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Energy Pathways  

SunChaser2 Curriculum

Overview

The purpose of this curriculum is to provide an exciting, hands-on, and comprehensive introduction to the concept of energy and its uses that can be presented to a group of students in a short time (1-2 hours) in conjunction with the SunChaser2 mobile education unit. Instead of exposing students to a rapid fire succession of disconnected or irrelevant facts, this curriculum instead strives to lead students to trace out the three primary paths by which energy flows in our world, and illustrate the differences. Students are lead wherever possible by asking them a series of questions and providing them with hands-on examples.

Table of Contents

• Synopsis

• Materials

• What is Energy?

• The Biological Energy Pathway

• The Fossil Fuel Energy Pathway

• The Renewable Energy Pathway

• Worksheet

Synopsis

• What is Energy? 

Energy Types, Transport, Conservation, and Transformations

• The Biological Pathway:

Sun --> Plants (photosynthesis) --> Animals --> Heat 

• The Fossil Fuel Pathway:

Sun --> Ancient Plants and Animals --> Fossil Fuels

--> Turbines/Engines --> Electrical Devices --> Heat

• The Renewable Energy Pathway:

Sun --> Wind/Water/Light --> Collectors --> Storage

--> Efficient Devices --> Heat

Materials 

For classroom presentations of the biological and fossil fuel pathways, you will need:

• Picture of a coal-fired power plant (included below!)

• Global Warming temperature graph (included below!)

• Hand-dynamo powered flashlight (with dynamo visible) - can be purchased at most science related toy stores

• Fossil fern - Can be purchased at many fossil stores

• Piece of coal - Science departments at many high schools have a sample

• Piece of charred wood

• Cup of oil

Materials that accompany the SunChaser2 used for presentation of the renewable energy pathway include:

• Earth Globe and a yellow painted soccer ball 

• SunChaser2:

  • Photovoltaic powered water fountain

  • Sunoven

  • Complete onboard photovoltaic system

  • Complete onboard hot water system

  • Solar water distiller

  • Burning Mirror and wood

  • Toy solar cars

What is Energy?

• What is energy? (Begin intuitively and pragmatically: Its that special stuff that is needed for any physical movement, to make devices such as appliances and cars function, to keep the house warm, to cook food, etc)

• What are the different types of energy? (Mechanical energy- a rolling ball has "kinetic" energy, a ball sitting on the table has "potential" energy, Chemical energy - food and batteries, Electrical Energy - the energy that's delivered by wires and used by appliances, Thermal Energy - Heat, the microscopic vibrations of molecules in solids or the microscopic kinetic energy of gas molecules,  Light Energy - Light is made of little energy packets called "photons").

• How is energy transported? (Radiation - Low-frequency (invisible) light is emitted by all objects. This helps hot things to cool off (in addition to loss of heat through conduction and convection). Convection - Moving matter, such as air and water, can simply carry the heat energy contained from one place to another. Conduction - Heat energy "diffuses" inside a solid or gas from a hot place to a cooler place: Basically, the microscopic kinetic or vibration energy is transferred from molecule to molecule in an energy bucket brigade).

• Can energy be created or destroyed? (No! All the energy in the Universe was always here and will always be here. Energy is conserved).

• What happens when light hits a surface? (Its either reflected or absorbed).

• What happens to light energy when the light is absorbed? (Its converted into heat, or sometimes chemical energy in a "photochemical reaction").

• What other transformations of energy are there? (When you run, you convert chemical energy - food sugars that is - into mechanical energy and heat. When you turn on a light, you convert electrical energy into light energy and heat. When you rub your fingers on the table, you convert mechanical energy into heat via friction. When you boil water, you first convert chemical or electrical energy into heat, and then some of the heat is converted into the kinetic mechanical energy of the boiling water. Nuclear reactions in the Sun and elsewhere can actually transform matter into energy and energy into matter). 

