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Learn about the formation, types, and usage of fossil fuels such as coal, oil, and natural gas. Discover the problems associated with their use and explore the potential of solar energy as a sustainable alternative.
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Energy Resources P. Lobosco
Fossil Fuels • Fossil fuels formed hundreds of millions of years ago from the remains of dead plants and animals. The dead plants and animals were buried under layers of sediments. Over millions of years het and pressure changed the sediments into rocks and the plant and animal remains into fossil fuels.
Main Fossil Fuels • The main fossil fuels are coal, oil and natural gas. • Fossil fuels are rich in hydrocarbons. • In the process of combustion or burning the hydrocarbons combine with oxygen and heat energy and light energy are released.
Problems with Fossil Fuel Use • Some deposits of coal and oil contain large amounts of sulfur which release large amount of pollutants when burned.
Coal • Coal is a solid fossil fuel. • There are four stages of coal development: peat, lignite, bituminous coal and anthracite.
Peat • Peat is a soft substance made of decayed plant fibers. When burned, it gives off a great deal of smoke but little heat energy.
Lignite • Pressure from the layers of rocks above it changes peat into lignite. Lignite is soft and has a woody texture. It is also low in heat energy.
Bituminous Coal • Added pressure turns lignite into bituminous coal. It is also soft coal found deep within the Earth. This is the most abundant type of coal.
Anthracite • Tremendous pressure turns bituminous coal into anthracite. It is extremely hard and brittle and almost pure carbon. Reserves are known deposits that can be developed. The major reserves of anthracite in the United States are located in Pennsylvania and the intersection of Nevada, Utah and Idaho.
Oil and Natural Gas • Liquid fossil fuel is called oil or petroleum. Oil is found in areas that were once covered by oceans. When plants and animals in the oceans died, they sank to the ocean floor and were covered by sediments. The layers changed into rocks such as limestone, sandstone and shale. Pressure from the rocks and bacteria changed the plant and animal remains into oil.
Crude Oil • Limestone and sandstone contain tiny pores. Oil droplets seeped through these pores and through cracks in the rock layers forming underground pools of oil known as crude oil. Most crude oil is obtained by drilling wells into underground deposits.
Other Oil Sources • Two sources near the surface are tar sands and oil shale. Tar sands are layers of sand soaked with thick petroleum. Oil shale is a gray rock containing a tar-like material.When oil shale is heated to a high temperature it releases hydrocarbon vapor that can be changed into crude oil.
Natural Gas • Natural gas is usually found associated with oil deposits. Because natural gas is less dense than oil, it rises above the oil. As a result, natural gas deposits are usually located above oil deposits. The most common natural gas is methane.
Uses of Fossil Fuels • Fossil fuels are the main sources of energy for industry, transportation and homes. Industry is the major consumer followed by transportation. Transportation relies o liquid fuels such as gasoline that are produced from crude oil.
Crude Oil Refining • Before crude oil can be used it must be refined or the impurities must be removed. Then the oil can be used to make heating oil, gasoline, kerosene, asphalt and petrochemicals. Some petrochemicals are used to make plastics, fabrics, medicines and building materials.
Natural Gas • Natural gas is less expensive and cleaner than oil or coal but the reserves are limited.
Fossil Fuel Shortages • Since 1900, the population of the United States has increased from 76 million to over 299 million in 2006. Energy use has increased 10 times. The United States with only 5% of the population uses more than 30% of the energy produced in the world. In one day humans can use an amount of oil that took 1000 years to form.
Energy from the Sun • Life on Earth would not be possible without energy from the sun. To be useful, solar energy must be collected, converted and stored. Solar energy is received in the form of light. It must be converted into other forms of energy, such as heat and electricity before it can be used. It must also be stored for use when it is not shining.
Solar Energy • Solar energy is one the most resourceful sources of energy for the future. One of the reasons for this is that the total energy we receive each year from the sun is around 35,000 times the total energy used by man. However, about 1/3 of this energy is either absorbed by the outer atmosphere or reflected back into space (a proccess called albedo).
