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Coal

Coal

Coal is a naturally occurring combustible material consisting primarily of the element carbon. It also contains low percentages of solid, liquid, and gaseous hydrocarbons and/or other materials, such as compounds of nitrogen and sulfur. Coal is usually classified into subgroups known as anthracite, bituminous, lignite, and peat. The physical, chemical, and other properties of coal vary considerably from sample to sample.

Origins of coal

Coal is often referred to as a fossil fuel. That name comes from the way in which coal was originally formed. When plants and animals die, they normally decay and are converted to carbon dioxide, water, and other products that disappear into the environment. Other than a few bones, little remains of the dead organism.

At some periods in Earth's history, however, conditions existed that made other forms of decay possible. The bodies of dead plants and animals underwent only partial decay. The products remaining from this partial decay are coal, oil, and natural gasthe so-called fossil fuels.

Words to Know

Anthracite: Hard coal; a form of coal with high heat content and a high concentration of pure carbon.

Bituminous: Soft coal; a form of coal with less heat content and pure carbon content than anthracite, but more than lignite.

British thermal unit (Btu): A unit for measuring heat content in the British measuring system.

Coke: A synthetic fuel formed by the heating of soft coal in the absence of air.

Combustion: The process of burning; a form of oxidation (reacting with oxygen) that occurs so rapidly that noticeable heat and light are produced.

Gasification: Any process by which solid coal is converted to a gaseous fuel.

Lignite: Brown coal; a form of coal with less heat content and pure carbon content than either anthracite or bituminous coal.

Liquefaction: Any process by which solid coal is converted to a liquid fuel.

Oxide: An inorganic compound whose only negative part is the element oxygen.

Peat: A primitive form of coal with less heat content and pure carbon content than any form of coal.

Strip mining: A method for removing coal from seams located near Earth's surface.

To imagine how such changes may have occurred, consider the following possibility. A plant dies in a swampy area and is quickly covered with water, silt, sand, and other sediments. These materials prevent the plant debris from reacting with oxygen in the air and decomposing to carbon dioxide and watera process that would occur under normal circumstances. Instead, anaerobic (pronounced an-nuh-ROBE-ik) bacteria (bacteria that do not require oxygen to live) attack the plant debris and convert it to simpler forms: primarily pure carbon and simple compounds of carbon and hydrogen (hydrocarbons).

The initial stage of the decay of a dead plant is a soft, woody material known as peat. In some parts of the world, peat is still collected from boggy areas and used as a fuel. It is not a good fuel, however, as it burns poorly and produces a great deal of smoke.

If peat is allowed to remain in the ground for long periods of time, it eventually becomes compacted. Layers of sediment, known as over-burden, collect above it. The additional pressure and heat of the overburden gradually converts peat into another form of coal known as lignite or brown coal. Continued compaction by overburden then converts lignite into bituminous (or soft) coal and finally, into anthracite (or hard) coal.

Coal has been formed at many times in the past, but most abundantly during the Carboniferous Age (about 300 million years ago) and again during the Upper Cretaceous Age (about 100 million years ago).

Today, coal formed by these processes is often found layered between other layers of sedimentary rock. Sedimentary rock is formed when sand, silt, clay, and similar materials are packed together under heavy pressure. In some cases, the coal layers may lie at or very near Earth's surface. In other cases, they may be buried thousands of feet underground. Coal seams usually range from no more than 3 to 200 feet (1 to 60 meters) in thickness. The location and configuration of a coal seam determines the method by which the coal will be mined.

Composition of coal

Coal is classified according to its heating value and according to the percentage of carbon it contains. For example, anthracite contains the highest proportion of pure carbon (about 86 to 98 percent) and has the highest heat value (13,500 to 15,600 Btu/lb; British thermal units per pound) of all forms of coal. Bituminous coal generally has lower concentrations of pure carbon (from 46 to 86 percent) and lower heat values (8,300 to 15,600 Btu/lb). Bituminous coals are often subdivided on the basis of their heat value, being classified as low, medium, and high volatile bituminous and subbituminous. Lignite, the poorest of the true coals in terms of heat value (5,500 to 8,300 Btu/lb), generally contains about 46 to 60 percent pure carbon. All forms of coal also contain other elements present in living organisms, such as sulfur and nitrogen, that are very low in absolute numbers but that have important environmental consequences when coals are used as fuels.

Properties and reactions

By far the most important property of coal is that it burns. When the pure carbon and hydrocarbons found in coal burn completely, only two products are formed, carbon dioxide and water. During this chemical reaction, a relatively large amount of heat energy is released. For this reason, coal has long been used by humans as a source of energy for heating homes and other buildings, running ships and trains, and in many industrial processes.

Environmental problems associated with burning coal. The complete combustion of carbon and hydrocarbons described above rarely occurs in nature. If the temperature is not high enough or sufficient oxygen is not provided to the fuel, combustion of these materials is usually incomplete. During the incomplete combustion of carbon and hydrocarbons, other products besides carbon dioxide and water are formed. These products include carbon monoxide, hydrogen, and other forms of pure carbon, such as soot.

During the combustion of coal, minor constituents are also oxidized (meaning they burn). Sulfur is converted to sulfur dioxide and sulfur trioxide, and nitrogen compounds are converted to nitrogen oxides. The incomplete combustion of coal and the combustion of these minor constituents results in a number of environmental problems. For example, soot formed during incomplete combustion may settle out of the air and deposit an unattractive coating on homes, cars, buildings, and other structures. Carbon monoxide formed during incomplete combustion is a toxic gas and may cause illness or death in humans and other animals. Oxides of sulfur and nitrogen react with water vapor in the atmosphere and then settle out in the air as acid rain. (Acid rain is thought to be responsible for the destruction of certain forms of plant and animalespecially fishlife.)

In addition to these compounds, coal often contains a small percentage of mineral matter: quartz, calcite, or perhaps clay minerals. These components do not burn readily and so become part of the ash formed during combustion. This ash then either escapes into the atmosphere or is left in the combustion vessel and must be discarded. Sometimes coal ash also contains significant amounts of lead, barium, arsenic, or other elements. Whether airborne or in bulk, coal ash can therefore be a serious environmental hazard.

Coal mining

Coal is extracted from Earth using one of two major methods: sub-surface or surface (strip) mining. Subsurface mining is used when seams of coal are located at significant depths below Earth's surface. The first step in subsurface mining is to dig vertical tunnels into the earth until the coal seam is reached. Horizontal tunnels are then constructed off the vertical tunnel. In many cases, the preferred way of mining coal by this method is called room-and-pillar mining. In room-and-pillar mining, vertical columns of coal (the pillars) are left in place as the coal around them is removed. The pillars hold up the ceiling of the seam, preventing it from collapsing on miners working around them. After the mine has been abandoned, however, those pillars may collapse, bringing down the ceiling of the seam and causing the collapse of land above the old mine.

Surface mining can be used when a coal seam is close enough to Earth's surface to allow the overburden to be removed easily and inexpensively. In such cases, the first step is to strip off all of the overburden in order to reach the coal itself. The coal is then scraped out by huge power shovels, some capable of removing up to 100 cubic meters at a time. Strip mining is a far safer form of coal mining for coal workers, but it presents a number of environmental problems. In most instances, an area that has been strip-mined is terribly scarred. Restoring the area to its

original state can be a long and expensive procedure. In addition, any water that comes in contact with the exposed coal or overburden may become polluted and require treatment.

Resources

Coal is regarded as a nonrenewable resource, meaning it is not replaced easily or readily. Once a nonrenewable resource has been used up, it is gone for a very long time into the future, if not forever. Coal fits that description, since it was formed many millions of years ago but is not being formed in significant amounts any longer. Therefore, the amount of coal that now exists below Earth's surface is, for all practical purposes, all the coal available for the foreseeable future. When this supply of coal is used up, humans will find it necessary to find some other substitute to meet their energy needs.

Large supplies of coal are known to exist (proven reserves) or thought to be available (estimated resources) in North America, Russia and other parts of the former Soviet Union, and parts of Asia, especially China and India. China produces the largest amount of coal each year, about 22 percent of the world's total, with the United States (19 percent), the former members of the Soviet Union (16 percent), Germany (10 percent), and Poland (5 percent) following.

China is also thought to have the world's largest estimated resources of coal, as much as 46 percent of all that exists. In the United States, the largest coal-producing states are Montana, North Dakota, Wyoming, Alaska, Illinois, and Colorado.

Uses

For many centuries, coal was burned in small stoves to produce heat in homes and factories. As the use of natural gas became widespread in the latter part of the twentieth century, coal oil and coal gas quickly became unpopular since they were somewhat smoky and foul smelling. Today, the most important use of coal, both directly and indirectly, is still as a fuel, but the largest single consumer of coal for this purpose is the electrical power industry.

The combustion of coal in power-generating plants is used to make steam, which, in turn, operates turbines and generators. For a period of more than 40 years beginning in 1940, the amount of coal used in the United States for this purpose doubled in every decade. Although coal is no longer widely used to heat homes and buildings, it is still used in industries such as paper production, cement and ceramic manufacture, iron and steel production, and chemical manufacture for heating and for steam generation.

Another use for coal is in the manufacture of coke. Coke is nearly pure carbon produced when soft coal is heated in the absence of air. In most cases, 1 ton of coal will produce 0.7 ton of coke in this process. Coke is valuable in industry because it has a heat value higher than any form of natural coal. It is widely used in steelmaking and in certain chemical processes.

Conversion of coal

A number of processes have been developed by which solid coal can be converted to a liquid or gaseous form for use as a fuel. Conversion has a number of advantages. In a liquid or gaseous form, the fuel may be easier to transport. Also, the conversion process removes a number of impurities from the original coal (such as sulfur) that have environmental disadvantages.

One of these conversion methods is known as gasification. In gasification, crushed coal is forced to react with steam and either air or pure oxygen. The coal is converted into a complex mixture of gaseous hydrocarbons with heat values ranging from 100 Btu to 1000 Btu. One day it may be possible to construct gasification systems within a coal mine, making it much easier to remove the coal (in a gaseous form) from its original seam.

In the process of liquefaction, solid coal is converted to a petroleum-like liquid that can be used as a fuel for motor vehicles and other applications. On the one hand, both liquefaction and gasification are attractive technologies in the United States because of its very large coal resources. On the other hand, the wide availability of raw coal means that expensive new technologies have been unable to compete economically with the natural product.

[See also Carbon family; Petroleum; Pollution ]

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Coal

Coal


Coal, a naturally occurring combustible solid, is one of the world's most important and abundant energy sources. From its introduction 4,000 years ago as a fuel for heating and cooking, to its nineteenth- and twentieth-century use in generating electricity and as a chemical feedstock , coal, along with oil and natural gas, has remained an important source of energy. The United States alone has 1.7 trillion short tons of identified coal resources (natural deposits) and enough recoverable reserves (coal that can be developed for use) to meet its energy needs until the year 2225. Its demonstrated reserves include 274 billion short tons that existing technology can recover, representing 25 percent of the world's 1.08 trillion short tons of recoverable coal, and 508 billion short tons of coal that existing technology can potentially mine economically. Its recoverable reserves contain more than twice the energy of the Middle East's proven oil reserves. About 100 countries have recoverable reserves; 12 countriesamong them Canada, the People's Republic of China, Russia, Poland, Australia, Great Britain, South Africa, Germany, India, Brazil, and Colombiapossess the largest reserves.

Origin, Composition, and Structure of Coal

Geologists believe that underground coal deposits formed about 250300 million years ago, when much of Earth was swamp covered with thick forest and plant growth. As the plants and trees died, they sank under Earth's wet surface, where insufficient oxygen slowed their decay and led to the formation of peat. New forests and plant life replaced the dead vegetation, and when the new forests and plants died, they also sank into the swampy ground. With the passage of time and accompanying heat buildup, underground layers

of dead vegetation began to accumulate, becoming tightly packed and compressed, and gave rise to different kinds of coal, each with a different carbon concentration: anthracite, bituminous coal, subbituminous coal, and lignite. The English geologist William Hutton (17981860) reached this conclusion in 1833 when he found through microscopic examination that all varieties of coal contained plant cells and were of vegetable origin, differing only in the vegetation composing them. Because of its origin in ancient living matter, coal, like oil and gas, is known as a fossil fuel. It occurs in seams or veins in sedimentary rocks; formations vary in thickness, with those in underground mines 0.72.4 meters (2.58 feet) thick and those in surface mines, as in the western United States, sometimes 30.5 meters (100 feet) thick.

Until the twentieth century chemists knew very little about the composition and molecular structure of the different kinds of coal, and as late as the 1920s they still believed that coal consisted of carbon mixed with hydrogen-containing impurities. Their two methods of analyzing or separating coal into its components, destructive distillation (heating out of contact with air) and solvent extraction (reacting with different organic solvents such as tetralin), showed only that coal contained significant carbon, and smaller percentages of the elements hydrogen, oxygen, nitrogen, and sulfur. Inorganic compounds such as aluminum and silicon oxides constitute the ash. Distillation produced tar, water, and gases. Hydrogen was the chief component of the gases liberated, although ammonia, carbon monoxide and dioxide gases, benzene and other hydrocarbon vapors were present. (The composition of a bituminous coal by percentage is roughly: carbon [C], 7590; hydrogen [H], 4.55.5; nitrogen [N], 11.5; sulfur [S], 12; oxygen[O], 520; ash, 210; and moisture, 110.) Beginning in 1910, research teams under the direction of Richard Wheeler at the Imperial College of Science and Technology in London, Friedrich Bergius (18841949) in Mannheim, and Franz Fischer (18771938) in Mülheim made important contributions that indicated the presence of benzenoid (benzenelike) compounds in coal. But confirmation of coal's benzenoid structure came only in 1925, as a result of the coal extraction and oxidation studies of William Bone (18901938) and his research team at Imperial College. The benzene tri-, tetra-, and other higher carboxylic acids they obtained as oxidation products indicated a preponderance of aromatic structures with three-, four-, and five-fused benzene rings, and other structures with a single benzene ring. The simplest structures consisted of eight or ten carbon atoms, the fused-ring structures contained fifteen or twenty carbon atoms.

Classification and Uses of Coal

European and American researchers in the nineteenth and early twentieth centuries proposed several coal classification systems. The earliest, published in Paris in 1837 by Henri-Victor Regnault (18101878), classifies types of coal according to their proximate analysis (determination of component substances, by percentage), that is, by their percentages of moisture, combustible matter, fixed carbon, and ash. It is still favored, in modified form, by many American coal scientists. Another widely adopted system, introduced in 1919 by the British scientist Marie Stopes (18801958), classifies types of coal according to their macroscopic constituents: clarain (ordinary bright coal), vitrain (glossy black coal), durain (dull rough coal), and fusain, also called mineral charcoal (soft powdery coal). Still another system is based on ultimate analysis (determination of component chemical elements, by percentage), classifying types of coal according to their percentages of fixed carbon, hydrogen, oxygen, and nitrogen, exclusive of dry ash and sulfur. (Regnault had also introduced ultimate analysis in his 1837 paper.) The British coal scientist Clarence A. Seyler developed this system in 18991900 and greatly expanded it to include large numbers of British and European coals. Finally, in 1929, with no universal classification system, a group of sixty American and Canadian coal scientists working under guidelines established by the American Standards Association (ASA) and the American Society for Testing Materials (ASTM) developed a classification that became the standard in 1936. It has remained unrevised since 1938.

The ASAASTM system established four coal classes or ranksanthracite, bituminous, subbituminous, and lignitebased on fixed-carbon content and heating value measured in British thermal units per pound (Btu/lb). Anthracite, a hard black coal that burns with little flame and smoke, has the highest fixed-carbon content, 8698 percent, and a heating value of 13,50015,600 Btu/lb (equivalent to 14.216.5 million joules/lb [1 Btu=1,054.6 joules, the energy emitted by a burning wooden match]). It provides fuel for commercial and home heating, for electrical generation, and for the iron, steel, and other industries. Bituminous (low, medium, and high volatile ) coal, a soft coal that produces smoke and ash when burned, has a 4686 percent fixed-carbon content and a heating value of 11,00015,000 Btu/lb (11.615.8 million joules/lb). It is the most abundant economically recoverable coal globally and the main fuel burned in steam turbine-powered electric generating plants. Some bituminous coals, known as metallurgical or coking coals, have properties that make them suitable for conversion to coke used in steelmaking. Subbituminous coal has a 4660

percent fixed-carbon content and a heating value of 8,30013,000 Btu/lb (8.813.7 million joules/lb). The fourth class, lignite, a soft brownish-black coal, also has a 4660 percent fixed-carbon content, but the lowest heating value, 5,5008,300 Btu/lb (5.88.8 million joules/lb). Electrical generation is the main use of both classes. In addition to producing heat and generating electricity, coal is an important source of raw materials for manufacturing. Its destructive distillation (carbonization) produces hydrocarbon gases and coal tar, from which chemists have synthesized drugs, dyes, plastics, solvents, and numerous other organic chemicals. High pressure coal hydrogenation or liquefaction and the indirect liquefaction of coal using FischerTropsch syntheses are also potential sources of clean-burning liquid fuels and lubricants.

Environmental Concerns

The major disadvantage of using coal as a fuel or raw material is its potential to pollute the environment in both production and consumption. This is the reason why many coal-producing countries, such as the United States, have long had laws that regulate coal mining and set minimum standards for both surface and underground mining. Coal production requires mining in either surface (strip) or underground mines. Surface mining leaves pits upon coal removal, and to prevent soil erosion and an unsightly environment, operators must reclaim the land, that is, fill in the pits and replant the soil. Acid mine water is the environmental problem associated with underground mining. Water that seeps into the mines, sometimes flooding them, and atmospheric oxygen react with pyrite (iron sulfide) in the coal, producing acid mine water. When pumped out of the mine and into nearby rivers, streams, or lakes, the mine water acidifies them. Neutralizing the mine water with lime and allowing it to settle, thus reducing the presence of iron pyrite before its release, controls the acid drainage.

Coal combustion emits sulfur dioxide and nitrogen oxides, both of which cause acid rain . Several methods will remove or reduce the amount of sulfur present in many coals or prevent its release into the atmosphere. Washing the coal before combustion removes pyritic sulfur (sulfur combined with iron or other elements). Burning the coal in an advanced-design burner known as a fluidized bed combustor, in which limestone added to coal combines with sulfur in the combustion process, prevents sulfur dioxide from forming. Scrubbing the smoke released in the combustion removes the sulfur dioxide before it passes into the atmosphere. In a scrubber, spraying limestone and water into the smoke enables the limestone to absorb sulfur dioxide and remove it in the form of a wet sludge. Improved clean coal technologies inject dry limestone into the pipes leading from the plant's boiler and remove sulfur dioxide as a dry powder (CaSO3) rather than a wet sludge. Scrubbing does not remove nitrogen oxides, but coal washing and fluidized bed combustors that operate at a lower temperature than older plant boilers reduce the amount of nitrogen oxides produced and hence the amount emitted.

Clean coal technologies and coal-to-liquid conversion processes have led to cleaner burning coals and synthetic liquid fuels, but acid rain remains a serious problem despite society's recognition of its damaging effects since 1852. Global warming resulting from the emission of the greenhouse gases, carbon dioxide, methane, and chlorofluorocarbons , is another coal combustion problem that industry and government have largely ignored since 1896, but it can no longer be avoided without serious long-term consequences.

Conclusion

Coal remains the world's most abundant fossil fuel, and along with petroleum and natural gas, it will continue to provide most of the world's energy. But all three are finite resources, and society should consume them wisely, not wastefully, in order to extend their lifetimes and reduce their harmful emissions. The conservation of fossil fuels and the development of alternative energies, such as solar and wind power, are pathways to a global society's cleaner energy future.

see also Fossil Fuels; Global Warming; Steel.

Anthony N. Stranges

Bibliography

Lowry, H. H., ed. (1945). Chemistry of Coal Utilization, Vols. 1 and 2. New York: Wiley.

Lowry, H. H., ed. (1963). Chemistry of Coal Utilization, Supplementary Vol. New York: Wiley.

Internet Resources

Kentucky Coal Council. "Kentucky Coal Education." Available from <http://www.coaleducation.org>.

U.S. Department of Energy, Office of Fossil Energy. "Home Page." Available from <http://www3.fossil.energy.gov/>.

U.S. Geological Survey, Energy Resources Program. "National Coal Resources Assessment (NCRA)." Available from <http://energy.er.usgs.gov/NCRA/>.

World Coal Institute. "Home Page." Available from <http://www.wci-coal.com>.

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Coal

Coal


Coal is a brown-to-black combustible rock that originated from peat deposits in large swamp environments, through their burial to great depths and over a few hundred thousand to tens of millions of years. During burial peat is converted first into lignite, then subbituminous and bituminous coal, and, uncommonly, anthracite. Due to the loss of moisture during burial (peat has about 90 percent in its natural state, bituminous coal as little as 2 to 3 percent) and the chemical changes in the plant material that are induced by the rising temperature during burial to thousands of feet (increased carbon and decreased oxygen contents in particular), the heating value of coal increases significantly from peat to lignite and on to bituminous coal and anthracite.

The various environments that prevailed in the peat swamps (e.g., forests with large trees; marshes with sedges, grasses, and reeds) produced various kinds of peat and thus coal with significantly different properties. The major coal typesbanded, nonbanded, and impure coalare easily recognizable. Banded coals are most common. In subbituminous and bituminous coal the bands are composed of vitrain (shiny, glassy, brittle), clarain (bright luster, tough), durain (dull luster, hard), and fusain (charcoal-like, soft). Under the microscope, the so-called macerals become visible. Many of these clearly reveal their plant origin (e.g., sporinite, cutinite, resinite, alginite), whereas others have lost much or all of the plants' original cell structure (e.g., vitrinite, collinite, inertinite, semifusinite).


Coal Mining and Pollution

Coal is recovered from the ground either by underground or surface mining. Underground mining creates voids over many square miles. Two basically different methods are used: longwall and room-and-pillar mining. In longwall mining all coal is recovered from the mined panels; hence, subsidence occurs at the surface almost immediately and it is planned for. Room-and-pillar mining leaves about half of the coal in the ground as pillars to support the surface and prevent subsidence. However, subsidence may still occur because coal pillars or the floor strata under them fail, sometimes decades after mining (this sort of unplanned subsidence is a significant problem in major coal-producing states of the past). Subsidence causes damage to structures and interferes with the drainage of surface water; it may also impact aquifers. Coal left in the ground may catch fire, for example, through spontaneous combustion. Mine fires are difficult to control; some have burned for decades, even centuries. They can cause considerable local pollution, as well as other problems. Coal also always contains methane (CH4), most of which is released into the atmosphere during mining. On the average, the deeper a mine, the more methane it generates. Methane is a very potent greenhouse gas and contributes to global warming. Another significant environmental problem is related to underground mines that operated above the local drainage level. The mine workings collect and conduct water that oxidizes the ever-present pyrite (FeS2) in coal-bearing strata and causes acid mine drainage into the local drainage system. This is a common problem in the mountainous Appalachian coal fields where many old mines were operated at shallow depth above valley floors.