• How was energy and its properties discovered? (Mechanical energy and its properties where discovered several hundred years ago by scientists as soon as they started using mathematical equations to describe the way things move in the world. Without these equations, it would be hard to know or even show that energy is conserved, and without that proof, no one would probably even bother trying to define the word energy. The fact that heat is also energy only became understood about 150 years ago - this was hard to understand because heat is microscopic energy and therefore invisible, and the true nature of light as little packets of energy only became understood about 100 years ago - again because the packets themselves are not visually distinguishable, so that indirect means were needed to infer their existence).

The Biological Pathway:

(Presented in the classroom - see materials list above)

• Where did you get your energy this morning? (Breakfast!)

• What is food made of? (Plants and Animals)

• Where did plants get their energy? (From the Sun! Point out some plants - emphasize that they are all solar collectors)

• Point out that we are literally surrounded by solar collectors!

• What is the process that plants capture energy called? (photosynthesis)

• What does the word "photo" mean? (light)

• What is light made of? (little packets of energy called "photons")

• What does "synthesis" mean? (to put together)

• What do plants synthesize with sunlight? (sugar)

• Is sugar a kind of energy? (yes - stored, chemical energy)

• So what really ultimately powers your body? (the Sun! Strongly emphasize that the students themselves are actually solar powered.)

• Have you realized before that you are solar powered?

• What powers the Sun? (nuclear reactions called "fusion")

• What does the word "fusion" mean? (to combine)

• How does nuclear fusion make energy? (Fusion makes hydrogen into helium by "fusing" hydrogen atoms into helium atoms. When the hydrogen nuclei combine, they release a lot of energy, analogous to the way your hands make a loud sound when you clap them together)

• Re-emphasize to the students that they themselves are solar powered!

• Ask the students if they know what friction is (when things rub together, mechanical energy gets converted into heat).

• Have the students rub their hands together and feel the heat. 

• Ask the students what happens to their energy after they use it to do something? (Most of it gets converted into heat, and eventually radiated back out into the Universe. Some examples: Your body gives off lots of heat. When you make a sound, the air vibrations eventually get converted into heat. When things rub together, heat is generated.)

The Fossil Fuel Pathway:

(Presented in the classroom - see materials list above)

• What brings energy to the lights in our classroom? (electrical wires)
• Where do the wires come from? (from power plants)
• Show a picture of a coal-fired power plant:

(A coal-fired power plant in New Mexico)

• How does the power plant get its energy? (from burning coal)
• Show them the sample of coal (our sample is "bituminous" coal -about 80% carbon, from Grants, New Mexico, and unlike Pennsylvanian or Mississippian coal which was formed long before Dinosaurs roamed the earth, this local coal was formed from plants and animals in the Cretaceous Period - 65 to 179 million years ago - and therefore can actually contain the remnants of dinosaurs as well as plants). 
• How does the power plant generate electricity from burning coal? (by heating water to turn a turbine).
• Show them the dynamo-flashlight, and explain how it works. Let them all try it.
• What is coal made of and where does it come from? (It's the left over carbon from plants and animals that died millions of years ago that became buried and compressed under ground).
• Show them the charred wood - explain how its similar to the coal (its also the carbon "skeleton" of a plant, and both are colored black).
• Show them the fossil fern: Explain what it is and how it formed
• Emphasize that coal is also a kind of fossil
• How did ancient plants get their energy? (from the Sun!)
• How do we get coal? (We have to mine it from the ground).
• Therefore, where did the energy of the lights in the room ultimately come from? (from the Sun!)
• What is good about burning coal? (There is quite a bit of it, and its easy to find and use).
• What is bad about burning coal? (Discuss the following: how mining disrupts the land, how burning coal produces air pollution, and that coal must someday run out if we keep using it).
• Introduce and explain the term "nonrenewable energy".
• What kind of pollution is created by burning coal? (In order of decreasing amounts: carbon dioxide, sulfur dioxide, mercury, uranium, and other).
• What is the "greenhouse effect"? (the heating of a room or space enclosed by glass when sunlight falls on it)
• Why does the greenhouse effect happen? (because light energy can get in, but heat energy can't get out)
• What is global warming? (Global warming is a gradual warming of Earth's surface that many scientists suspect is caused by burning fossil fuels, ozone depletion, deforestation, methane produced by cows, and by other lesser sources of greenhouse gases)
• If the students are old enough, discuss the following global temperature graph:

