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Coal is a carbon-rich rock formed from plants that grew millions of years ago. Coal is a major source of electricity in the United States and the largest source of energy for electricity generation worldwide.


A coal-fired power plant in Westport, Kentucky on the Ohio River. Image Copyright © Michael Collier.

Coal is a rich source of energy formed from plants that grew in swamps tens to hundreds of millions of years ago. The plants were buried deeply under younger and younger layers of dirt and rock, heated, and compressed into a carbon-rich rock.[1] Burning coal releases more carbon dioxide per unit of energy produced than any other fossil fuel.[2]   Read more

Frequently Asked Questions

Latest News

Power lines. Image Credit: U.S. Department of Energy
January 23, 2018 The Senate Energy and Natural Resources Committee held a hearing on January 23 that underscored concerns surrounding the reliability and resiliency of the electrical power system, particularly under certain weather conditions, such as the deep freeze or bomb cyclone that the U.S....
Nuclear power plant, Czech Republic
January 8, 2018 On January 8, the Federal Energy Regulation Commission (FERC) rejected a proposal that was submitted by Secretary of Energy Rick Perry in September 2017 to subsidize the operating costs of coal and nuclear power plants, since the rule did not satisfy certain statutory standards....
Excavator mining
May 25, 2017 The House Natural Resources Subcommittee on Energy and Mineral Resources held a legislative hearing on a discussion draft of the Community Reclamation Partnerships Act (H.R.__) to be introduced by Representative Darin LaHood (R-IL-18). This legislation would streamline efforts to clean...
Nuclear power plant, Czech Republic
February 16, 2017 Rep. Keith Rothfus (R-PA-12) introduced legislation (H.R.1119) to modify existing regulations applying to coal-refuse-to-energy power plants on February 16. The bill acts to exempt these specific power plants from emission standards required under the Environmental Protection...
#MapOfTheDay! Check out this interactive map of Iowa coal mines from @iowadnr
#MapOfTheDay! Today the Critical Issues Program (@AGI_GeoIssues) shared an interactive map of coal mines in Iowa from the Iowa Department of Natural Resources (@IowaDNR), which you can find at For information about coal mining, check out our Coal Basics.
Excavator mining
August 9, 2016 The Department of the Interior’s (DOI) Office of Surface Mining Reclamation and Enforcement (OSMRE) has issued guidance suggesting that states move away from accepting self-bonding, where companies use their current financial health as collateral to guarantee reclamation of lands...
June 22, 2016 The White House Council of Economic Advisers (CEA) released a report entitled, “The Economics of Coal Leasing on Federal Lands: Ensuring a Fair Return to Taxpayers”. This report is part of a larger ongoing review of the federal coal leasing program – the first such review since the...
April 5, 2016 The Environmental and Energy Study Institute (EESI) held a webinar entitled, “Can Coal Country Thrive in a Clean Energy Economy?” The speakers were Tara Ritter of the Institute for Agriculture & Trade Policy, Julie Lawhorn of the Appalachian Regional Commission (ARC), Brett...
March 25, 2016 The Department of the Interior (DOI) released a notice of intent (NOI) that the Bureau of Land Management (BLM) will prepare a Programmatic Environmental Impact Statement (PEIS) to evaluate potential reforms to the federal coal program. The NOI comes after a DOI announcement in...

Case Studies & Factsheets

Screenshot of the USEITI case studies showing the Campbell County case study highlighted
U.S. Extractive Industries Transparency Initiative

The U.S. Extractive Industries Transparency Initiative (USEITI) has produced a series of case studies on extractive industries across the United States, focusing on coal, copper, gold, iron, natural gas, and oil. The case study on coal mining in Campbell County, Wyoming can be found here. The...

Screenshot of the USEITI case studies showing the Boone, Logan and Mingo counties case study highlighted
U.S. Extractive Industries Transparency Initiative

The U.S. Extractive Industries Transparency Initiative (USEITI) has produced a series of case studies on extractive industries across the United States, focusing on coal, copper, gold, iron, natural gas, and oil. The case study on coal mining in West Virginia's Boone, Logan, and Mingo counties...

