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Energy. We know it when we see its effects but have a hard time explaining it. If you ask students to picture the concept of energy, they might conjure up the images in this collection. They might have difficulty explaining how the photographs represent energy, however. Students can understand that images of food, gasoline, and sunlight represent energy, but they might not know how humans have, for millennia, engineered ways to store energy and use energy transformation to do work.
Some of the photographs in this collection illustrate the impact of energy as movement, light, or heat; others show mechanisms engineered to capture, store, and distribute energy. Ask students to consider the costs and benefits of different energy-capturing systems. In addition to the physical science concept of energy, science, and engineering topics directly and indirectly related to the photographs, include natural resources, human impact on earth, and defining and delimiting engineering problems.
Note: In talking about energy, it is easy to use language that suggests that energy is created or destroyed. Strictly speaking, however, energy is conserved in our universe, according to the first law of thermodynamics. Terms such as “generated” or “lost” are common in conversations about energy. When teaching about energy, however, use terms such as convert, flow, distribute, store, release, transfer, transform, input, and outflow. “Heat energy” is a common conversational term. To be accurate, however, “heat” should be used to describe the transfer of thermal energy.
The content is in accordance with the Next Generation Science Standards (NGSS), specifically:
Other sections that might be relevant are:
Framework for Science Education
A Framework for K-12 Science Education. Practices, Crosscutting Concepts, and Core Ideas.
http://www.nap.edu/catalog.php?record_id=13165
Additional energy-related educational materials and activities from the Department of Energy
http://energy.gov/science-innovation/science-education
Additional energy-related educational materials and activities from the National Renewable Energy Laboratory
http://www.nrel.gov/education/educational_resources.html
Interactive map of energy sources in the United States from the U.S. Energy Information Administration
http://www.eia.gov/state/maps.cfm?src=home-f3
Interactive tables with numbers for production, capacity, and other features of different energy sources, by country, adjustable for different units and years from the U.S. Energy Information Administration
http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm
Ask Nature resources on biomimicry
http://www.asknature.org
Production statistics from the U.S. Energy Information Administration
Using the interactive tables, teachers and students can get current data on how much energy comes from various sources such as nuclear, fossil fuels or renewables.
http://www.eia.gov/countries/data.cfm
Renewable energy cost comparisons
http://www.renewable-energysources.com/
Maya Pedal
http://mayapedal.org
Bike-powered gym
http://inhabitat.com/human-powered-gyms-in-hong-kong/
Students will:
Before doing these activities, students should be familiar with the conservation of energy—that it is not created or destroyed, but can be stored and released. Students should recognize that photos of light or motion represent effects of energy.
In pairs or small groups, ask students to talk—and possibly write about—what they picture when they hear the word “energy.” Then have the students look at the photos (projected or on handouts) and talk about how the photos represent energy. Have students identify the types of energy involved in each photographed system, and the inputs, processes, and outputs they see. Students might notice energy types, inputs and outputs (such as movement or light), and processes (such as cranks or wheels). Some students might know terms such as kinetic, thermal, or chemical bond energy. Have students brainstorm other examples of systems for capturing and using energy. Depending on the photos used, they might think of traditional or modern windmills, or new methods, such as solar panels.
Emphasize that, at this point, no ideas are considered right or wrong. Some discussion points might be to note the movement energy of water, waves, and wind; thermal and light energy of sunlight; and stored chemical energy in organic matter such as wood. Human metabolism releases stored chemical energy in food. That energy can be used for movement, such as riding a bicycle. A point to raise in discussions is how photographers visually convey energy: for example, how the water photos emphasize waves and motion rather than tranquility.
This information is not for classroom content, but to prepare teachers for the photographs, activities, and potential questions from students.
A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (p. 128–29) has background material for these activities:
In ordinary language, people speak of “producing” or “using” energy. This refers to the fact that energy in concentrated form is useful for generating electricity, moving or heating objects, and producing light, whereas diffuse energy in the environment is not readily captured for practical use. Therefore, to produce energy typically means to convert some stored energy into a desired form—for example, the stored energy of water behind a dam is released as the water flows downhill and drives a turbine generator to produce electricity, which is then delivered to users through distribution systems. Food, fuel, and batteries are especially convenient energy resources because they can be moved from place to place to provide processes that release energy where needed. A system does not destroy energy when carrying out any process. However, the process cannot occur without energy being available. The energy is also not destroyed by the end of the process. Most often some or all of it has been transferred to heat the surrounding environment; in the same sense that paper is not destroyed when it is written on, it still exists but is not readily available for further use.
Naturally occurring food and fuel contain complex carbon-based molecules, chiefly derived from plant matter that has been formed by photosynthesis. The chemical reaction of these molecules with oxygen releases energy; such reactions provide energy for most animal life and for residential, commercial, and industrial activities.
Electric power generation is based on fossil fuels (i.e., coal, oil, and natural gas), nuclear fission, or renewable resources (e.g., solar, wind, tidal, geothermal, and hydropower). Transportation today chiefly depends on fossil fuels, but the use of electric and alternative fuel (e.g., hydrogen, biofuel) vehicles is increasing. All forms of electricity generation and transportation fuels have associated economic, social, and environmental costs and benefits, both short and long term. Technological advances and regulatory decisions can change the balance of those costs and benefits.
