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Coal: the story on HearLore | HearLore
Coal
Coal is a combustible black or brownish-black sedimentary rock, formed as layers called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. It is a fossil fuel, formed when plants decay into peat which is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits formed from wetlands called coal forests that covered much of the tropics during the late Carboniferous and early Permian. Coal is used primarily as a fuel. While coal has been known and used for thousands of years, its usage was limited until the Industrial Revolution. With the invention of the steam engine, coal consumption increased. In 2020, coal supplied about a quarter of the world's primary energy and over a third of its electricity. Some iron and steel-making and other industrial processes burn coal. The extraction and burning of coal damages the environment and human health, causing premature death and illness, and is the largest source of carbon dioxide contributing to climate change. Over fifteen billion tonnes of carbon dioxide were emitted by burning coal in 2024, which was more than a quarter of total global greenhouse gas emissions. As part of worldwide energy transition, many countries have reduced or eliminated their use of coal power. The United Nations Secretary General asked governments to stop building new coal plants by 2020. A record amount of coal was burnt in 2024, but consumption is expected to peak before 2030. To meet the Paris Agreement target of keeping global warming below coal use needs to halve from 2020 to 2030, and phasing down coal was agreed upon in the Glasgow Climate Pact. The largest consumer and importer of coal is China, which mines almost half the world's coal, followed by India with about a tenth. Indonesia and Australia export the most, followed by Russia.
The Ancient Forests That Became Stone
The conversion of dead vegetation into coal is called coalification. At various times in the geologic past, the Earth had dense forests in low-lying areas. In these wetlands, the process of coalification began when dead plant matter was protected from oxidation, usually by mud or acidic water, and was converted into peat. The resulting peat bogs, which trapped immense amounts of carbon, were eventually deeply buried by sediments. Then, over millions of years, the heat and pressure of deep burial caused the loss of water, methane and carbon dioxide and increased the proportion of carbon. The grade of coal produced depended on the maximum pressure and temperature reached, with lignite produced under relatively mild conditions, and sub-bituminous coal, bituminous coal, or anthracite produced in turn with increasing temperature and pressure. Of the factors involved in coalification, temperature is much more important than either pressure or time of burial. Subbituminous coal can form at temperatures as low as 50 degrees Celsius while anthracite requires a temperature of at least 200 degrees Celsius. Although coal is known from most geologic periods, 90% of all coal beds were deposited in the Carboniferous and Permian periods. Paradoxically, this was during the Late Paleozoic icehouse, a time of global glaciation. However, the drop in global sea level accompanying the glaciation exposed continental shelves that had previously been submerged, and to these were added wide river deltas produced by increased erosion due to the drop in base level. These widespread areas of wetlands provided ideal conditions for coal formation. The rapid formation of coal ended with the coal gap in the Permian-Triassic extinction event, where coal is rare. Favorable geography alone does not explain the extensive Carboniferous coal beds. Other factors contributing to rapid coal deposition were high oxygen levels, above 30%, that promoted intense wildfires and formation of charcoal that was all but indigestible by decomposing organisms; high carbon dioxide levels that promoted plant growth; and the nature of Carboniferous forests, which included lycophyte trees whose determinate growth meant that carbon was not tied up in heartwood of living trees for long periods. One theory suggested that about 360 million years ago, some plants evolved the ability to produce lignin, a complex polymer that made their cellulose stems much harder and more woody. The ability to produce lignin led to the evolution of the first trees. But bacteria and fungi did not immediately evolve the ability to decompose lignin, so the wood did not fully decay but became buried under sediment, eventually turning into coal. About 300 million years ago, mushrooms and other fungi developed this ability, ending the main coal-formation period of earth's history. Although some authors pointed at some evidence of lignin degradation during the Carboniferous, and suggested that climatic and tectonic factors were a more plausible explanation, reconstruction of ancestral enzymes by phylogenetic analysis corroborated a hypothesis that lignin degrading enzymes appeared in fungi approximately 200 million years ago. One likely tectonic factor was the Central Pangean Mountains, an enormous range running along the equator that reached its greatest elevation near this time. Climate modeling suggests that the Central Pangean Mountains contributed to the deposition of vast quantities of coal in the late Carboniferous. The mountains created an area of year-round heavy precipitation, with no dry season typical of a monsoon climate. This is necessary for the preservation of peat in coal swamps. Coal is known from Precambrian strata, which predate land plants. This coal is presumed to have originated from residues of algae. Sometimes coal seams are interbedded with other sediments in a cyclothem. Cyclothems are thought to have their origin in glacial cycles that produced fluctuations in sea level, which alternately exposed and then flooded large areas of continental shelf.
