COAL Powering Modern Society
CONTENTS Coal: Powering Modern Society.................. 3 How Coal Is Formed....................................... 4 Types of Coal.................................................. 5 25 States with Coal Mining........................... 6 How Coal Is Produced.................................... 7 Three Types of Underground Mines............. 8 Federal and State Regulations Govern Coal Mining..................................... 10 The People Who Mine Coal......................... 12 Moving Coal to Market................................ 13 Using Coal in America................................. 14 What Is Coal’s Future?.................................. 15 New Technologies for Coal.......................... 17 About the American Coal Foundation.......................................... 19
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Coal: Powering Modern Society Coal was one of man’s earliest sources of heat and light. The Chinese mined it more than 3,000 years ago. The first recorded discovery of coal in the U.S. was by French explorers on the Illinois River in 1679, and the earliest recorded commercial mining occurred in 1750 near Richmond, Virginia. In the nineteenth century, coal grew rapidly in importance—and from 1850 to 1950, it was America’s most important energy fuel. Today, coal is a $30 billion-ayear industry, accounting for nearly 40 percent of our electric power generation, supplying coke for the nation’s steel industry, and providing a source of foreign exchange as an export commodity. An abundant supply of low-priced energy has helped make America the richest nation on Earth. Our energy comes in many different forms, but experts estimate that more than 80 percent of the U.S.’s recoverable fossil fuels take the form of coal. Coal is so abundant that we can meet our energy needs for another 200-250 years at the current rate of use. The rest of our in-ground energy sources include oil, natural gas and natural gas liquids, bituminous and shale oil, and uranium. Today’s coal industry has been transformed from the image people remember from a bygone era, when coal was predominantly used to heat homes and power trains. Now well-trained, highly skilled men and women produce coal using modern, sophisticated technologies and equipment. The coal industry emphasizes worker safety and health and works hard to minimize the environmental effects of mining. In addition, American coal continues to be the most affordable and reliable source of energy in the U.S. Society’s use of coal also has changed greatly. Coal replaced wood as our primary energy source and helped to stop deforestation in the U.S. In the mid-nineteenth century, coal fueled America’s growing industrial movement. Among other things, it was used to melt glass, heat forges, kiln lime and cement, and process wood pulp. Steam engines drove factory machines through elaborate schemes of pulleys. Coal-powered railroads moved vast amounts of raw materials, finished goods, and people throughout the country. By the early 1950s, the nation was turning away from the direct use of coal. Oil and natural gas—cheap, abundant, and easy to move and store—displaced coal in railroad transportation, home heating, and certain industrial applications. At the same time, nuclear power was being widely promoted as the energy form of the future. But in the 1970s, oil and natural gas supplies tightened while prices surged and the nation learned a painful lesson about dependence on foreign energy. Also, the promise of nuclear power began to dim, so coal took on renewed meaning as the nation’s premier energy source.
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Today, coal is used primarily to generate nearly 40 percent of the nation’s electric power, comprising the largest source of fuel for this vital market. Forecasters predict an even more robust role for coal in the future globally as electric power continues to grow as a major source of energy in the world’s developing countries. Equally important, work on new coal combustion technologies is advancing, reflecting the industry’s commitment to minimizing its impact on the environment. In the past four decades, these technologies have removed 90 percent of regulated emissions for coal-based power plants even as coal use has increased significantly. The American Coal Foundation was created to foster a better understanding of coal’s contribution to modern American life. This booklet offers a succinct picture. For more information about the coal industry and how coal is used, please visit our website (www.teachcoal.org) or write to:
American Coal Foundation 101 Constitution Ave. NW, Suite 500 East, Washington, D.C. 20001-2133 info@teachcoal.org
How Coal Is Formed
Coal is called a “fossil” fuel because it is formed from the remains of vegetation that grew as long as 400 million years ago. It is often referred to as “buried sunshine,” because the plants that formed coal captured energy from the sun through photosynthesis. Plant photosynthesis created the compounds that make up plant tissues. The most important element in the plant material is carbon, which gives coal most of its energy. Most of our coal was formed about 300 million years ago, when much of the Earth was covered by humid swamps. As plants and trees died, their remains sank to the bottom of the swampy areas, accumulating layer upon layer and eventually forming a soggy, dense material called peat.
A thick layer of peat developed as plant matter accumulated and hardened on the floor of a swamp. The matter built up as the plants that grew in the swamp died and sank to the bottom. Peat-forming swamps once covered much of the earth.
