ARTICLE-A-DAY Energy 6 Articles Check articles you have read: Energy Basics 486 words Forms of Energy 534 words Laws of Energy 287 words Sources of Energy 232 words Nonrenewable Energy Sources 182 words Renewable Energy Sources 361 words Page 1 of 13 ReadWorks.org 2018 ReadWorks, Inc. All rights reserved.
SHOW_ Basics Basics T his text is taken fro m the U.S. y Info rmatio n Administratio n s Kids Pag e. NO_PAEnergy Energy is the ability to do work Energy comes in different forms: He at (the rmal) Light (radiant) Motion (kine tic) Ele ctrical Che mical Nuclear energy Gravitational People use energy for everything from making a jump shot to sending astronauts into space. There are two types of energy: Stored (potential) energy Working (kinetic) energy For example, the food a person eats contains chemical energy, and a person's body stores this energy until he or she uses it as kinetic energy during work or play. Energy sources can be categorized as renewable or nonrenewable When people use electricity in their homes, the electrical power was probably generated by burning coal, by a nucle ar re action, or by a hydroe le ctric plant on a rive r, to name just a fe w sources. Therefore, coal, nuclear, and hydro are called energy sources. When people fill up a gas tank, the source might be petroleum refined from crude oil or ethanol made by growing and proce ssing corn. Energy sources are divided into two groups: Page 2 of 13
Energy Basics Renewable (an energy source that can be easily replenished) Nonrenewable (an energy source that cannot be easily replenished) Renewable and nonrenewable energy sources can be used as primary energy sources to produce useful energy such as heat or used to produce secondary energy sources such as electricity. When people use electricity in their homes, the electrical power was probably generated from burning coal or natural gas, a nuclear reaction, or a hydroelectric plant on a river, to name a few possible energy sources. The gasoline people use to fuel their cars is made from crude oil (nonrenewable energy) and may contain a biofuel (renewable energy) like ethanol, which is made from processed corn. The chart below shows the energy sources used in the United States. Nonrenewable energy sources accounte d for about 90% of all e ne rg y use d. Biomass, which include s wood, biofue ls, and biomass waste, is the largest renewable energy source, and it accounted for about half of all renewable energy and about 5% of total U.S. energy consumption. Renewable energy There are five main renewable energy sources: Solar energy from the sun Geothermal energy from heat inside the earth Wind energy Biomass from plants Hydropowe r from flowing water Nonrenewable energy Most of the energy consumed in the United States is from nonrenewable energy sources: Page 3 of 13
Energy Basics Pe trole um products Hydrocarbon g as liquids Natural gas Coal Nuclear energy Crude oil, natural gas, and coal are called fossil fuels because they were formed over millions of years by the action of heat from the earth's core and pressure from rock and soil on the remains (or fossils) of de ad plants and cre ature s like microscopic diatoms. Most of the pe trole um products consume d in the Unite d State s are made from crude oil, but pe trole um liquids can also be made from natural g as and coal. Nuclear energy is produced from uranium, a nonrenewable energy source whose atoms are split (through a process called nuclear fission) to create heat and, eventually, electricity. Page 4 of 13
SHOW_ of Energy of Energy T his text is taken fro m the U.S. Energ y Info rmatio n Administratio n s Kids Pag e. NO_PAForms Energy forms are either potential or kinetic. Potential energy comes in forms that are stored including che mical, g ravitational, me chanical, and nucle ar. Kine tic e ne rg y forms are doing work like e le ctrical, he at, lig ht, motion, and sound. What is energy? Scientists define energy as the ability to do work. Modern civilization is possible because people have learned how to change energy from one form to another and then use it to do work. We use energy to move cars along roads and boats through water, to cook food on stoves, to make ice in freezers, and to light our homes. Forms of energy Many forms of energy exist, but they all fall into two basic categories: Potential energy Kinetic energy P otential energy Potential energy is stored energy and the energy of position. Kinetic energy Kinetic energy is the motion of waves, e le ctrons, atoms, mole cule s, substance s, and obje cts. Chemical energy is energy stored in the bonds of atoms and mole cule s. Batte rie s, biomass, petroleum, natural gas, and coal are examples of chemical energy. Chemical energy is Radiant energy is electromagnetic energy that travels in transverse waves. Radiant energy include s visible lig ht, x- rays, g amma rays, and radio wave s. Lig ht is one type of radiant energy. Sunshine is radiant energy, which provides the fuel and warmth that make life on earth possible. Thermal energy, or heat, is the energy that comes from the movement of atoms and Page 5 of 13