Common questions
What is coal and how is it formed?
Coal is a combustible black or brownish-black sedimentary rock formed when plants decay into peat and are converted into coal by the heat and pressure of deep burial over millions of years. The process called coalification begins when dead plant matter is protected from oxidation by mud or acidic water and is eventually deeply buried by sediments. About 90% of all coal beds were deposited in the Carboniferous and Permian periods during the Late Paleozoic icehouse.
When was coal first used by humans and where?
The oldest intentional use of black coal was documented in Ostrava, Petřkovice, in a settlement from the older Stone Age on the top of Landek Hill between 25,000 and 23,000 years BC. In China, the earliest recognized use is from the Shenyang where by 4000 BC Neolithic inhabitants had begun carving ornaments from black lignite. Coal from the Fushun mine in northeastern China was used to smelt copper as early as 1000 BC.
How does coal use affect human health and the environment?
Globally coal is estimated to cause 800,000 premature deaths every year, mostly in India and China, due to air and water pollution from mining and processing. Burning coal is a major contributor to sulfur dioxide emissions which creates PM2.5 particulates and causes asthma, strokes, heart attacks, and lung cancer. Coal ash contains radioactive elements uranium and thorium and is hazardous to human beings and other living things.
Which countries consume and export the most coal in 2024?
China is the largest consumer and importer of coal, which mines almost half the world's coal and used 4520 Mt in 2022. Indonesia and Australia export the most coal, followed by Russia, with Indonesia being the largest exporter by volume in 2022 at 471 Mt. India is the second largest consumer with about a tenth of global consumption, followed by the European Union and the United States.
What are the global targets for reducing coal use by 2030?
To meet the Paris Agreement target of keeping global warming below 1.5 degrees Celsius or 2 degrees Celsius, coal use needs to halve from 2020 to 2030. The United Nations Secretary General asked governments to stop building new coal plants by 2020, and phasing down coal was agreed upon in the Glasgow Climate Pact. A record amount of coal was burnt in 2024, but consumption is expected to peak before 2030.
The oldest intentional use of black coal was documented in Ostrava, Petřkovice, in a settlement from the older Stone Age on the top of Landek Hill. According to radiocarbon dating, the site falls within the period 25,000 to 23,000 years BC. In China, the earliest recognized use is from the Shenyang where by 4000 BC Neolithic inhabitants had begun carving ornaments from black lignite. Coal from the Fushun mine in northeastern China was used to smelt copper as early as 1000 BC. Marco Polo, the Italian who traveled to China in the 13th century, described coal as black stones which burn like logs, and said coal was so plentiful, people could take three hot baths a week. The travels of Marco Polo the Venetian. 1914. pp.214-215. In Europe, the earliest reference to the use of coal as fuel is from the geological treatise On Stones c. 371 to 287 BC. Outcrop coal was used in Britain during the Bronze Age 3000 to 2000 BC, where it formed part of funeral pyres. In Roman Britain, the Romans were exploiting coals in all the major coalfields in England and Wales by the end of the second century AD. Coal from the Midlands was transported via the Car Dyke for use in drying grain. Coal cinders have been found in the hearths of villas and Roman forts, particularly in Northumberland, dated to around AD 400. In the west of England, contemporary writers described the wonder of a permanent brazier of coal on the altar of Minerva at Aquae Sulis modern day Bath, although in fact easily accessible surface coal from what became the Somerset coalfield was in common use in quite lowly dwellings locally. Evidence of coal's use for iron-working in the city during the Roman period has been found. In Eschweiler, Rhineland, deposits of bituminous coal were used by the Romans for the smelting of iron ore. No evidence exists of coal being of great importance in Britain before about AD 1000, the High Middle Ages. Coal came to be referred to as seacoal in the 13th century; the wharf where the material arrived in London was known as Seacoal Lane, so identified in a charter of King Henry III granted in 1253. Initially, the name was given because much coal was found on the shore, having fallen from the exposed coal seams on cliffs above or washed out of underwater coal outcrops. In 1257 to 1259, coal from Newcastle upon Tyne was shipped to London for the