time how long the radio will last using the capacitors. Ask another student to come up to charge the capacitors. This time see how long the tape player will last using the capacitors. Why would it take more energy to run the tape player compare to the radio? (Moving parts.)
How Efficient Are Your Appliances? (15 Minutes)
Ask for another volunteer to pedal the bike while the instructor holds the hair dryer and the fan. When the cyclist is up to speed, the instructor will switch the fan on so that it blows on the cyclist. Ask the cyclist if it is very hard to pedal while the fan is on. Now, switch off the fan and have the instructor holding the hair dryer turn it on while the cyclist continues to pedal. Ask the cyclist if he/she feels much difference in the amount of energy it takes to run the hair dryer. Is there as much airflow? Why not? Most of the electrical energy is converted to heat energy.
Ask the students to name some electrical appliances they use in their homes. Create a list of appliances they commonly use. Ask them to rank them in terms of energy efficiency. Which ones will be least expensive to run? Hint: energy efficiency.
"There Goes the Electric Bill" (10 Minutes)
Now that the students have seen how different appliances use differing amounts of power, bring up the topic of peak power demand times. Ask a student to come up and pedal the bike while you create a scenario of various students using the appliances at the same time as they come home form school or get ready to go out. What happens if everyone wants to use electricity at the same time?
Discuss peak demand times, black outs, and the general issue of building new power plants to supply electricity for peak times even though most of the time there is plenty of power. Discuss ways we could lessen or spread out our energy use. Demonstrate how one rider can power all of the appliances if they are turned on at different times. Discuss what they could do at home to spread out their electrical use over time.
Some of the ideas generated from the preceding discussion will lead into a discussion of energy conservation. Discuss the concept of demand-side management where the consumers control the need for electrical power. Demonstrate by having a student be the "power plant" while you add towns that are being supplied with electricity from the plant by adding one incandescent bulb to represent each new town. As you add the third or fourth town you will start experiencing "black outs". What should we do? Build a new power plant? Why or why not?
What are some other options? A student will no doubt suggest using compact fluorescent light bulbs to light the towns instead of the incandescent bulbs. Demonstrate that the "power plant" will have no trouble supplying power to all four towns if the residents all use compact fluorescent light bulbs. Students might also mention such things as using energy efficient appliances, turning off appliances while they are not in use, using alternative sources of energy for heat such as solar panels or wood, or not using certain appliances at all.
What Did You Learn? (Wrap-Up)(10 Minutes)
Here are some questions that summarize what was learned.
- What are some different sources of energy? (Sun, wind, water)
- What are some different forms of energy? (Geothermal, Nuclear Energy, Radiant Energy)
- Which bulbs use more electricity, compact fluorescent or incandescent? Why? (Incandescent bulbs, because 90% energy is heat and 10% energy is light.)
- Can we store electricity? How? (Yes. Use batteries or capacitors)
- What are some examples of renewable energy resources? (wind and water)
- What are some examples of non-renewable energy resources? (oil and coal)
- What are some negative environmental impacts of our energy use? (Digging mines for coal and oil, because we turn on lights when no one is in the room, leave the refrigerator door open while we decide what we want to eat or drink.)
- What can you do to help conserve energy? (Use fluorescent bulbs, recycle, reuse, don't buy products that use over wrapping, turn off lights when not in the room, turn down thermostat at night during the winter, turning down the air conditioner when no one is in the house, turn down the water heater, use mass transit, car pool, riding your bike, recycle old motor oil.)
Glossary
Amp: Unit of electrical quantity or current; number of electrons.
BTU: British thermal unit, which is a measure of the amount of heat energy required to raise the temperature of one pound of water one degree Fahrenheit.
Capacitor: A device for receiving and storing a charge of electricity.
Electromagnetic Waves: One of the waves that are spread out by simultaneous periodic variations of electric and magnetic field intensity and that include radio waves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
Electricity: A form of energy that can be generated by friction, induction, or chemical changes. Electricity is regarded as consisting of oppositely charged particles, electrons, and protons, which may be at rest or moving about.
Energy: Capacity to do work or make something move.
Fluorescent: An electric current passes through the gases within the bulb. The gases produce ultra violet radiation. When this radiation strikes the phosphor coating it causes it to glow.
Form of Energy: When a source of energy is changed into a useable energy.
Incandescent: When electrical current passes through the tungsten filament, it heats to the point where it glows and gives off a yellow-red light. To keep the filament from burning up immediately, it's housed in a vacuum.
Kilowatt: Equal to one thousand watts.
Kilowatt-hour: A unit of energy.
Kinetic Energy: The energy of motion.
Non-Renewable Energy: Resources that cannot be replenished relatively rapidly through natural processes.
Potential Energy: Energy at rest, which can be made active.
Renewable Energy: Resources that can be replenished relatively rapidly through natural processes (i.e. sunlight, wind, and wood).
Source of Energy: Where energy comes from.
Volt: Unit of electrical force.
Watt: Unit of electrical power
Appendix A
| | 20 Watt Compact Fluorescent | 75 Watt Incandescent |
| Light Output (lumens) | 1200 | 1200 |
| Rated life of the lamp (hours) | 10,000 | 750 |
| Energy Use over 10,000 hours | 200 Kilowatt Hours (KWH) | 750 Kilowatt Hours (KWH) |
Energy Cost @ $.07 per KWH
(over period of 10,000 hours) | $14.00 | $52.50 |
| Number lamps needed to produce equivalent amount of light for 10,000 hours | 1 | 13
(13x750 KWH = 9,750) |
| Purchase cost of lamps | 1 @ $26.00 | 13 @ $.75 = $9.75 |
Total Cost to buy and operate each over period
of 10,000 hours | $14.00 + $26.00 = $40.00 | $52.50 + $9.75 = $62.25 |
| Difference in Total Cost $22.25 | LESS expensive | MORE expensive |
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