Deposits of loose mineral matter, called sediments, covered the peat bed. As these sediments continued to pile over the bed, they compressed the peat.
Pressure on the peat increased as the sediments became more compact and heavier. Some sediments hardened into rock. The ever-increasing weight and pressure turned the peat into coal. (Adapted from World Book Encyclopedia)
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Over long periods of geologic time, the Earth’s surface changed, and seas and great rivers buried the peat with deposits of sand, clay, and other mineral matter. Sandstone and other sedimentary rocks were formed, and the pressure caused by their weight squeezed water from the peat. Increasingly deeper burial (and the heat associated with it) gradually changed the peat to coal. Scientists estimate it took three to seven feet of compacted plant matter to form one foot of bituminous coal. Coal formation is a continuing process (some of our newest coal is a mere 1 million years old). Today, in areas such as the Great Dismal Swamp in North Carolina and Virginia, the Okefenokee Swamp in Georgia, and the Everglades in Florida, plant life decays and subsides, and will eventually be covered by silts, sands, and other materials. Perhaps millions of years from now, those areas will contain large coal beds.
Types of Coal We use the term “coal” to describe a variety of fossilized plant materials, but no two are exactly alike. People who study coal are called coal petrographers. They assess coal for its heating value, ash melting temperature, sulfur and other impurities, mechanical strength, and many other chemical and physical properties. Since coal is used in many different applications such as chemistry and steel-making, the specific properties of coal must be analyzed when matching specific coals to a particular application.
TYPES OF COAL
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Anthracite Anthracite is coal with the highest carbon content, between 86–98 percent, and a heat value of nearly 15,000 Btus-per-pound. Most frequently associated with home heating, anthracite is a very small segment of the U.S. coal market. There are 7 billion tons of anthracite reserves in the U.S., found mostly in 11 northeastern counties in Pennsylvania. Bituminous The most plentiful form of coal in the U.S., bituminous coal is used primarily to generate electricity and make coke for the steel industry. The fastest-growing market for coal, though still a small one, is supplying heat for industrial processes. Bituminous coal has a carbon content ranging from 45–86 percent and a heat value of 10,500 to 15,500 Btus-per-pound. Subbituminous Ranking below bituminous is subbituminous coal, with 35-45 percent carbon content and a heat value between 8,300 and 13,000 Btus-per-pound. Reserves are located mainly in a half-dozen Western states and Alaska. Although its heat value is lower than bituminous coal, this coal generally has a lower sulfur content than other types, which makes it attractive for use in electric generation. Lignite Lignite is a geologically young coal that has the lowest carbon content, 25-35 percent, and a heat value ranging between 4,000 and 8,300 Btus-per-pound. Sometimes called brown coal, it is mainly used for electric power generation and coal gasification.
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coals
Coal is classified into four general categories, or “ranks.” They range from lignite through subbituminous and bituminous to anthracite, reflecting the progressive response of individual deposits of coal to increasing heat and pressure. The carbon content of coal supplies most of its heating value, but other factors also influence the amount of energy it contains per unit of weight. The amount of energy in coal is expressed in British Thermal Units (Btu) per pound. A Btu is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. About 90 percent of the coal in this country falls in the bituminous and subbituminous categories, which rank below anthracite and, for the most part, contain less energy per unit of weight. Bituminous coal predominates in the Eastern and Mid-continent coal fields, while subbituminous coal is generally found in the Western states and Alaska. Lignite ranks the lowest and is the youngest of the coals. Most lignite is mined in Texas and North Dakota, but large deposits also are found in Montana and some Gulf Coast states.