Forms of Energy converted to thermal energy when people burn wood in a fireplace or burn gasoline in a car's engine. Mechanical energy is energy stored in objects by tension. Compressed springs and stretched rubber bands are examples of stored mechanical energy. Nuclear energy is energy stored in the nucleus of an atom the energy that holds the nucleus together. Large amounts of energy can be released when the nuclei are combined or split apart. G ravitational energy is energy stored in an object's height. The higher and heavier the object, the more gravitational energy is stored. When a person rides a bicycle down a steep hill and picks up speed, the gravitational energy is converting to motion energy. Hydropower is another example of gravitational energy, where gravity forces water down through a hydroe le ctric turbine to produce e le ctricity. molecules in a substance. Heat increases with increases in the speed that these particles move. Geothermal energy is the thermal energy in the earth. Motion energy is energy stored in the movement of objects. The faster they move, the more energy is stored. It takes energy to get an object moving, and energy is released when an object slows down. Wind is an e xample of motion e ne rg y. A dramatic example of motion energy is a car crash a car comes to a total stop and releases all of its motion energy at once in an uncontrolled instant. Sound is the movement of energy through substance s in long itudinal (compre ssion/rare faction) wave s. Sound is produced when a force causes an object or substance to vibrate. The energy is transferred throug h the substance in a wave. Typically, the energy in sound is smaller than in other forms of energy. Electrical energy is delivered by tiny charged particle s calle d e le ctrons, typically moving through a wire. Lightning is an example of electrical energy in nature. Page 6 of 13
SHOW_ NO_PALaws of Energy of Energy T his text is taken fro m the U.S. Energ y Info rmatio n Administratio n s Kids Pag e. Energy is neither created nor destroyed To scie ntists, conservation of energy doe s not me an saving e ne rg y. Inste ad, the law of conse rvation of energy says that energy is neither created nor destroyed. When people use energy, it doesn't disappear. Energy changes from one form of energy into another form of energy. A car engine burns gasoline, converting the chemical energy in gasoline into mechanical energy. Solar photovoltaic cells change radiant energy into electrical energy. Energy changes form, but the total amount of energy in the universe stays the same. Scientists at the U.S. Department of Energy think they have discovered a mysterious new form of energy called "dark energy" that is actually causing the universe to grow! Source: National Energy Education Development Project (public domain) Converting one form of energy into another Energy efficiency is the amount of useful energy obtained from a system. A perfectly energy-efficient machine would convert all of the energy put into the machine to useful work. In reality, converting Page 7 of 13
Laws of Energy one form of energy into another form of energy always involves a conversion into useable (or useful energy) and unusable (or unuseful) forms of energy. Most energy transformations are not efficient. The human body is a good example. The human body is like a machine, and the fuel it requires is food. Food gives a person energy to move, breathe, and think. Howe ve r, the human body isn't ve ry e fficie nt at conve rting food into use ful work. The human body is less than 5% efficient most of the time. The rest of the energy is converted to heat, which may or may not be useful, depending on how cool or warm a person wants to be. You can really feel that heat when you exercise! Page 8 of 13
SHOW_ of Energy of Energy T his text is taken fro m the U.S. Energ y Info rmatio n Administratio n s Kids Pag e. NO_PASources We use many different energy sources to do work. Energy sources are classified as renewable or nonrenewable. Renewable and nonrenewable energy can be converted into secondary energy sources like electricity and hydrogen. Most of our energy is nonrenewable In the United States, most of our energy comes from nonrenewable energy sources. Coal, petroleum, natural gas, and uranium are examples of nonrenewable energy sources. Nonrenewable energy sources are used to make electricity, to heat our homes, to move our cars, and to manufacture products. These energy sources are called nonrenewable because their supplies are limited. Petroleum, for e xample, was forme d millions of ye ars ag o from the re mains of ancie nt se a plants and animals. Use of renewable energy is growing Page 9 of 13
