ENVIRONMENTAL LITERACY TEACHER GUIDE SERIES Energy Potential A Guide for Teaching Energy in Grades 3 to 8 CHAPTER Energy in Human Systems 2 by Ivan Salinas ave you ever wondered how understand what actually happens to Having a solid understanding of basic chemical energy in gasoline the gasoline to make the car run. energy transformations can help lay the H can become kinetic energy groundwork for understanding more that moves cars on a road? Or how Energy in Our Lives complex human-engineered devices. burning coal in a power plant provides Engines and power plants will interest In Chapter 1, several forms of energy electrical energy to our homes? Both many of your students. Children are were presented (chemical potential, may be mysterious for your students innately curious about how things electrical, nuclear, kinetic, light, and as well. Students see outlets in their work, especially in systems they come heat). We utilize all of these everyday, homes and power lines running into contact with each and every often without even recognizing it. through their neighborhoods, but they day. Before introducing the internal Many students may not know to look may wonder where this electricity workings of engines and power plants, for these changes or have the language comes from. How did the power plant consider reviewing several examples of to describe them. The following list of start with coal, uranium, or other energy transformations that students examples may provide a starting point resources, to make the electricity? experience close to home. Ask students for your discussions on energy changes. Students also know that we put if they can think of any examples, such These examples tap into some of the gasoline into our cars, but eventually as eating food and then having more most common experiences that people, the tank becomes empty and must be energy or plants converting solar energy including children, have as they go refilled. It is likely that they do not into chemical energy to live and grow. about their everyday activities. 26 Energy in Human Systems GRADE STANDARD EEI UNIT found in food, but water is not a source of energy for our bodies. Food is the Grade 3 3 1 a-d ultimate source of chemical energy that our bodies use to function. When Grade 4 4 1 c-e 4 1 g digested and metabolized in our bodies, 4 1 5 Reflections of Where We Live food can be changed to kinetic energy (movement of fluids inside the body, Grade 5 as well as movement of body parts Grade 6 6 3 a-d (such as a beating heart, a turning 6 6 a-b Energy: It’s Not All the Same to You! head or clapping hands), in the form Energy and Material Resources: Renewable or Not? of electricity (electrical impulses in the body’s nervous system), or heat (to Grade 7 maintain a constant body temperature). Grade 8 8 3 a When people consume more food than 8 5 c their energy needs demand, the body accumulates reservoirs of energy-rich substances from this food, such as fat, Energy for Our Bodies. Students after consuming too many sweets or usually not immediately available to use are naturally curious about how their “sugar lows” after not eating for long but stored as chemical energy. bodies work. They grow up hearing periods of time. In order for our bodies Illumination. The world at night is that the human body is typically 98.6° to work properly, we need to have a an amazing web of light. Europe and Fahrenheit but may wonder why. They steady stream of food and water. Water the East Coast of the United States light may wonder why we have “sugar highs” helps transport chemicals that are up in a fantastic display when viewed CHAPTER OVERVIEW From the engines in our cars to the power plants that supply our communities, Student Thinking: people depend on energy for almost all of our daily needs. Yet how much do Burning Gasoline 32 we know about where our electricity comes from? How much do we know Pictures of Practice: about how our cars run on gasoline? We simply fill our gas tanks or flip a Energy From Cars 33 switch and things work as they should. Student Thinking: While Chapter 1 introduced different forms of energy, this chapter takes Electrical Energy 35 a closer look at how energy changes in human systems, from internal Pictures of Practice: combustion engines to power plants. We will consider historical changes Where Does Electricity in engines, from steam engines to combustion engines to electric cars. All Come From? 36 of these engines transform energy in different ways in order to transport people or goods around the globe. We are currently in the midst of a wave In the Classroom: of changes, with the introduction of hybrid and electric engines. We may not Comparing Power Plants 40 know what the engines of our future will look like, but we can be certain they Student Thinking: will transform energy resources to meet our transportation needs. Renewable and Nonrenewable 43 Additionally, this chapter outlines how energy is transformed in power plants. Electricity can be created from a variety of energy forms, including fossil fuels, Case Study: Support nuclear energy, hydropower, biomass, geothermal energy, and more. This for Renewables 44 electricity is then transported to our homes, schools, and businesses through In the Classroom: an extensive network of power lines—or power grid. Scientists and engineers Generating Energy 46 are currently exploring ways to improve efficiency of our power distribution systems to conserve energy, with increasing attention to a move from nonrenewable energy to renewable energy. Energy in Human Systems 27 from space. Thousands of years ago, Teaching light on Earth came only from the sun. Tip Then we discovered fuels that we could use for fire, and later candles and lamps, For a quick activity to illustrate heat emission, plug in two lamps—one and the devices that produce light with a compact fluorescent lightbulb (CFL), and one with a traditional, proliferated. It is inconceivable for most incandescent bulb. In a few minutes, students can measure the Americans to imagine their activities surface temperature on each bulb and note that the CFL has a lower stopping at night. There are many parts temperature; less heat is being emitted. See Chapter 6, Pictures of of the world today, though, that do Practice: Energy Efficiency of Lightbulbs, to watch this activity unfold not live with this 24-hour availability in a fourth- and fifth-grade classroom, or view the following web link of light. Their activities are seriously for information about CFL bulbs: http://www.energystar.gov/index. curtailed when the sun sets. Some of cfm?fuseaction=find_a_product.showProductGroup&pgw_code=LB. your students may come from or have family still living in these conditions. The light from both candles and electric lights result from energy order to transport people and goods all Temperature Maintenance. transformations. The chemical energy around the globe. We will take a closer Cold weather requires heating of home from the wax or paraffin (fat) gives look at these energy changes later in the and work environments for both health off light as it burns. In electric lights, chapter. and comfort. Hot weather requires electricity is transformed to light in an Drinking Water. Students may cooling systems (such as refrigerators) electrical resistor (the bulb filament). not realize that even getting water from to maintain food from rotting as well In both cases, heat is produced too, and their home’s faucets requires energy to as for comfort and health in our homes often this heat is considered a waste change forms. The water that comes in the forms of fans or air conditioning. product. Engineers are trying to design out of the faucet is moving and is In each case, energy changes several bulbs that give off the same amount of pressurized. This requires electrical- or times. If a fire is lit, the chemical energy light, but use less electricity, and give gas-fueled pumps to move the water. in wood is changed to heat and light. If off less heat (for example LED and CFL There is also another type of pump that a fan or air conditioner is turned on, it bulbs as described in Chapter 1). Giving uses differences in height and gravity to is likely that some form of energy was off less heat means the bulb is more change gravitational potential energy changed into electrical energy. What energy efficient. into kinetic energy. many of us overlook is that because Transportation. Transportation heat is once again a by-product of (movement from one location to energy transformation, it is produced another) requires energy to change and will have to be “pumped out” of forms. Even long ago, the chemical air conditioners and refrigerators, also energy in food was changed to motion requiring energy. in our bodies to run, row boats, or ride Electrical Devices. Like heating horses. Machines that we use today and cooling systems, many appliances, for transportation, such as cars, trains, instruments, and machines require airplanes also undergo processes to electricity to work. We need kinetic change energy from one form into energy and heat in dishwashers and motion (kinetic) energy. In some cases, laundry machines, we need light and energy is transformed from an electrical sound for cell phones, televisions, source, such as in an electrical car, to and stereos. Making these appliances kinetic energy. Chemical energy is work involves several steps of energy transformed from fossil fuels in cars, transformations, often starting with trucks, and airplanes to kinetic energy the burning of a fuel in power plants to as well.