For surface mining, large machines are used to remove all rocks and/or soil above the coal bed or beds to gain access to it or them (usually at depths of less than 150 to two hundred feet). Any surface drainage and aquifers in the overburden will be severely impacted within the vicinity of the mine pit. Also, the fertility of agricultural land becomes a concern. Modern mining laws require the careful monitoring of groundwater at mines and the restoration of proper drainage and fertility to farmland, to its premining levels, through reclamation . Contaminated water (e.g., water containing suspended fine solids and/or dissolved minerals) may run off the open pit and must be treated before release into the local drainage system.

Modern mining laws seek to remedy or minimize the above-mentioned environmental and other problems related to the mining and cleaning of coal, as well as many other related concerns. See the table for a listing of the top producers of coal by state.

LEADING COAL-PRODUCING STATES OF THE UNITED STATES
rank state 2001 production
source: adapted from u.s. department of energy.
1 wyoming 365.6
2 west virginia 160.4
3 kentucky 132.6
4 pennsylvania 76.4
5 texas 45.0
6 montana 39.1
7 indiana 37.1
8 illinois 33.8
9 colorado 33.4
10 virginia 32.5
11 north dakota 30.5
12 new mexico 29.6
13 utah 27.0
14 ohio 25.3
15 alabama 19.2
16 arizona 13.4
  other states 20.4
  u.s.a. 1,121.3

Coal Cleaning and Pollution

Many mined coals, especially from eastern and Midwestern coal fields, contain significant mineral matter in their raw mined stateup to about half by weightand they are cleaned before sale. Preparation plants, capable of cleaning or processing several million tons of coal a year, generate large quantities of refuse that must be disposed of locally, safely, and in an environmentally sound manner. The materials rejected by a cleaning plant tend to be enriched in iron sulfides (FeS2: pyrite and marcasite) in particular; these oxidize easily into sulfates, causing the acidification of any water that percolates through and exits from refuse piles; acid water in turn tends to dissolve various other minerals, creating products that are potentially harmful to plants, animals, and humans. Cleaning plants always reject some coal, together with the incombustible material; spontaneous combustion can cause refuse piles to catch fire, which emit pollutants and are difficult to control.


Coal Utilization and Pollution

Coal, due to its origin from plants, is composed primarily of the "organic" elements carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulfur (S). Whenever coal is used, it eventually ends up being burned, either through direct combustion in boilers, for example, those in large electric utility power plants, or after conversion into intermediate products like coke . Of all the oxidation products of these elements, carbon dioxide (CO2) has become a major concern because it is a powerful greenhouse gas that accumulates in the atmosphere and is considered the primary cause of global warming. Sulfur and nitrogen oxides (SO2, NOx ), when released into the atmosphere from power plants, become a human health hazard and lead to the formation of acid rain downwind. This has been an important social and political issue for several decades, and various laws have been enacted that force power companies to limit the emission of sulfur and nitrogen oxides. All "new" (since 1970) electric power plants must remove most of the SO2 from their flue gas, using various types of scrubbers . A cost-effective way to control SO2 total emissions has been emissions trading, the federal government's decision to award a limited number of SO2 "pollution allowances" to utilities that they are permitted to trade; this allows industry to decide at which plants it is most cost-effective to add scrubbers. The 1970 Clean Air Act (CAA) exempted existing power plants from this requirement, assuming that they would be shut down in the near future. To close this loophole, the 1977 CAA amendments established the "new source review" process (NSR), which requires a careful review of any changes performed in "old" (pre-1970) plants to determine whether they represent "routine maintenance, repair, and replacement" or a significant upgrading in which the plant would become subject to the same rules as new plants. Over the years these reviews became highly controversial because of the gray area between "routine maintenance" and "significant upgrading." In response, after a multiyear review process, the U.S. Environmental Protection Agency (EPA) proposed revisions of the regulations in late 2002, intending to overcome these widely recognized problems, provide greater flexibility for power companies to improve old plants, lead to increases in energy efficiency, and decrease pollution. However, environmental and political groups have challenged the proposed new regulations. One proposal to resolve the controversy would be to abolish the NSR process entirely and expand the pollution allowances trading system to old power plants. By capping the number of allowances over time, total pollution could be further lowered.

Besides these major elements, coal always contains a large number of other elements in minor and trace amounts. Some of these are highly toxic, for instance, mercury (Hg), arsenic (As), cadmium (Cd), lead (Pb), selenium (Se), and uranium (U). Because coal is burned in such large quantities, primarily to generate electricity (nearly a billion tons in the United States alone!), even trace amounts add up to large quantities being released into the atmosphere. The 1990 Amendments to the Clean Air Act identify 189 hazardous air pollutants (HAPs), eighteen of which are associated with coal. Of particular concern are those elements that form volatile compounds during coal burning and are carried into the atmosphere with the flue gas. The 1990 amendments require the EPA to study the health effects of HAPs and develop appropriate regulations for their control.

Even cleaned coal still contains incombustible minerals (about 5 to 15 percent by weight) that are converted into ash when coal is burned at very high temperatures. Some ash particles are small and light enough to be carried up tall chimneys into the atmosphere with the flue gas (fly ash). Most power plants are required to remove fly ash from flue gas, using bag houses or electric precipitators. Both methods are highly efficient. However, tiny particles (PM-10 ) may still escape. Because of their potential harm to humans, they have been targeted for regulation in recent years. Coarsergrained ash remains at the bottom of boilers (bottom ash); it is removed and disposed of nearby. Fortunately, this material is rather inert and of limited environmental concern.

see also Acid Rain; Air Pollution; Carbon Dioxide; Electric Power; Emissions Trading; Fossil Fuels; Global Warming; Greenhouse Gases; Methane; NOx (Nitrogen Oxides); Particulates; Scrubbers.

Bibliography

ASTM. "Standard Classification of Coals by Rank," Standard D388. In Annual Book of ASTM Standards, Vol. 05.05. New York.

ASTM. "Standard Terminology Relating to Megascopic Description of Coal and Coal Seams and Microscopic Description and Analysis of Coal," Standard D2796. In Annual Book of ASTM Standards, Vol. 05.05. New York.


Internet Resources

U.S. Environmental Protection Agency. "Clean Air Act of 1970" and "1990 Amendments to the Clean Air Act." Available from http://www.epa.gov.

U.S. Office of Surface Mining. Public Law 95-87, "The Surface Mining Control and Reclamation Act of 1977 (SMCRA)." Available from http://www.osmre.gov/smcra.htm.

Heinz H. Damberger

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Coal

COAL

COAL is a major source of energy in the United States. It formed as the legacy of trees and plants that grew in primeval swamps and forests. For millions of years, the debris of these jungles accumulated in shallow water or in boggy soil, decayed, and was converted into peat bogs. The mountain-building era subjected these bogs to extreme pressures as well as to the internal heat of the earth. The combination of these factors transformed the peat into coal. Coal has the same chemical composition as diamonds and is sometimes referred to as "black diamonds."


The conversion of peat into coal is estimated by geologists to have taken hundreds of thousands of years.

Bituminous coal is the most abundant type of coal in the United States and the one most commonly used for power generation, heating, and industrial purposes. Nearly all eastern bituminous coals have "coking" properties. Coking is a heating process that breaks down coal, leaving the relatively pure carbon needed for metallurgy. Many western bituminous coals are noncoking, or "free burning." Bituminous coals used in the coking process are heated in a sealed oven. After the volatile liquids and gases have been driven off, the coke, a porous, dull-gray mass, remains. The by-products driven off during the carbonization process, consisting of gases, light oils, and tar, have many important uses in the chemical industry.

The only source for anthracite coal, which is a clean-burning coal with little volatile matter, is northeastern Pennsylvania, although history records small deposits in Rhode Island during the early nineteenth century. Anthracite production peaked during 1917, when 100 million tons were produced and nearly 150,000 miners toiled to reach that tonnage. Another peak was reached in 1944 when 64 million tons were produced with a workforce of 78,000 men. After that time, the consumption of anthracite coal declined; by 1973 only 6,000 men were employed in the industry. Similar statistics for the bituminous coal industry record the first peak in production in 1918, when 550 million tons were mined with a labor force of 615,000. The maximum production by the industry occurred in 1947, when 630 million tons were produced with a labor force of 420,000 miners. In 1974 approximately 590 million tons of coal were produced with a labor force of only 125,000 miners.

The coal-producing areas of the United States are divided into six large provinces: the Eastern province, the Interior province, the Gulf province, the Northern Plains province, the Rocky Mountain province, and the Pacific Coast province. Coal mining activity migrated west ward from its eighteenth-century beginnings in the Eastern province, and significant production was reported from the Interior province during the 1830s. By the late 1850s the Pacific Coast province was producing significant amounts of coal, as was the Gulf province in the late 1860s. The Rocky Mountain province began producing well into the mid-1870s and the Northern Plains province in the late 1870s.

The Eastern, or Appalachian, field, after its modest beginning as a small mine along the Monongahela River opposite Fort Pitt (now Pittsburgh, Pennsylvania), in 1760, became the most important source of bituminous coal for the nation. Beginning in western Pennsylvania, it extends southwesterly into Alabama and contains large mining operations in the states of Pennsylvania, Ohio, West Virginia, Kentucky, Tennessee, Virginia, and Alabama. Pennsylvania was for many years the largest producer of coal in the province, but after 1946 it was superseded by West Virginia. The Eastern province was responsible for approximately two-thirds of the total coal produced in the United States in the mid-1970s.

West of the Appalachian field is the Interior province, which is subdivided into eastern and western portions. The eastern portion includes deposits through most of Illinois, western Indiana, and western Kentucky; the western portion covers deposits in Iowa, Missouri, eastern Kansas, Oklahoma, and Arkansas. Two isolated fields included in the Interior province are in Texas and central Michigan.

The Eastern and Interior provinces have always furnished most of the coal produced in the United States and contain the largest reserves of coking coals. The coal-fields found in the other provinces contain the largest percentage of reserves on a tonnage basis but consist mainly of subbituminous coals and lignites. With lower-grade coals and locations remote from major consuming industries, they have not been extensively developed, although development is assured in the ever-pressing need for additional energy supplies.


Scientists evaluate a region's coal supply by measuring its reserves and resources. Reserves are the amount of coal that is commercially accessible and can be readily mined. Resources are the total amount of coal in a region, whether or not it is accessible. In 2002, the total U.S. estimated recoverable coal reserves was some 274 billion short tons, while U.S. coal production for 2001 was approximately 1.1 billion short tons. The U.S. Geological Survey estimated in 1997 that the identified resources of U.S. coal were some 1,731 billion short tons. With improved technological innovations and increased efficiency in mining methods, these reserves and resources could be greatly extended.

Coal is mined by two principal methods, underground and surface operations, and both practices are widely used in the United States. Coal seams within two hundred feet of the earth's surface are generally more adaptable to surface mining methods, although attention must also be paid to the content and thickness of the over-burden (rock and other material) on the coal seam and to the thickness of the seam. Strip mining is often used to mine surface coal. In this method, huge earth-moving machines strip away areas of vegetation, and explosives shatter sedimentary rock to access underlying coal deposits. Area and contour mining methods allow for strip mining of hilly areas, as machines move away landscape and slice large cuts into a hillside to access coal. Giant augers that bore into hillsides and throw out buried coal are also used on rough terrain. In the late 1990s, coal mining companies started using global positioning system (GPS) and satellite technology to track mines and machinery and increase their efficiency.

Mechanization of underground mining operations received its greatest impetus with the introduction of Joy loading machines in the early 1920s. Earlier attempts to introduce machinery to the industry proved unsuccessful except for the first successful undercutting machine, introduced in 1877. The introduction of rubber-tired haulage units in 1936 gave further impetus to mechanization, and during the late 1940s total mechanization of underground operations was becoming a reality. Mechanization of mining operations increased significantly after World War II, with a trend toward larger capacity machinery and the elimination of many laborious manual operations. Improved under ground machinery has led to continuous mining. U.S. coal production rose rapidly during the nineteenth century, from an annual production in 1800 of approximately 120,000 tons to approximately 265 million tons by 1900. The average output per man per day exceeded twenty tons, a significant increase over the five ton average prior to extensive mechanization.

The U.S. coal industry has been subjected to labor unrest, loss of important markets, and most importantly, has exposed workers to tremendous dangers. Under-ground coal miners were constantly exposed to dangerous gases such as explosive methane and poisonous carbon monoxide. After a mine explosion in the 1800s, miners took to releasing a canary into mine shafts to test for poisonous gases before entering. If the canary did not return, miners improved ventilation systems down the shaft. The coal dust produced in the blasts and hauling was also extremely flammable and harmful to miners' lungs. Prolonged inhalation of coal dusts produces pneumoconiosis, or black lung disease, as well as a number of other problems, such as heart disease, emphysema, and cancer. Mining protests and labor activism in the 1900s brought about much reform in mining conditions.

The environmental impact of recovering coal increased concern over mining methods during the late twentieth century. Strip mining destroys large areas of vegetation and habitat, leaving them exposed to erosion. The waste products of strip mining create acid drainage that combines with oxygen in water and air to create sulfuric acid, polluting water and contaminating soil. Burning coal produces greenhouse gases that trap heat in the earth's atmosphere and lead to global warming. Sulfur dioxide emissions combine with water and oxygen in air to form acid rain. Since the U.S. Clean Air Act passed in 1970, and was revised in 1990, industries that burn coal are required to reduce emissions of carbon dioxide and sulfur to safer levels. Coal mining companies are required to submit detailed reports of mining plans to ensure minimal destruction of the environment. In 1986 the U.S. government and private industry began working together through the Clean Coal Technology Program to find cleaner, more efficient methods of mining coal and using its energy.

BIBLIOGRAPHY

Blatz, Perry K. Democratic Miners: Work and Labor Relations in the Anthracite Coal Industry, 1875–1925. Albany: State University of New York Press, 1994.

Bowman, John R. Capitalist Collective Action: Competition, Cooperation, and Conflict in the Coal Industry. New York: Cambridge University Press, 1989.

Dix, Keith. What's a Coal Miner to Do?: The Mechanization of Coal Mining. Pittsburg, Pa.: University of Pittsburg Press, 1988.

Fishback, Price V. Soft Coal, Hard Choices: The Economic Welfare of Bituminous Coal Miners, 1890–1930. New York: Oxford University Press, 1992.

Seltzer, Curtis. Fire in the Hole: Miners and Managers in the American Coal Industry. Lexington: University Press of Kentucky, 1985.

J. H.Hoffman/h. s.

See alsoAir Pollution ; Anthracite Strike ; Appalachia ; Coal Mining and Organized Labor ; Conservation ; Energy Industry .

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Coal Chamber

Coal Chamber

Rock group

For the Record

Selected discography

Sources

A self-described spooky core group, Coal Chamber emerged from the Los Angeles music scene in the mid-1990s as part of a wave of gothic- and industrial-inspired metal bands. Although the band shared a love of confrontational lyrics and driving guitars with the grunge bands that dominated the musical landscape at the time, its members also reacted against the down-to-earth image of most Seattle-based groups with theatrical stage shows, costumes, and makeup. As vocalist Dez Fafara told Alternative Press in September of 1999, Were trying to forge ahead with a different kind of style, musically and looks-wise. If people are going to peg us as anything, were the crazy band that says, Be yourself.

Coal Chamber had its origins in 1994 with two Los Angeles musicians, singer Dez Fafara and guitarist Miguel Meegs Rascon, who met through a classified ad in a local newspaper. The roommate of Farfaras girlfriend, Rayna Foss, soon joined the band as a bassist, though she had only six months of experience playing the instrument. Every show that was considered rock music, we were there, Rascon told Guitar One about the bands early days. And eventually we started playing shows, we started hooking up with

For the Record

Members include Mikee Cox, drums; Dez Fafara (born B. Dez Fafara), vocals; Rayna Foss-Rose (born Rayna Foss), bass guitar; Meegs Rascon (born Miguel Rascon), guitar.

Formed in Los Angeles, CA, 1994; gained following on Los Angeles club circuit; released first album, Coal Chamber, 1997; toured on Ozzfest 98; released second album, Chamber Music, 1999.

Addresses: Record company Roadrunner Records, 902 Broadway, 8th Floor, New York, NY 10010; 9229 Sunset Blvd., Suite 705, Los Angeles, CA 90069, website: http://www.roadrun.com. Website Coal Chamber Official Website: http://www.coalchamber.com.

other bands, and before you know it, our shows start-edgetting packed, and we developed a following. After a year of paying its dues on the club circuit and promoting itself with flyers and demo tapes, the band had a promising deal with Roadrunner Records.

Despite the groups optimism, however, the initial run of Coal Chamber was short-lived; after Fafara married his girlfriend, he left the group and it appeared that the deal with Roadrunner Records would be lost. But in 1995, Fafara divorced his wife, rejoined the group, and regained the deal at Roadrunner. The final piece of the Coal Chamber lineup, drummer Mikee Cox, joined the band in 1997, when he was just 19 years old. As Cox later told Drums!, I went straight from high school to being on tour on a bus for two years.

The timing of the group was fortunate. After a heyday in the 1980s with bands such as Mötley Crüe and Poison, the Los Angeles metal scene was making a comeback in the mid-1990s. At a time when Seattle-based grunge ruled the airwaves and record-buyer consciousness was raised across the nation, Los Angeles concert crowds filled the metal clubs that lined the Sunset Strip. Coal Chamber quickly developed a friendly rivalry on the Strip with competing alternative metal band Korn. One of singer Fafaras fondest memories from the bands earliest days was playing a sold-out show at the Whiskey-A-Go-Go while Korn played a sold-out set at the Roxy in 1995. In an effort to differentiate themselves from the rest of the metal bands, however, Coal Chambers members concentrated on creating a distinct image for the band, with outrageous stage makeup, numerous tattoos and piercings, and gothic-oriented costumes. The fact that the band also included a female member on bass guitar helped it gain a unique profile among the new crop of Los Angeles metal bands.

Coal Chamber entered the studio to record its self-titled debut effort, which was released in February of 1997 to generally good reviews in the metal and mainstream press. In a three-star review, a Q magazine critic even anointed the band flag-bearers for the post-slacker, no-hoper generation. Without much radio or video play, however, the band focused on touring as a means to break through to new listeners. The group gained a new manager on one such tour, Ozzfest 98. When the tour began, Coal Chamber was a supporting act on the second stage. Sharon Osbourne, wife of headliner Ozzy Osbourne, decided that the group deserved a spot on the main stage and took on the act as its manager as well. The Osbournes served as informal mentors to the group, even inviting its members to their home in England to celebrate the singers birthday. Meanwhile, the band contributed two songs to soundtracks in 1998: Blisters appeared on the soundtrack to The Bride of Chucky, while Not Living appeared on the soundtrack for Strangeland.

While its debut did not make a significant impact on the sales charts, the large audiences of Ozzfest gave the band greater confidence in its abilities as well as higher aspirations for the music it wanted to make. In the 1999 Alternative Press article written about Coal Chambers second release, Chamber Music, Fafara said, We needed to make a huge departure from the hip-hop-metal thing, so we jumped off the cliff while the train was still moving and came up with a new sound. Were still heavy rock and roll, but I think were giving people a little more in terms of ear candy, something a little more tangible to listen to. In an interview with the MTV website, Rascon echoed the sentiment: I think we definitely created our own sound. This is like our defining album. Weve always wanted to stick to the darker side of music with these elements, and thats what we did with all the new sounds and keyboard sounds.

Fafara also polished his vocals for the groups sophomore effort, taking voice lessons to broaden his vocal range and adapt his style to a greater range of songs. I never became a vocalist before we made this album, he told Metal Edge. I went to a coach, and he helped me hit these lows and highs like never before. I had never gone into those waters in the past. Continuing to serve as the bands primary songwriter, Fafara also concentrated on writing lyrics that turned away from the nihilism of many metal bands. I like to think of myself as a storyteller, rather than a singer or songwriter, he told the magazine. I think that were a dark rock n roll band with a really positive message. One track that showed Fafaras direction on Chamber Music, Tylers Song, was written as a message to his young son to persevere against school bullies.

The effort to diversify its sound was welcomed by critics such as a Washington Post reviewer who noted the bands progress toward a more hospitable brand of musical pillage. A Los Angeles Times critic also approved of Chamber Musics move to thoughtful strains of optimism that muscle their way through the cuts grinding digs and lacerating rhythms, offering fans something more than a soundtrack for partying and destruction. The bands more significant breakthrough, however, came with a remake of the Peter Gabriel song Shock the Monkey with guest vocals by Osbourne. With attention from radio and video outlets for the song, Coal Chamber made further headway with a broader audience; it even gained a higher East Coast profile with a guest appearance on The Howard Stern Show with manager Sharon Osbourne. The troubled character of Mafia son Tony Soprano Jr. from the hit HBO show The Sopranos even sported a Coal Chamber sweatshirt as a sign of his teenage angst.

Married to Sevendust drummer Morgan Rose, Rayna Foss-Rose took a short break from touring in order to have a baby in 1999, making her the third of the bands members to become a parent. Fafara explained the impact of parenthood to the Los Angeles Times, saying, Everybody is bummed and angry. But I try to give them something else lyrically, to base their life around, other than just pure hate. We all grow up, we all learn to hate. You look into a childs eyes and you want to instill something positivesomething that can get them through that.

Hoping for a long career despite the volatility of the music business, Coal Chamber continued to tour almost nonstop and entered the studio for its third effort, Dark Days, planned for a spring 2002 release. As Fafara told Alternative Press in 1999, Two albums, three albums, four albums, thats nothing to me. I think were going to be the best band ever in five years.

Selected discography

Coal Chamber, Roadrunner, 1997.

(Contributor) The Bride of Chucky (soundtrack), BMG/Sanctuary, 1998.

(Contributor) Strangeland (soundtrack), TVT, 1998.

Chamber Music, Roadrunner, 1999.

Sources

Periodicals

Album Network, September 24, 1999.

Alternative Press, September 1999, pp. 6568.

Amusement Business, November 8, 1999, p. 6.

Drum!, September/October 1999, p. 39.

Guitar One, July 1999.

Guitar Player, March 2000, p. 47.

Guitar World, October 1999, pp. 3840.

Los Angeles Times, April 16, 2000, p. E1.