• Explain that the graph shows the average temperature of the northern hemisphere over the past 1000 years. During the first 800 years, the graph shows a gradual decrease, which is thought to have been caused by the way the tilt in the Earth's axis changes in relation to the Sun and the Earth's orbit around the Sun. The last 100 years show a sudden increase in temperature which is attributed by many to greenhouse gases. 
• What compounds in the atmosphere trap heat, and thus play the role of the glass covering a greenhouse, causing global warming? (In order of decreasing magnitude - water vapor, carbon dioxide, methane, and then other lesser greenhouse gases).
• Explain that people are not yet completely sure about how much global warming there will be yet, for example, because we do not know how to predict the effect on cloud formation and other aspects of climate. But most scientists believe that some kind of dramatic climate change is almost certain occur.
• How does a car gets its energy? (from gasoline)
• Where does gasoline come from? (from refining oil)
• Where does oil come from? (from drilling in the ground)
• How was oil created? (the same way as coal).
• Show them the oil sample - point out how its almost the same color as coal.
• Emphasize that oil is also made of ancient plants and animals
• Ask them if they've heard of "natural gas"
• What is natural gas used for? (for heating buildings, cooking food, and even powering some vehicles)
• Where does natural gas come from? (from drilling in the ground, just like oil)
• How is natural gas created? (its made from ancient plants and animals, just like coal and oil)
• Emphasize again that fossil fuel energy really comes from the Sun, but that its really old solar energy, and not renewable.
• Ask the students what eventually happens to the energy used by appliances, heating homes, cooking, driving, etc. (It mostly gets converted to heat, and radiated back out into the Universe).

The Renewable Energy Pathway:

 (with the SunChaser2)