Passive Solar Heating • In a passive heating system, the windows of a building are positioned so that sunlight enters directly and heats the building. Shades covering the windows hold in the heat during the night. The problem is that when the sun is not shining, the source of heat is gone and a backup heating system is needed such as a wood stove.
Water • Passive solar heating can be used for water. Between 30 and 50% of the energy used in homes is used to heat water. Solar hot-water systems could save up to 50% of the energy cost of heating water. Solar hot-water systems can be used year round.
Active Solar Heating • An active solar heating system involves collecting the sun’s energy in a solar collector. A black surface absorbs energy from the sun and converts it into heat. The surface is covered with plastic or glass panels to trap the heat. Water is heated by pumping it through pipes on the surface. The heated water then flows though a storage tank. The heated water is pumped throughout the building for heat and hot water. The water returns to the solar collector to be reheated by the sun.
Solar Cells • Solar Cells are called photovoltaic cells. They convert sunlight directly into electricity. Solar cells are used in calculators. A solar cell is made of extremely thin layers of silicon. When sunlight strikes the surface, electrons flow across the layers. This flow of elections is an electric current. Each solar cell produces 1 watt of electricity.
Use of Solar Cells • Solar cells were first used on a large scale in 1958 to generate electricity abroad the Vanguard 1. Almost every area of the United States has sufficient resources for PV systems. A 90 square mile system could produce enough electricity to meet the country’s peak demand.
Power Towers • An array of mirrors can be used to focus sunlight onto a boiler mounted on a tower. The sun’s heat converts water in the boiler into steam, which drives a turbine to generate electricity. The first solar plant was called Solar One.
Problems with PV Systems • Producing PV systems produces some toxic chemicals and small quantities of hazardous wastes. • The major drawback for solar cell use in homes, school and factories has been their cost compared to fossil fuels.
Wind and Water • Throughout history people have used the energy of wind and water. Wind energy has been used to propel sailing ships, turn mill wheels, and pump water from wells. Water mills were once common along small streams and rivers. Today this energy is used to generate electricity.
Wind Energy • Winds are caused by the uneven heating of the Earth’s atmosphere by the sun. Wind energy is an indirect form of solar energy. Small windmills were built in the United States in the 1860’s. Early windmills were used to pump water out of the ground. Later they produced electricity.
Use of Wind Energy • Wind energy is one of the fastest growing energy sources in the United States, its capacity increased 25% from 1990 to 2003. It only increased 6% in 2004 due to the expiration of the Production Tax Credit.
Problems with Wind Energy • There are concerns about the visual impact, noise pollution and the death of birds. • The power is intermittent. Well-situated wind turbines can produce power about 65-80% of the time, although they often run at less than maximum capacity.
Water Energy • Water energy is also an indirect form of solar energy. Energy from the sun causes water to evaporate from lakes and oceans. This water vapor enters the atmosphere and condenses to form cloud. From clouds water falls back to the Earth. Runoff from rain or snow forms rivers which empty into the oceans and the cycle begins again.
Water Mills • In the late 1700’s, water mills in the United States provided energy for machine looms to make cloth or for turning millstones to grind grains. By the 1800’s most water mills had been replaced by steam engines. With the invention of the electric light, demand increased and water mills were used again.
Hydroelectric Power • The use of mechanical energy of running water to generate usable electricity is called hydroelectric power. Dams hold back millions of tons of water in reservoirs. Some of this water is drawn through pipes into the power plant where it flows through turbines. The rushing water turns the blades of the turbines and produces electricity.
Problems with Hydroelectric Power • The places where the large dams can be built is limited. Hydroelectric power plants can be harmful to the environment. Fish migration patterns may be altered. The reservoirs have also flooded surrounding lands. It can also lower oxygen levels in water.