smiths and lime-burners building Westminster Abbey. Coal continues to arrive on beaches around the world from both natural erosion of exposed coal seams and windswept spills from cargo ships. Many homes in such areas gather this coal as a significant, and sometimes primary, source of home heating fuel. These easily accessible sources had largely become exhausted or could not meet the growing demand by the 13th century, when underground extraction by shaft mining or adits was developed. The alternative name was pitcoal, because it came from mines. Cooking and home heating with coal in addition to firewood or instead of it has been done in various times and places throughout human history, especially in times and places where ground-surface coal was available and firewood was scarce, but a widespread reliance on coal for home hearths probably never existed until such a switch in fuels happened in London in the late sixteenth and early seventeenth centuries. Historian Ruth Goodman has traced the socioeconomic effects of that switch and its later spread throughout Britain and suggested that its importance in shaping the industrial adoption of coal has been previously underappreciated. The development of the Industrial Revolution led to the large-scale use of coal, as the steam engine took over from the water wheel. In 1700, five-sixths of the world's coal was mined in Britain. Britain would have run out of suitable sites for watermills by the 1830s if coal had not been available as a source of energy. In 1947 there were some 750,000 miners in Britain, but the last deep coal mine in the UK closed in 2015. A grade between bituminous coal and anthracite was once known as steam coal as it was widely used as a fuel for steam locomotives. In this specialized use, it is sometimes known as sea coal in the United States. Small steam coal, also called dry small steam nuts DSSN, was used as a fuel for domestic water heating. Coal played an important role in industry in the 19th and 20th century. The predecessor of the European Union, the European Coal and Steel Community, was based on the trading of this commodity.
The Chemical Alchemy Of Black Rock
The use of coal as fuel causes health problems and deaths. The mining and processing of coal causes air and water pollution. Coal-powered plants emit nitrogen oxides, sulfur dioxide, particulate pollution, and heavy metals, which adversely affect human health. Coalbed methane extraction is important to avoid mining accidents. The deadly London smog was caused primarily by the heavy use of coal. Globally coal is estimated to cause 800,000 premature deaths every year, mostly in India and China. Preventing disease through healthy environments: a global assessment of the burden of disease from environmental risks. World Health Organization 2006. Burning coal is a major contributor to sulfur dioxide emissions, which creates PM2.5 particulates, the most dangerous form of air pollution. Coal smokestack emissions cause asthma, strokes, reduced intelligence, artery blockages, heart attacks, congestive heart failure, cardiac arrhythmias, mercury poisoning, arterial occlusion, and lung cancer. Coal Pollution Damages Human Health at Every Stage of Coal Life Cycle, Reports Physicians for Social Responsibility. Physicians for Social Responsibility. psr.org the 18th of November 2009. Burt, Erica; Orris, Peter and Buchanan, Susan April 2013. Scientific Evidence of Health Effects from Coal Use in Energy Generation. University of Illinois at Chicago School of Public Health, Chicago, Illinois, US. Annual health costs in Europe from use of coal to generate electricity are estimated at up to €43 billion. In China, early deaths due to air pollution coal plants have been estimated at 200 per GW-year, however they may be higher around power plants where scrubbers are not used or lower if they are far from cities. Improvements to China's air quality and human health would grow with more stringent climate policies, mainly because the country's energy is so heavily reliant on coal. And there would be a net economic benefit. A 2017 study in the Economic Journal found that for Britain during the period 1851 to 1860, a one standard deviation increase in coal use raised infant mortality by 6 to 8% and that industrial coal use explains roughly one-third of the urban mortality penalty observed during this period. Breathing in coal dust causes coalworker's pneumoconiosis or black lung, so called because the coal dust literally turns the lungs black. In the US alone, it is estimated that 1,500 former employees of the coal industry die every year from the effects of breathing in coal mine dust. Huge amounts of coal ash and other waste is produced annually. Use of coal