CAPTURING SOLAR ENERGY Students will learn that solar collectors absorb radiant energy, convert it into heat, and hold the heat. OBJECTIVES The students will be able to Explain how solar collectors work. Explain the importance of renewable energies to reduce the ecological footprint. VOCABULARY Radiant Energy: energy traveling in waves; esp., electromagnetic radiation, as heat, light, or X-rays Greenhouse Effect: The phenomenon whereby the earth's atmosphere traps solar radiation, caused by the presence in the atmosphere of gases such as carbon dioxide, water vapor, and methane that allow incoming sunlight to pass through but absorb heat radiated back from the earth's surface. Non-Renewable Energy: Energy resources which are consumed much faster than nature can create them. (i.e. fossil fuels) Renewable Energy: Energy resources that are naturally regenerated over a short time scale and derived directly from the sun (such as solar), indirectly from the sun (such as wind, hydropower, and biomass), or from other natural movements and mechanisms of the environment (such as geothermal and tidal energy). MATERIALS/EQUIPMENT Glass of water 2 white and 2 black containers Plastic wrap Rubber bands Thermometers Water Data sheet TIME NEEDED: 45 minutes (½ hour is used for containers to heat up) DEGREE OF PHYSICAL ACTIVITY: low RUNNING THE ACTIVITY Show students a glass of water. Ask them: How can we make the water hot? After suggestions have been made, point out that any way of heating the water requires energy – from electricity, gas, the sun, etc. Ask the students what they know about renewable and non-renewable energies. If students are unfamiliar with these terms, explain the difference: non-renewable energies come from sources that took millions of years to create so we have a limited supply of them. Examples include coal, natural gas, and oil. Renewable energies will not run out – they are constantly being replaced. Examples include energy made with sun, wind, geothermal, biomass, and hydropower. Explain that students will be doing an experiment today to see how solar energy is used for more than just generating electricity. Show students the four containers – 2 painted white, 2 painted black. Have students fill each container about 1/3 full with room temperature water. Record the starting temperature in each container. Put plastic wrap over the top of one of the black containers and one of the white containers, holding it in place with the rubber band. Place the containers in the sun for at least ½ hour, more if time permits. Use this time to help students recall what they already know about solar heating: ask students what sidewalks and asphalt streets feel like on hot summer days – what does it feel like when you are wearing a dark shirt on a sunny day. Ask the students to predict what will happen to the temperatures in the white and black containers. Explain that many people use solar panels to trap the sun’s heat energy to warm water in their homes or businesses. The warm water is stored in insulated containers so it can be used later. While the containers sit in the sun, visit the site’s solar water heaters to talk about how they work and what they provide for this facility. After the half hour, go back to the containers. Feel the containers. Then record the temperatures. Compare the results between the covered and uncovered containers - why was there a difference? Have the students discuss why they got the results that they did. Discuss with the students the idea of passive solar energy: how we can take advantage of the fact that dark-colored things will absorb radiant energy and release it slowly over time. Homes that are designed to face south “catch” as much sunlight as possible in the wintertime so there is less need for heating from other sources. Discuss other ways we use solar energy – to create electricity, to run calculators, to dry clothes (when we hang them outside). Point out that solar energy is actually the source of another kind of renewable energy – wind power: sunlight heats the Earth which creates wind which we can use as a renewable energy source. Discuss how using solar energy is good for the environment. (e.g. doesn’t pollute, doesn’t require digging up fuels from deep underground, reduces the amount resources we require to live the kind of life we’re used to). Wrap-Up In journals or through class discussions, have the students answer these questions: 1. How can we use the sun as a heat source? 2. How does this site use solar energy? 3. How could I make use of solar energy at school or at home? WAYS TO USE/INTEGRATE THIS ACTIVITY Use with Solar Ovens STEM CONNECTIONS Science: Students will be predicting and testing. Technology: Students will be using digital thermometers. Math: Students will be taking measurements and analyzing data. SOURCE(S) Adapted from these curricula: What Does the Sun Give Us? www1.eere.energy.gov/education/pdfs/solar_whatdoessungiveus.pdf Exploring Solar Energy www1eere.energy.gov/education/pdfs/solar_exploringsolarenergystudent.pdf Solar Matters II. www.fsec.ucf.edu/en/education/k-12/curricula/sm2/ APPENDIX A: Standards Subject Grade Level Code Science K-12 (2010) 4 220.127.116.11.1 4 18.104.22.168.1 4 22.214.171.124.1 Technology (ISTE) (2007) 5 126.96.36.199.1 6 188.8.131.52.2 6 184.108.40.206.3 8 220.127.116.11.2 K-12 1.b K-12 4.a K-12 4.b K-12 4.c Standards Benchmark Objects have observable properties that can be measured. Energy appears in different forms, including heat and electromagnetism. Energy can be transformed within a system or transferred to other systems or the environment. Tools and mathematics help scientists and engineers see more, measure more accurately, and do things that they could not otherwise accomplish. Energy can be transformed within a system or transferred to other systems or the environment. Energy can be transformed within a system or transferred to other systems or the environment. Current and emerging technologies have enabled humans to develop and use models to understand and communicate how natural and designed systems work and interact. Students demonstrate creative thinking, construct knowledge, and develop innovative products and processes using technology. Students use critical thinking skills to plan and conduct research, manage projects, solve problems, and make informed decisions using digital tools and resources. Students use critical thinking skills to plan and conduct research, manage projects, solve problems, and make informed decisions using digital tools and resources. Students use critical thinking skills to plan and conduct research, manage projects, solve problems, and make informed decisions using digital tools and resources. Measure temperature, volume, weight and length using appropriate tools and units. Describe the transfer of heat energy when a warm and a cool object are touching or placed near each other. Identify several ways to generate heat energy. Use appropriate tools and techniques in gathering, analyzing and interpreting data. Trace the changes of energy forms, including thermal, electrical, chemical, mechanical or others as energy is used in devices. Describe how heat energy is transferred in conduction, convection and radiation. Determine and use appropriate safety procedures, tools, measurements, graphs and mathematical analyses to describe and investigate natural and designed systems in Earth and physical science contexts. Students use models and simulations to explore complex systems and issues. Students identify and define authentic problems and significant questions for investigation. Students plan and manage activities to develop a solution or complete a project. Students collect and analyze data to identify solutions and/or make informed decisions.