Powder River Basin
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The Powder River Basin is a region in southeast Montana and northeast Wyoming about 120 miles east to west and 200 miles north to south known for its coal deposits. It is both a topographic drainage and geologic structural basin. The basin is so named because it is drained by the Powder River, although it is also drained in part by the Cheyenne River, Tongue River, Bighorn River, Little Missouri River, Platte River, and their tributaries.
Major cities in the area include Gillette and Sheridan, Wyoming and Miles City, Montana. The area is very sparsely populated and is known for its rolling grasslands and semiarid climate.
It is the single largest source of coal mined in the United States, and contains one of the largest deposits of coal in the world. Most of the active coal mining in the Powder River Basin actually takes place in drainages of the Cheyenne River. Because of the Powder River Basin, Wyoming has been the top coal-producing state in the United States since 1988. In 2007, the Powder River Basin alone produced 436 million short tons (396 million tonnes) of coal, more than twice the production of second-place West Virginia, and more than the entire Appalachian region.[1] The Black Thunder Coal Mine is the most productive coal mine in the United States; in 2006 this single mine produced 84 million metric tons of coal, more than any state except Wyoming, West Virginia, and Kentucky.[2]
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[edit] Geologic history
The Powder River Basin contains a section of Phanerozoic rocks up to 17,000 feet thick, from Cambrian to Holocene.
[edit] Cretaceous
The thickest section of the Powder River Basin is composed of Cretaceous rocks, an overall regressive sequence of mostly marine shales and sandstones deposited in the Western Interior Seaway.
[edit] Tertiary
The coal beds of the region began to form about 60 million years ago when the land began rising from a shallow sea. The rise of the Black Hills uplift on the east and the Hartville uplift on the southeast side of the basin created the present outline of the Powder River Basin.
When the coal beds were forming the climate in the area was subtropical, averaging about 120 inches (3,000 mm) of rainfall a year. For some 25 million years, the basin floor was covered with lakes and swamps. Because of large area of the swamps, the organic material accumulated into peat bogs instead of being washed to the sea. Periodically the layers of peat were covered with sediments washed in from nearby mountains. Eventually the climate became drier and cooler. The basin filled with sediment and buried the peat under thousands of feet, compressing the layers of peat and forming coal. Over the last several million years, much of the overlying sediment has eroded away, leaving the coal seams near the surface.
[edit] Coal
It is estimated that Powder River Basin coal deposits contain over 800 billion US tons of coal, with the thickness of the seams in the region ranges up to 200 feet (60 m) and averages nearly 80 feet. In 2005, in excess of 325 million US tons of coal have been mined annually, more than 25% of the total U.S. production.[3] The majority of the coal mined in the PRB is part of the Fort Union Formation (Paleocene), with the low sulfur and ash content of the coal in the region makes it very desirable. Coal supplies about half of the United States electricity supplies, with the PRB mines supplying around 40% of the coal that fuels those stations, mainly to the east of the Rocky Mountains for generating electricity.[4]
[edit] Coal mining companies currently operating in the Powder River Basin
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[edit] Power plants fueled from Powder River Basin coal
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[edit] Petroleum
The Powder River Basin also contains major deposits of petroleum. The oil and gas are produced from rocks ranging from Pennsylvanian to Tertiary, but most comes from sandstones in the thick section of Cretaceous rocks.
[edit] Coalbed methane
Recent controversy surrounds the extensive coalbed methane extraction in the region. In the last decade, nearly 7000 of these wells have been drilled. Extracting the gas requires water to be pumped to the surface in order to release the gas trapped in the coal seam. While some of the water is successfully utilized in agriculture production such as livestock water and crop irrigation, some waters are naturally high in salinity. There has been controversy on how to best manage these saline waters.
[edit] Uranium
The region also contains major deposits of uranium, contained in sandstones. (See Uranium mining in Wyoming). The Wasatch Formation (Eocene) contains the uranium ore "roll front" type deposits found in the Pumpkin Buttes District. Cameco Corporation subsidiary Power Resources Inc. operates uranium mines in the basin.