• Begin with the photovoltaic powered water pump:
  • Ask them if they know what the photovoltaic panel is called (a "solar panel").
  • Ask them to explain what is happening (have them block and unblock the panel, making the water shut off and on).
  • Show them the water pump itself, and explain that it's just circulating the water, not heating it.
  • Ask them what kind of energy the pump needs (electrical) - prompt their answer by showing them the wire.
  • Ask them what kind of energy the solar panel must then be producing (electrical).
  • Point out the beautiful crystal patterns on the panel.
  • Ask them if they've ever seen crystal patterns like that (galvanized steel, frost patterns on the window).
  • Explain that the crystals are made of highly purified sand, with a little bit of other elements, such as boron, added to create the right electrical properties.
  • Ask them what the little lines across the panel are (little wires, to capture the electricity).
  • Explain that each small section of the panel is called a solar cell, and that these are wired together to make a solar panel.
  • Now describe the whole process - the sun shines on the panel, which makes the electrons in the crystals move. These electrons intercept the little wires, and flow the circuit, thereby making the pump go.
  • Explain that this kind of solar cells are called a "photovoltaic" cells. Remind them of the meaning of the word "photo" (light) and explain that "voltaic" comes from "volts" which means "electrical pressure".
  • Ask them what they can do with a system like this (make a fountain for a garden, pump water for animals)
  • Ask them what is good about using a solar panel (you don't have to burn fossil fuels to get electricity).
• Next introduce the SunOven:
  • Ask them to explain what the device is (a sunoven, or solar oven).
  • Ask them to explain how it works, beginning with the reflective panels.
  • Cover the word "reflection" in detail.
  • Ask them if the reflectors will get hot (no - because the energy is reflected into the sun oven).
  • Ask them why there is glass over the oven (to let light into the oven while trapping the heat in the oven).
  • Ask them what this process is called (the "greenhouse effect").
  • Ask them what color the sunoven is inside (black)
  • Ask them why its black inside - cover the word "absorb".
  • Ask them "If there are two cars in the parking lot - one white and one black - which one will feel hot if you touch it?" (the black one)
  • Explain that the black surface not only absorbs the light, but also changes it into heat.
  • If the students are old enough, explain that the heat is radiated from the black surface as low-frequency (sub-visible) light, and that this light mostly cannot travel through the glass, and is therefore trapped.
  • Explain that the Sunoven can get to 400 degrees fahrenheit on a clear, windless, summer day.
  • Ask them why the air is warm in summer (because the Earth is essentially a giant solar oven, where the air, especially carbon dioxide and water vapor act like the glass to produce a greenhouse effect). 
  • Emphasize that the kind of energy the sunoven uses (heat energy) is different from the kind the photovoltaic panel used (electrical energy), and that these two examples really demonstrate two basic kinds of solar energy devices - those for electricity, and those for thermal (heat) energy.
  • Ask them if cooking takes alot of energy (yes).
  • Ask them why a solar oven is good (because you can cook without burning fossil fuels).
• Now move to the arrays on the SunChaser2:
  • Ask them which panels are for electricity and which are for heat (The ones that have the little solar cells and wires are for electricity - the one that has glass and is black inside is for heat - in this case for heating water).
  • Point out that there is a water pipe coming into the bottom of the hot water panel.
  • Explain that the solar hot water panel is called a "flat plate collector", and is different from a "photovoltaic" panel.
• Move around to the back:
  • Have the students form a large semicircle around the back of the trailer.
  • Explain and demonstrate how the cold water is pumped into the bottom of the panel with a solar powered pump, and how solar heated water comes out of the top of the hot water panel.
  • Ask them why it is green (so the panel won't freeze on a winter night).
  • Explain that the green water is not the water one uses directly, but that the heat in the water has to be transferred into a water tank with a device called a "heat exchanger".
  • Explain that the cement slab shows how you can have hot water pipes running underneath the floor to heat the house - "radiant floor heating".
  • In groups of three, have the students come up and feel the hot water tank.
  • Ask the students if it takes alot of energy to heat water (yes)
  • Ask the students why the solar hot water heater is good (you don't have to burn alot of fossil fuels to get hot water).
• Now go inside the SunChaser2:
  • Remind them of the photovoltaic panels on the back (there is a picture of the panels inside).
  • Ask them what kind of energy do they produce (electricity).
  • Ask them what you can use that electricity for? (name some appliances).
  • Now demonstrate the appliances on board.
  • Emphasize that the energy of the lights they see really came from the Sun recently.
  • Ask them what would happen on a cloudy day or at night? (it wouldn't work!)
  • Ask them what you need to do to still make it work? (you need to store the solar energy - prompt them by asking how a flashlight gets its energy).
  • Show them the batteries.