Maxim, July 2000.

Metal Edge, December 1999, p. 2829.

Q, May 1997.

Washington Post, September 17, 1999, N17.

Online

Coal Chamber, MTV.com, http://www.mtv.com/bands/az/coaLchamber/artist.jhtml (November 20, 2001).

Timothy Borden

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Coal

Coal

Coal is a naturally occurring combustible material consisting primarily of the element carbon , but with low percentages of solid, liquid, and gaseous hydrocarbons and other materials, such as compounds of nitrogen and sulfur. Coal is usually classified into the sub-groups known as anthracite, bituminous, lignite, and peat. The physical, chemical, and other properties of coal vary considerably from sample to sample.

Coal forms primarily from ancient plant material that accumulated in surface environments where the complete decay of organic matter was prevented. For example, a plant that died in a swampy area would quickly be covered with water , silt, sand , and other sediments. These materials prevented the plant debris from reacting with oxygen and decomposing to carbon dioxide and water, as would occur under normal circumstances. Instead, anaerobic bacteria (bacteria that do not require oxygen to live) attacked the plant debris and converted it to simpler forms: primarily pure carbon and simple compounds of carbon and hydrogen (hydrocarbons). Because of the way it is formed, coal (along with petroleum and natural gas ) is often referred to as a fossil fuel.

The initial stage of the decay of a dead plant is a soft, woody material known as peat. In some parts of the world, peat is still collected from boggy areas and used as a fuel. It is not a good fuel, however, as it burns poorly and with a great deal of smoke.

If peat is allowed to remain in the ground for long periods of time, it eventually becomes compacted as layers of sediment, known as overburden, collect above it. The additional pressure and heat of the overburden gradually converts peat into another form of coal known as lignite or brown coal. Continued compaction by overburden then converts lignite into bituminous (or soft) coal and finally, anthracite (or hard) coal. Coal has been formed at many times in the past, but most abundantly during the Carboniferous Age (about 300 million years ago) and again during the Upper Cretaceous Age (about 100 million years ago).

Today, coal formed by these processes is often found in layers between layers of sedimentary rock . In some cases, the coal layers may lie at or very near the earth's surface. In other cases, they may be buried thousands of feet or meters under ground. Coal seams range from no more than 3197 ft (160 m) or more in thickness. The location and configuration of a coal seam determines the method by which the coal will be mined.

Coal is classified according to its heating value and according to its relative content of elemental carbon. For example, anthracite contains the highest proportion of pure carbon (about 86%98%), and has the highest heat value (13,50015,600 Btu/lb [British thermal units per pound]) of all forms of coal. Bituminous coal generally has lower concentrations of pure carbon (from 46%86%) and lower heat values (8,30015,600 Btu/lb). Bituminous coals are often sub-divided on the basis of their heat value, and are classified as low, medium, and high volatile bituminous and sub-bituminous. Lignite, the poorest of the true coals in terms of heat value (5,5008,300 Btu/lb) generally contains about 46%60% pure carbon. All forms of coal also contain other elements present in living organisms, such as sulfur and nitrogen, that are very low in absolute numbers, but that have important environmental consequences when coals are used as fuels .

By far the most important property of coal is that it combusts. When the pure carbon and hydrocarbons found in coal burn completely, only two products are formed, carbon dioxide and water. During this chemical reaction, a relatively large amount of energy is released. The release of heat when coal is burned explains the fact that the material has long been used by humans as a source of energy, for the heating of homes and other buildings, to run ships and trains, and in many industrial processes.

The complete combustion of carbon and hydrocarbons described above rarely occurs in nature. If the temperature is not high enough or sufficient oxygen is not provided to the fuel, combustion of these materials is usually incomplete. During the incomplete combustion of carbon and hydrocarbons, other products besides carbon dioxide and water are formed, primarily carbon monoxide, hydrogen, and other forms of pure carbon, such as soot.

During the combustion of coal, minor constituents are also oxidized. Sulfur is converted to sulfur dioxide and sulfur trioxide, and nitrogen compounds are converted to nitrogen oxides. The incomplete combustion of coal and the combustion of these minor constituents result in a number of environmental problems. For example, soot formed during incomplete combustion may settle out of the air and deposit an unattractive coating on homes, cars, buildings, and other structures. Carbon monoxide formed during incomplete combustion is a toxic gas and may cause illness or death in humans and other animals. Oxides of sulfur and nitrogen react with water vapor in the atmosphere and then are precipitated out as acid rain . Acid rain is thought to be responsible for the destruction of certain forms of plant and animal (especially fish) life.

In addition to these compounds, coal often contains a few percent of mineral matter: quartz , calcite, or perhaps clay minerals . These do not readily combust and so become parts of the ash. The ash then either escapes into the atmosphere or is left in the combustion vessel and must be discarded. Sometimes coal ash also contains significant amounts of lead , barium, arsenic, or other compounds. Whether air borne or in bulk, coal ash can therefore be a serious environmental hazard.

Coal is extracted using one of two major techniques, sub-surface or surface (strip) mining. The former method is used when seams of coal are located at significant depths below Earth's surface. The first step in sub-surface mining is to dig vertical tunnels into the earth until the coal seam is reached. Horizontal tunnels are then constructed laterally off the vertical tunnel. In many cases, the preferred method of mining coal by this method is called room-and-pillar mining. In this method, vertical columns of coal (the pillars) are left in place as coal around them is removed. The pillars hold up the ceiling of the seam, preventing it from collapsing on miners working around them. After the mine has been abandoned, however, those pillars may often collapse, bringing down the ceiling of the seam and causing subsidence in land above the old mine.

Surface mining can be used when a coal seam is close enough to the earth's surface to allow the overburden to be removed economically. In such a case, the first step is to strip off all of the overburden in order to reach the coal itself. The coal is then scraped out by huge power shovels, some capable of removing up to 100 cubic meters at a time. Strip mining is a far safer form of coal mining, but it presents a number of environmental problems. In most instances, an area that has been strip-mined is scarred, and restoring the area to its original state is a long and expensive procedure. In addition, any water that comes in contact with the exposed coal or overburden may become polluted and require treatment.

Coal is regarded as a non-renewable resource, meaning that it was formed at times during Earth's history, but significant amounts are no longer forming. Therefore, the amount of coal that now exists below the earth's surface is, for all practical purposes, all the coal that humans have available to them for the foreseeable future. When this supply of coal is used up, humans will find it necessary to find some other substitute to meet their energy needs.

Large supplies of coal are known to exist (proven reserves) or thought to be available (estimated resources) in North America , the former Soviet Union, and parts of Asia , especially China and India. According to the most recent data available, China produces the largest amount of coal each year, about 22% of the world's total. China is also thought to have the world's largest estimated resources of coal, as much as 46% of all that exists.

For many centuries, coal was burned in small stoves to produce heat in homes and factories. Today, the most important use of coal, both directly and indirectly, is still as a fuel. The largest single consumer of coal as a fuel is the electrical power industry. The combustion of coal in power generating plants is used to make steam, which in turn, operates turbines and generators. For a period of more than 40 years, beginning in 1940, the amount of coal used in the United States for this purpose doubled in every decade. Coal is no longer widely used to heat homes and buildings, as was the case a half century ago, but it is still used in industries such as paper production, cement and ceramic manufacture, iron and steel production, and chemical manufacture for heating and for steam generation.

See also Environmental pollution

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coal

coal, fuel substance of plant origin, largely or almost entirely composed of carbon with varying amounts of mineral matter.

Types

There is a complete series of carbonaceous fuels, which differ from each other in the relative amounts of moisture, volatile matter, and fixed carbon they contain. Of the carbonaceous fuels, those containing the largest amounts of fixed carbon and the smallest amounts of moisture and volatile matter are the most useful to humans. The lowest in carbon content, peat, is followed in ascending order by lignite and the various forms of coal—subbituminous coal or black lignite (a slightly higher grade than lignite), bituminous coal, semibituminous (a high-grade bituminous coal), semianthracite (a low-grade anthracite), and anthracite.

Lignite and subbituminous coal, because of the high percentage of moisture they contain, tend to crumble on exposure to the air. Bituminous coal, being more consolidated, does not crumble easily; it is a deep black in color, burns readily, and is used extensively as fuel in industries and on railroads and in making coke. Anthracite, which is nearly pure carbon, is very hard, black, and lustrous and is extensively used as a domestic fuel. Cannel coal, a dull, homogeneous variety of bituminous coal, is composed of pollen grains, spores, and other particles of plant origin. It ignites and burns easily, with a candlelike flame, but its fuel value is low.

Formation

The vegetable origin of coal is supported by the presence in coal of carbonized fibers, stems, leaves, and seeds of plants, which can be detected with the naked eye in the softer varieties and with the microscope in harder coal. Sometimes carbonized tree stumps have been found standing in layers of coal. The general interpretation of these facts is that coal originated in swamps similar to present-day peat bogs and in lagoons, probably partly from plants growing in the area and partly from plant material carried in by water and wind. From the thickness of coal seams, it is assumed that the coal swamps were located near sea level and were subject to repeated submergence, so that a great quantity of vegetable matter accumulated over a long period of time.

The initial processes of disintegration and decomposition of the organic matter were brought about by the action of bacteria and other microorganisms. Peat, the first product formed, is altered to form lignite and coal through metamorphism. The pressure of the accumulated layers of overlying sediments and rock upon the submerged plant matter forced out much of the water and caused some of the volatile substances to escape and the nonvolatile carbon material to form a more compact mass. The greater the stress exerted in the process of metamorphism, the higher was the grade of coal produced. Cannel coal was probably formed in ponds, rather than in lagoons or swamps, as it occurs in lenticular masses and is frequently found to contain fossil fish. Coal was formed chiefly in the Carboniferous period of geologic time, but valuable deposits date also from the Permian, Triassic, Jurassic, Cretaceous, and Tertiary periods.

Natural Occurrence

Coal is found in beds or seams interstratified with shales, clays, sandstones, or (rarely) limestones. It is usually underlaid by an underclay (a layer of clay containing roots of plants). The coal is removed by strip (surface) mining or underground mining methods (see coal mining).

The chief coal fields of the United States are the Appalachian (from N Pennsylvania into Alabama), the Eastern Interior (Illinois, Kentucky, and Indiana), the Northern Interior (Michigan), the Western Interior (Iowa, Kansas, Missouri, Oklahoma, and Arkansas), the Rocky Mountain (Colorado, Wyoming, Utah, New Mexico, Montana, and North Dakota), the Pacific (Washington), and the Gulf Coast (Texas, Arkansas, and Louisiana). In Europe the chief coal-producing countries are Germany, Russia, Ukraine, and Poland. There are valuable coal fields in China, India, Indonesia, Australia, South Africa, and Korea but only a few in South America, mainly in Colombia.

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coal

coal A brown or black carbonaceous deposit derived from the accumulation and alteration of ancient vegetation, which originated largely in swamps or other moist environments. As the vegetation decomposed it formed layers of peat, which were subsequently buried (for example, by marine sediments following a rise in sea level or subsidence of the land). Under the increased pressure and resulting higher temperatures the peat was transformed into coal. Two types of coal are recognized: humic (or woody) coals, derived from plant remains; and sapropelic coals, which are derived from algae, spores, and finely divided plant material.

As the processes of coalification (i.e. the transformation resulting from the high temperatures and pressures) continue, there is a progressive transformation of the deposit: the proportion of carbon relative to oxygen rises and volatile substances and water are driven out. The various stages in this process are referred to as the ranks of the coal. In ascending order, the main ranks of coal are: lignite (or brown coal), which is soft, brown, and has a high moisture content; subbituminous coal, which is used chiefly by generating stations; bituminous coal, which is the most abundant rank of coal; semibituminous coal; semianthracite coal, which has a fixed carbon content of between 86% and 92%; and anthracite coal, which is hard and black with a fixed carbon content of between 92% and 98%.

Most deposits of coal were formed during the Carboniferous and Permian periods. More recent periods of coal formation occurred during the early Jurassic and Tertiary periods. Coal deposits occur in all the major continents; the leading producers include the USA, China, Ukraine, Poland, UK, South Africa, India, Australia, and Germany. Coal is used as a fuel and in the chemical industry; by-products include coke and coal tar.

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coal

coal A carbon-rich mineral deposit formed from the remains of fossil plants. These are deposited initially as peat, but burial and increase in temperatures at depth bring about physical and chemical changes. The process of ‘coalification’ results in the production of coals of different ranks (‘coal series’), from peat, through the bituminous coals and lignite to anthracite. Each rank marks a reduction in the percentage of volatiles and moisture, and an increase in the percentage of carbon. They are termed ‘woody’ or ‘humic’ coals if formed from fragments of trees or bushes. If the major constituents of coal are pollen grains and/or finely divided plant debris, the term ‘sapropelic coal’ is used.

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coal

coal Carbon-rich mineral deposit formed from the remains of fossil plants. These are deposited initially as peat, but burial and increase in temperatures at depth bring about physical and chemical changes. The process of ‘coalification’ results in the production of coals of different ranks (‘coal series’), from peat, through the bituminous coals and lignite, to anthracite. Each rank marks a reduction in the percentage of volatiles and moisture, and an increase in the percentage of carbon. They are termed ‘woody’ or ‘humic’ coals if formed from fragments of trees or bushes. If the major constituents of coal are pollen grains and/or finely divided plant debris, the term ‘sapropelic coal’ is used.

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coal

coal / kōl/ • n. a combustible black or dark brown rock consisting mainly of carbonized plant matter, found mainly in underground deposits and widely used as fuel: [as adj.] a coal fire. ∎  a red-hot piece of coal or other material in a fire: the glowing coals. • v. [tr.] provide with a supply of coal: [as n.] (coaling) the coaling and watering of the engine. DERIVATIVES: coal·y adj. ORIGIN: Old English col (in the senses ‘glowing ember’ and ‘charred remnant’), of Germanic origin; related to Dutch kool and German Kohle. The sense ‘combustible mineral used as fuel’ dates from Middle English.

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coal

coal Blackish, solid fuel formed from the remains of fossil plants. In the carboniferous and tertiary periods, swamp vegetation subsided to form peat bogs. Sedimentary deposits buried the bogs, and the resultant increase in pressure and heat produced lignite (brown coal), then bituminous coal and finally anthracite if temperature increased sufficiently. This is termed the coal rank series; each rank of coal represents an increase in carbon content and a reduction in the proportion of natural gas and moisture. Lignite is a poorer fuel than anthracite.

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coal

coal †glowing piece of wood OE.; †charcoal XIII; black mineral used for fuel XIII (orig. seacoal). OE. col, corr. to OFris., MLG. kole, MDu. cole (Du. kool), OHG. kol(o) (G. kohle), ON. kol, of uncert. orig.

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Coal

Coal. A description among Coptic, Ethiopic, and E. Syrian Christians of the sacramental body of Christ. The description is derived from Isaiah 6. 6 f.

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coal

coalbarcarole, bole, bowl, cajole, coal, Cole, condole, console, control, dhole, dole, droll, enrol (US enroll), extol, foal, goal, hole, Joel, knoll, kohl, mol, mole, Nicole, parol, parole, patrol, pole, poll, prole, rôle, roll, scroll, Seoul, shoal, skoal, sole, soul, stole, stroll, thole, Tirol, toad-in-the-hole, toll, troll, vole, whole •Creole •carriole, dariole •cabriole • capriole •aureole, gloriole, oriole •wassail-bowl • fishbowl • dustbowl •punchbowl • rocambole • farandole •girandole • manhole • rathole •armhole • arsehole • hellhole •keyhole, kneehole •peephole •sinkhole • pinhole • cubbyhole •hidey-hole • pigeonhole •eyehole, spyhole •foxhole •knothole, pothole •borehole, Warhol •porthole • soundhole • blowhole •stokehole • bolthole • loophole •lughole, plughole •chuckhole • buttonhole • bunghole •earhole • waterhole • wormhole •charcoal • caracole • Seminole •pinole

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Coal

Coal


Consisting of altered remains of plants, coal is a widely used fossil fuel. Generally, the older the coal, the higher the carbon content and heating value. Anthracite coal ranks highest in carbon content, then bituminous coal, subbituminous coal, and lignite (as determined by the American Society for Testing Materials). Over 80% of the world's vast reserves occur in the former Soviet Union, the United States, and China. Though globally abundant, it is associated with many environmental problems, including acid drainage , degraded land, sulfur oxide emissions, acid rain , and heavy carbon dioxide emissions. However, clean coal-burning technologies, including liquified or gasified forms, are now available.

Anthracite, or "hard" coal, differs from the less altered bituminous coal by having more than 86% carbon and less than 14% volatile matter. It was formerly the fuel of choice for heat purposes because of high Btu (British Thermal Unit) values, minimally 14,500, and low ash content. In the United States, production has dropped from 100 million tons in 1917 to about seven million tons as anthracite has been replaced by oil, natural gas , and electric heat. Predominantly in eastern Pennsylvania's Ridge and Valley Province, anthracite seams have a wavelike pattern, complicating extraction. High water tables and low demand are the main impediments to expansion.

Bituminous coal, or "soft" coal, is much more abundant and easier to mine than anthracite but has lower carbon content and Btu values and higher volatility. Historically dominant, it energized the Industrial Revolution, fueling steam engines in factories, locomotives, and ships. Major coal regions became steel centers because two tons of coal were needed to produce each ton of iron ore. This is the only coal suitable for making coke, needed in iron smelting processes. Major deposits include the Appalachian Mountains and the Central Plains from Indiana through Oklahoma.

Subbituminous coal ranges in Btu values from 10,500 (11,500 if agglomerating) down to 8,300. Huge deposits exist in Wyoming, Montana, and North Dakota with seams 70 ft (21.4 m) thick. Though distant from major utility markets, it is used extensively for electrical power generation and is preferred because of its abundance, low sulfur content,

Coal Production From 19502000
Date Anthricite Bituminous Lignite Subbituminous
Coal production from 1950 through 2000. MMst stands for million short tons.
1950 44.08 516.31 0.00 0.00
1960 18.82 415.51 0.00 0.00
1970 9.73 578.47 8.04 16.42
1980 6.06 628.77 47.16 147.72
1990 3.51 693.21 88.09 244.27
2000 4.51 548.47 88.74 433.78

and good grinding qualities. The latter makes it more useful than the higher grade, but harder, bituminous coal because modern plants spray the coal into combustion chambers in powder form. Demand for this coal skyrocketed following the 1973 OPEC oil embargo and subsequent restrictions on natural gas use in new plants.

Lignite, or "brown" coal, is the most abundant, youngest, and least mature of the coals, with some plant texture still visible. Its Btu values generally range below 8,300. Although over 70% of the deposits are found in North America, mainly in the Rocky Mountain region, there is little production there. It is used extensively in many eastern European countries for heating and steam production. Russian scientists have successfully burned lignite in situ, tapping the resultant coal gas for industrial heating. If concerns over global warming are satisfied, future liquefying and gasifying technologies could make lignite a prized resource.

[Nathan H. Meleen ]


RESOURCES

BOOKS

Hartshorne, T., and J. W. Alexander. Economic Geography. 3rd ed. Englewood Cliffs, NJ: Prentice-Hall, 1988.

PERIODICALS

Young, G. "Will Coal Be Tomorrow's Black Gold?" National Geographic 148 (August 1975): 234-259.

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Coal

Coal

A Historical Perspective
What is Coal?
Classifications of Coal
Locations of Coal Deposits
Coal Mining Methods
Coal Mining Safety and Health Risks
Coal in the Domestic Market
Coal and the Environment
Coal Exports
International Coal Production and Consumption
Future Trends in the Coal Industry

A Historical Perspective

Even though it had been a source of energy for centuries, coal was first used on a large scale during the Industrial Revolution in England. From the mid-eighteenth to the mid-nineteenth centuries, the sky was filled with billowing columns of black smoke. Soot covered the towns and cities, and workers breathed the thick coal dust swirling around them. Environmental issues, if they were considered at all, were far less important than the jobs the factories provided. Factory owners had little reason or incentive to control the smoke pouring out of their plants—the environmental and public health effects of pollution were not as well understood as they are today, so government imposed little, if any, regulation on manufacturing.

In the United States early colonists used wood to heat their homes because it was so plentiful. Coal was not as readily available and far more expensive. Before the Civil War (1861–1865), some industries used coal as a source of energy, but its use expanded greatly with the building of railroads across the country. In fact, coal became such a fundamental part of American industrialization that some historians call this era the coal age. As in England, Americans considered the development of industry a source of national pride. Photographs and postcards of the time proudly featured trains and steel mills belching dark smoke into gray skies.

The Energy Information Administration (EIA) notes in Annual Energy Review 2007 (June 2008, http://www.eia.doe.gov/aer/pdf/aer.pdf) that by the early twentieth century coal had become the major fuel in the United States, accounting for nearly 75% of the nation’s energy requirements. However, as oil—which was much cleaner— became a favored fuel for heating homes and offices, and gasoline powered the growing number of cars, coal’s dominance declined. By 1949 coal accounted for 37% of the energy consumed. It fell further out of favor in the 1950s and 1960s until, in the early 1970s, coal provided as little as 17% of the nation’s energy. By then it had been overtaken by concerns about pollution, along with the emergence of nuclear power as a promising energy source.

In 1973, however, the oil embargo by the Organization of Petroleum Exporting Countries made many Americans reconsider. The embargo clearly demonstrated the nation’s heavy reliance on foreign sources of energy and the potentially crippling effect that dependence could have on the U.S. economy. Consequently, the nation revived its interest in domestic coal as a plentiful and economical energy source.

According to the article ‘‘Primary Sources: The President’s Proposed Energy Policy’’ (2002, http://www.pbs.org/wgbh/amex/carter/filmmore/ps_energy.html), President Jimmy Carter (1924–) called for an increase in domestic coal production by two-thirds—to about 1 billion short tons (907 billion t) annually by 1985. He proposed a ten-year, $10 billion program to spark that production. He also asked utility companies and other large industries to convert their operations to coal. In 2007 more coal was produced in the United States than any other form of energy: 23.5 quadrillion British thermal units (Btu), or 33% of all energy produced. (See Table 1.1 and Figure 1.6 in Chapter 1.) Coal was the third-largest source of energy consumed in the United States in 2007, after petroleum and natural gas. (See Figure 1.7 in Chapter 1.)

What is Coal?

Coal is a black, combustible, mineral solid. It developed over millions of years as plant matter decomposed in an airless space under increased temperature and pressure. Coal beds, sometimes called seams, are found in the earth between beds of sandstone, shale, and limestone and range in thickness from less than an 1 inch (2.5cm) to more than 100 feet (30 m). Approximately 5 to 10 feet (1.5 to 3 m) of ancient plant material were compressed to create each foot of coal.

