Coal is formed from dead plant matter that decays into peat. Over millions of years, the heat and pressure from deep burial transform this peat into coal, increasing its carbon content while releasing water, methane, and carbon dioxide.

What geological periods are most associated with coal formation?

The vast majority of coal deposits, approximately 90%, were formed during the late Carboniferous (Pennsylvanian) and Permian periods. These times were characterized by extensive wetlands and coal forests covering much of the Earth's tropical land areas.

What is the process called that converts dead vegetation into coal?

The process by which dead vegetation is converted into coal is known as coalification. This involves the gradual transformation of plant matter into peat and then into various ranks of coal under heat and pressure.

What factors contributed to the extensive coal deposition during the Carboniferous period?

Several factors contributed to the large coal deposits of the Carboniferous period: high oxygen levels promoted wildfires and charcoal formation, high carbon dioxide levels encouraged plant growth, and the determinate growth of lycophyte trees meant carbon was quickly buried rather than tied up in living wood for long periods. Additionally, the formation of vast wetlands in low-lying areas and river deltas provided ideal conditions for peat preservation.

What is the significance of lignin in coal formation?

One theory suggests that the evolution of lignin, a complex polymer that made plant stems woody, contributed to coal formation. Initially, bacteria and fungi could not decompose lignin, leading to the burial of woody material that eventually became coal. The later evolution of lignin-degrading fungi is thought to have ended this main period of coal formation.

What are the different ranks of coal, from lowest to highest?

The ranks of coal, representing increasing metamorphic grade due to heat and pressure, are: peat (a precursor), lignite (brown coal), sub-bituminous coal, bituminous coal, and anthracite (hard coal or black coal). Graphite is also mentioned as a difficult-to-ignite form.

What is the primary use of coal?

The primary use of coal is as a fuel. It is used extensively for electricity generation and in various industrial processes, including iron and steel-making.

How did the Industrial Revolution impact coal consumption?

The Industrial Revolution led to a significant increase in coal consumption, particularly with the invention and widespread adoption of the steam engine, which replaced water wheels as a primary power source.

What percentage of the world's primary energy and electricity did coal supply in 2020?

In 2020, coal supplied approximately a quarter of the world's primary energy and over a third of its electricity.

What is the significance of the Paris Agreement regarding coal use?

To meet the Paris Agreement target of limiting global warming to below 2°C (3.6°F), coal use needs to be halved from 2020 to 2030. The Glasgow Climate Pact also agreed upon the concept of 'phasing down' coal.

Which countries are the largest consumers and exporters of coal?

In 2020, China was the largest consumer and importer of coal, accounting for nearly half of global production. India followed as a major consumer. Indonesia and Australia are the largest exporters, followed by Russia.

What is the etymological origin of the word 'coal'?

The word 'coal' originated from the Old English word 'col', which traces back to the Proto-Germanic '*kula(n)' and the Proto-Indo-European root '*g(e)u-lo-', meaning 'live coal'. Cognates exist in various Germanic languages.

What is the chemical composition of bituminous coal on a dry, ash-free basis?

Bituminous coal, on a dry, ash-free basis, has a chemical composition of approximately 84.4% carbon, 5.4% hydrogen, 6.7% oxygen, 1.7% nitrogen, and 1.8% sulfur by weight.

What chemical processes occur during coalification?

Coalification primarily involves dehydration (removing water), decarboxylation (removing carbon dioxide), and demethanation (removing methane). These processes increase the carbon content and alter the structure of the coal.

What are macerals in the context of coal?

Macerals are components of coal that originate from specific plant parts and retain some of their original properties. Key examples include vitrinite (from woody parts), lipinite (from spores and algae), and inertite (from burnt woody parts).

What is Hilt's Law in geology?

Hilt's Law is a geological observation stating that, within a localized area, the deeper a coal seam is found, the higher its rank or grade. This generally holds true due to increasing temperature with depth, though metamorphism can cause lateral rank changes.

What was the earliest documented intentional use of black coal?

The oldest documented intentional use of black coal was found in Ostrava, Czech Republic, at a settlement dating back to the older Stone Age (25,000–23,000 BC).

How was coal used in ancient China?

In China, Neolithic inhabitants used black lignite for carving ornaments as early as 4000 BC. By 1000 BC, coal from the Fushun mine was used to smelt copper.

What did Marco Polo observe about coal during his travels in China?

Marco Polo, during his 13th-century travels in China, described coal as 'black stones... which burn like logs' and noted its abundance, stating that people could take three hot baths a week due to its availability.

How did the Romans utilize coal in Britain?

In Roman Britain, Romans exploited coal in 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 drying grain, and coal cinders have been found in Roman villas and forts.

What is 'seacoal' and 'pitcoal'?

