Coal - Environmental And Health Concerns About Coal
plants air emissions dioxide
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
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, suchas 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 damageto forests, lakes, and other ecosystems.
|Coal prices, selected years, 1949–2003|
|(Dollars per short ton)|
|Bituminous Coal||Subbituminous Coal||Lignite1||Anthracite||Total|
|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)|
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 promotesettling of the dust.
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
|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 irritation||Cars, refineries, dry cleaners|
|Particulate matter (PM-IO)||Bronchitis, cancer, lung damage||Dust, pesticides|
|Carbon monoxide (CO)||Blood oxygen carrying capacity reduction, cardiovascular and nervous system impairments||Cars, power plants, wood stoves|
|Sulphur dioxide (SO2)||Respiratory tract impairment, destruction of lung tissue||Power plants, paper mills|
|Lead (Pb)||Retardation and brain damage, esp. children||Cars, nonferrous smelters, battery plants|
|Nitrogen dioxide (NO2)||Lung damage and respiratory illness||Power 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
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 CleanAir 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 qualityimprovement.
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 canbe 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 useof 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 thisequipment. 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 ofenvironmental 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.