Coal is used as a fuel and in the production of coal gas, water gas, many coal-tar compounds, and coke (the solid substance left after coal gas and coal tar have been extracted from coal). When coal is burned, its fossil energy—sunlight converted and stored by plants over millions of years—is released. One short ton (0.9 t) of coal produces 22 million Btu on average, about the same heating value as 22,000 cubic feet (623 cubic m) of natural gas, 160 gallons (606 L) of home heating oil, or a cord of seasoned firewood measuring 4 feet by 4 feet by 8 feet (1.2 by 1.2 by 2.4 m). (A short ton is 2,000 pounds [907 k].)

Classifications of Coal

There are four basic types of coal. Classifications, or coal ranks, are based on how much carbon, volatile matter, and heating value are contained in the coal:

  • Anthracite (hard coal) is the highest-ranked coal. It is hard and jet-black, with a moisture content of less than 15%. It contains approximately 22 million to 28 million Btu per ton, with an ignition temperature of approximately 925° to 970° Fahrenheit (496° to 521° C). Anthracite, which is used for generating electricity and space heating, is mined mainly in northeastern Pennsylvania. (See Figure 4.1.)
  • Bituminous (soft coal) is the most common. It is dense and black, with a moisture content of less than 20% and an ignition range of 700° to 900° Fahrenheit (371° to 482° C). With a heating value of 19 million to 30 million Btu per ton, bituminous coal is used to generate electricity, for space heating, and to produce coke. It is mined chiefly in the Appalachian and midwestern regions of the United States. (See Figure 4.1.)
  • Subbituminous coal (black lignite) is dull black in color and generally contains 20% to 30% moisture. Used for generating electricity and for space heating, it contains 16 million to 24 million Btu per ton. Black lignite is mined primarily in the western United States. (See Figure 4.1.)
  • Lignite, the lowest-ranked coal, is brownish-black in color and has a high moisture content. It tends to disintegrate when exposed to weather. Lignite contains about 9 million to 17 million Btu per ton and is used mainly to generate electricity. Most lignite is mined in North Dakota, Montana, Texas, California, and Louisiana. (See Figure 4.1.)

In 2007 domestic mines produced over 1.1 billion short tons (998 million t) of all types of coal. About 93% of it was bituminous (535 million short tons [485 million t]) and subbituminous (531 million short tons [482 million t]) coal. (See Table 4.1.) Lignite accounted for much of the remainder. Very little of the total was anthracite.

Locations of Coal Deposits

Coal is found in about 450,000 square miles (1.2 million sq km), or 13%, of the total land area of the United States. Figure 4.1 shows the coal-bearing areas of the United States. Geologists divide U.S. coalfields into the Appalachian, Interior, and Western regions. The Appalachian region is subdivided into three areas: Northern (Maryland, Ohio, Pennsylvania, and northern West Virginia), Central (eastern Kentucky, Tennessee, Virginia, and southern West Virginia), and Southern Appalachia (Alabama). The Interior region includes mines in Arkansas, Illinois, Indiana, Iowa, Kansas, western Kentucky, Louisiana, Missouri, Oklahoma, and Texas. The Western region is divided into the Northern Great Plains (northern Colorado, Montana, North and South Dakota, and Wyoming), the Rocky Mountains, the Southwest (Arizona, southern Colorado, New Mexico, and Utah), and the Northwest (Alaska and Washington).

Before 1999 most of the nation’s coal was mined east of the Mississippi River. Miners had been digging deeper and deeper into the Appalachian Mountains for years before bulldozers began cutting open the rich coal seams of eastern Montana. In 1965 western mines produced 27.4 million short tons (24.9 million t), only 5% of the national total. By 1999, however, western production had increased more than twentyfold, to 570.8 million short tons (517.8 million t), or 52% of the total. (See Table 4.1.) The amount of coal mined east of the Mississippi that year was 529.6 million short tons (480.4 million t). In 2007 mines west of the Mississippi produced 668.4 million short tons (606.4 million t)—58% of the total—whereas eastern mines produced 477.2 million short tons (432.9 million t).

The growth in coal production in the western states resulted, in part, because of an increased demand for low-sulfur coal, which is concentrated there. Low-sulfur coal burns cleaner and is considered less dangerous to the environment. In addition, the coal is closer to the surface, so it can be extracted by surface mining, which is cheaper and more efficient. Improved rail service has also made it easier to deliver this low-sulfur coal to electric power plants located east of the Mississippi River.

Coal Mining Methods

The method used to mine coal depends on the terrain and the depth of the coal. Before the early 1970s most coal was taken from underground mines. Since then, coal production has shifted to surface mines. (See Table 4.1 and Figure 4.2.)

Underground mining is required when the coal lies more than 200 feet (61 m) below ground. The depth of most underground mines is less than 1,000 feet (305 m), but a few are 2,000 feet (610 m) deep. In underground mines, some coal must be left untouched to form pillars that prevent the mines from caving in.

Figure 4.3 shows three types of underground mines: a shaft mine, a slope mine, and a drift mine. In a shaft mine, elevators take miners and equipment up and down a vertical shaft to the coal deposit. By contrast, the entrance to a slope mine is an incline from the aboveground opening. In a drift mine, the mineshaft runs horizontally from the opening in the hillside. As Figure 4.3 shows, workers and equipment are moved externally up the side of a hill or mountain to the entry.

Surface mines are usually less than 200 feet (61 m) deep and can be developed in flat or hilly terrain. On large plots of relatively flat ground workers use a technique known as area surface mining. Rock and soil that lie above the coal—called overburden or spoil—are loosened by drilling and blasting and then dug away. Another technique, contour surface mining, follows coal deposits along hillsides. (See Figure 4.3.) Open pit mining—a combination of area and contour mining—is used to mine thick, steeply inclined coal deposits.

TABLE 4.1 Coal production, selected years 1949–2007
SOURCE: Adapted from “Table 7.2. Coal Production, Selected Years, 1949–2007 (Million Short Tons),” in Annual Energy Review 2007, U.S. Department of Energy, Energy Information Administration, Office of Energy Markets and End Use, June 2008, http://www.eia.doe.gov/aer/pdf/aer.pdf (accessed June 28, 2008)
[Million short tons]
RankMining methodLocation
Year Bituminous coala Subbituminous coal Lignite Anthracitea Underground Surfacea East of the Mississippia West of the Mississippia Totala
1949437.9(b)(b)42.7358.9121.7444.236.4480.6
1950516.3(b)(b)44.1421.0139.4524.436.0560.4
1955464.6(b)(b)26.2358.0132.9464.226.6490.8
1960415.5(b)(b)18.8292.6141.7413.021.3434.3
1965512.1(b)(b)14.9338.0189.0499.527.4527.0
1970578.516.48.09.7340.5272.1567.844.9612.7
1971521.322.28.78.7277.2283.7509.951.0560.9
1972556.827.511.07.1305.0297.4538.264.3602.5
1974545.742.215.56.6278332.1518.191.9610.0
1976588.464.825.56.2295.5389.4548.8136.1684.9
1978534.096.834.45.0242.8427.4487.2183.0670.2
1980628.8147.747.26.1337.5492.2578.7251.0829.7
1982620.2160.952.44.6339.2499.0564.3273.9838.1
1984649.5179.263.14.2352.1543.9587.6308.3895.9
1986620.1189.676.44.3360.4529.9564.4325.9890.3
1988638.1223.585.13.6382.2568.1579.6370.7950.3
1990693.2244.388.13.5424.5604.5630.2398.91,029.1
1992651.8252.290.13.5407.2590.3588.6409.0997.5
1994640.3300.588.14.6399.1634.4566.3467.21,033.5
1996630.7340.388.14.8409.8654.563.7500.21,063.9
1998640.6385.985.85.3417.7699.8570.6547.01,117.50
1999601.7406.787.24.8391.8708.6529.6570.81,100.40
2000574.3409.285.64.6373.7700507.5566.11,073.60
2002572.1438.482.51.4357.4736.9492.9601.41,094.3
2003541.5442.686.41.3352.8719469.2602.51,071.80
2004561.5465.483.51.7367.6744.5484.8627.31,112.1
2005571.2474.783.91.7368.6762.9493.8637.71,131.5
2006R561.6R515.384.21.5R359.0R803.7R490.8672.0R1,162.7
2007E534.9E530.6E78.5E1.6E351.3E794.3E477.2E668.4P1,145.6
aBeginning in 2001, includes a small amount of refuse recovery.
bIncluded in “bituminous coal.”
R = Revised.
P = Preliminary.
E = Estimate.
Note: Totals may not equal sum of components due to independent rounding.

The growth of surface mining and the closure of non-productive mines led to increases in coal mining productivity through the 1980s and 1990s. (See Figure 4.4.) Because surface mines are easier to work, they average up to three times the productivity of underground mines. According to the EIA, in Annual Energy Review 2007, the productivity for surface mines was 10.2 short tons (9.3 t) of coal per miner hour in 2007, whereas productivity for underground mines was 3.4 short tons (3.1 t) per miner hour. In 2000 the combined average productivity for both mining methods reached an all-time high of 6.9 short tons (6.3 t) per miner hour. In 2007 combined average productivity was 6.3 short tons (5.7 t) per miner hour.

Coal Mining Safety and Health Risks

Mining safety in the United States is overseen by the Mine Safety and Health Administration (MSHA), which was formed in 1978 after Congress passed the Federal Mine Safety and Health Act of 1977. The law established mandatory health and safety standards for mines and required that mine operators and miners comply with them. It also provided assistance to states to develop and enforce effective state mine health and safety programs and expanded research and development aimed at preventing accidents and diseases associated with mining occupations.

Throughout its history, coal mining has been a physically challenging and dangerous occupation, with a recognized risk for injury or disease. As early as 1822 the term miner’s asthma was used to describe the breathing difficulties and coughing often experienced by mine workers.

In addition, mine accidents can occur without warning, including cave-ins, fires, underground floods, equipment failures, and gas explosions. (Flammable gases, notably methane, are found naturally in coal mines.) In underground mines these accidents carry the additional risk of trapping miners in the mine without air, water, or food.

Fatalities

The MSHA states in ‘‘Coal Fatalities for 1900 through 2007’’ (2008, http://www.msha.gov/stats/centurystats/coalstats.asp) that a total of 104,655 people were killed in coal mining accidents from 1900 through 2007. In ‘‘Coal Mining Disasters’’ (April 18, 2008, http://www.cdc.gov/niosh/mining/statistics/discoal.htm), the National Institute for Occupational Safety and Health (NIOSH) finds that in records dating back to 1839, 13,819 fatalities in the United States have resulted from 616 coal mine disasters; a mine disaster is a mine accident that claims five or more lives. The number of disasters peaked during the period 1901 through 1925, when 297 large accidents occurred. The most deadly event in U.S. history occurred when explosions in the Monongah mines in Monongah, West Virginia, claimed 362 lives in December 1907. The MSHA shows that 1907 was, in fact, the deadliest year on record, with 3,242 fatalities. According to NIOSH, of the twenty-six U.S. disasters that caused one hundred or more fatalities, seventeen of them took place between 1901 and 1925.

With a death toll of 125 and more than 1,100 injured, the deadliest coal mining accident in recent decades was the massive Buffalo Creek flood in southern West Virginia in February 1972. The West Virginia Division of Culture and History notes in Buffalo Creek (2008, http://www.wvculture.org/hiStory/buffcreek/bctitle.html) that after several days of heavy rain, a dam burst that was holding mine wastewater in a series of hillside pools. Over 132 million gallons (500 million L) of water then poured out and rushed through the valley below in the form of a black wave that reached 15 to 20 feet (4.6 to 6.1 m) high. The power of the water smashed structures and moved whole houses and railroad cars downstream. Terrified residents ran up nearby hills to get above the water level. Within minutes several communities located along a 17-mile (27.4-km) stretch of Buffalo Creek were devastated, and the town of Saunders was completely destroyed.

Coal mining has dramatically increased its safety record since the early and mid-twentieth century. Tighter regulations, improvements in technology, and preventive programs are credited with lowering—though not eliminating—many of the risks undertaken by miners. NIOSH indicates that from 1981 through August 2007 there were thirteen coal mine disasters that killed five or more people. The worst accident during this period was a mine fire that claimed twenty-seven lives at the Wilberg Mine in Orangeville, Utah, in December 1984. According to the MSHA, in 2005 there were twenty-three fatalities, the fewest fatalities recorded between 1900 and 2007.

The January 2006 mine disaster at the Sago Mine in Tallmansville, West Virginia, was the worst mining disaster in the United States since thirteen miners were killed in 2001 in a mine in Brookwood, Alabama, and the worst in West Virginia since seventy-eight were killed at the Consol No. 9 mine in Farmington in 1968. Sago claimed the lives of twelve miners. One miner survived. The miners were trapped following an explosion of methane gas that may have been triggered by a lightning strike; investigators theorized that a buildup of gas over the holidays might have contributed to the disaster, as the blast occurred shortly after the first shift returned to work on January 2. The explosion disabled the mine’s internal communication system, which interfered with rescue operations. Rescue was also delayed because the air in the mine contained high concentrations of carbon monoxide and methane, which made it unsafe for rescue workers. Of those who perished, one was believed to have been killed by the initial blast, and the others succumbed to carbon monoxide poisoning.

One of the most recent mine disasters was investigated by Congress, and possible criminal charges against the owners of the mine were discussed. On August 6, 2007, six miners were trapped when a portion of the Crandall Canyon Mine collapsed. Crandall Canyon is located about 140 miles (225 km) south of Salt Lake City, Utah. An owner of the mine said a small earthquake collapsed the mine, whereas others believed the recorded seismic activity was due to the tremendous force of the mine collapse. Eleven days into the rescue effort, three rescue workers were killed and seven injured when an additional collapse of the mine occurred. The bodies of the original six trapped miners were never recovered. U.S. House of Representatives and U.S. Senate committees and the U.S. Department of Labor all conducted independent investigations into the disaster and mining practices at Crandall Canyon. Investigations revealed that the mine collapse was likely due to retreat mining, a risky practice in which some coal is removed from the pillars that support the mine roof. These compromised pillars often collapse under the weight of the rock above. By May 2008 there were calls for the U.S. Department of Justice to open a criminal investigation into the tragedy.

Long-Term Health Risks

Besides the risk of injury or death, coal miners face a wide range of long-term health concerns, including muscle and joint conditions, hearing loss brought on by excessive noise, and respiratory illnesses associated with dust, fumes, and chemical exposure. One serious illness associated with mining is coal workers’ pneumoconiosis, also known as black lung disease, which results from repeated inhalation of coal dust. However, this risk has been drastically reduced through the use of dust masks and respirators, by covering the walls of mine tunnels and shafts with pulverized white rock to lower the level of the dust, and by spraying water to settle the dust.

Deaths from pneumoconiosis as an underlying cause have decreased dramatically from a peak of about 1,250 deaths in 1972 to about 250 deaths in 2004. (See Figure 4.5.) The age-adjusted death rate from pneumoconiosis was approximately 22 deaths per 1 million people aged fifteen and over in 1972 and dropped to about 3 deaths per 1 million in 2004.

Coal in the Domestic Market

Overall Production and Consumption

In Annual Energy Review 2007, the EIA indicates that the nation consumed 625.3 million short tons (567.3 million t) of coal in 1977. Thirty years later, in 2007, consumption had grown to more than 1.1 billion short tons (998 million t)—nearly twice as much. Increases in consumption were in the electric power sector, as existing power plants switched to coal from more expensive oil and natural gas and many new coal-fired power plants were constructed. Consumption of coal in the residential, commercial, and industrial sectors decreased from 1949 to 2007. (See Figure 4.6.)

Coal Consumption by Sector

In the electric power sector, coal is pulverized and burned to heat boilers that produce steam, which drives generators that create electricity. Each ton of coal used to drive a generator produces about 2,000 kilowatt-hours (kWh) of electricity. In household terms, each pound of coal produces enough electricity to light ten 100-watt lightbulbs for one hour.

In the twenty-first century, electric power companies are by far the largest consumers of coal today. (See Figure 4.6 and Figure 4.7.) They accounted for 93% of domestic coal consumption, or slightly more than 1 billion short tons (907.2 million t), in 2007. According to the EIA, in Annual Energy Review 2007, coal-fired plants produced 2 trillion kWh of electricity, or 49% of U.S. electricity net generation, in 2007. Net generation refers to the power available to the system—it does not include power used at the generating plant, but it does include power that may be lost during transmission and distribution.

The industrial sector was the second-largest consumer of coal in 2007, accounting for 7% of coal use, or 79.2 million short tons (71.9 million t). (See Figure 4.6 and Figure 4.7.) Coal is used in many industrial applications, including the chemical, cement, paper, synthetic fuels, metals, and food-processing industries.

Coal was once a significant fuel source in the residential and commercial sectors. (See Figure 4.6.) In 1949 these sectors together used 116.5 million short tons (105.7 million t) of coal, or 24% of all coal consumption. After the 1940s, however, coal was replaced by oil, natural gas, and electricity, which are cleaner and more convenient. The EIA notes that by 1970 only 16.1 million short tons (14.6 million t) of coal were used in the residential and commercial sectors. Since then, residential and commercial coal use has continued to decline, falling to 3.3 million short tons (3 million t) in 2007, or far less than 1% of total coal use.

The Price of Coal

In 2007 the average price of a short ton of coal was $21.23 in real dollars (i.e., adjusted for inflation), which was slightly higher than the all-time low of $16.78 in 2000 and 2003, and only 42% of the all-time high of $50.92 per short ton in real dollars in 1975. (See Table 4.2.) On a per-Btu basis, coal remains the least expensive fossil fuel. According to the EIA, in Annual Energy Review 2007, in 2007 the average cost of coal was $1.62 per million Btu, compared to $9.92 per million Btu for natural gas and $23.92 per million Btu for retail electricity.

Coal and the Environment

Problems

In 1306 King Edward I (1239–1307) of England so objected to the noxious smoke from London’s coal-burning fires that he banned the use of coal by everyone except blacksmiths. Since then, the potential for pollution has multiplied exponentially, given the amount of fossil fuels, such as coal, that are burned worldwide.

The Greenhouse Effect. Coal-fired electric power plants emit gases that are considered harmful to the environment. Scientists have learned that burning huge quantities of fossil fuels causes a greenhouse effect, in which gases released from the fuels trap heat in the earth’s atmosphere, raising temperatures. Manav Tanneeru reports in ‘‘Global Warming: A Natural Cycle or Human Result?’’ (CNN.com, April 8, 2008) that according to the National Research Council, the earth has warmed about 1° Fahrenheit (0.6° C) in the past one hundred years. Some of the effects of the added heat are immediate, whereas others happen over long periods of time.

Much of the gas that causes the greenhouse effect is carbon dioxide. In 2006 the combustion of coal in the United States produced 2.1 billion metric tons (2.3 million short tons) of carbon dioxide, or 36% of the total carbon dioxide emissions from all fossil fuels used in the United States. (See Figure 4.8.)

Acid Rain. Acid rain is any form of precipitation that contains a greater-than-normal amount of acid. In many parts of the world it has caused significant damage to forests and lakes.

Even nonpolluted rain is slightly acidic: rainwater combines with the carbon dioxide normally found in the air to produce a weak acid called carbonic acid. However, pollutants in the air can increase the acidity of rain and other forms of precipitation, such as snow and fog. Chemicals such as oxides of sulfur and nitrogen, which are released during the combustion of fossil fuels, create highly acidic precipitation. The amount of these oxides in the air is directly related to the amount and content of automobile exhaust and industrial and power plant emissions.

Community Health Issues. Emissions from coal-fired power plants include mercury, sulfur oxides, and nitrogen oxides. Mercury can reach humans when they eat fish contaminated by mercury that, after being emitted into the air, settles in lakes and streams. Mercury can cause birth defects in newborns exposed to it in the womb. Sulfur oxides and nitrogen oxides contribute to air pollution, which is known to cause respiratory impairments. (See Table 4.3.)

Solutions

The Clean Coal Technology Program. In 1984 Congress established the Clean Coal Technology program, which directed the U.S. Department of Energy to administer projects that would demonstrate that coal could be used in environmentally and economically efficient ways. The cost of the projects was to be shared by industry and government.

Clean Coal Technology and the Clean Air Act. The stated goal of both Congress and the Department of Energy has been to develop cost-effective ways to burn coal more cleanly, both to control acid rain and air pollution and to reduce the nation’s dependence on imported fuels. One strategy is a slow, phased-in approach that allows utility companies and states to reduce their emissions in stages.

The burning of coal can be made cleaner by using physical or chemical methods. Scrubbers, a common physical method used to reduce sulfur dioxide emissions, filter coal emissions by spraying a lime or calcium compound and water across the emission stream before it leaves the smoke-stack. The sulfur dioxide bonds to the spray and settles as a mudlike substance that can be pumped out for disposal. However, scrubbers are expensive to operate, so mechanical and fabric particulate collectors are the most common emissions cleaners. Even though they are cheaper to operate than scrubbers, they are less effective. Some utilities use cooling towers to reduce the heat in emissions before they are released into the atmosphere and to reduce some pollutants. Chemical cleaning, a relatively new technology, uses biological or chemical agents to clean emissions.

The Clean Air Act of 1990 placed restrictions on sulfur dioxide and nitrogen oxide emissions; the restrictions first took effect in 1995 and were tightened in 2000. Each round of regulation requires utilities to find lower-sulfur coal or to install cleaner technology, such as scrubbers. The first Clean Air Act, passed in 1970, sought to change air-quality standards at new generating stations while exempting existing coal-fired plants. Under the 1990 act, older plants are also bound by the 1970 regulations. In addition, plants with coal-fired boilers must be built to reduce sulfur emissions by 70% to 90%. When new plants that burn high-sulfur coal are built, about 30% of their construction costs are spent on pollution control equipment. Up to 5% of the plants’ power output is used to operate this equipment. Research is under way to develop technology to lower these costs.