25 States with Coal Mining
Although 90 percent of the country’s coal reserves are concentrated in 10 states, coal is mined in 25 states. Montana has the most coal, with 25 percent of demonstrated reserves. Wyoming, third among states with the most coal, is first in coal output, accounting for 40 percent of annual production. U.S. coal reserves—the world’s largest—contain three times as much energy as all the oil in Saudi Arabia. A brief look at some numbers explains why coal is the country’s most abundant energy resource. According to the United States Geological Survey, we have 1.7 trillion tons of identified coal resources—coal for which geological evidence and engineering studies provide reliable information about location, rank, quality, and quantity. Geologists recognize that more coal deposits are likely to be discovered in the future, so they estimate total coal resources could amount to 4 trillion tons. 6
Where Coal Is Produced State
Thousand Short Tons
Wyoming 401,442 West Virginia 120,425 Kentucky 90,862 Pennsylvania 54,719 Illinois 48,486 Texas 44,178 Indiana 36,720 Montana 36,694 Colorado 28,556 North Dakota 27,529 Other States 126,847 TOTAL 1,016,458 Source: U.S. Energy Information Administration (EIA)
Percent of U.S. 39.5 11.8 8.9 5.4 4.8 4.3 3.6 3.6 2.8 2.7 12.6 100.0
Much of the coal we know about cannot be mined today, because it would be too costly or existing technology does not allow it. It may be too deep, for example, or the quality may not meet current needs. So to be realistic, experts estimate that 480 billion tons of coal is potentially recoverable with today’s technology. This is called the demonstrated reserve base.
How Coal Is Produced Coal found close to the surface can be uncovered and removed by large machines in a process called surface mining. Surface mining techniques account for 66 percent of coal produced in the U.S.—and 79 percent in Western states, where some deposits are 100 feet thick or more. Only in recent decades has surface mining come to play an important role in the U.S. coal industry. The development and use of large power equipment provided the impetus that moved surface mining into prominence. During the 1970s, it became the leading method of coal mining. Today’s surface mines are large, intensively engineered, and highly efficient operations. When an area is to be mined, topsoil and subsoil are removed first and set aside to be used later in reclaiming the land. Then, specially designed machines—draglines, or large shovels—remove the rock and other material, called overburden, to expose the bed of coal. Smaller shovels load the coal into large trucks that remove the coal from the pit. Once the coal is removed, the area is reclaimed, returning it to its original state. First, overburden is replaced, followed by placement of topsoil, and the area is restored to its original contour as nearly as possible. Vegetation native to the area is planted to anchor
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Shaft Mine Where coal lies deep underground, Slope Mine Where coal is nearer the surface, shafts are dug straight down to the coal. access to the coal can be created by driving They provide access for miners, a path for the gently slanting tunnels. removal of coal, and fresh air exchange.
Drift Mine Where coal outcrops on the slope of a mountainside, an entrance can be tunneled in at the level of the coal.
the soil and return the land to a natural, productive state. Reclaimed lands are a valuable resource that can support farm crops, provide new wildlife habitats, enhance recreational opportunities, and even serve as sites for commercial development. The complete mining operation is scheduled so that as one area is being mined, another is being reclaimed where coal was removed. Since 1970, more than 2.4 million acres of coal mine lands have been reclaimed.
Three Types of Underground Mines Underground mining methods are used where the coal seam is too deep for surface mining. Most underground mining takes place east of the Mississippi, especially in the Appalachian Mountain states. Coal production was once dominated by underground mining methods, but the growth of coal mining in the West changed that. Now, only 34 percent of our coal comes from underground mines. Underground mines differ according to how the coal seam is situated with respect to the surface. If the coal deposit outcrops (appears at the surface) on a hillside, a drift mine can be driven horizontally into the seam. Where the bed of coal is relatively close to the surface, yet too deep to be recovered by surface mining, a slope mine can be constructed—with the mine shaft slanting down from the surface to the coal seam. The most common type of underground mine is the shaft mine. To reach the coal, which may be as deep as 2,000 feet, vertical shafts are cut through the overburden to the coal bed, which is then excavated by machines.
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In deep mines, the seam is mined in carefully engineered patterns that keep as much as half of the coal in place to help support the roof of the active mining area. This “room and pillar” method requires that large columns of coal remain between mined-out areas—“rooms”— which are created when the coal is mined, either by continuous mining machines or conventional methods. The largest amount of coal taken from underground mines is produced using a machine called a continuous miner. This machine has a large, rotating, drum-shaped cutting head studded with carbide-tipped teeth that break up the seam of coal. Large gathering arms on the machine scoop the coal directly onto a built-in conveyor for loading into the waiting shuttle cars. In conventional mining, a machine resembling an oversized chain saw cuts into the coal. This gives the coal an area to expand into during blasting. Holes are drilled for explosives that blast apart chunks of coal. Machines called loaders scoop the coal onto conveyors, which dump the coal into shuttle cars that haul it out through the shaft. This traditional method of mining accounts for about 9 percent of total production. In both continuous and conventional mining, the roof over the mined-out area is supported for safety. The most important development in roof support—both in terms of safety and cost—has been the “roof bolt.” Roof bolts are long rods driven into the roof to bind several layers of weak strata into a layer strong enough to support its own weight. Roof bolts also can anchor a weak immediate roof to a strong, firm structure above. Machines are used to drill holes, position the bolts, and tighten them. An increasingly popular and more efficient means of underground mining—developed in Europe and introduced in the U.S. in the early 1950s—is longwall mining technology. Longwall mining today accounts for about one-third of total underground coal production.