generates hundreds of millions of tons of ash and other waste products every year. These include fly ash, bottom ash, and flue-gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals, along with non-metals such as selenium. World Coal Association Environmental impact of Coal Use. Around 10% of coal is ash. Coal ash is hazardous and toxic to human beings and some other living things. Coal ash contains the radioactive elements uranium and thorium. Coal ash and other solid combustion byproducts are stored locally and escape in various ways that expose those living near coal plants to radiation and environmental toxics. Coal mining, coal combustion wastes, and flue gas are causing major environmental damage. Water systems are affected by coal mining. For example, the mining of coal affects groundwater and water table levels and acidity. Spills of fly ash, such as the Kingston Fossil Plant coal fly ash slurry spill, can also contaminate land and waterways, and destroy homes. Power stations that burn coal also consume large quantities of water. This can affect the flows of rivers, and has consequential impacts on other land uses. In areas of water scarcity, such as the Thar Desert in Pakistan, coal mining and coal power plants contribute to the depletion of water resources. One of the earliest known impacts of coal on the water cycle was acid rain. In 2014, approximately 100 Tg/S of sulfur dioxide SO2 was released, over half of which was from burning coal. After release, the sulfur dioxide is oxidized to H2SO4 which scatters solar radiation, hence its increase in the atmosphere exerts a cooling effect on the climate. This beneficially masks some of the warming caused by increased greenhouse gases. However, the sulfur is precipitated out of the atmosphere as acid rain in a matter of weeks, whereas carbon dioxide remains in the atmosphere for hundreds of years. Release of SO2 also contributes to the widespread acidification of ecosystems. Human Impacts on Atmospheric Chemistry, by PJ Crutzen and J Lelieveld, Annual Review of Earth and Planetary Sciences, Vol. 29: 17 to 45 Volume publication date May 2001. Disused coal mines can also cause issues. Subsidence can occur above tunnels, causing damage to infrastructure or cropland. Coal mining can also cause long lasting fires, and it has been estimated that thousands of coal seam fires are burning at any given time. For example, Brennender Berg has been burning since 1668, and is still burning in the 21st century. The production of coke from coal produces ammonia, coal tar, and gaseous compounds as byproducts which if discharged to land, air or waterways can pollute the environment. The Whyalla steelworks is one example of a coke producing facility where liquid ammonia was discharged to the marine environment. The largest and most long-term effect of coal use is the release of carbon dioxide, a greenhouse gas that causes climate change. Coal-fired power plants were the single largest contributor to the growth in global CO2 emissions in 2018, Gençsü 2019, p. 8, 40% of the total fossil fuel emissions, and more than a quarter of total emissions. Coal mining can emit methane, another greenhouse gas. In 2016 world gross carbon dioxide emissions from coal usage were 14.5 gigatonnes. For every megawatt-hour generated, coal-fired electric power generation emits around a tonne of carbon dioxide, which is double the approximately 500 kg of carbon dioxide released by a natural gas-fired electric plant. The emission intensity of coal varies with type and generator technology and exceeds 1200 g per kWh in some countries. In 2013, the head of the UN climate agency advised that most of the world's coal reserves should be left in the ground to avoid catastrophic global warming. To keep global warming below 1.5 degrees Celsius or 2 degrees Celsius hundreds, or possibly thousands, of coal-fired power plants will need to be retired early. Thousands of coal fires are burning around the world. Those burning underground can be difficult to locate and many cannot be extinguished. Fires can cause the ground above to subside, their combustion gases are dangerous to life, and breaking out to the surface can initiate surface wildfires. Coal seams can be set on fire by spontaneous combustion or contact with a mine fire or surface fire. Lightning strikes are an important source of ignition. The coal continues to burn slowly back into the seam until oxygen air can no longer reach the flame front. A grass fire in a coal area can set dozens of coal seams on fire. Coal fires in China burn an estimated 120 million tons of coal a year, emitting 360 million metric tons of CO2, amounting to 2 to 3% of the annual worldwide production of CO2 from fossil fuels.