TABLE 4.2 Coal prices, selected years 1949–2007
SOURCE: Adapted from “Table 7.8. Coal Prices, Selected Years, 1949–2007 (Dollars per Short Ton),” in Annual Energy Review 2007, U.S. Department of
Energy, Energy Information Administration, Office of Energy Markets and End Use, June 2008, http://www.eia.doe.gov/aer/pdf/aer.pdf (accessed June 28,
2008)
[Dollars per short ton]
Bituminous coal Subbituminous coal Lignitea Anthracite Total
Year Nominal Realb Nominal Realb Nominal Realb Nominal Realb Nominal Realb
1949c4.90c29.97(c)(c)2.3714.498.9054.435.2432.05
1950c4.86c29.40(c)(c)2.4114.589.3456.505.1931.40
1955c4.51c24.06(c)(c)2.3812.708.0042.684.6925.02
1960c4.71c22.38(c)(c)2.2910.888.0138.074.8322.96
1965c4.45c19.75(c)(c)2.139.458.5137.764.5520.19
1970c6.30c22.88(c)(c)1.866.7611.0340.066.3423.03
1971c7.13c24.66(c)(c)1.936.6812.0841.787.1524.73
1972c7.78c25.79(c)(c)2.046.7612.4041.117.7225.59
1974c16.01c46.11(c)(c)2.196.3122.1963.9015.8245.56
1975c19.79c52.08(c)(c)3.178.3432.2684.8919.3550.92
1976c20.11c50.03(c)(c)3.749.3033.9284.3919.5648.66
1978c22.64c49.48(c)(c)5.6812.4135.2577.0421.8647.77
198029.1753.9811.0820.507.6014.0642.5178.6624.6545.61
198232.1551.2513.3721.319.7915.6149.8579.4727.2543.44
198430.6345.2712.4118.3410.4515.4548.2271.2725.6137.85
198628.8440.4812.2617.2110.6414.9344.1261.9223.7933.39
198827.6636.5410.4513.8110.0613.2944.1658.3422.0729.16
199027.4333.629.7011.8910.1312.4239.4048.2921.7626.67
199226.7831.009.6811.2110.8112.5134.2439.6421.0324.34
199425.6828.458.379.2710.7711.9336.0739.9619.4121.50
199625.1726.827.878.3910.9211.6436.7839.1918.5019.71
199824.8725.786.967.2111.0811.4942.9144.4817.6718.32
200024.1524.157.127.1211.4111.4140.9040.9016.7816.78
200226.5725.57.347.0511.0710.6347.7845.8617.9817.26
200326.7325.127.737.2611.210.5349.8746.8717.8516.78
200430.56R27.928.127.4212.2711.2139.77R36.3319.9318.21
200536.80R32.578.68R7.6813.49R11.9441.00R36.2823.59R20.88
2006R39.32R33.73R9.95R8.54R14.00R12.01R43.61R37.41R25.16R21.58
2007E40.8334.1211.019.214.8912.4451.2342.8125.421.23
aBecause of withholding to protect company confidentiality, lignite prices exclude Texas for 1955–1977 and Montana for 1974–1978. As a result, lignite prices for 1974–1977 are for
North Dakota only.
bIn chained (2000) dollars, calculated by using gross domestic product implicit price deflators.
cThrough 1978, subbituminous coal is included in “bituminous coal.”
R = Revised.
E = Estimate.
Note: Prices are free-on-board (F.O.B.) rail/barge prices, which are the F.O.B. prices of coal at the point of first sale, excluding freight or shipping and insurance costs.
Web pages: For all data beginning in 1949, see http://www.eia.doe.gov/emeu/aer/coal.html. For related information, see http://www.eia.doe.gov/fuelcoal.html.

When President George W. Bush (1946–) took office in 2001, he promised to ease the regulations for older coal-burning plants to keep them up and running. His energy policy would have allowed the plants to modify their equipment and structures without adding pollution control measures, as long as they met certain conditions. Fifteen state governments and environmental and public health groups brought suit to stop this interpretation of the Clean Air Act. In April 2006 the Bush policy was rejected by the courts. In his 2008 State of the Union address, President Bush (January 28, 2008, http://www.whitehouse.gov/stateoftheunion/2008/initiatives/energy.html) urged the use of clean coal technology for generating electricity and the funding of new technologies that can produce power from coal with less carbon dioxide emissions.

The Clean Air Interstate Rule and the Clean Air Mercury Rule. In March 2005 the U.S. Environmental Protection Agency (EPA) announced the Clean Air Interstate Rule (CAIR). It focused primarily on twenty-eight eastern states and the District of Columbia, where sulfur dioxide and nitrogen oxide emissions contributed significantly to fine particle and ozone pollution. Under the regulations, coal-burning power plants would have to install advanced pollution-control technologies, use coal that burned cleaner, or make other changes to reduce emissions of sulfur dioxide and nitrogen oxide that travel across state borders. The EPA expected the regulation, which would go into effect in 2009 and be fully implemented between 2020 and 2025, would reduce sulfur dioxide emissions by 70% and nitrogen oxide emissions by 60% from 2003 levels. However, the state of North Carolina and some companies that produce electric power had opposed the rule and filed suit, contending that the EPA had overstepped its authority. In July 2008 a federal appeals court struck down CAIR, agreeing with the plaintiffs and stating, in addition, that it had found several flaws in the regulation.

TABLE 4.3 Air pollutants, health risks, and contributing sources
Fred Seitz and Christine Plepys, “Table 1. Criteria Air Pollutants, Health Risks and Sources,” in Healthy People 2000: Statistical Notes, no. 9, Centers for Disease Control and Prevention, National Center for Health Statistics, September 1995, http://www.cdc.gov/nchs/data/statnt/statnt09.pdf (accessed July 3, 2008)
Pollutants Health risks Contributing sources
Ozone* (O3)Asthma, reduced respiratory function, eye irritationCars, refineries, dry cleaners
Particulate matter (PM-IO)Bronchitis, cancer, lung damageDust, pesticides
Carbon monoxide (CO)Blood oxygen carrying capacity reduction, cardiovascular and nervous system impairmentsCars, power plants, wood stoves
Sulphur dioxide (SO2)Respiratory tract impairment, destruction of lung tissuePower plants, paper mills
Lead (Pb)Retardation and brain damage, Cars, nonferrous esp. childrenCars, nonferrous smelters, battery plants
Nitrogen dioxide (NO2)Lung damage and respiratory illnessPower plants, cars, trucks
*Ozone refers to tropospheric ozone which is hazardous to human health.

In March 2005 the EPA also announced the Clean Air Mercury Rule (CAMR). The EPA expected mercury emissions from electric power plants to be reduced by nearly 70% from 1999 levels when the rule was fully implemented. The state of New Jersey challenged the legality of the rule because its provisions were not stringent enough to meet the standards of the Clean Air Act. In February 2008 a federal appeals court struck down CAMR, agreeing that the EPA failed to fulfill its obligations under the Clean Air Act by allowing utilities to make mercury cuts from some coal-fired units and not others. In March 2008 the EPA asked the court to reexamine its decision. In May 2008 the court refused.

Carbon Dioxide Capture. In ‘‘Germany Leads ‘Clean Coal’ Pilot’’ (BBC News, September 3, 2008), Roger Harrabin reports that in September 2008 the first coal-fired plant that captures and stores its own carbon dioxide emissions began operations in northern Germany. The Schwarze Pump power station is a pilot project that will help determine whether the new technology used in the plant is economically and practically feasible. The European Union expects to build ten to twelve full-scale power plants using the clean coal technology within the next few years if the pilot experiment is successful.

Coal Exports

Since 1950 the United States has produced more coal than it has consumed, allowing it to become a significant exporter. However, exports of this energy source have declined dramatically since 1991, when the United States exported 109 million short tons (98.9 million t) of coal. (See Table 4.4.) In 2007 the U.S. exported 59.2 million short tons (53.7 million t).

The EIA reports in Annual Energy Review 2007 that coal made up 28% of all U.S. energy exports in 2007. The countries that bought the most U.S. coal from the United States were Canada, Japan, Italy, Germany, the Netherlands, and Brazil, respectively. (See Table 4.4.)

International Coal Production and Consumption

In Annual Energy Review 2007, the EIA reports that slightly more than 6.8 billion short tons (6.1 billion t) of coal were produced worldwide in 2006, and accounted for 122.5 quadrillion Btu (27%) of the world energy production in 2005. (See Table 1.4 in Chapter 1.) In 2006 China produced the most coal—more than 2.6 billion short tons (2.4 billion t)—followed by the United States, which mined almost 1.2 billion short tons (1.1 billion t). (See Figure 4.9.) Other major coal producers in order of amount produced included India, Australia, Russia, South Africa, Germany, and Indonesia.

TABLE 4.4 Coal exports by country of destination, selected years 1960–2007
SOURCE: Adapted from “Table 7.4. Coal Exports by Country of Destination, 1960–2007 (Million Short Tons),” in Annual Energy Review 2007, U.S. Department of Energy, Energy Information Administration, Office of Energy Markets and End Use, June 2008, http://www.eia.doe.gov/aer/pdf/aer.pdf (accessed June 28, 2008)
[Million short tons]
Europe
YearCanada Brazil Belgiuma Denmark France Germanyb Italy Netherlands Spain Turkey United Kingdom Other Total Japan Other Total
196012.81.11.10.10.84.64.92.80.3NA2.417.15.61.338.0
196112.111.1.74.34.82.6.2NA2.015.76.61.036.4
196212.31.31.3(s).95.16.03.3.8NA(s)1.819.16.51.040.2
196414.81.12.3(s)2.25.28.14.21.4NA2.626.06.51.149.5
196616.51.71.8(s)1.64.97.83.21.2NA(s)2.523.17.81.050.1
196817.11.81.11.53.84.31.51.5NA1.915.515.8.951.2
197019.121.93.65.04.32.13.2NA(s)1.821.827.61.271.7
197218.71.91.11.72.43.72.32.1NA2.41.116.918.01.256.7
197414.21.31.12.71.53.92.62.0NA1.4.916.127.31.860.7
197616.92.22.2(s)3.51.04.23.52.5NA.82.119.918.82.160.0
197815.71.51.11.7.63.21.1.8NA.42.211.010.12.540.7
198017.53.34.61.77.82.57.14.73.4NA4.16.041.923.16.091.7
198218.63.14.82.89.02.311.35.95.61.62.06.051.325.87.5106.3
198420.44.73.90.63.80.97.65.52.31.52.93.932.816.37.281.5
198614.55.74.42.15.40.810.45.62.62.42.95.942.611.411.485.5
198819.25.36.52.84.30.711.15.12.52.03.76.445.114.111.395.0
199015.55.88.53.26.91.111.98.43.82.15.27.458.413.312.7105.8
199111.27.17.54.79.51.711.39.64.72.26.28.265.512.313.0109.0
199215.16.47.23.88.11.09.39.14.52.05.66.657.312.311.4102.5
19949.25.54.90.52.90.37.54.94.11.33.46.035.810.210.771.4
1996126.54.61.33.91.19.27.14.12.26.27.747.210.514.290.5
199820.76.53.20.33.21.25.34.53.21.65.95.333.87.79.478.0
200018.84.52.90.13.01.03.72.62.71.83.33.925.04.45.858.5
200216.73.52.41.31.03.11.71.90.61.91.815.61.32.639.6
200320.83.51.80.31.30.52.82.01.81.11.52.115.1(s)3.643.0
200417.84.41.70.11.10.62.12.51.51.32.02.315.24.46.248.0
200519.54.22.10.11.30.72.52.61.91.91.84.118.82.15.449.9
200619.94.52.20.41.61.73.32.11.61.22.64.220.80.34.149.6
2007P18.46.52.10.12.42.33.54.61.51.43.45.827.1(s)7.159.2
aThrough 1999, includes Luxembourg.
bThrough 1990, data for Germany are for the former West Germany only. Beginning in 1991, data for Germany are for the unified Germany, i.e., the former East Germany and West
Germany.
P = Preliminary.
NA = Not Available.
— = No data reported.
(s) = Less than 0.05 million short tons.
Note: Totals may not equal sum of components due to independent rounding.

The world consumption of coal in 2006 totaled nearly 6.8 billion short tons (6.2 billion t). China consumed the most, using nearly 2.6 billion short tons (2.4 billion t), followed by the United States, which used slightly more than 1.1 billion (997.9 million t) short tons. (See Figure 4.10.) Other major consumers in order of amount consumed included India, Germany, Russia, Japan, and South Africa.

Future Trends in the Coal Industry

In Annual Energy Outlook 2008 (June 2008, http:// www.eia.doe.gov/oiaf/aeo/pdf/0383(2008).pdf), the EIA provides forecasts for domestic coal production. The Annual Energy Outlook 2008 reference case represents the EIA’s updated projections in 2008 after the Energy Independence and Security Act of 2007 was passed relating to the increased production of biofuels under the Renewable Fuel Standard mandate.

Coal production in the United States is expected to increase to 1.2 billion short tons (1.1 billion t) by 2015, to 1.4 billion short tons (1.3 billion t) by 2025, and to 1.5 billion short tons (1.4 billion t) by 2030. (See Table 4.5.) Domestic coal consumption is projected to surpass coal production in 2015, 2025, and 2030, with the gap widening at each benchmark. Electric power generation is expected to use most of the coal produced in 2015 (approximately 1.1 billion short tons [997.9 million t]), 2025 (approximately 1.3 billion short tons [1.2 billion t]), and 2030 (1.4 billion short tons [1.3 billion t]). The projections assume the provisions of the Clean Air Act are being enforced.

Coal minemouth prices (the price of coal at the mouth of the mine before transportation and other costs are added) are projected to generally decrease during the projection period from $24.63 per short ton in 2006 to $23.38 in 2015, to $22.75 in 2025, and then rise slightly to $23.32 in 2030. (See Table 4.5.)

The EIA also predicts that U.S. coal exports—about 4% of the coal mined in 2006—will decline to only 2% of coal mined by 2030. (See Table 4.5.) All projections expect the United States to become a net importer of coal after 2015.

TABLE 4.5 Comparison of coal forecasts, 2015, 2025, and 2030
SOURCE: Adapted from “Table 13. Comparison of Coal Projections, 2015,
2025, and 2030 (Million Short Tons, Except Where Noted),” in Annual
Energy Outlook 2008, U.S. Department of Energy, Energy Information
Administration, Office of Integrated Analysis and Forecasting, June 2008,
http://www.eia.doe.gov/oiaf/aeo/pdf/0383(2008).pdf (accessed July 2, 2008)
Projection 2006 AEO2008
reference case
Production1,1631,215
Consumption by sector
Electric power1,0261,125
Coke plants2321
Coal-to-liquids016
Other industrial/buildings6564
Total 1,114 1,225
Net coal exports15.33.3
Exports49.645.3
Imports34.342
Minemouth price
(2006 dollars per short ton)24.6323.38
(2006 dollars per million Btu)1.211.17
Average delivered price to electricity
generators
(2006 dollars per short ton)33.8534.24
(2006 dollars per million Btu)1.691.74
2025 forecast
Production1,1631,363
Consumption by sector
Electric power1,0261,303
Coke plants2320
Coal-to-liquids046
Other industrial/buildings6562
Total 1,114 1,431
Net coal exports15.357.3
Exports49.635.5
Imports34.392.8
Minemouth price
(2006 dollars per short ton)24.6322.75
(2006 dollars per million Btu)1.211.16
Average delivered price to electricity
generators
(2006 dollars per short ton)33.8534.03
(2006 dollars per million Btu)1.691.74
2030 forecast
Production1,1631,455
Consumption by sector
Electric power1,0261,401
Coke plants2318
Coal-to-liquids064
Other industrial/buildings6562
Total 1,114 1,545
Net coal exports15.377.7
Exports49.634.6
Imports34.3112.3
Minemouth price
(2006 dollars per short ton)24 6323.32
(2006 dollars per million Btu)1.211.19
Average delivered price to electricity
generators
(2006 dollars per short ton)33.8535.03
(2006 dollars per million Btu)1.691.78

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Coal

Coal

Origins of coal

Composition of coal

Properties and reactions

Environmental problems associated with the burning of coal

Coal mining

Resources

Uses

Conversion of coal

Resources

Coal is a naturally occurring combustible material consisting primarily of the element carbon, but with low percentages of solid, liquid, and gaseous hydro-carbons and other materials, such as compounds of nitrogen and sulfur. Coal is usually classified into the sub-groups known as anthracite, bituminous, lignite, and peat. The physical, chemical, and other properties of coal vary considerably from sample to sample.

Origins of coal

Coal forms primarily from ancient plant material that accumulated in surface environments where the

complete decay of organic matter was prevented. For example, a plant that died in a swampy area would quickly be covered with water, silt, sand, and other sediments. These materials prevented the plant debris from reacting with oxygen and decomposing to carbon dioxide and water, as would occur under normal circumstances. Instead, anaerobic bacteria (bacteria that do not require oxygen to live) attacked the plant debris and converted it to simpler formsprimarily pure carbon and simple compounds of carbon and hydrogen (hydrocarbons). Because of the way it is formed, coal (along with petroleum and natural gas) is often referred to as a fossil fuel.

The initial stage of the decay of a dead plant is a soft, woody material known as peat. In some parts of the world, peat is still collected from boggy areas and used as a fuel. It is not a good fuel, however, as it burns poorly and with a great deal of smoke.

If peat is allowed to remain in the ground for long periods of time, it eventually becomes compacted as layers of sediment, known as overburden, collect above it. The additional pressure and heat of the over-burden gradually converts peat into another form of coal known as lignite or brown coal. Continued compaction by overburden then converts lignite into bituminous (or soft) coal and finally, anthracite (or hard) coal. Coal has been formed at many times in the past, but most abundantly during the Carboniferous Age (about 300 million years ago) and again during the Upper Cretaceous Age (about 100 million years ago).

Today, coal formed by these processes is often found in layers between layers of sedimentary rock. In some cases, the coal layers may lie at or very near the Earths surface. In other cases, they may be buried thousands of feet or meters under ground. Coal seams range from no more than 3 to 197 ft (1 to 60 m) or more in thickness. The location and configuration of a coal seam determines the method by which the coal will be mined.

Composition of coal

Coal is classified according to its heating value and according to its relative content of elemental carbon. For example, anthracite contains the highest proportion of pure carbon (about 86 to 98%) and has the highest heat value13, 500 to 15, 600 Btu/lb (British thermal units per pound)of all forms of coal. Bituminous coal generally has lower concentrations of pure carbon (from 46 to 86%) and lower heat values (8, 300 to 15, 600 Btu/lb). Bituminous coals are often sub-divided based on their heat value, being classified as low, medium, and high volatile bituminous and sub-bituminous. Lignite, the poorest of the true coals in terms of heat value (5, 500 to 8, 300 Btu/lb) generally contains about 46 to 60% pure carbon. All forms of coal also contain other elements present in living organisms, such as sulfur and nitrogen, that are very low in absolute numbers, but that have important environmental consequences when coals are used as fuels.

Properties and reactions

By far the most important property of coal is that it combusts. When the pure carbon and hydrocarbons found in coal burn completely only two products are formed, carbon dioxide and water. During this chemical reaction, a relatively large amount of energy is released. The release of heat when coal is burned explains the fact that the material has long been used by humans as a source of energy, such as for the heating of homes and other buildings, to run ships and trains, and in many industrial processes.

Environmental problems associated with the burning of coal

The complete combustion of carbon and hydro-carbons described above rarely occurs in nature. If the temperature is not high enough or sufficient oxygen is not provided to the fuel, combustion of these materials is usually incomplete. During the incomplete combustion of carbon and hydrocarbons, other products besides carbon dioxide and water are formed, primarily carbon monoxide, hydrogen, and other forms of pure carbon, such as soot.

During the combustion of coal, minor constituents are also oxidized. Sulfur is converted to sulfur dioxide and sulfur trioxide, and nitrogen compounds are converted to nitrogen oxides. The incomplete combustion of coal and the combustion of these minor constituents results in a number of environmental problems. For example, soot formed during incomplete combustion may settle out of the air and deposit an unattractive coating on homes, cars, buildings, and other structures. Carbon monoxide formed during incomplete combustion is a toxic gas and may cause illness or death in humans and other animals. Oxides of sulfur and nitrogen react with water vapor in the atmosphere and then are precipitated out as acid rain. Acid rain is thought to be responsible for the destruction of certain forms of plant and animal (especially fish) life.

In addition to these compounds, coal often contains a few percent of mineral matter: quartz, calcite, or perhaps clay minerals. These materials do not readily combust and so become part of the ash. The ash then either escapes into the atmosphere or remains in the combustion vessel and must be discarded. Sometimes coal ash also contains significant amounts of lead, barium, arsenic, or other compounds. Whether air borne or in bulk, coal ash can therefore be a serious environmental hazard.

Coal mining

Coal is extracted from the Earth using one of two major techniques, sub-surface or surface (strip) mining. The former method is used when seams of coal are located at significant depths below the Earths surface. The first step in sub-surface mining is to dig vertical tunnels into Earth until the coal seam is reached. Horizontal tunnels are then constructed laterally off the vertical tunnel. In many cases, the preferred method of mining coal by this method is called room-and-pillar mining. In this method, vertical columns of coal (the pillars) are left in place as coal around them is removed. The pillars hold up the ceiling of the seam, preventing it from collapsing on miners working around them. After the mine has been abandoned, however, those pillars may often collapse, bringing down the ceiling of the seam and causing subsidence in land above the old mine.

Surface mining can be used when a coal seam is close enough to the Earths surface to allow the over-burden to be removed economically. In such a case, the first step is to strip off all of the overburden in order to reach the coal itself. The coal is then scraped out by huge power shovels, some capable of removing up to 130 cubic yards (100 cubic meters) at a time. Strip mining is a far safer form of coal mining, but it presents a number of environmental problems. In most instances, an area that has been strip mined is terribly scarred, and restoring the area to its original state is a long and expensive procedure. In addition, any water that comes in contact with the exposed coal or overburden may become polluted and require treatment.

Resources

Coal is regarded as a nonrenewable resource, meaning that it was formed at times during the Earths history, but significant amounts are no longer forming. Therefore, the amount of coal that now exists below the Earths surface is, for all practical purposes, all the coal that humans have available to them for the foreseeable future. When this supply of coal is used up, humans will find it necessary to find some other substituteto meet their energy needs.

Large supplies of coal are known to exist (proven reserves) or thought to be available (estimated resources) in North America, Russia (the former Soviet Union), and parts of Asia, especially China and India. According to 2005 statistics from the World Coal Institute, China produces the largest amount of coal each year, about 45% of the worlds total, followed by the United States 19%, India 8%, Australia 6%, South Africa 5%, Russia 4%, Indonesia 3%, Poland 2%, and Columbia 1%. China is also thought to have the worlds largest estimated resources of coal, as much as 46% of all that exists. In the United States, the largest coal-producing areas are the Appalachian Basin (including the states of Pennsylvania, West Virginia, Tennessee, Ohio, and Alabama) the Illinois Basin (including Illinois, Indiana, and Kentucky), the western areas of the Powder River Basin, Green River Basin, Uinta Basin, and San Juan Basin (including Montana, North Dakota, Wyoming, New Mexico, Utah, and Colorado), and Alaska.