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In a continuous, smooth motion, a rotating shear on the mining machine moves back and forth along the face—or wall—of a block of coal, cutting the coal and dropping it onto a conveyor where it is removed from the mine. The block of coal being mined is several hundred feet long, thus the name longwall. Where longwall mining machines are used, room-and-pillar arrangements are not created throughout the entire mine—although pillars of coal are left to support the roof in “haulageways” (tunnels) used by people and machines moving about the mine. The longwall miner itself has a hydraulically operated steel canopy that holds up the roof and protects miners working at the face of the coal seam. As the longwall miner cuts progressively deeper into the block of coal, the shield advances with it—allowing the unsupported roof in the mined-out area behind the shield to collapse in a controlled and safe manner.
Federal and State Regulations Govern Coal Mining Coal mining is one of the most extensively regulated industries in the U.S. Before one shovel of soil can be turned, or one ton of coal removed from the ground, a company must comply with numerous laws and regulations. Meeting all the requirements is arduous and timeconsuming, even for the most efficient and well-managed companies. As long as 10 years can elapse between the start of planning a mine and mining the first ton of coal. The process begins with a mining company providing detailed information about such activities as: • how the coal will be mined, • how the land will be reclaimed, • how mining activities will affect the quality and quantity of surface and underground sources of water, and • the effects of coal transportation from the mine. Surface mining operators must also consider the soil and prevailing climatological conditions prior to mining because the land has to be returned to approximately the same physical contour, and to a state of productivity equal to or better than the pre-mining condition. Wildlife habitats cannot be permanently disrupted, and archeological resources must be protected. The Surface Mining Control and Reclamation Act (SMCRA), the principal federal surface mining law, sets forth many requirements for operators to meet. These include public hearings and procedures for obtaining permits. To make certain that lands being mined will be restored, the law requires companies to post bonds—some as high as $10,000 per acre— to cover reclamation costs. Concern for the environment was not always a high priority for society. Consequently, in some areas of the country, abandoned mines mar the landscape. The mine operators stopped mining because the coal seam was exhausted, companies went bankrupt, or for some other reason they no longer could or would mine coal. To restore these “orphan lands” and eliminate unsightly and unsafe conditions, today’s coal producers pay a special tax on every ton of coal they produce. The money, which goes into the federal Abandoned Mine Lands (AML) Fund,
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This area is known as Porcupine Creek Reach 1 reclamation, some of the earliest reclamation at North Antelope Mine in Wyoming. It is the result of a specialized reclamation effort to restore the function of an alluvial valley floor, which is how the area was characterized pre-mining. An alluvial valley floor is an area that stores water subsurface, providing sub-irrigation to plants. They are important areas in dry regions like this one. The pool was constructed to assist with recharge of the replaced alluvial material and also provides a water source for numerous wildlife species using the area, including deer, antelope, ducks, geese, frogs, and others. The fence seen in the photo is part of the grazing management of this area, which includes cattle use.
provides financing for reclamation projects initiated by state agencies. The AML Fund was established in 1977 under Title IV of SMCRA. This law is enforced by the federal Office of Surface Mining (OSM) at the U.S. Department of the Interior. Based on OSM data, it is estimated that orphan mined lands totaling an area greater than the size of the state of Delaware have been reclaimed since 1977. Over time, as today’s coal producers pay with tax contributions to the AML Fund, the percentage of reclaimed lands will rise. Regulation of Surface Mining As long ago as the 1930s some states had reclamation laws on their books. But in the late 1970s, when there was significant energy development activity in the West, Congress enacted SMCRA, which mandated strict regulation of surface mining. It became the first comprehensive national surface mining law. The most extensive regulations affecting surface mining are a consequence of SMCRA. Under the law, individual states that establish federally approved enforcement programs have the primary responsibility for enforcing mining regulations in their jurisdictions. Where no such programs exist, the federal law is implemented by the OSM. Other federal laws with significant impact are the Clean Air Act, the Clean Water Act, and the National Environmental Policy Act. In addition, each state where surface mining occurs has its own set of laws and regulations to protect water quality and wildlife habitats. Beyond the specific requirements of the federal laws already noted, many other legislative acts affect some or all surface mining in this country.
