ENERGY SOURCES. reflect

Transcription

1 reflect Imagine a car that could travel more than 200 miles using only one gallon of gas. Does this seem like a car of the future? Automakers are in the process of producing such an automobile. (In fact, a prototype model has been around since 2002.) This lightweight car would use much less gasoline than any cars currently on the road. Why is it important to consume fewer resources such as gasoline? Gasoline is a source of energy There are two main sources of energy. for cars. We get energy from many sources on Earth. Energy is the ability to do work. We use it to heat our homes, light our lamps, and power our cars and computers. We call these sources energy resources. Blowing air moves these windmills, or turbines. As the turbines move, they generate electricity. The supply of some energy resources is limited. Nature cannot make them as quickly as we use them. These are nonrenewable resources. Once a nonrenewable energy resource is used up, it is no longer available to us. The gasoline we use to power most cars is a nonrenewable resource. Nature makes other energy resources more quickly than we use them. Their supply is practically unlimited! These renewable resources include sunlight, wind, and water. Even on cloudy days, the Sun sends thousands of times more energy to Earth than humans use. As the Sun rises in the sky each day, the supply of solar power is renewed. Similarly, winds are continually blowing and water is continually flowing around the planet. We can use the energy from moving air and water to produce electricity to power our electric devices. Fossil fuels are nonrenewable. Humans get much of their energy by burning coal, oil, and natural gas. We call these energy resources fossil fuels because they are formed from plants and animals that died millions of years ago. Because fossil fuels take millions of years to form, they are nonrenewable energy resources. Eventually, we will use them all up. 1

2 Fossil fuels have many advantages. They are relatively inexpensive to obtain and use. They produce large amounts of energy when burned. They are nonrenewable, yet they are still plentiful. Scientists estimate there are still hundreds of billions of tons of coal and hundreds of billions of barrels of oil remaining on Earth. Fossil fuels also have many disadvantages. Because they are nonrenewable, we cannot rely on them indefi nitely. Some scientists estimate that within the next years, our supplies will run out. Burning fossil fuels also releases pollutants into the air. One of these pollutants is carbon dioxide, a gas that traps heat at Earth s surface. Scientists agree that adding carbon dioxide to Earth s atmosphere is a cause of global warming. It is also very difficult to remove some fossil fuels from Earth without damaging the environment from the mining and drilling that takes place. For example, as we move oil through pipes and on ships, it sometimes spills. Oil can also leak from our vehicles. These accidental spills can cause lots of damage to wildlife and the environment. So can improperly disposing of oil never dump oil down a drain! We burn fossil fuels at power plants. The energy released by the fuels as they burn is converted into electricity and sent to homes and other buildings. global warming: the increase in Earth s average temperature over time Nuclear power is a nonrenewable energy source. All matter is made up of tiny particles held together by forces called bonds. Humans can break these bonds to release large amounts of energy called nuclear power. One of the most important advantages of nuclear power is that it does not produce much air pollution or contribute to global warming. (Most of the gas released from a nuclear power plant is water vapor.) The fuel needed to produce nuclear power is relatively inexpensive, and it releases much more energy than fossil fuels. However, nuclear plants are expensive to build and maintain. Although they do not pollute the air, they produce large amounts of dangerous waste that is not easy to store or get rid of. Nuclear power is also nonrenewable we use up the fuel more quickly than nature can make it. Between 15 and 20% of the world s electricity is produced at nuclear power plants. 2

3 look out! Nuclear power plants are dangerous because they contain radioactive materials. When a substance is radioactive, its particles are breaking apart. These particles can damage nearby organisms. When some people think of nuclear energy, they remember terrible accidents that have happened at nuclear power plants. In 1986, a large nuclear power plant in Chernobyl, Ukraine, released dangerous materials into the surrounding environment. Many plants and animals including people died or were seriously injured. In 2011, an earthquake caused the release of dangerous materials at a nuclear plant in Fukushima, Japan. Nuclear power plants in the United States and other countries are regulated and inspected routinely. Still, the risk of terrible accidents causes some people to oppose nuclear energy. Renewable energy resources can replace nonrenewable ones. In the United States, we use many more nonrenewable energy resources than renewable ones. In the past few years, energy use from several renewable energy resources has greatly increased. Let s take a look at some of the most commonly used renewable energy resources. This solar panel collects and stores sunlight. The energy is then used to power this streetlight. Solar Power: Sunlight is probably the most important energy resource on Earth. It warms the planet and provides plants with the energy they need to make food. Humans can also use sunlight to heat buildings and power machines. Today, many scientists are working to find more and better uses for solar power. Unlike most energy sources, solar power does not produce air or water pollution. Although the Sun shines only part of the time, batteries allow us to store solar energy to use later. However, solar panels are expensive. The process of making them can produce harmful waste, and old solar panels can be diffi cult to safely dispose of. 3

