Coal takes millions of years to form
Coal is a combustible black or brownish-black sedimentary rock with a high amount of carbon and hydrocarbons. Coal is classified as a nonrenewable energy source because it takes millions of years to form. Coal contains the energy stored by plants that lived hundreds of millions of years ago in swampy forests.
Layers of dirt and rock covered the plants over millions of years. The resulting pressure and heat turned the plants into the substance we call coal.
Types of coal
Coal is classified into four main types, or ranks: anthracite, bituminous, subbituminous, and lignite. The ranking depends on the types and amounts of carbon the coal contains and on the amount of heat energy the coal can produce. The rank of a coal deposit is determined by the amount of pressure and heat that acted on the plants over time.
Anthracite contains 86%–97% carbon and generally has the highest heating value of all ranks of coal. Anthracite accounted for less than 1% of the coal mined in the United States in 2022. All anthracite mines in the United States are in northeastern Pennsylvania. In the United States, anthracite is mainly used by the metals industry.
Bituminous coal contains 45%–86% carbon. Bituminous coal in the United States is between 100 million and 300 million years old. Bituminous coal is the most abundant rank of coal found in the United States, and it accounted for about 46% of total U.S. coal production in 2022. Bituminous coal is used to generate electricity and is an important fuel and raw material for making co*king coal for the iron and steel industry. Bituminous coal was produced in at least 16 states in 2022, but five states accounted for about 78% of total bituminous production. The top five bituminous producing states and their percentage share of total U.S. bituminous production in 2022 were:
- West Virginia—31%
- Illinois—14%
- Pennsylvania—14%
- Kentucky—11%
- Indiana—9%
Subbituminous coal typically contains 35%–45% carbon, and it has a lower heating value than bituminous coal. Most subbituminous coal in the United States is at least 100 million years old. In 2022, subbituminous coal accounted for about 46% of total U.S. coal production. The five subbituminous producing states and their percentage share of total U.S. subbituminous production in 2022 were:
- Wyoming—89%
- Montana—8%
- New Mexico—2%
- Colorado—2%
- Alaska—<1%
Lignite contains 25%–35% carbon and has the lowest energy content of all coal ranks. Lignite coal deposits tend to be relatively young and were not subjected to extreme heat or pressure. Lignite is crumbly and has high moisture content, which contributes to its low heating value. In 2022, five states produced lignite, which accounted for 8% of total U.S. coal production. The five lignite-producing states and their percentage share of total U.S. lignite production in 2022 were:
- North Dakota—56%
- Texas—36%
- Mississippi—7%
- Louisiana—1%
- Montana—<1%
The Great Plains Synfuels Plant in North Dakota converts lignite to synthetic natural gas that is sent in natural gas pipelines to consumers in the eastern United States.
Last updated: October 24, 2023, with data available at the time of update.
FAQs
Coal is a combustible black or brownish-black sedimentary rock with a high amount of carbon and hydrocarbons. Coal is classified as a nonrenewable energy source because it takes millions of years to form. Coal contains the energy stored by plants that lived hundreds of millions of years ago in swampy forests.
What EIA emissions come from coal? ›
In 2022, CO2 emissions from burning coal for energy accounted for about 19% of total U.S. energy-related CO2 emissions and for about 55% of total CO2 emissions from the electric power sector. U.S. air pollution laws now require most fly ash emissions to be captured by pollution-control devices.
What is the outlook for coal in EIA? ›
Coal markets
Based on our updated forecast of electricity demand that increases coal-fired generation, we expect the U.S. electric power sector will consume about 395 MMst of coal in 2024, with consumption falling by 2% in 2025.
What is coal explained? ›
Coal is a sedimentary deposit composed predominantly of carbon that is readily combustible. Coal is black or brownish-black, and has a composition that (including inherent moisture) consists of more than 50 percent by weight and more than 70 percent by volume of carbonaceous material.
What are 5 facts about coal? ›
Coal: Fast Facts About Coal
- Total demand for U.S. coal reached 1.05 billion tons in 2010.
- 33% of U.S. electricity is generated from coal.
- 9 out of every 10 tons of coal mined each year in the U.S. is used for domestic electricity generation.
- Each person in the U.S. uses 3.4 tons of coal annually.
Types of coal. Coal is classified into four main types, or ranks: anthracite, bituminous, subbituminous, and lignite. The ranking depends on the types and amounts of carbon the coal contains and on the amount of heat energy the coal can produce.
How does coal produce emissions? ›
Chemically, coal is mostly carbon, which, when burned, reacts with oxygen in the air to produce carbon dioxide, a heat-trapping gas. When released into the atmosphere, carbon dioxide works like a blanket, warming the earth above normal limits.
How to calculate CO2 emissions from coal? ›
Carbon dioxide emissions per ton of coal were determined by multiplying heat content times the carbon coefficient times the fraction oxidized times the ratio of the molecular weight of carbon dioxide to that of carbon (44/12).
What is the future of coal in 2024? ›
On the supply side, global coal production is expected to decrease slightly in 2024 after steady growth the year before. In 2024, coal production in China is moderating after two years of staggering growth. In India, the push to boost coal production continues, with a supply increase of around 10% expected in 2024.
Why is coal bad for the environment? ›
Along with adding to greenhouse gas pollution, burning coal emits toxic and carcinogenic substances into our air, water and land, severely affecting the health of miners, workers and surrounding communities.
Coal-fired plants produce electricity by burning coal in a boiler to produce steam. The steam produced, under tremendous pressure, flows into a turbine, which spins a generator to create electricity. The steam is then cooled, condensed back into water and returned to the boiler to start the process over.
What are the 4 stages of coal formation? ›
There are four stages in coal formation: peat, lignite, bituminous and anthracite. The stage depends upon the conditions to which the plant remains are subjected after they were buried – the greater the pressure and heat, the higher the rank of coal.
What burns the most coal? ›
The electric power sector has accounted for the majority of U.S. coal consumption since 1961. U.S. coal consumption by consuming sector and by amount—in million short tons (MMst) —and percentage share of total coal consumption in 2022 was: Electric power—469.9 MMst—91.7% Industrial total—41.9 MMst—8.2%
Which country is the largest producer of coal in the world? ›
China is the largest coal-producing country in the world, with production reaching 3,942 million tonnes, a 2.5% growth. The country's coal mine production is expected to remain flat, at a CAGR of just 1.1% between 2021 and 2025, to reach 4.1 billion tonnes in 2025.
How many years of coal is left? ›
World Coal Reserves
The world has proven reserves equivalent to 133.1 times its annual consumption. This means it has about 133 years of coal left (at current consumption levels and excluding unproven reserves).
What emissions come from coal mines? ›
Methane (CH4) is produced during coalification (the process of coal formation). Only a fraction of this remains trapped under pressure in the coal seam and surrounding rock strata. This trapped methane is released during the mining process when the coal seam is fractured.
What share of GHG emissions is coal? ›
Coal is a cheap and abundant resource, and carbon dioxide (CO2) from coal use is responsible for about 40 percent of global greenhouse gas (GHG) emissions from fossil fuel use.
What pollutants are generated when coal is burned? ›
Coal-fired power plants single-handedly generate 35 percent of dangerous mercury emissions in the United States, as well as two-thirds of U.S. sulfur dioxide emissions (which contribute to acid rain) and the vast majority of soot (particulate matter) in our air.
What types of environmental impacts are associated with the use of coal? ›
Environmental impacts associated with using coal as an energy source are particulate emission, ground level ozone, smog and acid rain. Coal and fuel oil combustion emit fly ash particles into the atmosphere, which contribute to air pollution problems.