Although energy cannot be destroyed, it can be converted into less useful forms. In designing a system for energy storage, for energy distribution, or to perform some practical task (e.g., to power an airplane), it is important to design for maximum efficiency—thereby ensuring that the largest possible fraction of the energy is used for the desired purpose rather than being transferred out of the system in unwanted ways (e.g., through friction, which eventually results in heat energy transfer to the surrounding environment). Improving efficiency reduces costs, waste materials, and many unintended environmental impacts.
In small groups or pairs, have students choose a photo to examine, and explain how energy is being captured, stored, or transferred in the system in the photograph. Students should discuss the state of the energy and the system before and after the situation shown in the photo. (Note that this exercise is mainly designed for high school students, so middle school students might use less sophisticated terms. High school students with more science experience might use more advanced terms. For example, they might discuss if they are seeing the capture of kinetic energy, or the release of chemical bond energy as heat.) In small groups or pairs, have students select a series of related photos and assemble them to portray a designed energy system. If the photos are not adequate to show a complete system, have the students identify the missing step. Remind students to try to use words that emphasize transfer and conservation of energy in the universe, rather than terms that suggest creation, generation, or loss of energy.
Have students make a diagram—for example, a flow chart or systems diagram—that shows the transformation of energy in each photo.
Engineers work to design practical solutions to real-world problems by breaking them down into smaller, solvable problems. Spend a few minutes thinking like an engineer, considering a solution to a problem based on priorities and thinking about trade-offs and limitations. Use this type of thinking to describe ways that humans do or could take advantage of the energy source shown in one of the photographs and use it to do work.
Systems developed for capturing energy from a particular source often have similar design elements; however, the designs for individual energy-capturing systems vary, depending on a variety of factors.
This information is not for classroom content, but to prepare teachers for the photographs, activities, and potential questions from students.
Any system designed to capture energy for work has associated criteria and constraints that are defined by a variety of factors. Consideration of scientific principles and other relevant knowledge may limit possible solutions. For example, extracting, processing, transporting, and using fossil fuels have environmental impacts. Hydroelectric and nuclear power plants create risks and benefits for a region. Renewable energy sources, such as wind turbines, solar panels, and biofuel production, have production costs and demands and require space. Costs and requirements change as technology advances but are often limited by geographic constraints or situations.
In this activity, students will focus on one of the energy sources highlighted in the second activity. Students will use photographs showing different systems designed to capture, store, and transfer wind energy to analyze different design features of wind energy systems, thinking about the environmental factors involved in different solutions. Small group and class discussions will consider the design benefits of different systems that take advantage of energy sources. Students will have the opportunity to apply engineering design strategies to locations and situations in their own communities.
Part 1
Materials:
Give students a photograph to work on, possibly in pairs. (Optional: Start by making a diagram, as in Energy Systems, to show the flow of energy in the system in the photograph.) Show the energy flow from the source through the processing equipment to a specific use, such as a home, car, or school.
Next, consider the space required for the energy-capturing system in the photograph. If the photo has an associated scale, for example, 1 cm = 5 m, calculate the dimensions of the energy-capturing system. If the photo does not have an associated scale, use a familiar item in the photo (such as a person or vehicle) to estimate the dimensions. For example, use an average height of 170 cm per person, or guess that a tree might be 5 or 10 meters high to calculate the length and width of solar panels or wind turbines.
Have students look at the background features of the photographs and note the general geographical features and the expected climate of the region.
As a class, share the footprint—the dimensions—of each energy-capturing system. Discuss the amount of space required for the different systems as well as requirements.
Thinking about the space and other requirements, discuss the advantages and disadvantages, such as environmental impact, risks to the surrounding community, the sustainability of the energy source, or aesthetic impact. For example, if this system were installed in your state or region, what ecosystems might be affected? What else might the space be used for?
Note: Using the activity results, students will be able to discuss the space requirements. For the other features, they could generate hypotheses about advantages and disadvantages of the energy-harnessing systems, such as the sustainability of a system that requires a steady supply of wind or sun, or complaints that people might have about the aesthetics of various systems. For a more in-depth activity, have students choose one of the systems and research its advantages and disadvantages more fully.
Part 2
Using the estimates from Part 1, based on the photos of the solar array and wind turbine, have students go outside and plot or map out their estimates of the size of the energy-capturing systems. Back in the classroom, have students discuss and identify factors besides size that would be required to using the systems in their community.
Part 3
In this part of the activity:
Give students photos of wind turbines. Based on the variety of designs shown in the photos, have students make one or more models that explore options for blade design and turbine structure. After they have sketched or described their own models, have the students research and design an option that might work locally. (Option: An Internet search might find directions for building and testing a mock wind turbine.)
Look at the background features of all the photographs.
Compare the advantages and disadvantages that the class came up with for the energy-capturing systems in the photographs to the pros and cons of the predominant systems in your area. Do you think your region has the optimal energy option? Why or why not? (Interactive maps and tables from the U.S. Energy Information Administration can answer questions about energy capacity and consumption in different regions and by different sources. See References and Further Reading.)
What sources of energy are we not yet using effectively? What is needed to use or improve our use of these energy sources?