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Energy is the ability to do work. Some forms of energy can be seen and felt. Other forms are stored energy, waiting to do work. The forms of energy that can be seen and felt include light and heat. For example, you can see sunshine and feel its heat. When wood burns in a fireplace, its light can be seen and its heat felt. There is stored energy in the wood before it is burned, or in the food that people eat, waiting to be put to work. There is also stored energy in the rock at the top of a wall waiting to fall off, or the child's body at the top of the arc of a swing, pausing before coming back down. Stored energy also includes gas, coal and oil, all fuels made from fossilized plants that were growing millions of years ago. Energy is locked inside, waiting to be released when the fuel is burned. Then the energy can be put to work, heating our homes, lighting our lights and moving our cars. |
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Sustainable energy sources can produce power without wearing out the source. Sustainable sources are continually renewed. With power from the sun, including wind, water, living materials, like trash and farm waste, and from geothermal sources, the source of the power doesn't wear out. Power from fossil fuels, like oil, gas and coal, as well as nuclear power relies on resources that are being used up. These sources also produce various forms of pollution when they make power. In addition to using sustainable energy forms, people need to practice energy conservation, reducing waste and improving energy efficiency. This will decrease the impact of our energy use on the environment in order to have a future with a clean earth, and to have power when we truly need it. |
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About Energy Sources
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Biomass power is the process of making energy from plant and animal matter. Industrial wastes such as sugar cane stalks, sawdust, straw and organic material, as well as energy crops like sugar cane, corn and trees can be turned into fuel. The original material can be burned directly, gasified, biologically, or chemically converted to biogas or other fuels. Anaerobic bacteria digests the material, making biogas in the biological process. Chemical or biochemical conversions make methano, ethanol, or other fuels. Biomass energy is most economical when the power plant is near the organic source and when both the heat and energy produced are used. Many biomass plants use two or more different fuel sources to make power all year long when one waste product is not available. Energy made from biomass often makes less pollution than fossil fuel power. It is also a sustainable form of energy. |
Visit a Trash-to-Energy Plant
Learn about Biomass Energy
National Renewable Energy Laboratory 's (NREL) Biomass Resources |
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Fossil fuels include petroleum (oil), natural gas and coal. Fossil fuels are made from plants and animals that lived millions of years ago and died. That organic material was buried in layers of sediment. After it decayed, it was heated and compressed deep underground. The plant and animal matter changed into crude oil. Today oil companies drill for the crude oil and take it to refineries where it is changed into fuel oils, gas and many other products. The world's top 5 countries for oil production are Saudi Arabia, Russia, the United States, Iran and China. The top 5 oil states are Texas, Alaska, California, Louisiana and Oklahoma. Pollution from fossil fuels includes carbon dioxide, nitrous oxide and sulfur dioxide. Fossil fuels are a non-sustainable form of energy. |
Visit a Coal - Fired Power Station
Visit a Coal Mine
Visit a Coal Export Facility |
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Geothermal energy comes from the heat of the earth. Radioactive decay in the earth's crust and volcanoes make heat. Deep wells, up to 4500 meters deep, are drilled into hot dry rock, hot water or steam sources. The heat is then used directly, in heat pumps or as steam to drive turbines to make electricity. Geothermal energy is classified according to the temperature of the source rock. Low temperature is less than 90°C, while moderate temperature is between 90° and 150°C. High temperature sources, more than 150°C, are found near volcanoes. Some of the problems with geothermal energy include air pollution from radon gas, hydrogen sulfide, methane and ammonia. Mineral deposits also harm geothermal equipment. Geothermal sources are found all over the world and supply reliable, inexpensive power. Depending upon the source and methods, geothermal energy can be a sustainable form of energy. |
Learn about Geothermal Energy
National Renewable Energy Laboratory's (NREL) Geothermal Educational Resources |