Sources of Energy Renewable energy sources include biomass, geothermal energy, hydropower, solar energy, and wind energy. They are called renewable energy sources because they are naturally replenished regularly. Day after day, the sun shines, the wind blows, and rivers flow. Renewable energy sources are used for electricity generation, for heat generation, and for transportation fuels. How are secondary sources of energy different than primary energy sources? Electricity and hydrogen are different than other energy sources because they are secondary sources of energy. Secondary sources of energy energy carriers are used to store, move, and deliver energy in an easily useable form. Another energy source must be used to make secondary sources of energy like electricity and hydrogen. Page 10 of 13
SHOW_ NO_PA Nonrenewable Energy Sources Nonrenewable Energy Sources T his text is taken fro m the U.S. Energ y Info rmatio n Administratio n s Kids Pag e. Energy sources are of two types: nonrenewable and renewable. Energy sources are considered nonrenewable if they cannot be replenished (made again) in a short period of time. On the other hand, renewable energy sources such as solar and wind can be replenished naturally. Nonrenewable Basics The four major nonrenewable energy sources are Crude oil Natural gas Coal Uranium (nuclear energy) Nonrenewable energy sources come out of the ground as liquids, gases, and solids. We use crude oil to make liquid petroleum products such as gasoline, diesel fuel, and heating oil. Propane and other hydrocarbon g as liquids, such as butane and e thane, are found in natural g as and crude oil. All fossil fuels are nonrenewable, but not all nonrenewable energy sources are fossil fuels Coal, crude oil, and natural gas are all considered fossil fuels because they were formed from the burie d re mains of plants and animals that live d millions of ye ars ag o. Uranium ore, a solid, is mine d and conve rte d to a fue l use d at nucle ar powe r plants. Uranium is not a fossil fue l, but it is classifie d as a nonre ne wable fue l. Page 11 of 13
SHOW_ NO_PA Renewable Energy Sources Renewable Energy Sources T his text is taken fro m the U.S. Energ y Info rmatio n Administratio n s Kids Pag e. Re ne wable e ne rg y source s including biomass, hydropowe r, g e othe rmal, wind, and solar provide 8% of the energy used in the United States. Most renewable energy goes to producing electricity. What is renewable energy? Renewable energy sources can be replenished. There are five commonly used renewable energy sources: Biomass include s: Wood and wood waste Municipal solid waste Landfill gas and biogas Ethanol Biodiesel Hydropowe r Geothermal Wind Solar What role does renewable energy play in the United States? More than 150 years ago, wood supplied nearly 90% of the nation's energy needs. As more consumers began using coal, petroleum, and natural gas, the United States relied less on wood as an energy source. Today, the use of renewable energy sources is increasing, especially biofuels, solar, and wind. In 2015, about 10% of total U.S. energy consumption was from renewable energy sources (or about Page 12 of 13
Renewable Energy Sources 9.7 quadrillion British the rmal units (Btu) 1 quadrillion is the numbe r 1 followe d by 15 ze ros). More than half of U.S. re ne wable e ne rg y is use d for producing e le ctricity, and about 13% of U.S. e le ctricity generation was from renewable energy sources in 2015. Renewable energy plays an important role in re ducing greenhouse gas emissions. When renewable energy sources are used, the demand for fossil fuels is re duce d. Unlike fossil fue ls, nonbiomass renewable sources of energy (hydropower, geothermal, wind, and solar) do not dire ctly e mit greenhouse gases. The consumption of biofue ls and nonhydroelectric renewable energy sources more than doubled from 2000 to 2015, mainly because of state and federal government mandates and incentives for renewable energy. The U.S. Energy Information Administration (EIA) projects that the use of renewable energy in the United States will continue to grow through 2040. Why don't we use more renewable energy? In general, renewable energy is more expensive to produce and to use than fossil fuel energy. Favorable renewable resources are often located in remote areas, and it can be expensive to build power lines from the renewable energy sources to the cities that need the electricity. In addition, renewable sources are not always available: Clouds reduce electricity from solar power plants. D ays with low wind re duce e le ctricity from wind farms. Droughts reduce the water available for hydropower. Page 13 of 13