  • Explain that they are different from car batteries - they are "deep-cycle" batteries that are designed to be drained alot and recharged over and over, and that they made of lead and acid.
  • Ask them if they know what dc electricity is ("direct current" - the voltage, or electrical pressure, is constant).
  • Explain that this is the kind of electricity that batteries have.
  • Ask them if they know what ac electricity stands for ("alternating current" - the voltage oscillates continuously).
  • Explain that alternating current is what generators (for example in power plants) make, and that this is the kind of electricity that appliances use and that comes from wall sockets.
  • Explain that we use ac for houses because its easier to transmit over long distances, and is naturally the type of electricity that generators make.
  • Explain that the inverter converts the dc electricity of the batteries to ac.
  • Compare incandescent light bulbs to fluorescent bulbs
  • Ask them why its better to use fluorescent bulbs (they use less energy, which is good because that way you don't burn as much fossil fuels or you don't need as large and expensive solar system).
• Now go outside and have the students stand in circle:
  • Explain how the Earth goes around the Sun (you may want to have one student hold the Sun ball in the center, and another student walk around the Sun while spinning the globe).
  • Explain why we have seasons (show how the Earth's axis doesn't change (at least quickly), and how that generates the seasons as we move around the Sun).
  • Explain that the Sun goes straight overhead during summer, but crosses to the south in winter.
• Now turn to the display boards:
  • Explain how Native Americans built Pueblo Bonito (at Chaco Canyon) and the Mesa Verde ruins to take advantage of the Southern Sun in the winter for heat, and the overhanging cliff to block the Sun in the Summer.
  • Explain how the thick adobe of these dwellings helps both to keep the buildings cool in summer during the day and warm in winter at night, by storing the Sun's energy during the day and radiating back out at night.
  • Explain that you can do this in a regular house - show them the pictures of solar houses on the wall.
  • Emphasize that solar houses can look like regular houses.
  • Explain that the main ingredients are:
    • Insulation - so you don't let heat out during cold days, or hot air in during hot days.
    • Solar gain - windows on the south side so that alot of light can come in during the winter but not during the summer.
    • Thermal mass (like the adobe) - Lots of masonry to absorb and store solar energy during the daytime.
  • Explain that this is called "passive solar design" because it does not use any solar panels, pumps, pipes, etc.
  • Explain that the hot water system on the back is called an "active" solar system because it uses solar panels, pumps, pipes, etc.
  • Finally, emphasize that you can use solar energy to:
    • Get electricity
    • Heat water
    • Heat your house
  • Explain that many people all over the US, and especially in New Mexico, do this.
  • Again, emphasize that this is a good approach because it doesn't need to burn fossil fuels, and can therefore help in preventing disruption of land by mining, pollution, and global warming.
• Summarize the big picture:
  • Ask the students why they think solar energy is not used for everything. Discuss the following ideas:
    • Renewable energy technology is very somewhat new, still under development, and still more expensive than fossil fuels (but gradually getting closer).
    • Emphasize that many people think renewable energy is actually less expensive if the impacts on the environment and subsidies for fossil fuels are taken into account. 
    • It takes a long time to replace old technologies that are so large and expensive.
    • It takes a long time to convince people to try new things.
    • Emphasize to students that their generation might have a good chance to use solar energy, but that they will have to be good citizens to help promote it by:
      •  learning about it, 
      • using it, 
      • writing letters to their legislators, 
      • and voting for candidates who support it. 
• Now move to the toy solar cars:
  • Explain that the cars are powered by solar power, including the transmitter.
  • Explain that the solar energy is stored in capacitors in the bottom of the car (like batteries), so that the car can run even on a somewhat cloudy day, and can go through shade as well.
  • Let them each take a turn with the car.

Worksheet

1. What are the three energy pathways?
2. Where does all the energy in these pathways initially come from?
3. Where does most of the energy eventually go?
4. What does "photo" mean?
5. How do plants get their energy? 
6. Where did the energy of your body ultimately come from?
7. How does the Sun get its energy?
8. How do power plants get their energy?
9. Where does coal come from?
10. What is good about burning coal?
11. What is bad about burning coal?
12. What is renewable energy?
13. What is nonrenewable energy?
14. What kinds of energy can solar panels provide?
15. What are solar panels that produce electricity called?
16. What are solar panels that produce hot water called?
17. What is the greenhouse effect?
18. How does the Sunoven achieve a greenhouse effect? 
19. How does the Sun move in the sky in the winter and the summer?
20. What three things do you need to heat your house with the Sun in the winter but keep it cool in the summer?

Created by Benjamin Luce for NMSEA, 2000.

© NM Solar Energy Association 2000. This material may be used without permission for nonprofit educational purposes only, and only if used in unaltered form, including deletions.

Date of last revision: 02/16/01