Uses

For many centuries, coal was burned in small stoves to produce heat in homes and factories. Today, the most important use of coal, both directly and indirectly, is still as a fuel. The largest single consumer of coal as a fuel is the electrical power industry. The combustion of coal in power generating plants is used to make steam that, in turn, operates turbines and generators. For a period of more than 40 years, beginning in 1940, the amount of coal used in the United States for this purpose doubled in every decade. Coal is no longer widely used to heat homes and buildings, as was the case a half century ago, but it is still used in industries such as paper production, cement and ceramic manufacture, iron and steel production, and chemical manufacture for heating and for steam generation.

Another use for coal is in the manufacture of coke. Coke is nearly pure carbon produced when soft coal is heated in the absence of air. In most cases, one ton of coal will produce 0.7 ton of coke in this process. Coke is of value in industry because it has a heat value

KEY TERMS

Anthracite Hard coal; a form of coal with high heat content and high concentration of pure carbon.

Bituminous Soft coal; a form of coal with less heat content and pure carbon content than anthracite, but more than lignite.

British thermal unit (Btu) A unit for measuring heat content in the British measuring system.

Coke A synthetic fuel formed by the heating of soft coal in the absence of air.

Combustion A form of oxidation that occurs so rapidly that noticeable heat and light are produced.

Gasification Any process by which solid coal is converted to a gaseous fuel.

Lignite Brown coal; a form of coal with less heat content and pure carbon content than either anthracite or bituminous coal.

Liquefaction Any process by which solid coal is converted to a liquid fuel.

Peat A primitive form of coal with less heat content and pure carbon content than any form of coal.

Strip mining A method for removing coal from seams that are close to the Earths surface.

higher than any form of natural coal. It is widely used in steel making and in certain chemical processes.

Conversion of coal

A number of processes have been developed by which solid coal can be converted to a liquid or gaseous form for use as a fuel. Conversion has a number of advantages. In a liquid or gaseous form, the fuel may be easier to transport, and the conversion process removes a number of impurities from the original coal (such as sulfur) that have environmental disadvantages.

One of the conversion methods is known as gasification. In gasification, crushed coal is reacted with steam and either air or pure oxygen. The coal is converted into a complex mixture of gaseous hydrocarbons with heat values ranging from 100 to 1, 000 Btu. One suggestion has been to construct gasification systems within a coal mine, making it much easier to remove the coal (in a gaseous form) from its original seam.

In the process of liquefaction, solid coal is converted to a petroleum-like liquid that can be used as a fuel for motor vehicles and other applications. On the one hand, both liquefaction and gasification are attractive technologies in the United States because of our very large coal resources. On the other hand, the wide availability of raw coal means that new technologies have been unable to compete economically with the natural product.

During the twentieth century, coal oil and coal gas were important sources of fuel for heating and lighting homes. However, with the advent of natural gas, coal distillates quickly became unpopular since they are somewhat smoky and foul smelling. In the 2000s, petroleum continues to be used more often than coal in industries across the United States. However, coal is still important in producing electricity. In fact, over 85% of the coal used in the United States is used by electric power plants.

See also Air pollution; Hydrocarbon.

Resources

BOOKS

Gorbaty, Martin L., John W. Larsen, and Irving Wender, eds. Coal Science. New York: Academic Press, 1982.

Miller, Bruce G. Coal Energy Systems. Amsterdam and Boston, MA: Elsevier Academic Press, 2005.

Morris, Craig. Energy Switch: Proven Solutions for a Renewable Future. Gabriola Island, Canada: New Society Publishers, 2006.

PERIODICALS

Jia, Renhe. Chemical Reagents For Enhanced Coal Flotation. Coal Preparation 22, no. 3 (2002): 123-149.

Majee, S.R. Sources Of Air Pollution Due To Coal Mining And Their Impacts In The Jaharia Coal Field. Environment International 26, no. 1-2 (2001): 81-85.

OTHER

World Coal Institute (WCI). Home page of WCI. <http://www.worldcoal.org/index.as> (accessed October 5, 2006).

David E. Newton

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Coal

Coal

Introduction

Most of the world's electricity is produced by burning coal, a black, rocky substance consisting mostly of carbon. Coal is also used to fire cement-production kilns and to produce coke (a reduced form of coal) burned in steel manufacture. Coal is destructive to mine, and burning it releases pollutants that cause acid rain and lung cancer, including sulfur dioxide (SO2) and mercury.

However, coal burning is also the cheapest source of baseline electric generation and its use is increasing around the world. Many proposals have been made for technologies to collect the carbon dioxide (CO2) emitted from coal burning and inject it underground or into the ocean. As of 2007, a number of test projects for this technique, known as carbon capture and storage or sequestration, were under way, but no coal-fired power plant was actually sequestering its CO2 output. Some liquid fuels were also being produced from coal, although without sequestration this technology actually increases the amount of CO2 released per unit of energy released.

Proposals have been made to generate clean-burning hydrogen from coal by sequestering the CO2 released by this process. Despite high hopes for such technologies, especially carbon capture and storage, as of early 2008 the burning of coal remained the largest single source of greenhouse-gas emissions and was a major source of air pollution as well, causing several hundred thousand deaths annually.

Historical Background and Scientific Foundations

Formation and History of Coal

Coal is a flammable black rock consisting mostly of carbon. It is composed of the compressed, chemically transformed remnants of plants that grew in vast swamps that flourished from about 286 to 300 million years ago, a period named the Carboniferous because of its association with coal. Because coal was formed in swamps, it tends to occur in extensive horizontal layers called seams or beds. In the millions of years after its formation, coal was covered by sediments that eventually hardened into sedimentary rock.

Today, to obtain coal humans must either tunnel under this rock or, if it is not too thick, strip it away— along with the overlying landscape—to expose the underlying coal seam. This practice, known as strip mining, includes the practice of mountaintop removal, in which the upper portions of entire mountains are removed and cast down into adjacent valleys. Strip mining destroys the original ecology and landscape of the mined area, but because of its cheapness is increasingly used worldwide.

The several grades or qualities of coal are classified according to their hardness and composition. Softer, lower-carbon coals burn more poorly and pollute more, but are in greater supply. The hardest, highest-carbon coal is anthracite, a black rock that is over 90% carbon by weight. Bituminous coal is from 70% to 90% carbon, and tends to be black or dark brown; lignite, the lowest grade, is 60% to 70% carbon. Although estimates of world coal resources are based partly on guesswork, most experts agree that many billions of tons of coal remain in underground deposits.

Small quantities of coal also appear on Earth's surface as outcroppings. This outcrop coal has always been accessible to human beings, and has been used as a fuel for several thousand years. However, for most of the last 800,000 years, wood has been humankind's primary fuel because it is more widely distributed. Coal mining began in earnest in the thirteenth century in Britain, with the rest of Europe soon following suit. Coal became an important fuel at this time because the forests of Europe had been mostly cut down for fuel and timber, creating the world's first energy crisis. Coal mining solved the crisis and began the large-scale emission by human beings of CO2 to Earth's atmosphere.

Decaying or burning wood also releases CO2, but does not increase total atmospheric CO2 because the carbon in the wood was extracted by the growing tree from CO2 in the air originally. Although the carbon found in coal and other fossil fuels was also originally extracted from the air by green plants, this was done so many millions of years ago that the reappearance of that carbon in today's atmosphere is equivalent to adding brand-new carbon to the environment.

From the Middle Ages to the early eighteenth century, coal burning remained small in scale by today's standards and did not release enough CO2 to affect Earth's climate. Coal was burned in furnaces or fireplaces to heat buildings and to cook, brew, and the like, but machinery that could be powered by coal had not yet been invented. In 1712, British inventor Thomas Newcomen (1663–1729) demonstrated the world's first coal-powered steam engine for pumping water. The Newcomen engine proved a commercial success and served as a forerunner for more efficient coal-powered steam engines in factories, boats, and trains. It allowed the water in coal mines to be pumped out more cheaply than did the horse-powered pumps that had been used until that time. For the first time, a fossil fuel was both expanding demand for itself and making its own extraction more economical.

With the invention of commercially viable and popular steam engines, the switch from muscle and wind power to mechanical power based on fossil fuels had begun. By 1800 it was far advanced in the textile industry and other sectors, and CO2 began to be released in quantities large enough to eventually change Earth's climate. The concentration of CO2 in the atmosphere in 1750, about 280 parts per million, is used today as the pre-industrial standard against which subsequent anthropogenic (human-made) increases in greenhouse gases are measured.

By 2007, atmospheric CO2 stood at about 383 parts per million, a 36.8% increase from 1750. Most of this increase had come from coal, with the second-largest share of total anthropogenic CO2 coming from oil. As of 2007, humans had released a total of about 170 billion tons of carbon into the atmosphere from burning coal, about half of which had been absorbed by the oceans and other carbon sinks.

WORDS TO KNOW

ACID RAIN: A form of precipitation that is significantly more acidic than neutral water, often produced as the result of industrial processes.

ANTHROPOGENIC: Made by people or resulting from human activities. Usually used in the context of emissions that are produced as a result of human activities.

BASELINE GENERATION: Generation of electricity for baseline demand, that is, demand that is steady around the clock. Demand for electricity rises above baseline during the daytime and during heat waves, when power demand for air conditioning peaks.

CARBON SEQUESTRATION: The uptake and storage of carbon. Trees and plants, for example, absorb carbon dioxide, release the oxygen, and store the carbon. Fossil fuels were at one time biomass and continue to store the carbon until burned.

FOSSIL FUELS: Fuels formed by biological processes and transformed into solid or fluid minerals over geological time. Fossil fuels include coal, petroleum, and natural gas. Fossil fuels are non-renewable on the timescale of human civilization, because their natural replenishment would take many millions of years.

GREENHOUSE GASES: Gases that cause Earth to retain more thermal energy by absorbing infrared light emitted by Earth's surface. The most important greenhouse gases are water vapor, carbon dioxide, methane, nitrous oxide, and various artificial chemicals such as chlorofluorocarbons. All but the latter are naturally occurring, but human activity over the last several centuries has significantly increased the amounts of carbon dioxide, methane, and nitrous oxide in Earth's atmosphere, causing global warming and global climate change.

INDUSTRIAL REVOLUTION: The period, beginning about the middle of the eighteenth century, during which humans began to use steam engines as a major source of power.

OUTCROPPING: Any rock formation that is accessible from the surface without digging: a protruding mass of rock, usually connected to a larger, buried mass of similar rock.

RENEWABLE ENERGY: Energy obtained from sources that are renewed at once, or fairly rapidly, by natural or managed processes that can be expected to continue indefinitely. Wind, sun, wood, crops, and waves can all be sources of renewable energy.

Coal Usage and Resources

Anthropogenic greenhouse-gas emissions have increased ever since the beginning of the Industrial Revolution, with the most rapid growth occurring most recently. Despite added dependence on oil, which became essential to transportation in the late nineteenth and early twentieth centuries, and on natural gas, which was first exploited on a mass scale in the 1950s and 1960s, coal has remained important. As of 2006, the world was using more coal than ever, namely about 6.3 billion tons (5.7 billion metric tons), 7.6% more than in 2005 and about twice as much as in 1990. As of 2005, 35% of world primary energy (that is, heat energy from fuel before it is transformed into electricity or other forms, as well as electricity produced directly, as by hydroelectric dams, solar cells, or windmills) was obtained from oil, 25% from coal, 21% from natural gas, 12% from renewables (including hydroelectricity), and 6% from nuclear power. About 90% of coal was used for electricity generation, with most of the rest being used to provide heat in the steel and concrete industries.

Coal's role was particularly important in making electricity. Heat from burning coal is used to make pressurized steam, which turns turbines that turn generators that produce electricity. In 2006, 40% of world electricity came from coal, 20% from natural gas, 16% from hydroelectric dams, 15% from nuclear power, 7% from oil, and 2% from miscellaneous sources, including non-hydro renewables. In specific countries, the mix varied: in Poland, for example, 93% of electricity was coal-generated in 2006, while in Germany only 47% was. In the United States, the world's largest energy consumer, 56% of electricity was coal-generated.

Although wind power had become the cheapest form of new electric generating capacity by 2007, it could not be used for baseline generation. Baseline generation is the making of electricity to meet steady, around-the-clock demand. Wind is not suitable for baseline because wind turbines only make electricity when the wind is blowing, so coal remains the cheapest source of baseline electricity. In 2007, coal cost about one sixth as much per unit of energy released as did oil or natural gas.

Estimates of how much coal remains in the ground worldwide vary widely. Energy experts distinguish between coal reserves and coal resources. Reserves are quantities of undug coal that are proven to exist and to be recoverable. Resources are coal deposits whose existence is assumed based on past patterns of discovery, but which have not been actually found. Estimates of world coal resources (undiscovered coal) are unreliable, and shrank from 1980 to 2005 by about 50%, to a little less than 1 trillion tons. World coal reserves are considerably smaller, about half a trillion tons.

Eighty-five percent of proven coal reserves are found in six countries, namely the United States, Russia, India, China, Australia, and South Africa. The United States holds about 30% of world reserves, some 120 billion tons. However, figures even for supposedly proven reserves can be inaccurate: in 2004, Germany decreased its official estimate of its hard coal reserves by 99%, from 23 billion tons (21 billion metric) to 183 million tons (166 million metric). The change, according to the World Energy Council, was due to the fact that earlier estimates of reserves—supposedly proven— were in fact mostly speculative.

In 2005, China was the world's largest coal producer and consumer, producing about 1.1 billion tons (998 million metric) a year, with reserves of 59 billion tons (54 billion metric), giving an annual depletion rate of 1.9% per year. The United States was second, producing 576 billion tons (523 billion metric) a year; Australia was third, producing 202 billion tons (183 billion metric) a year; and India was fourth, producing 200 billions tons (183 billion metric) a year. Although the United States was producing more coal by weight in 2005 than ever before, more of the coal being produced was low-carbon sub-bituminous coal. Thus, in terms of energy production, the country's coal industry had actually peaked in 2000. Although global coal production was rising, a 2007 study by the Energy Watch Group predicted that world coal production was likely to peak around 2030 at about 30% above 2007 levels, then decline slowly thereafter to 1990 levels by about 2100.

Impacts and Issues

Coal and the Environment

Coal is the most destructive form of obtaining primary energy in routine use. (The byproducts of nuclear power generation can be exploited to produce nuclear weapons, which have essentially unlimited destructive capacity, but this is not routine.) Coal's damage to the environment begins during mining. Strip mining, which supplies about 70% of coal from the United States, annihilates existing landscapes above the area mined for coal and destroys additional area that is buried under the removed overburden, as the layer of soil, rock, and forest covering the coal seam is termed. In both shaft and strip mines, sulfur associated with coal dissolves in water, forming sulfuric acid (H2SO4) that runs off into streams. Toxic heavy metals dissolve in the acidic water and accumulate in aquatic food chains. Solid mine wastes are bulky, toxic, and often flammable. Coal mines release methane (CH4), another greenhouse gas.

When coal is burned, it releases scores of pollutants, including mercury, sulfur dioxide (which returns to Earth as acid rain), nitrogen oxides, soot particles, mercury, cadmium, uranium, and lead. According to a 2007 World Bank report, air pollution from coal causes on the order of 400,000 deaths annually in China. A 2004 study commissioned by environmental groups but carried out by a firm often employed by the U.S. Environmental Protection Agency (EPA) found that coal burning causes about 24,000 deaths a year in the United States, including over 8,000 from lung cancer. The accuracy of the latter study was disputed by representatives of the coal industry.

Coal and Climate Change

Coal is a major contributor to anthropogenic climate change. As of 2004, about 84% of global anthropogenic greenhouse-gas emissions were from energy production, with 95% of these emissions (that is, about 80% of all greenhouse-gas emissions) consisting of CO2 released from burning fossil fuels. The other 5% of greenhouse-gas emissions from energy production consisted of methane from coal mining and hydroelectric dams and nitrogen-oxygen (NOx) compounds from fuel burning. Because coal is more carbon-intensive than oil or natural gas, releasing almost all its energy from combustion of carbon rather than of hydrogen, it produces a larger share of CO2 emissions than it does of primary energy. Coal produced only 25% of global primary energy, but 40% of global CO2 emissions. Coal is about twice as carbon-intensive as natural gas.

In the early 2000s, global CO2 emissions were rapidly increasing. From 2003 to 2004 alone, annual emissions increased by over 1.2 billion tons (1.1 billion metric) of CO2, with 86% of this rise caused by increasing energy demand in developing countries. Increased coal usage accounted for 60% of the 2003 to 2004 increase in global CO2 emissions.

Large underground coal fires, especially in China, are a significant source of greenhouse gases, although estimates of their magnitude vary widely. Estimates of CO2 output from Chinese coal fires alone range from 150 to 450 million tons (136 to 408 million metric) of CO2 per year (0.33-1% of annual global CO2 emissions).

Alternative Coal Technologies

If global warming is to be stabilized at a 3.6°F(2°C) change, widely cited by scientists as the approximate limit for non-catastrophic climate change, low-carbon power sources will have to dominate by mid-century. A 2003 study published in Science projected that by about 2050, 75% to 100% of total power demand would have to be met by non-CO2-releasing sources to stabilize warming at this level. At the same time, however, energy demand was projected to grow. Although many experts were urging a rapid expansion of nuclear power, and by 2007 renewable energy resources such as wind were already expanding rapidly (over 30% per year for wind power), most expansion in primary energy was expected to come from coal.

By 2007, concern was mounting about the impact of coal on climate. In October of that year, the state of Kansas became the first governmental body in the United States to cite CO2 emissions as a reason for refusing a construction permit for a new coal-fired electric generation plant. A legal basis for the action had been supplied in April 2007, by a U.S. Supreme Court decision ruling that greenhouse gases, including CO2, are pollutants under the terms of the federal Clean Air Act.

The only way to use steady or increasing amounts of coal while decreasing CO2 emissions is to employ carbon capture and storage (CCS) technologies, also known as carbon sequestration or clean coal technology. There are a number of CCS technology concepts, but all involve pumping CO2 from power plants into ocean waters or deep underground reservoirs rather than allowing it to escape into the air. As of 2007, several industrial-scale demonstration projects were in operation. For example, in Ketzin, Germany, a pilot project was injecting CO2 into sandstone 2,600 ft (800 m) underground. Over two years, the project planned to sequester 66,000 tons (60,000 metric tons) of CO2, about the same amount emitted in a year by 40,000 cars. The European Union was considering requiring all new coal plants in Europe to include CCS technology from 2020 onward, with some experts urging a moratorium on all new coal-plant construction until CCS technology could be applied.

Concerns about CCS involved its cost, whether marine sequestration would enhance acidification of the oceans, and whether gas pumped into underground reservoirs would remain there. Also, some critics of the technology were concerned that making coal less harmful in greenhouse terms will encourage reliance on the fuel, whose extraction is environmentally destructive regardless of how it is burned.

See Also Carbon Sequestration Issues; Energy Contributions; Nuclear Power; Renewable Energy; Wind Power.

BIBLIOGRAPHY

Books

Miller, Bruce G. Coal Energy Systems. San Diego, CA: Academic Press, 2004.

Periodicals

Berstein, Lenny, et al. “Carbon Dioxide Capture and Storage: A Status Report” Climate Policy 6 (2006): 241-246.

Caldeira, Ken. “Climate Sensitivity Uncertainty and the Need for Energy Without CO2 Emission.” Science 299 (2003): 2052-2054.

“Coal Use Grows Despite Warming Worries.” The New York Times (October 28, 2007).

Holloway, Sam. “Storage of Fossil Fuel-Derived Carbon Dioxide Beneath the Surface of the Earth.” Annual Review of Energy and the Environment 26 (2001): 145-166.

Kintisch, Eli. “Report Backs More Projects to Sequester CO2 from Coal.” Science 315 (2007): 1481.

Mufson, Steven. “Democrats Push Coal-to-Liquids Energy Plan.” The Washington Post (June 13, 2007).

Mufson, Steven. “Power Plant Rejected Over Carbon Dioxide for First Time.” The Washington Post (October 19, 2007).

Quadrelli, Roberta. “The Energy-Climate Challenge: Recent Trends in CO2 Emissions from Fuel Combustion.” Energy Policy 35 (2007): 5938-5952.

Sanderson, Katharine. “King Coal Constrained.” Nature 3449 (2007): 14-15.

Stauffer, Hoff. “New Sources Will Drive Global Emissions.” Energy Policy 35 (2007): 5433-5435.

Web Sites

“Emissions of Greenhouse Gases in the United States 2005.” U.S. Energy Information Administration, November 2006. < http://www.eia.doe.gov/oiaf/1605/ggrpt/carbon.html> (accessed November 5, 2007).

Metz, Bert H., et al. “IPCC Special Report on Carbon Dioxide Capture and Storage.” Intergovernmental Panel on Climate Change, 2005. < http://www.ipcc.ch/activity/srccs/SRCCS.pdf> (accessed November 5, 2007).

Sharp, Philip, et al. “The Future of Coal.” Massachusetts Institute of Technology, 2007. < http://web.mit.edu/coal/The_Future_of_Coal.pdf> (accessed November 5, 2007).

Larry Gilman

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Coal

Coal

Coal is a naturally occurring combustible material consisting primarily of the element carbon , but with low percentages of solid, liquid, and gaseous hydrocarbons and other materials, such as compounds of nitrogen and sulfur . Coal is usually classified into the sub-groups known as anthracite, bituminous, lignite, and peat. The physical, chemical, and other properties of coal vary considerably from sample to sample.


Origins of coal

Coal forms primarily from ancient plant material that accumulated in surface environments where the complete decay of organic matter was prevented. For example, a plant that died in a swampy area would quickly be covered with water , silt, sand , and other sediments. These materials prevented the plant debris from reacting with oxygen and decomposing to carbon dioxide and water, as would occur under normal circumstances. Instead, anaerobic bacteria (bacteria that do not require oxygen to live) attacked the plant debris and converted it to simpler forms: primarily pure carbon and simple compounds of carbon and hydrogen (hydrocarbons). Because of the way it is formed, coal (along with petroleum and natural gas ) is often referred to as a fossil fuel.

The initial stage of the decay of a dead plant is a soft, woody material known as peat. In some parts of the world, peat is still collected from boggy areas and used as a fuel. It is not a good fuel, however, as it burns poorly and with a great deal of smoke.

If peat is allowed to remain in the ground for long periods of time, it eventually becomes compacted as layers of sediment, known as overburden, collect above it. The additional pressure and heat of the overburden gradually converts peat into another form of coal known as lignite or brown coal. Continued compaction by overburden then converts lignite into bituminous (or soft) coal and finally, anthracite (or hard) coal. Coal has been formed at many times in the past, but most abundantly during the Carboniferous Age (about 300 million years ago) and again during the Upper Cretaceous Age (about 100 million years ago).