Fig. 1. Exposure of sandstone capping an economic coal bed. Credit: J. Shaulis, Pennsylvania Geological Survey

Defining the Problem Despite Pennsylvania’s long history as a major coal producer, information on the coal geology (Fig. 1), remaining resources, and extent of past mining is not available for many areas of the state. Such information is critical for present and future coal exploration and...

Research Database Publications

Cover of OFR04-09 ; Source: Kansas Geological Survey
2004, Kansas Geological Survey (KGS)
Coal is the most abundant energy source in the world, and it is a major source of hydrocarbons, particularly gas. The coalification process, whereby plant material is progressively converted to coal, generates large quantities of methane-rich gas, which are stored within the coal. The presence of...
Cover of Coal Resources Summary Report; Source: Wyoming Geological Survey
2015, Wyoming State Geological Survey (WSGS)
Affordable energy for the nation has propped up the Wyoming coal industry that has recently been impacted by competing fuel sources, congested railways, and impending environmental regulations. Despite these challenges, Wyoming produced 39 percent of all the coal mined in the United States in 2013...
Cover of OFR04-37 ; Source: Kansas Geological Survey
2004, Kansas Geological Survey (KGS)
Exploration for and the production of natural gas from coal (termed coalbed methane or CBM in the report) continues to develop rapidly in eastern Kansas and especially in southeast Kansas. During this study period 1774 wells were determined to have been drilled for exploration or production of...
Cover image of position statement; Image credit: SME
2012, Society for Mining, Metallurgy, and Exploration Inc. (SME)
In a future world of 8.5 billion people in 2035, the Energy Information Administration’s (EIA) projected 50% increase in energy consumption will require true “all of the above” energy resource use from oil, gas, renewables, nuclear, and coal. In particular, coal will continue to be the world’s...
Cover of MBMG 651 ; Source: Montana Bureau of Mines and Geology (MBMG)
2014, Montana Bureau of Mines and Geology (MBMG)
This report presents groundwater data collected through September 2013 from within the Montana portion of the Powder River Basin, with an emphasis on data collected during water year 2013 (October through September). This is the 11th year in which the Montana coalbed-methane (CBM) regional...
Cover of PP1625d; Source: USGS
2002, U.S. Geological Survey (USGS)
The goal of this resource assessment of Illinois Basin coals is to provide an overview of the geologic setting, distribution, resources, and quality of Pennsylvanian-age coals in the basin as part of the U.S. Geological Survey's National Coal Resource Assessment Project (NCRA). The area of coal-...
Cover of USGS_2015-3037; Source: USGS
2015, U.S. Geological Survey (USGS)
Coal ash is a residual waste product primarily produced by coal combustion for electric power generation. Coal ash includes fly ash, bottom ash, and flue-gas desulfurization products (at powerplants equipped with flue-gas desulfurization systems). Fly ash, the most common form of coal ash, is used...
Cover of GF15; Source: Ohio Geological Survey
2014, Ohio Geological Survey (OGS)
Coal has been mined in Ohio since 1800. Mining technology has evolved from pick and shovel to the highly automated, computer-controlled equipment used today. There are two basic types of coal mines: surface mines and underground mines. Since 1800, approximately 3.9 billion tons of coal have been...
Cover of C574; Source: Illinois Geological Survey
2009, Illinois State Geological Survey (ISGS)
More than 122 million tons of coal combustion by-products (CCBs) are produced nationwide each year by coal-burning utilities that generate electricity. About 60% of these CCBs are disposed of as waste (American Coal Ash Association 2006). In addition to fly ash and bottom ash CCBs, the annual...
Coal Geology of Iowa - 2002 Keystone Coal Industry Manual, Iowa Geological Survey
2002, Iowa Geological Survey (IGS)
Most of Iowa's coal production has been from coals in the Cherokee Group. Lesser production has come from the Marmaton Group, and other minor production from the Virgil Supergroup. Most coal produced in th e state supplies electric utilities and industry.