About 8,000 Mt of coal are produced annually, about 90% of which is hard coal and 10% lignite. just over half is from underground mines. The coal mining industry employs almost 2.7 million workers. More accidents occur during underground mining than surface mining. Not all countries publish mining accident statistics so worldwide figures are uncertain, but it is thought that most deaths occur in coal mining accidents in China: in 2017 there were 375 coal mining related deaths in China. Most coal mined is thermal coal also called steam coal as it is used to make steam to generate electricity but metallurgical coal also called metcoal or coking coal as it is used to make coke to make iron accounts for 10% to 15% of global coal use. China mines almost half the world's coal, followed by India with about a tenth. At 471 Mt and a 34% share of global exports, Indonesia was the largest exporter by volume in 2022, followed by Australia with 344 Mt and Russia with 224 Mt. Other major exporters of coal are the United States, South Africa, Colombia, and Canada. In 2022, China, India, and Japan were the biggest importers of coal, importing 301, 228, and 184 Mt respectively. Russia is increasingly orienting its coal exports from Europe to Asia as Europe transitions to renewable energy and subjects Russia to sanctions over its invasion of Ukraine. The price of metallurgical coal is volatile and much higher than the price of thermal coal because metallurgical coal must be lower in sulfur and requires more cleaning. Coal futures contracts provide coal producers and the electric
The Black Lung And The Burning Earth
power industry an important tool for hedging and risk management. In some countries, new onshore wind or solar generation already costs less than coal power from existing plants. However, for China this is forecast for the early 2020s and for southeast Asia not until the late 2020s. In India, building new plants is uneconomic and, despite being subsidized, existing plants are losing market share to renewables. In many countries in the Global North, there is a move away from the use of coal and former mine sites are being used as a tourist attraction. In 2022, China used 4520 Mt of coal, comprising more than half of global coal consumption. India, the European Union, and the United States, were the next largest consumers of coal, using 1162, 461, and 455 Mt respectively. Over the past decade, China has almost always accounted for the lion's share of the global growth in coal demand. Therefore, international market trends depend on Chinese energy policy. Although the government effort to reduce air pollution in China means that the global long-term trend is to burn less coal, the short and medium term trends may differ, in part due to Chinese financing of new coal-fired power plants in other countries. Preliminary analysis by International Energy Agency IEA indicates that global coal exports reached an all-time high in 2023. Through to 2026, the IEA expects global coal trade to decline by about 12%, driven by growing domestic production in coal-intensive economies such as China and India and coal phase-out plans elsewhere, such as in Europe. While thermal coal exports are expected to decline by about 16% by 2026, exports of metallurgical coal are expected to slightly increase by almost 2%. In 2018 was invested in coal supply but almost all for sustaining production levels rather than opening new mines. In the long term coal and oil could cost the world trillions of dollars per year. Coal alone may cost Australia billions, whereas costs to some smaller companies or cities could be on the scale of millions of dollars. The economies most damaged by coal via climate change may be India and the US as they are the countries with the highest social cost of carbon. Bank loans to finance coal are a risk to the Indian economy. China is the largest producer of coal in the world. It is the world's largest energy consumer, and coal in China supplies 60% of its primary energy. However two fifths of China's coal power stations are estimated to be loss-making. Air pollution from coal storage and handling costs the US almost 200 dollars for every extra ton stored, due to PM2.5. Coal pollution costs the each year. Measures to cut air pollution benefit individuals financially and the economies of countries such as China. Subsidies for coal in 2021 have been estimated at, not including electricity subsidies, and are expected to rise in 2022. G20 countries provide at least of government support per year for the production of coal, including coal-fired power: many subsidies are impossible to quantify but they include in domestic and international public finance, in fiscal support, and in state-owned enterprise SOE investments per year. In Indonesia, coal power is subsidized through a ceiling on the price that coal producers can charge from domestic consumers. At the same time, the producers are obliged to provide specific amounts of coal to domestic consumers. This ensures that domestic consumers get coal at a discounted price and the producers lose money that they could otherwise have earned from selling the coal on the international market. In the EU state aid to new coal-fired plants is banned from 2020, and to existing coal-fired plants from 2025. As of 2018, government funding for new coal power plants was supplied by Exim Bank of China, the Japan Bank for International Cooperation and Indian public sector banks. Coal in Kazakhstan was the main recipient of coal consumption subsidies totalling US$2 billion in 2017. Coal in Turkey benefited from substantial subsidies in 2021. Some coal-fired power stations could become stranded assets, for example China Energy Investment, the world's largest power company, risks losing half its capital. However, state-owned electricity utilities such as Eskom in South Africa, Perusahaan Listrik Negara in Indonesia, Sarawak Energy in Malaysia, Taipower in Taiwan, EGAT in Thailand, Vietnam Electricity and EÜAŞ in Turkey are building or planning new plants. As of 2021 this may be helping to cause a carbon bubble which could cause financial instability if it bursts. Countries building or financing new coal-fired power stations, such as China, India, Indonesia, Vietnam, Turkey and Bangladesh, face mounting international criticism for obstructing the aims of the Paris Agreement. In 2019, the Pacific Island nations in particular Vanuatu and Fiji criticized Australia for failing to cut their emissions at a faster rate than they were, citing concerns about coastal inundation and erosion. In May 2021, the G7 members agreed to end new direct government support for international coal power generation. Coal is the official state mineral of Kentucky, and the official state rock of Utah and West Virginia. These US states have a historic link to coal mining. Some cultures hold that children who misbehave will receive only a lump of coal from Santa Claus for Christmas in their stockings instead of presents. It is also customary and considered lucky in Scotland to give coal as a gift on New Year's Day. This occurs as part of first-footing and represents warmth for the year to come.