Use of Hydroelectric Power • Only 2 percent of the dams in the United States produce electricity. According to the Department of Energy, by adding hydroelectric projects to those dams where it is financially and environmentally feasible, this country could increase its hydropower capacity by 17,000 MW.
Nuclear Energy • The heat and light of the sun are produced as a result of reactions taking place deep within the nuclei of atoms. Atoms are the basic building blocks of matter. The nucleus is the center of an atom made up of protons and neutrons. Nuclear energy is produced when the nucleus is split.
Nuclear Fission • In 1939, nuclear fission was discovered. Nuclear fission is the splitting of an atomic nucleus into two smaller nuclei, during which nuclear energy is released. The most common type of fission reaction is the splitting of a uranium-235 nucleus.
Uranium-235 • To split a uranium-235 nucleus, scientists must shoot a neutron into the nucleus. When it strikes a uranium-235 nucleus, the nucleus is split into two smaller nuclei. During this process, two or more neutrons are released from the uranium-235 nucleus. Energy is released as well.
Chain Reaction • Each neutron released during a fission reaction is capable of causing another fission reaction by splitting another uranium-235 nucleus. The neutrons released by each of these reactions can then split several more nuclei. This process in which the splitting of one nucleus causes the splitting of another is called a chain reaction.
Explosion • If a nuclear chain reaction is uncontrolled, the nuclear energy that is released will create a huge explosion. If the reaction is carefully controlled, the energy can be used.
Nuclear Power Plants • The energy released during nuclear fission is mostly in the form of hear energy. In a nuclear power plant, this heat energy is used to convert water into steam. The steam then passes through a turbine in an electric generator. The steam spins the blades of the turbine, which produces electricity.
Nuclear Reactors • Fission reactions in a nuclear power plant are produced and controlled in a nuclear reactor. The main parts of a nuclear reactor are the containment building and the reactor vessel, which contains the fuel rods and the control rods.
Reactor Vessel • The reactor vessel is the central part of a nuclear reactor. It is within the reactor vessel that nuclear fission takes place. To begin a fission reaction, nuclear fuel rods are placed in the reactor vessel. The most common nuclear fuel is uranium-235. When neutrons strike the fuel rods containing pellets of uranium-235, nuclear fission begins. It takes many rods.
Control Rods • In order for a fission reaction to produce useful energy, the overall speed of the reaction must be carefully controlled. To control the rate of the reaction, neutron-absorbing control rods, often made of cadmium, are placed between the fuel rods to slow down the reaction. If removed, the reaction speeds up.
Use of Nuclear Power There are now some 440 commercial nuclear power reactors operating in 31 countries, They produce16% of the world's electricity, as base-load power, and their efficiency is increasing. • 56 countries operate a total of 284 research reactors reactors and a further 220 reactors power ships and submarines.
Safety of Nuclear Power • There is a possibility of nuclear radiation leaking into the environment. • There is the problem of how to dispose of radioactive nuclear waste. • There is the possibility of nuclear meltdown resulting from overheating due to loss of cooling water. • There is the problem of security.
Nuclear Fusion • Nuclear fusion is the combining of two atomic nuclei to produce one larger nucleus, with the release of nuclear energy. Nuclear fusion produces far more energy per atom than nuclear fission. Nuclear fusion is the reaction that produces the energy given off by the stars.
Sun • The sun is composed mainly of hydrogen. Within the sun, enormous heat and pressure cause the nuclei of hydrogen atoms to combine or fuse into helium nuclei. During this fusion process, some of the mass of the hydrogen is converted into energy.
Power from Nuclear Fusion • To be able to generate useful energy from nuclear fusion, scientists must be able to produce controlled fusion reactions. There are problems involved in producing and sustaining the extremely high temperatures needed for fusion. If possible, it would inexpensive and less polluting than nuclear fission.
Alternative Energy Sources • Geothermal • Tidal • Wave • Ocean Thermal • Biomass • Hydrogen