4 Geothermal: The Sun is Earth s main source of energy. However, our planet also produces its own energy deep beneath the surface. We call this geothermal energy. (Geo- means Earth and thermal means heat. ) Geothermal energy is a clean energy source that produces little waste. Geothermal plants are relatively inexpensive to run, and they can generate power around the clock. However, the initial cost of building a geothermal plant is high, and they can exist only where lots of Earth s heat rises to the surface like near hot springs or geysers. Additionally, geothermal energy is not easy to transport. Some geothermal energy comes from warm water and rock near Earth s surface. Other energy comes farther down, from extremely hot, molten rock (magma). This dam on Lake Travis produces hydroelectric power in central Texas. Hydropower: Hydroelectric plants use the energy of flowing water as it moves downstream. (Hydro- means water. ) The water spins turbines to produce electricity. Dams are often built near hydroelectric plants. The dams control the fl ow of water the dams can be shut off if power is not needed. Hydropower is a clean energy source that does not pollute the environment. Yet, dams are expensive to build and maintain. They can cause fl ooding and disrupt the surrounding ecosystem by slowing or even stopping the flow of water in a river. In addition, power plants sometimes release heated water back into the ecosystem. Plants and animals living downstream of the dam may not be able to adapt to these changes. Wind: Like flowing water, blowing air can spin turbines to produce electricity. These energy resources convert the motion, or kinetic energy, of natural processes into electrical energy we can use. Also like hydropower, using wind energy does not produce pollution. However, wind turbines can be noisy and expensive to build. As they spin in the air, they can harm birds flying nearby. 4

5 Biomass: Biomass refers to living or recently living organisms we can use as energy resources. For example, corn plants are converted into a fuel called ethanol that can replace gasoline in cars. Biomass is a cheap resource that can be made from many common waste products. Unlike fossil fuels, biomass is renewable we can grow new plants quickly. However, burning biomass releases several harmful pollutants into the air. It also releases less energy than burning the same amount of fossil fuels. How can we manage our energy resources? We cannot rely on nonrenewable energy resources forever. It is important to fi nd ways to switch to renewable energy resources. Using more renewable resources is only part of a smart energy plan. In fact, a smart energy plan has at least three parts. Have you ever seen this symbol? It stands for Reduce, Reuse, and Recycle. To reduce our dependence on energy resources, we can use fewer of them for example, a person could walk or ride a bike instead of drive a car. When we reuse and recycle resources instead of throwing them away, we produce less waste. We also reduce our need for new energy resources. what do you think? How can you apply the ideas of Reduce, Reuse, and Recycle to your own life? Think of 3 5 ways you can change your behavior to use fewer energy resources. How can you encourage others in your community to conserve, or use fewer energy resources? Scientists in the Spotlight: Dr. Stephen Chu The goal of the United States Department of Energy is to focus on America s energy challenges for the present and the future. The current U.S. Secretary of Energy, Dr. Stephen Chu, helps carry out this goal. One of his main jobs is to lead the push to replace nonrenewable and polluting energy resources with renewable and clean energy resources. His other jobs include reducing America s dependence on oil from other countries and addressing the role of energy use on climate change. Dr. Chu was chosen for this position because of his scientifi c background. In 1997, Dr. Chu won the Nobel Prize in physics. He has taught physics at the University of California and Stanford University. He was also the director of alternative and renewable energy at the Lawrence Berkeley National Lab. 5

6 What do you know? Study the photographs of the energy resources below. Identify each energy resource as renewable or nonrenewable. Then, list two advantages and two disadvantages for each resource. Energy Source Solar Renewable/ Nonrenewable Advantages Disadvantages Biomass Coal Nuclear 6

7 connecting with your child Developing an Energy Plan To help your child learn more about energy sources, investigate different conservation practices available to manage your energy resources. First, evaluate your current use of energy resources: which renewable and nonrenewable energy resources do you use in different aspects of your life? Next, work with your child to create a plan for your home, school, or community to conserve energy resources and balance your use of renewable and nonrenewable resources. When developing your energy plan, identify how you can lower your dependence on fossil fuels and set reasonable goals. Encourage your child to develop a threestep plan consisting of a short-term goal, a medium-term goal, and a long-term goal. The short-term goal may include common energy saving methods such as reduce, reuse, and recycle. This may include turning off lights and appliances when not in use. Here are some questions to discuss with your child: What are ways that you can manage your energy usage? How can one person affect energy conservation in a community and in the world? What are ways that you can replace nonrenewable energy resources with renewable ones? Consider the different energy sources that you use: What are the advantages of each source? What are the disadvantages of each source? Your medium-term goals may be to create a plan for saving energy around the home for example, by replacing old appliances with energy-efficient ones. Long-term goals may apply to your whole community. For example, your child may begin by investigating the ways that your community uses energy. Then, your child may write a letter to your local government to articulate concerns and identify ways to conserve energy resources in the community. 7