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The People Who Mine Coal
LEGISLATIVE ACTS
Employee safety and health is the first priority of U.S. mining operations. Over the past 15 years, that commitment has led to a 52 percent cut in the rate of injuries.
American Indian Religious Freedom Act of 1978
Industry statistics show a significant reduction in the number of injury-producing accidents and, most dramatic of all, in 2013, the lowest fatality rate in history. At the same time, the amount of coal being mined has risen sharply. Improved safety, more advanced technology, and better labor relations have helped make U.S. coal mines among the safest and most productive in the world.
Bald Eagle Protection Act of 1969
Antiquities Act of 1906 Archeological and Historical Preservation Act of 1974
Endangered Species Act of 1963 Fish and Wildlife Coordination Act of 1934 Forest and Rangeland Resources Planning Act of 1974 Historic Preservation Act of 1966 Migratory Bird Treaty Act of 1918 Mining and Minerals Policy Act of 1970 Multiple Use Yield Act of 1960
As the technology of mining coal progressed, machines were developed to handle some of the operations, leading to a safer place to work. At the same time, coal mining companies recognize that a safe and healthy work place is a more efficient and productive one, so they put a great emphasis on accident prevention, safety inspections, and employee training.
National Environmental Policy Act National Forests Management Act of 1976 National Trails System Act Noise Control Act of 1976 Resource Conservation and Recovery Act Safe Drinking Water Act of 1974
Safety in coal mining is a prominent and highly regulated aspect of the business, and one that requires great diligence and close cooperation between everyone involved in mining. The Coal Mine Health and Safety Act of 1969 is the major legislative authority for a host of federal regulations governing safety in the industry.
Soil and Water Resources Conservation Act of 1977 Wild and Scenic Rivers Act Wilderness Act of 1964
The contemporary coal industry workforce is a continually evolving reflection of our society as a whole. According to the Bureau of Labor Statistics (BLS) and the National Institute for Occupational Safety and Health (NIOSH) estimates, the average coal miner is 45 years old and has 20 years of experience, including eight years with the same company. There are more than 6,000 women among the industry’s workforce of 135,000. 12
A coal miner’s average annual income is $81,000, and health, welfare, and other benefits are comprehensive. (See the chart on the right that compares the average income for coal employees to those of other industries.)
Average Income for Various Industries (Dollars per Hour)
Moving Coal to Market
Coal
$25.75
Steel
$23.63
Auto
$27.00
Chemicals
$29.87
Source: Bureau of Labor Statistics More than 60 percent (about twothirds) of all coal produced moves by railroad from mine to user. A large percentage is transported in “unit trains”—100 or more cars that can be loaded and unloaded automatically. Coal makes up a substantial part of the major railroads’ freight business. The next most significant mode of transportation for coal is the nation’s inland waterways system. One in every five tons of coal mined is transported by barge, accounting for nearly one-fourth of all barge business on the nation’s 25,000 miles of inland waterways. Only petroleum products account for a larger percentage. Smaller amounts of coal move by truck and by conveyor directly from mine to power plant.