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Hydrogen energy is made when hydrogen molecules combine with oxygen, producing water and heat in a chemical reaction. Hydrogen energy uses fuel cell technology. Fuel cells can be small enough to power a hand-held phone or large enough to supply electricity and hot water to a town. Fuel cells can also be mobile, powering vehicles. The fuels used vary from water, to fossil fuels or biofuels. Using solar power, water can be split into hydrogen and oxygen, a method called electrolysis. Other hydrogen-rich fuels, like natural gas, methanol, propane or gasoline, require "reformers" which extract the hydrogen from the fuel. Hydrogen energy made from water produces little pollution. Reformer-produced hydrogen energy does make some pollution, but less than in conventional power plants. Efficiency of hydrogen energy can be up to 80%, especially when the extra heat produced is also used. Hydrogen energy is a sustainable form of energy. |
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Hydropower uses the energy of falling water to make electricity or mechanical energy . As water falls a vertical distance (the "head"), the potential energy of that fall is released. Hydropower can be made at large dams or small weirs. It can even be produced in rivers using the natural flow of the water. The advantages of hydropower include low maintenance costs and no pollution. Building large dams to store water is costly, requiring considerations for flooding, siting and environmental factors. Hydropower installations can affect local wildlife, especially fish. Hydropower is a sustainable form of energy. |
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Learn about Hydropower |
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Nuclear energy is created from the fission, or splitting of uranium atoms. The most common fuel used is the uranium isotope known as uranium-235. This is made from uranium mined in the western United States, and then processed into 1" long pellets. Each pellet is equal in power to one ton of coal. In the reactor core of the nuclear plant, atoms of uranium are split, creating heat. This heat is collected by circulating water in the form of steam or pressurized water. The heat is then used to drive steam turbines. Up to 330,000 gallons of water a minute is used to carry the heat of the nuclear reaction. The wastes produced by nuclear energy are spent fuel, excess heat and the potential for radiation leaks. Used fuel rods are now stored at the nuclear plants, but may one day be stored in a facility like the proposed Yucca Mountain, Nevada repository for nuclear waste, now being discussed by the federal government. Nuclear energy is a non-sustainable form of energy.
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Visit the Surry Nuclear Power Station
Visit the National Atomic Museum
Visit the North America Nuclear Plant |
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Solar power uses the sun's rays to produce electricity and heat. Using photovoltaics, electricity is made directly from the sun's rays, while in Solar Thermal power the heat of the rays is used. Photovoltaics currently relies on three technologies. Monocrystalline and polycrystalline cells are silicon-based. Thin-film cells use semi-conductor materials. Photovoltaic cells in modules are connected to make arrays. More modules are added to increase the total electricity made. Batteries are used for storage of electricity when the sun's rays are absent. Solar power from photovoltaics has a high initial cost, but low running costs and a long life. With improving technology, the cost of solar power is decreasing. Solar Thermal power uses solar rays to produce heat. In high-temperature systems, mirrors concentrate rays, producing temperatures from 350° C to more than 1000° C. These high temperatures produce steam that is used to drive turbines or make hydrogen for fuel. Low temperature systems are used for space heating, hot water production, desalination , cooking and food processing. Solar energy makes no pollution and is a sustainable form of energy. |
Learn about Solar Energy
National Renewable Energy Laboratory's (NREL) Solar Resources |
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Wind power makes electrical or mechanical power. Wind moves two or three blades mounted on tall towers to drive turbines that create electricity. Each turbine can produce 600-1000 kW (1 megawatt) of electricity, enough to supply 600-1000 homes. Grouped together, several turbines form a wind farm. New technology has improved power output of turbines up to 2.5 MW. Variable speed turbines increase equipment life. Turbines can be placed offshore to take advantage of ocean winds and to reduce environmental impact. Offshore energy can then be stored in batteries or used to make hydrogen. Wind power creates no pollution and is a sustainable form of energy.
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Learn about Wind Power
National Renewable Energy Laboratory's (NREL) Wind Resources |
Links to Education
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