Natural Resources. Renewable Energy Resources. Renewable Energy Resources

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1 Natural Resources Renewable Energy Resources What do you think? Read the two statements below and decide whether you agree or disagree with them. Place an A in the Before column if you agree with the statement or a D if you disagree. After you ve read this lesson, reread the statements to see if you have changed your mind. Before Statement After 3. Renewable energy resources do not pollute the environment. 4. Burning organic material can produce electricity. Key Concepts What are the main sources of renewable energy? What are the advantages and disadvantages of using renewable energy What can individuals do to encourage the use of renewable energy Renewable Energy Resources The Sun and wind are renewable resources. Renewable resources come from natural processes that have been happening for billions of years and will continue to happen. Solar Energy Solar energy is energy from the Sun. Solar cells, such as those in watches and calculators, capture light energy and transform it to electric energy. Solar power plants can generate electricity for large areas. They transform energy in sunlight, which then turns turbines connected to generators. Some people use active solar energy in their homes. Solar panels gather and store solar energy to heat water and homes. Passive solar energy uses design elements that capture energy in sunlight. An example of passive solar energy is windows on the south side of a house that can let in sunlight to help heat a room. Wind Energy Have you ever dropped papers outside and had them scattered by the wind? If so, you experienced wind energy. This renewable resource has been used since ancient times to sail boats and to turn windmills. Today, wind turbines can produce electricity on a large scale. A group of wind turbines that produce electricity is called a wind farm. Make an Outline Summarize the information in the lesson by making an outline. Use the main headings in the lesson as the main headings in your outline. Use your outline to review the lesson. Reading Check 1. Explain How is wind energy a renewable resource? Reading Essentials Natural Resources 81

2 Visual Check 2. Describe How is the water in the reservoir used to produce electricity? Water Energy Like wind energy, flowing water has been used as an energy source since ancient times. Today, water energy produces electricity using different methods, such as hydroelectric power and tidal power. Hydroelectric Power Electricity produced by flowing water is called hydroelectric power. To produce hydroelectric power, humans build a dam across a powerful river. The figure below shows how flowing water is used to produce electricity. Hydroelectric Plant 1 Water behind the dam forms a reservoir. 2 Water behind the dam is released into tunnels. The stored energy of the water changes into kinetic energy as it flows downhill. 3 The energy of the flowing water turns a turbine that is connected to a generator. 4 As the generator spins, it produces electricity. Reading Check 3. State Which areas can produce tidal power? In a hydroelectric power plant, stored energy of the water changes into kinetic energy as it flows downhill. The energy of the flowing water turns a turbine that is connected to a generator. The generator produces electricity as it spins. Tidal Power Coastal areas that have great differences between high and low tides can be a source of tidal power. Water flows across turbines as the tide comes in during high tides and as it goes out during low tides. The flowing water turns turbines connected to generators that produce electricity. Geothermal Energy Earth s core is nearly as hot as the Sun s surface. This thermal energy flows outward to Earth s surface. Thermal energy from Earth s interior is called geothermal energy. 82 Natural Resources Reading Essentials

3 Geothermal Plant 2. The steam turns a turbine connected to an electric generator. 3. The steam cools in the cooling towers and condenses into water. Generator 1. Hot water from a geothermal reservoir rises through a pipe to the surface, where it turns to steam. Turbine 4. The water is pumped back down into the geothermal reservoir. Hot water Cool water Geothermal energy can be used to heat homes and generate electricity in power plants, such as the one shown in the figure above. People drill wells to reach hot, dry rocks or bodies of magma. The thermal energy from the hot rocks or magma heats water that makes steam. The steam turns turbines connected to generators that produce electricity. Biomass Energy Since humans first lit fires for warmth and cooking, biomass has been an energy source. Biomass energy is energy produced by burning organic matter, such as wood, food scraps, and alcohol. Wood is the most widely used biomass. Industrial wood scraps and organic materials, such as grass clippings and food scraps, are burned to generate electricity on a large scale. Biomass also can be converted into fuels for vehicles. Ethanol is made from sugars in plants such as corn. Ethanol often is blended with gasoline. This reduces the amount of oil used to make the gasoline. Adding ethanol to gasoline also reduces the amount of carbon monoxide and other pollutants released by vehicles. Another renewable fuel, biodiesel, is made from vegetable oils and fats. It emits few pollutants and is the fastest-growing renewable fuel in the United States. Visual Check 4. Summarize How does steam create electricity? Reading Check 5. State What is the most widely used biomass? Key Concept Check 6. Describe What are the main sources of renewable energy? Reading Essentials Natural Resources 83