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Using Coal in America There was a time when coal directly served a variety of important uses in our society. We burned it to heat homes. It powered the nation’s railroads and factories. Coal was—and still is—used to make coke, essential to the steelmaking process. The gaseous by-products of coke ovens were the raw material from which we derived hundreds of chemicals and other products—from aspirin to nylons—to meet the needs of a growing country. Today, coal’s most important contribution to our society is electricity. It is the fuel predominantly used to produce steam to drive the turbines of power plant generators. Electric utilities account for more than four-fifths of all the coal consumed in the U.S., satisfying almost half of the nation’s electricity requirements. Because the use of electricity as a major energy source is increasing—it accounts for more than half of the energy use outside the transportation sector—coal will remain a valuable component of our energy supply. The manufacturing of steel and iron, traditionally coal’s second-largest market, has slowed considerably in recent years. The widespread use of plastics as substitutes for metals, the effects of imported steel on domestic steelmakers, and changes in metallurgical technology have combined to reduce the amount of steel produced in the U.S. As a result, the consumption of coal for the production of coke also has been reduced somewhat, although it continues to be an essential ingredient in certain types of steelmaking. Aside from steel, the use of coal in the nation’s industrial sector has been growing. Industrial groups that have increased their use of coal include the chemical, cement, stone, clay, glass, paper, and food processing sectors. As a whole, they now constitute coal’s second-largest market after electric power generation. As the second-largest coal exporter in the world, the U.S. exports on average about 10 percent of its annual production to more than 40 countries worldwide. The U.S. has a variety of coal qualities available for export. Overseas customers purchase U.S. coal because it helps diversify
U.S. Coal Production Trends, 2002–2012 (Millions of Short Tons)
1094.30
2009
2010
2011
950 900
2002 2003 2004 2005 Source: National Mining Association
2006
2007
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2008
1016.45
1084.40
1171.80
1146.60
1131.50
1074.90
1,000
1071.80
1,050
1094.30
1,100
1112.10
1,150
1162.70
1,200
2012
their supply base. And while our production costs are competitive, transportation costs can make it difficult for U.S. coal to compete in some world markets where, due to geography, our competitors are closer to some customers.
What Is Coal’s Future? With a 200- to 250-year supply of coal under our feet, the picture of coal’s role in supplying electricity in the future should be hopeful. Modern coal combustion facilities—the nation’s electric power plants—use technology, engineering, and specialized equipment to remove most of the polluting elements from power plant emissions. The dark, sooty material called fly ash that once went up the stack is now removed by filters or by devices called precipitators. With precipitators, the flue gas is passed through an electric field. The ash particles become negatively charged and are attracted to positively charged collecting plates and later removed for disposal or other uses. This method eliminates 99.5 percent of fly ash. Coal contains sulfur, which combines with oxygen when the coal is burned to produce sulfur oxides (referred to as SOx). The effect of SOx on the environment has been the topic of significant debate for a number of years. Beginning in the 1970s, coal producers and major coal consumers initiated a number of efforts to reduce the amount of sulfur compounds emitted into the environment. Electric Power Fuel Combustion Emissions and Power Sector Coal Consumption 1970-2013 25,000
Coal Consump+on: Power Sector +168%
SO2 per Billion KWh
1,000
20,000
800 15,000
SO2 -‐92%
10,000
NOX -‐84%
600
400
PM10 -‐90%
5,000
200
0
0
Sources: EPA Air Trends Report and Energy Information Administration 2013 data are preliminary
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Coal Consump+on (Million Tons)
Emissions -‐ Tons Per Billion KWh
1,200
NOX per Billion KWh
PM10 per Billion KWh
Electric Power Sector ConsumpCon (Million Tons)
One effort included the use of flue gas scrubbers, which can remove up to 95 percent of the SOx from the stream of gases produced by coal combustion before it goes up the stack. In one process, sulfur dioxide in the flue gas reacts with a lime or limestone water slurry to form calcium sulfite or calcium sulfate (gypsum) sludge. In another, sulfur and sulfuric acid are produced as by-products. Other technologies can produce a dry by-product. Sulfur emissions (SO2—sulfur dioxide) also are being reduced by greater use of inherently low-sulfur coals. Since the Clean Air Act was passed in 1970, the sulfur dioxide emissions from electric utilities have decreased dramatically. Physically washing coal after it is mined and before it is burned is another way to reduce sulfur compound emissions. This process can remove sulfur-iron compounds (pyritic sulfur) from raw coal, but cannot remove organic sulfur, which is part of coal’s molecular structure. All of these techniques represent a significant investment in maintaining clean air. A single scrubber, for example, can cost more than $100 million to construct, and many millions of dollars a year to operate. There are more than 150 scrubbers installed and operating at U.S. utilities, and about 12 to 15 more are planned. Electric utilities have already spent more than $10 billion to control sulfur emissions, and the investment, which continues every year, has paid off. According to the U.S. Environmental Protection Agency, the SO2 emissions rate per KWh from electric utilities has gone down 91 percent since 1970. Coal use by utilities has gone up dramatically during the period. As new, technologically advanced power plants replace older, less efficient ones, the trend toward lower SO2 emissions is expected to be enhanced. As a fossil fuel, coal also contains carbon, which combines with oxygen to form carbon dioxide (CO2) during the combustion process. CO2 is one of five major greenhouse gases, which trap radiated heat and send it back to the earth’s surface.