[edit] Transportation
The cost of coal extracted from the mines would retail at the mines for around $5 a ton. However, the power stations and plants of the Eastern United States pay in excess of $30 ton - the difference made up by the cost of transportation.[5]
Due to the volumes and resultant cash flow from the coal that is accessible, there is a joint railway line owned by the BNSF Railway and the Union Pacific Railroad which runs the length of the southern section of the PRB. A third railroad, the Dakota, Minnesota and Eastern Railroad, has faced strong resistance from an unusual array of parties for its attempts to extend its rail line into the coal mining area - more so since its agreed purchase by the Canadian Pacific Railway.[6]
[edit] History
Originally a single track Burlington Northern Railway line, it ran south from Donkey Junction, Wyoming in the north 13 miles to Caballo, Wyoming; and then for 103 miles to Shawnee in Niobrara County, Wyoming.[7] The Chicago and North Western Railway ran close to the northern section, as did the UP at Caballo.
Having already formed the Western Railroad to distribute PRB coal, in 1982 C&NW and the Up formed Western Railroad Properties, Inc. (WRPI), to acquire half interest in BN coal line from Shawnee Junction to Coal Creek Jct. On December 15, 1986 WPRI purchased 11 miles more of BN line from Coal Crek Jct.to East Caballo Jct. Beginning June 27, 1983 constructed six miles of new railroad from Shawnee Jct. to Shawnee, rebuilt 45 miles of C&NW line from Shawnee to Crandall, Wyoming and 56 miles of new railroad from Crandall to Joyce, Nebraska. The first commercial train ran on August 16, 1984. UP acquired ownership of C&NW in April 1995.[8]
By 1985, single track for almost its entire length it was handling 19 million tons of coal - but implementation of the second stage of the Clean Air Act (1990) meant that demand for clean coal would rise quickly. The C&NW was struggling to be able financially to upgrade capacity to dual track, which resulted in numerous failures on the line in 1994, and C&NW's absorption by the UP in 1995.[9] The UP spent $855Million over the next five years via the Project Yellow III from 1996, expanding capacity over its entire network to handle coal shipments from the PRB.[10] By 2005 the Joint Line capacity had grown to handle an all-time record 325 million tons, and was either dual or three track capacity for its entire length.
[edit] Present
As a result of various trackage and locomotive failures on the Joint Line, in late 2004/early 2005 the line failed to deliver the amount of contracted coal supplies, and electricity rates increased by 15 percent.[4] Coal customers threatened to look at alternate sources of energy and transportation, including the Arkansas Electric Cooperative Corporation. As a result, the 280 mile expansion of the DM&E was approved by the Surface Transportation Board, and in 2006 the Joint Line capacity was planned to be raised again via a $200 million investment to provide three track capacity for its entire length plus a fourth track added over the steepest sections, including Logan Hill. These improvements will enable the Joint Line to handle in excess of 400 million tons of coal.[11]
Presently more than eighty train loads of coal, which vary in size from 125 to 150 cars, are shipped from southern PRB mines each day. In 2006, Union Pacific set a record by hauling 194 million tons of coal — an 8 percent increase compared with 2005 tonnage. The company achieved this by increasing train size, with trains averaging more than 15,000 tons, a 200-ton weight increase compared with fourth-quarter 2005’s average.[12]
[edit] See also
[edit] Notes
- ^ N. R. Jones and others, "Wyoming," Mining Engineering, May 2008, p.134.
- ^ E. Freme, Coal review, Mining Engineering, May 2007, p.52.
- ^ Notice of Availability of South Powder River Basin Coal Final Environmental Impact Statement, Wyoming. US Government Bureau of Land Management, Dept of the Interior (December 24, 2003). Retrieved on 2008-01-20.
- ^ a b Rails cause utility fuel shortages, electricity rate hikeRail Cure - August 2005
- ^ Coal: Dig It Up, Move It, Burn It - Wyoming's Powder River Basin
- ^ Railroad Battle Brewing
- ^ PRB Coal Update: BNSF Completes Third Main Track on Joint Line BNSF News - 5 November, 2007
- ^ UP History - Western Railroad Properties, Inc.
- ^ Western, Burlington Northern and Union Pacific railroads Railway Age - October 1994
- ^ UP will expand PRB coal lines Railway Age - Nov, 1996
- ^ UP, BNSF Announce Southern Powder River Basin Joint Line $100 Million Capacity Expansion Plan
- ^ UP sets annual coal tonnage record in Southern Powder River Basin Progressive Railroading - January 16, 2007
