- 1 Current policy issue
- 2 Physical composition
- 3 History
- 4 Mining
- 5 Transportation and electricity generation
- 6 Production
- 7 Environmental impacts
- 8 Technological advances
- 9 Ballot measures
- 10 See also
- 11 External links
- 12 References
Coal is a fossil fuel that has been used as an energy source in what is now the United States since the 1300s. Proponents of coal argue that the fuel is necessary because it provides jobs, keeps energy prices low and as technology improves it is becoming a cleaner energy source. Opponents of coal argue that the use of coal should be discontinued because of the pollution it creates and the negative impacts of that pollution on human health.
Current policy issue
The mining of coal has long been a dominant energy industry in the United States. However, the natural gas revolution, due in part to fracking, and the increased use of renewable energy, have made coal less competitive on two fronts: prices and consumer preferences. First, low natural gas prices are competing with traditionally low coal prices. Second, renewables are competing with coal as consumers demand less carbon intensive sources of electricity. Additionally, politicians and bureaucrats have been pushing to lower carbon emissions from coal, which is expected to affect coal prices significantly. The EIA has predicted that in 2035 natural gas will surpass coal as the largest source of energy used to generate electricity; for example, 16 percent of coal-generated electrical capacity is expected to be retired by 2020. If natural gas continues to compete with nuclear and coal electricity generation on price, the EIA anticipates that natural gas facilities will fill the void that will be left as older coal and nuclear power generation facilities are retired. The increased use of natural gas is not predicted to keep energy prices from rising, however, because as demand increases so will prices. According to the EIA natural gas prices are expected to rise from about $3.50 per thousand cubic foot to just over $8 per thousand cubic foot by 2040. Electricity prices are expected to rise from 9.8 cents per kilowatt hour to at least 11.1 cents per kilowatt hour, and even as high as 12.5 cents per kilowatt hour, as coal and nuclear energy production decreases.
The U.S. Environmental Protection Agency (EPA) is currently pushing stricter regulations for coal-fired power plants. On June 2, 2014 the EPA announced the Clean Power Plan, an initiative from the agency to curb carbon emissions. The goal is to cut carbon emissions by 30 percent of 2005 levels by 2030. The plan would set greenhouse gas emission limits for each state and it would be up to states to create and implement plans that would meet these greenhouse gas reduction targets. The plans states create must be submitted to the EPA by June 2016. These guidelines would be rate-based, meaning states would have to decrease their greenhouse gas emissions as a percentage of their current emission levels. The EPA will holding hearings throughout the country until to get public input on this plan the week of June 28, 2014. Coal-fired power plants are by far the largest emitters of greenhouse gases and are expected to pay the majority of the cost for this plan. These costs are expected to be passed on to consumers, this will increase energy prices in states that use coal to generate electricity.
Coal is composed of plant materials that have slowly been shaped by pressure and heat under the earth's surface to become a black or brown rock. After coal has been mined it is “readily combustible,” meaning it can be used as an energy sources without any refining. There are four types of coal: anthracite, lignite, bituminous and subbituminous. The amount of carbon in the coal determines what classification it falls under.
- Anthracite coal is 68 to 97 percent carbon and is mined mostly in northern Pennsylvania. This type of coal accounts for 0.2 percent of the coal mined in the United States.
- Lignite coal contains only 25 to 30 percent carbon and because of this, has the lowest energy content. This lack of energy is because this type of coal is newer, relative to the other types of coal, and has been subject to less pressure and heat. Lignite coal accounts for 7 percent of U.S. production. North Dakota and Texas lead the country in producing this type of coal.
- Bituminous coal is 45 to 86 percent carbon and is the most abundant type of coal found in the United States; it accounts for almost 50 percent of domestic production. Bituminous coal is mined in Pennsylvania, West Virginia and Kentucky. It is also used as a raw material in the iron and steel industries.
- Subbituminous coal contains 35 to 45 percent carbon. This type of coal accounts for 44 percent of domestic production. Wyoming leads the country in the production of subbituminous coal.
The first documented use of coal in the United States occurred in the Southwest in the 1300s when Hopi American Indians used coal for cooking and pottery making. Commercial coal mines opened in the 1740s and by the 1800s the Industrial Revolution had rapidly increased the demand for coal, which was viewed as a superior energy source to wood charcoal. Coal was used during the Industrial Revolution to power steamships and railroads. It wasn't until the 1880s that coal was used to generate electricity and has been generating electricity in the United States ever since.
Coal can be found both on the surface and underground. Surface mining requires the removal of top layers of the earth to reach the available coal. This type of mining is not very expensive relative to underground mining.
Underground mining is more expensive because there are large investments needed for equipment and mine building. There are three types of underground mines: slope, shaft and drift. When coal is mined underground it is found in coal seams, or layers. Coal is mined from these seams as far as 500 feet underground. To get to the coal, shafts are dug vertically into the earth that allow for ventilation and the transportation of miners, tools and coal. Miners are sent down these shafts, as they find coal they load it onto conveyer belts. The coal is then carried outside where it is crushed and cleaned and then shipped to power plants.