Today, coal formed by these processes is often found in layers between layers of sedimentary rock . In some cases, the coal layers may lie at or very near the earth's surface. In other cases, they may be buried thousands of feet or meters under ground. Coal seams range from no more than 3-197 ft (1-60 m) or more in thickness. The location and configuration of a coal seam determines the method by which the coal will be mined.

Composition of coal

Coal is classified according to its heating value and according to its relative content of elemental carbon. For example, anthracite contains the highest proportion of pure carbon (about 86%-98%) and has the highest heat value—13,500–15,600 Btu/lb (British thermal units per pound)—of all forms of coal. Bituminous coal generally has lower concentrations of pure carbon (from 46% to 86%) and lower heat values (8,300–15,600 Btu/lb). Bituminous coals are often sub-divided on the basis of their heat value, being classified as low, medium, and high volatile bituminous and sub-bituminous. Lignite, the poorest of the true coals in terms of heat value (5,500-8,300 Btu/lb) generally contains about 46%-60% pure carbon. All forms of coal also contain other elements present in living organisms, such as sulfur and nitrogen, that are very low in absolute numbers, but that have important environmental consequences when coals are used as fuels.


Properties and reactions

By far the most important property of coal is that it combusts. When the pure carbon and hydrocarbons found in coal burn completely only two products are formed, carbon dioxide and water. During this chemical reaction, a relatively large amount of energy is released. The release of heat when coal is burned explains the fact that the material has long been used by humans as a source of energy, for the heating of homes and other buildings, to run ships and trains, and in many industrial processes.


Environmental problems associated with the burning of coal

The complete combustion of carbon and hydrocarbons described above rarely occurs in nature. If the temperature is not high enough or sufficient oxygen is not provided to the fuel, combustion of these materials is usually incomplete. During the incomplete combustion of carbon and hydrocarbons, other products besides carbon dioxide and water are formed, primarily carbon monoxide ,hydrogen, and other forms of pure carbon, such as soot.

During the combustion of coal, minor constituents are also oxidized. Sulfur is converted to sulfur dioxide and sulfur trioxide, and nitrogen compounds are converted to nitrogen oxides. The incomplete combustion of coal and the combustion of these minor constituents results in a number of environmental problems. For example, soot formed during incomplete combustion may settle out of the air and deposit an unattractive coating on homes, cars, buildings, and other structures. Carbon monoxide formed during incomplete combustion is a toxic gas and may cause illness or death in humans and other animals. Oxides of sulfur and nitrogen react with water vapor in the atmosphere and then are precipitated out as acid rain . Acid rain is thought to be responsible for the destruction of certain forms of plant and animal (especially fish ) life.

In addition to these compounds, coal often contains a few percent of mineral matter: quartz, calcite, or perhaps clay minerals . These do not readily combust and so become part of the ash. The ash then either escapes into the atmosphere or is left in the combustion vessel and must be discarded. Sometimes coal ash also contains significant amounts of lead , barium , arsenic, or other compounds. Whether air borne or in bulk, coal ash can therefore be a serious environmental hazard.


Coal mining

Coal is extracted from the earth using one of two major techniques, sub-surface or surface (strip) mining . The former method is used when seams of coal are located at significant depths below the earth's surface. The first step in sub-surface mining is to dig vertical tunnels into the earth until the coal seam is reached. Horizontal tunnels are then constructed laterally off the vertical tunnel. In many cases, the preferred method of mining coal by this method is called room-and-pillar mining. In this method, vertical columns of coal (the pillars) are left in place as coal around them is removed. The pillars hold up the ceiling of the seam preventing it from collapsing on miners working around them. After the mine has been abandoned, however, those pillars may often collapse, bringing down the ceiling of the seam and causing subsidence in land above the old mine.

Surface mining can be used when a coal seam is close enough to the earth's surface to allow the overburden to be removed economically. In such a case, the first step is to strip off all of the overburden in order to reach the coal itself. The coal is then scraped out by huge power shovels, some capable of removing up to 100 cubic meters at a time. Strip mining is a far safer form of coal mining, but it presents a number of environmental problems. In most instances, an area that has been strip mined is terribly scarred, and restoring the area to its original state is a long and expensive procedure. In addition, any water that comes in contact with the exposed coal or overburden may become polluted and require treatment.


Resources

Coal is regarded as a non-renewable resource, meaning that it was formed at times during the earth's history, but significant amounts are no longer forming. Therefore, the amount of coal that now exists below the earth's surface is, for all practical purposes, all the coal that humans have available to them for the foreseeable future. When this supply of coal is used up, humans will find it necessary to find some other substitute to meet their energy needs.

Large supplies of coal are known to exist (proven reserves) or thought to be available (estimated resources) in North America , the former Soviet Union, and parts of Asia , especially China and India. According to the most recent data available, China produces the largest amount of coal each year, about 22% of the world's total, with the United States 19%, the former members of the Soviet Union 16%, Germany 10%, and Poland 5% following. China is also thought to have the world's largest estimated resources of coal, as much as 46% of all that exists. In the United States, the largest coal-producing states are Montana, North Dakota, Wyoming, Alaska, Illinois, and Colorado.


Uses

For many centuries, coal was burned in small stoves to produce heat in homes and factories. Today, the most important use of coal, both directly and indirectly, is still as a fuel. The largest single consumer of coal as a fuel is the electrical power industry. The combustion of coal in power generating plants is used to make steam which, in turn, operates turbines and generators. For a period of more than 40 years, beginning in 1940, the amount of coal used in the United States for this purpose doubled in every decade. Coal is no longer widely used to heat homes and buildings, as was the case a half century ago, but it is still used in industries such as paper production, cement and ceramic manufacture, iron and steel production, and chemical manufacture for heating and for steam generation.

Another use for coal is in the manufacture of coke. Coke is nearly pure carbon produced when soft coal is heated in the absence of air. In most cases, one ton of coal will produce 0.7 ton of coke in this process. Coke is of value in industry because it has a heat value higher than any form of natural coal. It is widely used in steel making and in certain chemical processes.


Conversion of coal

A number of processes have been developed by which solid coal can be converted to a liquid or gaseous form for use as a fuel. Conversion has a number of advantages. In a liquid or gaseous form, the fuel may be easier to transport, and the conversion process removes a number of impurities from the original coal (such as sulfur) that have environmental disadvantages.

One of the conversion methods is known as gasification. In gasification, crushed coal is reacted with steam and either air or pure oxygen. The coal is converted into a complex mixture of gaseous hydrocarbons with heat values ranging from 100 Btu to 1000 Btu. One suggestion has been to construct gasification systems within a coal mine, making it much easier to remove the coal (in a gaseous form) from its original seam.

In the process of liquefaction, solid coal is converted to a petroleum-like liquid that can be used as a fuel for motor vehicles and other applications. On the one hand, both liquefaction and gasification are attractive technologies in the United States because of our very large coal resources. On the other hand, the wide availability of raw coal means that new technologies have been unable to compete economically with the natural product.

During the last century, coal oil and coal gas were important sources of fuel for heating and lighting homes. However, with the advent of natural gas, coal distillates quickly became unpopular, since they were somewhat smoky and foul smelling.

See also Air pollution; Hydrocarbon.


Resources

books

Gorbaty, Martin L., John W. Larsen, and Irving Wender, eds. Coal Science. New York: Academic Press, 1982.


periodicals

Jia, Renhe. "Chemical Reagents For Enhanced Coal Flotation." Coal Preparation 22, no. 3 (2002): 123-149.

Majee, S.R. "Sources Of Air Pollution Due To Coal Mining And Their Impacts In The Jaharia Coal Field." Environment International 26, no. 1-2 (2001): 81-85.

Ryan III, T.W. "Coal-Fueled Diesel Development: A Technical Review." Journal of Engineering for Gas Turbines and Power (1994).


David E. Newton

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Anthracite

—Hard coal; a form of coal with high heat content and high concentration of pure carbon.

Bituminous

—Soft coal; a form of coal with less heat content and pure carbon content than anthracite, but more than lignite.

British thermal unit (Btu)

—A unit for measuring heat content in the British measuring system.

Coke

—A synthetic fuel formed by the heating of soft coal in the absence of air.

Combustion

—A form of oxidation that occurs so rapidly that noticeable heat and light are produced.

Gasification

—Any process by which solid coal is converted to a gaseous fuel.

Lignite

—Brown coal; a form of coal with less heat content and pure carbon content than either anthracite or bituminous coal.

Liquefaction

—Any process by which solid coal is converted to a liquid fuel.

Peat

—A primitive form of coal with less heat content and pure carbon content than any form of coal.

Strip mining

—A method for removing coal from seams that are close to the earth's surface.

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Coal

chapter 4
COAL

A HISTORICAL PERSPECTIVE

Although it had been used to create energy for centuries, the first large-scale use of coal occurred during the Industrial Revolution in England from the mid-eighteenth to the mid-nineteenth centuries. At that time the sky was filled with billowing columns of black smoke, soot covered the towns and cities, and workers breathed the thick coal dust swirling around them. Most people then were not concerned with environmental issues because the Industrial Revolution meant jobs to the workers, and factory owners had little desire to control the pollution their factories were creating. In addition, environmental and public health considerations were not as well understood as they are today.

In the United States early colonists used wood to heat their homes because it was so plentiful and coal was less available. Prior to the Civil War (1861–65), some industries used coal as a source of energy, but its major use began with the building of railroads across the country. After the Civil War ended, the United States began to expand its railway system westward and increase its manufacturing capacity. Coal became such a fundamental part of American industrialization that some have called this era the Coal Age. As in England, Americans considered the development of industry a source of national pride. Photographs and postcards of the time proudly featured railroad trains and steel mills with smokestacks belching dark smoke into gray skies.

By the early twentieth century coal had become the major fuel source in the United States, accounting for nearly 90% of the nation's energy requirements. As oil began to heat homes and offices, however, and the growing number of cars used gasoline, coal's dominance declined. By the end of World War II (1939–45), it accounted for only 38% of the energy consumption. Coal fell further out of favor as an energy source in the 1950s and 1960s as oil became more attractive as a cleaner fuel for heating homes and businesses. The decline of coal use continued, with coal producing as little as 18% of the energy used during some years in the early 1970s because of concerns about environmental pollution and the emergence of nuclear power as a promising energy source.

By 1973, however, Americans recognized they could no longer rely on imported oil for their energy. The OPEC oil embargo clearly demonstrated the nation's heavy reliance on foreign sources of energy and its potentially crippling effect on the American economy. Consequently, the nation revived its interest in domestic coal as a plentiful and economical energy source.

After the 1973 embargo, coal and nuclear fuel received more attention, especially in the electric utility sector. In 1977 President Jimmy Carter called for a two-thirds annual increase in national coal production by 1985. He also asked utility companies and other large industries to convert their operations to coal and proposed a ten-year, $10 billion program to encourage domestic coal production. In 2003 more coal was produced within the United States than any other form of energy, generating 22.3 quadrillion Btu and 32% of all energy produced. (See Figure 1.4 in Chapter 1.) Coal was the second largest source of energy consumed in the United States in 2003, after petroleum.

WHAT IS COAL?

Coal is a black, combustible, mineral solid that develops over millions of years from the partial decomposition of plant matter in an airless space, under increased temperature and pressure. Coal beds, sometimes called seams, are found in the earth between beds of sandstone, shale, and limestone and range in thickness from less than an inch to more than one hundred feet. Approximately five to ten feet of ancient, composted plant material have been compressed to create each foot of coal.

Coal is used as a fuel and in the production of coke (the solid substance left after coal gas and coal tar have been

FIGURE 4.1

extracted), coal gas, water gas, and many coal-tar compounds. When coal is burned, its fossil energy—sunlight converted and stored by plants over millions of years—is released. One ton of coal produces an average of 22 million Btu, about the same heating value as 22,000 cubic feet of natural gas, 159 gallons of distillate fuel oil, or one cord of seasoned firewood. (A cord is a stack of wood four feet by four feet by eight feet, or 128 cubic feet.)

CLASSIFICATIONS OF COAL

There are four basic types of coal. Classifications, or "coal ranks," are based on how much carbon, volatile matter, and heating value are contained in the coal.

  • Anthracite, or hard coal, is the highest ranked coal. It is hard and jet black, with a moisture content of less than 15%. Anthracite is used mainly for generating electricity and for space heating. It contains approximately 22 to 28 million Btu per ton, with an ignition temperature of approximately 925 to 970 degrees Fahrenheit. Anthracite is mined mainly in northeastern Pennsylvania. (See Figure 4.1.)
  • Bituminous, or soft coal, is the most common coal. It is dense and black, with a moisture content of less than 20% and an ignition range of 700 to 900 degrees Fahrenheit. Bituminous coal is used to generate electricity, for space heating, and to produce coke. Bituminous coal contains a heating value range of 19 to 30 million Btu per ton. It is mined chiefly in the Appalachian and Midwest regions of the United States. (See Figure 4.1.)
  • Sub bituminous coal, or black lignite, is dull black in color and generally contains 20 to 30% moisture. Black lignite is used for generating electricity and for space heating. It contains 16 to 24 million Btu per ton. Black lignite is mined primarily in the western United States. (See Figure 4.1.)

TABLE 4.1

Coal production, selected years, 1949–2003
(Million short tons)
Rank Mining method Location
Year Bituminous coal1 Subbituminous coal Lignite Anthracite1 Underground Surface East of the Mississippi1 West of the Mississippi1 Total1
1Beginning in 2001, includes a small amount of refuse recovery.
2Included in "Bituminous coal."
R = Revised.
P = Preliminary.
E = Estimate.
Note: Totals may not equal sum of components due to independent rounding.
Web Pages: For data not shown for 1951–1969, see http://www.eia.doe.gov/emeu/aer/coal.html. For related information, see http://www.eia.doe.gov/fuelcoal.html.
source: "Table 7.2. Coal Production, Selected Years, 1949–2003 (Million Short Tons)," in Annual Energy Review 2003, U.S. Department of Energy, Energy Information Administration, Office of Energy Markets and End Use, September 7, 2004, http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf (accessed September 28, 2004)
1949437.92242.7358.9121.7444.236.4480.6
1950516.32244.1421.0139.4524.436.0560.4
1955464.62226.2358.0132.9464.226.6490.8
1960415.52218.8292.6141.7413.021.3434.3
1965512.12214.9338.0189.0499.527.4527.0
1970578.516.48.09.7340.5272.1567.844.9612.7
1971521.322.28.78.7277.2283.7509.951.0560.9
1972556.827.511.07.1305.0297.4538.264.3602.5
1973543.533.914.36.8300.1298.5522.176.4598.6
1974545.742.215.56.6278.0332.1518.191.9610.0
1975577.551.119.86.2293.5361.2543.7110.9654.6
1976588.464.825.56.2295.5389.4548.8136.1684.9
1977581.082.128.25.9266.6430.6533.3163.9697.2
1978534.096.834.45.0242.8427.4487.2183.0670.2
1979612.3121.542.54.8320.9460.2559.7221.4781.1
1980628.8147.747.26.1337.5492.2578.7251.0829.7
1981608.0159.750.75.4316.5507.3553.9269.9823.8
1982620.2160.952.44.6339.2499.0564.3273.9838.1
1983568.6151.058.34.1300.4481.7507.4274.7782.1
1984649.5179.263.14.2352.1543.9587.6308.3895.9
1985613.9192.772.44.7350.8532.8558.7324.9883.6
1986620.1189.676.44.3360.4529.9564.4325.9890.3
1987636.6200.278.43.6372.9545.9581.9336.8918.8
1988638.1223.585.13.6382.2568.1579.6370.7950.3
1989659.8231.286.43.3393.8586.9599.0381.7980.7
1990693.2244.388.13.5424.5604.5630.2398.91,029.1
1991650.7255.386.53.4407.2588.8591.3404.7996.0
1992651.8252.290.13.5407.2590.3588.6409.0997.5
1993576.7274.989.54.3351.1594.4516.2429.2945.4
1994640.3300.588.14.6399.1634.4566.3467.21,033.5
1995613.8328.086.54.7396.2636.7544.2488.71,033.0
1996630.7340.388.14.8409.8654.0563.7500.21,063.9
1997653.8345.186.34.7420.7669.3579.4510.61,089.9
1998640.6385.985.85.3417.7699.8570.6547.01,117.5
1999601.7406.787.24.8391.8708.6529.6570.81,100.4
2000574.3409.285.64.6373.7700.0507.5566.11,073.6
2001611.3434.480.011.9380.61747.11528.81598.911,127.7
2002R572.1R438.4R82.5R1.4R357.4R736.9R492.9601.4R1,094.3
2003E559.2E428.4E80.6E1.3E351.2E718.3E468.2E601.3P1,069.5
  • Lignite, the lowest ranked coal, is brownish-black in color and has a high moisture content. It tends to disintegrate when exposed to weather. Lignite is used mainly to generate electricity and contains about 9 to 17 million Btu per ton. Lignite has an ignition temperature of approximately 600 degrees Fahrenheit. Most lignite is mined in North Dakota, Montana, Texas, California, and Louisiana. (See Figure 4.1.)

Bituminous coal accounts for the largest share of all coal production; sub bituminous is second. (See Table 4.1.) In 2003 production of all types of coal totaled nearly 1.1 billion short tons. (A short ton of coal is 2,000 pounds.) Of that, nearly 1 billion short tons (92%) were bituminous and sub bituminous coal. Lignite and anthracite accounted for the remainder.

LOCATIONS OF COAL DEPOSITS

Coal is found in about 13%, or 458,600 square miles, of the total land area of the United States. (See Figure 4.1.) Geologists have divided U.S. coalfields into three geographical zones: the Appalachian, Interior, and Western regions. The Appalachian region is subdivided into three areas: Northern (Ohio, Pennsylvania, Maryland, and northern West Virginia); Central (Virginia, southern West Virginia, eastern Kentucky, and Tennessee); and Southern Appalachia (Alabama). Coal production in the Interior region occurs in Illinois, Indiana, western Kentucky, Iowa, Missouri, Kansas, Arkansas, Oklahoma, Louisiana, and Texas. The Western region includes the Northern Great Plains (Montana, Wyoming, northern Colorado, and North and South Dakota), the Rocky Mountains, the Southwest (southern Colorado, Utah, Arizona, and New Mexico), and the Northwest (Washington and Alaska).

Historically, more coal has been mined east of the Mississippi River than west of the Mississippi, but the West's proportion of total production has increased almost every year since 1965, overtaking the east in 1999. (See Table 4.1.) In 1965 the production of coal in the West was 27 million short tons, only 5% of the national total. By 1999 western production had increased more than twenty-fold, to 570.8 million short tons, or 52% of the total. The amount of coal mined east of the Mississippi that year was 529.6 million short tons. In 2003 slightly more than 601 million short tons of coal were mined west of the Mississippi, while slightly more than 468 million short tons were mined to the east. Western production neared 56% of the total mined.

The growth in coal production in the West has been partly the result of environmental concerns that have led to an increased demand for low-sulfur coal, which is concentrated in the West. In addition, surface mining, which is cheaper and more efficient, is more prevalent in the West. Finally, improved rail service has made it easier to deliver this low-sulfur coal to utility plants located east of the Mississippi River.

COAL MINING METHODS

The method used to mine coal depends on the terrain and the depth of the coal. Prior to the early 1970s, most coal was taken from underground mines. Since that time, however, coal production has shifted from underground mines to surface mines. (See Table 4.1 and Figure 4.2.)

Underground mining is required when the coal lies deeper than 200 feet below ground level. The depth of most underground mines is less than 1,000 feet, but a few go down as far as 2,000 feet. In underground mines some coal must be left untouched in order to form pillars that prevent the mine from caving in. In both underground mines and surface mines, natural features such as folded, faulted, and interlaid rock strata reduce the amount of coal that can be recovered.

Surface mines are usually less than 200 feet deep and can be developed in flat or hilly terrain. Area surface mining is practiced on large plots of relatively flat ground, while contour surface mining follows coal beds along hillsides. (See Figure 4.3.) Open pit mining is used to mine thick, steeply inclined coal beds and uses a combination of contour and area mining methods.

FIGURE 4.2

The growing prevalence of surface coal mining and the closing of nonproductive mines led to increases in coal mining productivity through the 1980s and 1990s. (See Figure 4.4.) In 2000 average productivity reached an all-time high of seven short tons per miner hour. Productivity dipped a bit in 2001 and 2002, but by 2003 it had nearly returned to the 2000 level. Because surface mines are easier to work, they average up to three times the productivity of underground mines. In 2003 the productivity for surface mines was 10.7 short tons of coal per miner hour, while underground mines produced 4.1 short tons per miner hour, as reported in the Annual Energy Review 2003, published in 2004 by the Energy Information Administration (EIA) of the U.S. Department of Energy (DOE).

COAL IN THE DOMESTIC MARKET

Overall Production and Consumption

The EIA noted in its Annual Energy Review 2003 that the nation consumed 558.4 million short tons of coal in 1974. Twenty-nine years later, in 2003, consumption had grown to nearly 1.1 billion short tons. (Figure 4.5 shows the flow of coal in 2003.) The increases in coal consumption were greatest in the electric utility sector, as many existing electric power plants switched to coal from more expensive oil and gas, and many new, coal-fired power plants were constructed in the 1970s.

Coal Consumption by Sector

To make electricity, coal is pulverized and burned to produce steam, which then drives electric generators.

FIGURE 4.3

Each ton of coal used by an electric generator produces about 2,000 kilowatt-hours of electricity. In household terms each pound of coal produces enough electricity to light ten 100-watt light bulbs for one hour.

Electric utility companies are by far the largest consumers of coal today. (See Figure 4.5 and Figure 4.6.) They accounted for 92% of domestic coal consumption, or 1 billion short tons, in 2003. Coal-fired plants produced nearly 22.3 Btu of electricity, or 40% of U.S. electricity net generation, in 2003. (See Figure 1.5 in Chapter 1.)

The industrial sector was the second-largest consumer of coal in 2003, accounting for 8% of coal use (see Figure 4.6), or 85.4 million short tons. Coal is used in many industrial applications, including the chemical, cement, paper, synthetic fuels, metals, and food-processing industries.

Coal was once a significant fuel source in the residential and commercial sector. (See Figure 4.6.) In 1949 these sectors used 116.5 million short tons of coal. After the late 1940s, however, coal was replaced by oil, natural gas, and electricity, which are cleaner and more convenient. By 1970 only 16.1 million short tons of coal were used in the residential and commercial sectors. Since then, residential and commercial coal use has continued to decline, falling to 4.5 million short tons in 2003, or far less than 1% of total coal use.