4 Key Concept Check 7. Relate What are some advantages and disadvantages of using renewable energy Advantages and Disadvantages of Renewable Resources A big advantage of using renewable energy resources is that they can be replaced. They will be available for millions of years to come. In addition, renewable energy resources produce less pollution than fossil fuels. Using renewable resources has certain disadvantages, however. Some are costly or limited to certain areas. For example, large-scale geothermal plants are limited to areas with tectonic activity. Recall that tectonic activity involves the movement of Earth s plates. The table below lists the advantages and disadvantages of using renewable energy resources. Renewable Resources Advantages and Disadvantages Renewable Resource Advantages Disadvantages Solar energy Wind energy Water energy Geothermal energy Biomass energy Interpreting Tables 8. State the advantages and disadvantages of biomass energy. nonpolluting nonpolluting relatively inexpensive nonpolluting produces little pollution reduces amount of organic material discarded in landfills less energy produced on cloudy days no energy produced at night high cost of solar cells requires a large surface area to collect and produce energy on a large scale large-scale use limited to areas with strong, steady winds best sites for wind farms are far from urban areas and transmission lines potential impact on bird populations large-scale use limited to areas with fast-flowing rivers or great tidal differences negative impact on aquatic ecosystems production of electricity affected by long periods of little or no rainfall large-scale use limited to tectonically active areas habitat destruction from drilling to build a power plant air pollution results from burning some forms of biomass less energy efficient than fossil fuels; costly to transport Managing Renewable Energy Resources Renewable energy currently meets only 7 percent of U.S. energy needs. Most renewable energy comes from biomass. Solar energy, wind energy, and geothermal energy meet only a small percentage of U.S. energy needs. 84 Natural Resources Reading Essentials

5 Sources of Renewable Energy Resources Used in the United States Energy Resource Percent Biomass 53% Hydroelectric 36% Wind 5% Interpreting Tables 9. Interpret Wind accounts for what percentage of the renewable energy resources used in the United States? Geothermal 5% Solar 1% The table above shows the percentages of renewable energy resources used in the United States. Some states are passing laws that require the state s power companies to produce a percentage of electricity using renewable resources. Management of renewable resources often focuses on encouraging their use. Management Solutions The U.S. government has begun programs to encourage use of renewable resources. In 2009, billions of dollars were granted to the U.S. Department of Energy s Office of Efficiency and Renewable Energy for renewable energy research and programs that reduce the use of fossil fuels. What You Can Do You might be too young to own a house or a car, but you can help educate others about renewable energy resources. You can talk with your family about ways to use renewable energy at home. You can participate in a renewable energy fair at school. As a consumer, you also can make a difference by buying products that are made using renewable energy resources. Make a vertical, five-tab book to identify the advantages and disadvantages of alternative fuels. Solar Wind Water Geothermal Biomass Key Concept Check 10. Describe What can you do to encourage the use of renewable energy Reading Essentials Natural Resources 85

6 Mini Glossary biomass energy: energy produced by burning organic matter, such as wood, food scraps, and alcohol geothermal energy: thermal energy from Earth s interior solar energy: energy from the Sun wind farm: a group of wind turbines that produce electricity hydroelectric power: electricity produced by flowing water 1. Review the terms and their definitions in the Mini Glossary. Write a sentence discussing a disadvantage of solar energy. 2. Use what you have learned about renewable energy sources to complete the diagram. Source: the Sun s energy Source: biomass geothermal Source: What do you think Reread the statements at the beginning of the lesson. Fill in the After column with an A if you agree with the statement or a D if you disagree. Did you change your mind? Renewable Energy ConnectED Source: Log on to ConnectED.mcgraw-hill.com and access your textbook to find this lesson s resources. Sou rce: movement of rivers and tides END OF LESSON 86 Natural Resources Reading Essentials