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This “greenhouse effect” is a natural process that maintains the earth’s temperature at a level sufficient to support life. However, recent scientific and political debate has intensified over whether human activity—such as fossil fuel use and deforestation—has caused an acceleration of the natural greenhouse effect.
COAL COMBUSTION TECHNOLOGIES Fluidized Bed Combustion (FBC)
Crushed coal mixed with limestone is supported on a rising current of air. The “fluidized” mixture acts as a boiling liquid, mixing turbulently, thus assuring efficient combustion. The limestone reacts with the mixture and removes more than 90 percent of the sulfur. As a consequence, “scrubbers” (flue gas desulfurization) are now required for SO2 control. Because the operating temperature is lower than in conventional boilers, the formation of nitrogen oxides is minimized. The FBC technology lends itself to the design of smaller boilers that can be prefabricated as modular units and at less capital cost than conventional boilers of the same generating capacity. Because of these savings—and the favorable economics of adding additional generating capacity to a power plant only as it is needed—electric utilities and consumers both are expected to find this technology attractive.
While most scientists agree that global atmospheric CO2 and other greenhouse gases have risen in quantity over the past century, disagreement remains over whether or not these increases affect the Earth’s climate. Given coal’s role in meeting the world’s energy needs—both now and in the future—solutions to concerns over possible climate change will have to be global in nature and must carefully balance environmental objectives with viable options for continuing to fully utilize fossil fuels for energy production and for reducing global energy poverty.
Coal Gasification
As an alternative to direct combustion of coal, where heat produced is used to develop steam to drive generator turbines, a great deal of progress has been achieved on technologies that depend on first gasifying the coal. The gas itself can be burned to power gas turbines. Then, the remaining heat can be harnessed to produce steam to turn turbines. This type of arrangement, called combined cycle gasification, is extremely efficient and clean. At one demonstration plant in California, emissions of combustion products were comparable to those from a natural gas-fired facility, allowing the plant to meet California’s clean air requirements—the strictest in the country. Another advantage of the coal gasification process is that it can be carried on in close proximity to the mine site. Rather than shipping the bulky coal long distances to a power plant, the power from coal can be shipped by wire from the gasification plant.
New Technologies for Coal The Clean Air Act, which has been in effect since 1970 and was last amended in 1990, is the most stringent air pollution control law in the world. Because of it, and through the combined efforts of business, industry, citizens, and government, we enjoy some of the cleanest air to be found anywhere on the globe. American industry has spent $350 billion since 1970 to clean up the air, and each year the tab for pollution control totals another $33 billion.
Pollution control equipment accounts for up to 40 percent of the cost of a new power plant and 35 percent of operational costs, according to the Electric Power Research Institute. Those costs plus operating costs currently account for about $10 billion of the nation’s electric bills each year, and that number will rise even higher under new Clean Air Act requirements.
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Environmental concerns about coal use center on the emission of sulfur and nitrogen compounds and CO2. While coal is not the only nor the leading source of those emissions in our environment, coal combustion is a significant contributor, so as part of a national commitment to further reduce air pollution, more than a dozen advanced technologies for burning coal cleanly and more efficiently are being investigated. The development and demonstration of these technologies has required a substantial investment of more than $6 billion by government and private industry. The two coal combustion technologies in the table on the previous page and other advanced clean coal technologies hold the promise of generating more power with less fuel, reducing operating and maintenance costs, controlling more pollutants, producing marketable byproducts, and utilizing smaller plants that can be modularly built. But all technologies speak to the same goal: making more effective and efficient use of an abundant energy resource.
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About the American Coal Foundation The American Coal Foundation (ACF) is a non-profit educational organization supported by a coalition of coal producers and equipment suppliers. ACF’s objective is to educate the public about the advantages and potential of coal—coal is abundant, it’s affordable, it’s American, and with the commercialization of innovative new technologies, it can be used in an environmentally acceptable manner. ACF (www.teachcoal.org) provides online materials for energy education (coal production, distribution, usage, and research), including the ever-popular coal sample kit! The first kit is free of charge and contains samples of peat, lignite, bituminous, and anthracite coal, along with a brief description for each type of coal. An online order form is available at: http://teachcoal.org/energy-and-you/coal-kits/ For additional ordering information, please contact the American Coal Foundation at: info@teachcoal.org
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American Coal Foundation 101 Constitution Avenue, NW Suite 500 East Washington, D.C. 20001-2133
www.teachcoal.org