The Price of Coal

In 2003 the average price of coal fell to $17 per short ton, up slightly from the all-time low in 2000 and only 33% of the 1975 price in real dollars, which are adjusted for inflation. (See Table 4.2.) On a per-Btu basis, coal remains the least expensive fossil fuel. In 2000 the average cost of coal was $1.27 per million Btu, compared with $5.68 per million Btu for natural gas and $4.74 per million Btu for residential fuel oil, according to the Annual Energy Review 2003.

ENVIRONMENTAL AND HEALTH CONCERNS ABOUT COAL

Problems

The negative side of energy use—pollution of the environment—is not a recent problem. In 1306 King Edward I of England so objected to the noxious smoke from London's coal-burning fires that he banned coal's use by everyone except blacksmiths. The enormous scale of today's energy use has increased environmental concerns.

Coal-fired electric power plants emit gases that are harmful to the environment. Scientists believe that burning huge quantities of fossil fuels causes the "greenhouse

FIGURE 4.4

effect," in which gases from the fuels trap heat in the earth's atmosphere and cause increased warming, which threatens the environment. Burning coal also contributes to the formation of acid rain and to public health concerns. Sulfur dioxide, for instance, has been shown to cause respiratory problems.

Carbon dioxide accounts for the largest share of greenhouse gas emissions. In 2002 the combustion of coal in the United States produced 2.1 billion metric tons of carbon dioxide, or 36% of total carbon dioxide emissions from all fossil fuels used in the United States. (See Figure 4.7.)

acid rain. Acid rain is any form of precipitation that contains a greater-than-normal amount of acid. Even nonpolluted rain is slightly acidic (with a pH of about 5.6) because rainwater combines with the carbon dioxide normally found in the air to produce a weak acid called carbonic acid. But pollutants in the air can increase the acidity of rain and other forms of precipitation, such as snow and fog.

Chemicals such as oxides of sulfur and nitrogen, which are given off during the combustion of fossil fuels, are pollutants that combine with precipitation to form acids. These oxides increase in the air because of automobile exhaust, industrial and power plant emissions, and other fossil fuel combustion processes. In many parts of the world acid rain has caused significant damage to forests, lakes, and other ecosystems.

FIGURE 4.5

TABLE 4.2

Coal prices, selected years, 1949–2003
(Dollars per short ton)
Bituminous Coal Subbituminous Coal Lignite1 Anthracite Total
Year Nominal Real2 Nominal Real2 Nominal Real2 Nominal Real2 Nominal Real2
1Because of withholding to protect company confidentiality, lignite prices exclude Texas for 1955–1977 and Montana for 1974–1978. As a result, lignite prices for 1974–1977 are North Dakota only.
2In chained (2000) dollars, calculated by using gross domestic product implicit price deflators.
3Through 1978, subbituminous cola included in "Bituminous coal."
R = Revised.
E = Estimate.
Note: Prices are free-on-board (f.o.b.) rail/barge prices, which are the f.o.b. prices of coal at the point of first sale, excluding freight or shipping and insurance costs.
Web Pages: For data not shown for 1951–1969, see http://www.eia.doe.gov/emeu/aer/coal.html. For related information, see http://www.eia.doe.gov/fuelcoal.html.
source: "Table 7.8. Coal Prices, Selected Years, 1949–2003 (Dollars per Short Ton)," in Annual Energy Review 2003, U.S. Department of Energy, Energy Information Administration, Office of Energy Markets and End Use, September 7, 2004, http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf (accessed September 28, 2004)
194934.903,R29.97332.37R14.498.90R54.435.24R32.05
195034.863,R29.40332.41R14.589.34R56.505.19R31.40
195534.513,R24.06332.38R12.708.00R42.684.69R25.02
196034.713,R22.38332.29R10.888.01R38.074.83R22.96
196534.453,R19.75332.13R9.458.51R37.764.55R20.19
197036.303,R22.88331.86R6.7611.03R40.066.34R23.03
197137.133,R24.66331.93R6.6812.08R41.787.15R24.73
197237.783,R25.79332.04R6.7612.40R41.117.72R25.59
197338.713,R27.35332.09R6.5613.65R42.868.59R26.97
1974316.013,R46.11332.19R6.3122.19R63.9015.82R45.56
1975319.793,R53.08333.17R8.3432.26R84.8919.35R50.92
1976320.113,R50.03333.74R9.3033.92R84.3919.56R48.66
1977320.593,R48.16334.03R9.4334.86R81.5419.95R46.66
1978R22.643,R48.48335.68R12.4135.25R77.0421.86R47.77
197927.31R55.129.55R19.276.48R13.0841.06R82.8723.75R47.93
198029.17R53.9811.08R20.507.60R14.0642.51R78.6624.65R45.61
198131.51R53.3012.18R20.608.85R14.9744.28R74.9026.40R44.66
198232.15R51.2513.37R21.319.79R15.6149.85R79.4727.25R43.44
198331.11R47.7113.03R19.989.91R15.2052.29R80.1925.98R39.84
198430.63R45.2712.41R18.3410.45R15.4548.22R71.2725.61R37.85
198530.78R44.1512.57R18.0310.68R15.3245.80R65.7025.20R36.15
198628.84R40.4812.26R17.2110.64R14.9344.12R61.9223.79R33.39
198728.19R38.5111.32R15.4710.85R14.8243.65R59.6323.07R31.52
198827.66R36.5410.45R13.8110.06R13.2944.16R58.3422.07R29.16
198927.40R34.8810.16R12.939.91R12.6242.93R54.6521.82R27.78
199027.43R33.629.70R11.8910.13R12.4239.40R48.2921.76R26.67
199127.49R32.559.68R11.4610.89R12.9036.34R43.0321.49R25.45
199226.78R31.009.68R11.2110.81R12.5134.24R39.6421.03R24.34
199326.15R29.599.33R10.5611.11R12.5732.94R37.2719.85R22.46
199425.68R28.458.37R9.2710.77R11.9336.07R39.9619.41R21.50
199525.56R27.758.10R8.7910.83R11.7639.78R43.1918.83R20.44
199625.17R26.827.87R8.3910.92R11.6436.78R39.1918.50R19.71
199724.64R25.827.42R7.7810.91R11.4335.12R36.8118.14R19.01
199824.87R25.786.96R7.2111.08R11.4942.91R44.4817.67R18.32
199923.92R24.446.87R7.0211.04R11.2835.13R35.9016.63R16.99
200024.15R24.157.12R7.1211.41R11.4140.90R40.9016.78R16.78
200125.36R24.776.67R6.5211.52R11.2547.67R46.5717.38R16.98
2002R26.57R25.56R7.34R7.06R11.07R10.65R47.78R45.97R17.98R17.30
2003E26.5725.147.346.9511.0710.4847.7845.2117.9817.01

health issues. Emissions from coal-fired power plants include mercury, sulfur oxides, and nitrogen oxides. Mercury reaches humans when they eat fish contaminated by airborne mercury that settles in lakes and streams. Scientific data have not yet determined a significant link between mercury that originates from coal-fired power plants and significant health effects in humans. However, sulfur oxides and nitrogen oxides contribute to air pollution, which can cause upper respiratory conditions (see Table 4.3.)

Coal miners are at risk for developing pneumoconiosis (black lung disease), which results from chronic inhalation of coal dust. This risk has been drastically reduced, however, by using personal protective equipment such as dust masks and respirators, covering the walls of tunnels and shafts with pulverized white rock to lower the level of the dust, and spraying water to promote settling of the dust.

Solutions

the clean coal technology law. In 1984 Congress established the DOE's Clean Coal Technology (CCT) program (PL 98–473). Congress directed the DOE to administer cost-shared projects (financed by both industry and government) to demonstrate clean coal technologies. The demonstration projects had the goal of

FIGURE 4.6

TABLE 4.3

Air pollutants, health risks, and contributing sources
Pollutants Health risks Contributing sources
1Ozone refers to tropospheric ozone which is hazardous to human health.
source: Fred Seitz and Christine Plepys, "Table 1. Criteria Air Pollutants, Health Risks and Sources," in Healthy People 2000: Statistical Notes, Number 9, Centers for Disease Control and Prevention, National Center for Health Statistics, September 1995, http://www.cdc.gov/nchs/data/statnt/statnt09.pdf (accessed November 21, 2004)
Ozone1 (O3)Asthma, reduced respiratory function, eye irritationCars, refineries, dry cleaners
Particulate matter (PM-IO)Bronchitis, cancer, lung damageDust, pesticides
Carbon monoxide (CO)Blood oxygen carrying capacity reduction, cardiovascular and nervous system impairmentsCars, power plants, wood stoves
Sulphur dioxide (SO2)Respiratory tract impairment, destruction of lung tissuePower plants, paper mills
Lead (Pb)Retardation and brain damage, esp. childrenCars, nonferrous smelters, battery plants
Nitrogen dioxide (NO2)Lung damage and respiratory illnessPower plants, cars, trucks

using coal in more environmentally and economically efficient ways.

clean coal technology and the clean air act. The stated goal of both Congress and the DOE has been to

FIGURE 4.7

develop cost-effective ways to burn coal more cleanly, both to control acid rain and to improve the nation's energy security by reducing dependence on imported fuels. One strategy is a slow, phased-in approach in which utility companies and states reduce their emissions in stages.

Under the Clean Air Act of 1990 (PL 101–549), restrictions on sulfur dioxide and nitrogen oxide emissions took effect in 1995 and tightened in 2000. Each round of regulation requires coal-burning utilities to find lower-sulfur coal or to install cleaner technology, such as "scrubbers" that reduce smokestack emissions that contribute heavily to air pollution. When the first Clean Air Act was passed in 1970, it was aimed at changing the air-quality standards at new generating stations, and older coal-using plants were exempt. Under the 1990 act, older plants are also covered by the regulations.

In January 2004 the Environmental Protection Agency (EPA) proposed new regulations for reducing emissions of sulfur dioxide, nitrogen oxides, and mercury from coal-burning power plants. The Interstate Air Quality Rule focuses on twenty-nine eastern states whose sulfur dioxide and nitrogen oxide emissions are significantly contributing to fine particle and ozone pollution problems. The Utility Mercury Reductions Rule focuses on controlling mercury emissions from power plants. (When taken into the body, mercury can result in serious health effects in children.) These proposed actions strengthen Clean Air Act regulations and standards but are not specifically mandated by the Congress. When implemented, the EPA expects them to result in rapid and significant air quality improvement.

cleaner coal use. The coal-burning process can be cleaned by physical or chemical methods. Scrubbers, which are a physical method commonly used to reduce sulfur dioxide emissions, filter coal emissions by spraying lime or a calcium compound and water across the emission stream before it leaves the smokestack. The sulfur dioxide bonds to the spray and settles as a mudlike substance that can be pumped out for disposal. Scrubbers, however, are expensive to operate, so particulate collectors are the most common emissions cleaners for coal. While they are cheaper to operate than scrubbers, they are less effective. Cooling towers reduce heat released into the atmosphere and reduce some pollutants. Chemical cleaning, a relatively new technology not yet in widespread use, involves the use of biological or chemical agents to clean emissions.

Under the new environmental regulations of the 1990 Clean Air Act and its amendments, plants with coal-generated boilers must be built to reduce sulfur emissions by 70 to 90%. New, high-sulfur coal electricity plants, designed to meet emission standards, use 30% of their construction costs on pollution control equipment and take up to 5% of their power output to operate this equipment. Research to lower these costs is important because of the quantity of electricity produced with coal in the United States.

The EIA's Annual Energy Review 2003 (2004) notes that in 2002 coal-fired electricity plants that had environmental equipment installed had a production capacity of 329.5 gigawatts (1 gigawatt equals 1,000 megawatts). Of this capacity, 100% was generated within plants using particulate collectors, 47% in those with cooling towers, and 30% in those with scrubbers. (Some plants use more than type of environmental equipment so the figures add up to more than 100%.) The use of scrubbers is projected to increase as new regulations from the 1990 Clean Air Act and its amendments take effect.

COAL EXPORTS

Since 1950 the United States has produced more coal than it has consumed. The excess production has allowed the United States to become a significant exporter of coal to other nations. However, exports of this energy source have declined dramatically since 1991, when the U.S. exported 109 million short tons of coal. In 2003 the U.S. exported 43 million short tons, up from 39.6 million short tons in 2002, the lowest amount exported since 1961. (See Table 4.4.)

In 2003 coal made up 28% of all U.S. energy exports. (See Figure 1.5 in Chapter 1.) Europe received 35% of U.S. coal exports. The individual countries that bought the most U.S. coal were Canada, Brazil, Italy, and the Netherlands. (See Table 4.4.)

INTERNATIONAL COAL USAGE

The Annual Energy Review 2003 (2004) reported that world coal production was 1.1 billion short tons in 2002 and accounted for 21% of world energy production. China led the world in coal production, mining just over 1.5 billion short tons, followed by the United States at 1.1 billion short tons. (See Figure 4.8.) Other major producers were India, Australia, Russia, South Africa, Germany, and Poland.

World consumption of coal in 2002 totaled 5.3 billion short tons. Besides being the largest producer, China was

FIGURE 4.8

TABLE 4.4

Coal exports by country of destination, 1960–2003
(Million short tons)
Europe
Year Canada Brazil Belgium and Luxembourg Denmark France Germany1 Italy Netherlands Spain United Kingdom Other Total Japan Other Total
1Through 1990, data for Germany are for the former West Germany only. Beginning in 1991, data for Germany are for the unified Germany, i.e., the former East Germany and West Germany.
(s) = Less than 0.05 million short tons.
Note: Totals may not equal sum of components due to independent rounding.
source: "Table 7.4. Coal Exports by Country of Destination, 1960–2003 (Million Short Tons)," in Annual Energy Review 2003, U.S. Department of Energy, Energy Information Administration, Office of Energy Markets and End Use, September 7, 2004, http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf (accessed September 28, 2004)
196012.81.11.10.10.84.64.92.80.30.02.417.15.61.338.0
196112.11.01.00.10.74.34.82.60.20.02.015.76.61.036.4
196212.31.31.3(s)0.95.16.03.30.8(s)1.819.16.51.040.2
196314.61.22.7(s)2.75.67.95.01.50.02.427.76.10.950.4
196414.81.12.3(s)2.25.28.14.21.40.02.626.06.51.149.5
196516.31.22.2(s)2.14.79.03.41.4(s)2.325.17.50.951.0
196616.51.71.8(s)1.64.97.83.21.2(s)2.523.17.81.050.1
196715.81.71.40.02.14.75.92.21.00.02.119.412.21.050.1
196817.11.81.10.01.53.84.31.51.50.01.915.515.80.951.2
196917.31.80.90.02.33.53.71.61.80.01.315.221.41.256.9
197019.12.01.90.03.65.04.32.13.2(s)1.821.827.61.271.7
197118.01.90.80.03.22.92.71.62.61.71.116.619.71.157.3
197218.71.91.10.01.72.43.72.32.12.41.116.918.01.256.7
197316.71.61.20.02.01.63.31.82.20.91.314.419.21.653.6
197414.21.31.10.02.71.53.92.62.01.40.916.127.31.860.7
197517.32.00.60.03.62.04.52.12.71.91.619.025.42.666.3
197616.92.22.2(s)3.51.04.23.52.50.82.119.918.82.160.0
197717.72.31.50.12.10.94.12.01.60.62.115.015.93.554.3
197815.71.51.10.01.70.63.21.10.80.42.211.010.12.540.7
197919.52.83.20.23.92.65.02.01.41.44.423.915.74.166.0
198017.53.34.61.77.82.57.14.73.44.16.041.923.16.091.7
198118.22.74.33.99.74.310.56.86.42.38.857.025.98.7112.5
198218.63.14.82.89.02.311.35.95.62.07.651.325.87.5106.3
198317.23.62.51.74.21.58.14.23.31.26.433.117.96.177.8
198420.44.73.90.63.80.97.65.52.32.95.332.816.37.281.5
198516.45.94.42.24.51.110.36.33.52.710.345.115.49.992.7
198614.55.74.42.15.40.810.45.62.62.98.442.611.411.485.5
198716.25.84.60.92.90.59.54.12.52.66.634.211.112.379.6
198819.25.36.52.84.30.711.15.12.53.78.545.114.111.395.0
198916.85.77.13.26.50.711.26.13.34.58.951.613.812.9100.8
199015.55.88.53.26.91.111.98.43.85.29.558.413.312.7105.8
199111.27.17.54.79.51.711.39.64.76.210.465.512.313.0109.0
199215.16.47.23.88.11.09.39.14.55.68.557.312.311.4102.5
19938.95.25.20.34.00.56.95.64.14.16.937.611.911.074.5
19949.25.54.90.52.90.37.54.94.13.47.335.810.210.771.4
19959.46.44.52.13.72.09.17.34.74.710.748.611.812.488.5
199612.06.54.61.33.91.19.27.14.16.29.847.210.514.290.5
199715.07.54.30.43.40.97.04.84.17.29.241.38.011.883.5
199820.76.53.20.33.21.25.34.53.25.96.933.87.79.478.0
199919.84.42.10.02.50.64.03.42.53.24.322.55.06.758.5
200018.84.52.90.13.01.03.72.62.73.35.725.04.45.858.5
200117.64.62.80.02.20.95.42.11.62.53.320.82.13.648.7
200216.73.52.40.01.31.03.11.71.91.92.415.61.32.639.6
200320.83.51.80.31.30.52.82.01.81.53.215.1(s)3.643.0

FIGURE 4.9

also the largest consumer of coal in 2002, using more than 1.4 billion short tons, followed by the United States at 1.1 billion short tons. (See Figure 4.9.) Other major consumers included India, Germany, Russia, and Japan.

FUTURE TRENDS IN THE COAL INDUSTRY

In Annual Energy Outlook 2004 the EIA forecasted that domestic coal production will increase to almost 1.3 billion short tons by 2015 and increase slightly from there to almost 1.4 billion short tons by 2020 and approximately 1.5 billion short tons by 2025. (See Table 4.5.) Domestic consumption is projected to match production, reaching nearly 1.3 billion short tons in 2015, almost 1.4 billion short tons by 2020, and approximately 1.5 billion short tons by 2025. Electricity generation will still use the majority of coal in 2015 (approximately 1.2 billion short tons), 2020, and 2025. Total coal consumption for electricity generation is expected to increase by an average of 1.8% per year because of high natural gas prices.

Coal prices are projected to decline from $17.90 per short ton in 2002 (see Table 4.5) to a low of $16.19 per short ton in 2016. These price decreases will likely occur because of improvements in mine productivity, a shift to western production, declines in rail transportation costs, and competitive pressures on labor costs. After 2016 prices will likely rise as productivity improvements slow and the industry faces increasing costs to open new mining areas. By 2025 the price of coal is projected to rise to $16.57 per short ton. (See Table 4.5.) Nevertheless, this price is still below the 2002 price.

Environmental concerns about acid rain and global warming may continue to grow. The outlook for the U.S. coal industry could be affected by acid rain legislation, the development of clean coal technologies, and, over the longer term, the problem of global warming. Environmental issues will increasingly become international problems. China, with nearly five times the population of the United States and a growing economy, may surpass the United States in carbon emissions by 2020.

The EIA predicts that U.S. coal exports will decline from 6% in 2002 to less than 3% in 2025. This decline will likely be the result of a decline in the demand for coal in Europe and the Americas. Also, other countries are expected to reduce costs and gain currency exchange advantages against the U.S. dollar.

TABLE 4.5

Comparison of coal forecasts, 2015, 2020, and 2025
(Million short tons, except where noted)
AEO2004 Other forecasts
Projection 2002 Reference Low economic growth High economic growth EVA Hill & Associates
1The average coal price is a weighted average of the projected spot market FOB mine price for all domestic coal.
2The minemouth price represents an average for domestics team coal only. Exports and coking coal are not included in the average.
3The prices provided by Hill & Associates were converted from 2003 dollars to 2002 dollars in order to be consistent with AEO 2004.
Btu = British thermal unit.
NA = Not available.
source: "Table 33. Comparison of Coal Forecasts, 2015, 2020, and 2025 (Million Short Tons, except Where Noted)," in Annual Energy Outlook 2004, U.S. Department of Energy, Energy Information Administration, Office of Integrated Analysis and Forecasting, January 2004, http://tonto.eia.doe.gov/FTPROOT/forecasting/0383(2004).pdf (accessed November 16, 2004)
2015
Production 1,105 1,285 1,262 1,288 1,114 1,204
Consumption by sector
Electricity generation9761,2001,1801,2001,0421,144
Coking plants232121211818
Industrial/other677067736062
Total 1,066 1,291 1,269 1,295 1,120 1,224
Net coal exports 22.7 −6.1 −6.1 −6.1 −6.2 −20.4
Exports39.631.631.631.629.528.4
Imports16.937.737.737.735.748.8
Minemouth price
(2002 dollars per short ton)17.9016.4715.8416.7517.02117.782,3
(2002 dollars per million Btu)0.870.810.780.820.8310.812,3
Average delivered price to electricity generators
(2002 dollars per short ton)25.9624.3423.1725.10NA21.823
(2002 dollars per million Btu)1.261.221.161.25NA1.083
2020
Production 1,105 1,377 1,337 1,382 1,159 1,208
Consumption by sector
Electricity generation9761,3011,2631,3051,0951,158
Coking plants231919191717
Industrial/other677168755759
Total 1,066 1,391 1,349 1,399 1,169 1,234
Net coal exports 22.7 −14.4 −12.2 −15.7 −10.4 −25.6
Exports39.627.429.526.029.722.6
Imports16.941.741.741.740.148.2
Minemouth price
(2002 dollars per short ton)17.9016.3215.7816.9216.91116.942,3
(2002 dollars per million Btu)0.870.800.780.830.8310.772,3
Average delivered price to electricity generators
(2002 dollars per short ton)25.9624.0122.8725.03NA21.083
(2002 dollars per million Btu)1.261.201.151.24NA1.043
2025
Production 1,105 1,543 1,420 1,586 1,237 NA
Consumption by sector
Electricity generation9761,4771,3551,5101,184NA
Coking plants2317171716NA
Industrial/other6772688455NA
Total 1,066 1,567 1,441 1,612 1,254 NA
Net coal exports 22.7 −22.7 −19.8 −24.8 −17.8 NA
Exports39.623.026.021.030.0NA
Imports16.945.745.745.747.8NA
Minemouth price
(2002 dollars per short ton)17.9016.5715.6717.9516.971NA
(2002 dollars per million Btu)0.870.820.780.880.841NA
Average delivered price to electricity
generators
(2002 dollars per short ton)25.9624.3122.7526.29NANA
(2002 dollars per million Btu)1.261.221.141.30NANA

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