Transportation and electricity generation
Coal is typically transported by rail, barge, truck or conveyer belt to power plants. The graph to the right shows the type of transportation used for coal shipments from 2008 to 2013. Across this time period rail was the dominate mode of transportation. Barges, trucks and conveyer belts made up just under 30 percent of the remaining coal shipment methods used. The most cost-effective means of transporting coal over long distances is river barge. This method, however, is limited by the location of rivers, which pushes operators to transport coal by rail. Between 2008 and 2013 coal shipments shifted from trucks to river barges. Much of the network that transports coal is concentrated in the Eastern United States because it contains many of the country's smaller coal mines, railroads and coal-fired power plants. In the Western United States coal mines tend to be larger and the routes to get coal from a mine to a power plant are fewer.
Once coal is received it is then burned in a boiler and the steam produced from this boiler turns a turbine that generates electricity.
The U.S. has the world's largest supply of coal and because of this it is a net exporter. There is enough coal in the U.S. to meet current electricity needs for more than 200 years. In 2012, 81 percent of the more than one billion short tons of coal mined in the U.S. was used in American power plants. There are more than 600 coal-fired plants in the United States that generate 37 percent of the nation's electricity.
As with any energy development, traditional or even renewable, there are environmental impacts. The development of energy sources can affect the surrounding air, water, land and wildlife. The impacts below are the general impacts that mining can, or has been shown, to have. There can also be impacts specific to certain types of mining, or certain coal basins.
As coal is mined, cleaned and transported, methane is typically vented for safety purposes, which releases carbon dioxide. Additionally, when coal is burned it emits carbon dioxide, nitrogen dioxide, sulfur dioxide, acid gases and heavy metals. These pollutants have been linked to health issues, smog and acid rain. As seen in the charts below, in 2012, coal accounted for 18 percent of energy consumption in the U.S. and 31 percent of U.S. carbon emissions.
Water is needed to clean coal after it has been mined, to produce the steam that turns the turbine and to keep machinery cool during operation. This water, if discharged, can pollute clean bodies of water. Some coal companies have permits to discharge this water; these permits are regulated by the EPA. Rain can also come in contact with coal and carry pollutants from the coal to other bodies of water.
As coal is burned to generate electricity it creates coal ash. The coal mining and cleaning processes generate additional solid waste. Traditionally this waste was disposed of in abandoned mines and landfills. Because of technological advances, however, some of the waste can be recycled into cement and building materials.
Surface mining has a larger impact on the land than underground mining does. Both types of mining can contaminate soil, which can make the reclamation of abandoned mining sites difficult.
Because of coal's environmental impacts, the federal government has been investing in "clean coal technologies" since 1985. About $3 billion has been invested in these clean coal programs. One of the outcomes has been the invention of sulfur scrubbers. Scrubbers are made of limestone powder and when mixed with water and sprayed on coal these scrubbers pull sulfur from coal and prevent the pollutant from entering the atmosphere. Scientists have also invented nitrogen oxide (NOx) scrubbers that have reduced the amount of NOx released by 50 to 90 percent. Nitrogen oxide is a known contributor to smog. Special boilers allow coal to be burned more efficiently and with less NOx and sulfur pollution.
Coal can also be heated until it becomes a gas, a process known as gasification. This gaseous version can be used to turn a turbine and at the same time many of the pollutants can be filtered out of the coal. At least two power plants use this technology: one is in Tampa, Florida and the other is in West Terre Haute, Indiana.
Ballot measuresBelow is a list of coal related ballot measures across the United States.
- North Dakota Coal Development Impact Trust Fund Referendum, Amendment 5 (1980)
- North Dakota Oil Extraction Tax Initiative, Measure 6 (1980)
- This figure is the price for delivered natural gas to the electrical power sector in 2012 dollars.
- U.S. Energy Information Administration, "Implications of accelerated power plant retirements," April 28, 2014
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- U.S. Environmental Protection Agency, "Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units", June 2, 2014 (dead link)
- National Public Radio, "EPA Unveils New Proposal Targeting Greenhouse Gases," June 2, 2014
- New York Times, "Obama to Take Action to Slash Coal Pollution," June 1, 2014
- U.S. Environmental Protection Agency, "EPA Proposes First Guidelines to Cut Carbon Pollution from Existing Power Plants/Clean Power Plan is flexible proposal to ensure a healthier environment, spur innovation and strengthen the economy," June 2, 2014
- U.S. Energy Information Administration, “Glossary, C” accessed January 29, 2014
- U.S. Energy Information Administration, "Coal basics," accessed June 12, 2014
- U.S. Department of Energy, "A Brief History of Coal Use," February 12, 2013
- U.S. Department of Energy, "Coal Mining and Transportation," February 12, 2013
- U.S. Energy Information Administration, "Railroad deliveries continue to provide the majority of coal shipments to the power sector," June 11, 2014
- U.S. Environmental Protection Agency, "Coal," September 25, 2013
- U.S. Department of Energy, "The Cleanest Coal Technology - a Real Gas," March 29, 2011
- U.S. Department of Energy, "Cleaning up Coal," September 18, 2012
- U.S. Department of Energy, "The Clean Coal Technology Program," February 12, 2013
- U.S. Department of Energy, "Knocking the NOx Out of Coal," March 29, 2011
- U.S. Department of Energy, "A "Bed" for Burning Coal," February 12, 2013