'Seacoal' was a term used in 13th-century Britain for coal found on the shore, often washed from exposed seams or underwater outcrops. 'Pitcoal' was an alternative name for coal extracted from underground mines.

What role did coal play in the Industrial Revolution in Britain?

Coal was crucial for the Industrial Revolution in Britain, powering steam engines that replaced water wheels. In 1700, Britain mined five-sixths of the world's coal, and its availability prevented a potential energy bottleneck that might have limited the growth of watermills.

What are the main components of coal ash?

Coal ash, an undesirable non-combustible mixture of inorganic minerals, is a significant byproduct of coal combustion. Its composition, expressed in weight percent of oxides, typically includes silicon dioxide (SiO2), aluminum oxide (Al2O3), iron(III) oxide (Fe2O3), calcium oxide (CaO), magnesium oxide (MgO), titanium dioxide (TiO2), sodium oxide (Na2O) & potassium oxide (K2O), and sulfur trioxide (SO3).

What are the primary concerns regarding sulfur and nitrogen in coal?

Sulfur and nitrogen are incorporated into the organic fraction of coal as organosulfur and organonitrogen compounds. Upon combustion, these elements are released as SO2 and NOx, which are major air pollutants. While inorganic sulfur (like iron pyrite) can be removed mechanically, the organically bound sulfur and nitrogen are difficult to remove economically.

What is thermal coal, and how is it used?

Thermal coal, also known as steam coal, is primarily used for electricity generation. It is typically pulverized and burned in a boiler to produce steam, which drives turbines connected to generators.

What is Integrated Gasification Combined Cycle (IGCC) technology for coal power?

IGCC is a more efficient method of burning coal where the coal is first gasified to produce syngas (a mixture of carbon monoxide and hydrogen). This syngas then fuels a gas turbine, and the exhaust heat raises steam for a secondary steam turbine, improving overall efficiency and reducing local pollution compared to conventional methods.

What is coke, and how is it produced from coal?

Coke is a solid, carbonaceous residue produced by heating metallurgical coal (coking coal) in an oven without oxygen at high temperatures (up to 1,000°C). This process drives off volatile components and fuses the fixed carbon and ash, creating a material used as fuel and a reducing agent in smelting iron.

What are the byproducts of coke production from coal?

The production of coke from coal yields several byproducts, including coal tar, ammonia, light oils, and coal gas. These byproducts can be valuable chemical feedstocks but also pose environmental risks if not managed properly.

How is coal used in the production of chemicals?

Coal can serve as a feedstock for chemical production, primarily through coal gasification to produce syngas. Syngas is a building block for methanol, hydrogen, carbon monoxide, and subsequently, a wide range of derivative chemicals like fertilizers, olefins, and urea.

What is coal liquefaction?

Coal liquefaction is a process that converts coal into synthetic fuels similar to gasoline or diesel through hydrogenation or carbonization. However, it emits more carbon dioxide than liquid fuel production from crude oil and is costly, especially when combined with biomass or carbon capture.

What are the primary environmental impacts of coal mining?

Coal mining impacts water systems by affecting groundwater levels and acidity. It can also lead to spills of coal ash, contaminating land and waterways, and can cause land subsidence above underground tunnels. Additionally, thousands of coal seam fires burn globally, releasing dangerous gases.

What is acid rain, and how is coal related to it?

Acid rain is formed when sulfur dioxide (SO2) released into the atmosphere is oxidized into sulfuric acid (H2SO4). Burning coal is a major source of SO2 emissions, contributing significantly to acid rain, which can acidify ecosystems. While SO2 has a temporary cooling effect on climate, its acidic precipitation causes environmental damage.

What is 'black lung disease'?

Black lung disease, or coalworker's pneumoconiosis, is a respiratory illness caused by inhaling coal dust. The dust particles accumulate in the lungs, turning them black and leading to serious health consequences, with an estimated 1,500 former coal industry workers dying annually from it in the US.

What are the health effects associated with coal smokestack emissions?

Emissions from coal smokestacks can cause a range of health problems, including asthma, strokes, reduced intelligence, artery blockages, heart attacks, congestive heart failure, cardiac arrhythmias, mercury poisoning, arterial occlusion, and lung cancer.

How does coal use contribute to climate change?

The burning of coal releases large amounts of carbon dioxide (CO2), a potent greenhouse gas, into the atmosphere. CO2 traps heat, leading to global warming and climate change. Coal-fired power plants are a major contributor to global CO2 emissions.

What is 'clean coal' technology?

'Clean coal' technology refers to various methods aimed at reducing the environmental impact of coal. Initially, this included scrubbers and catalytic converters to reduce acid rain pollutants. More recently, the term has expanded to include carbon capture and storage (CCS) to mitigate greenhouse gas emissions, though critics argue coal itself cannot be truly 'clean'.

What is 'abated coal' in the context of climate agreements?

The term 'abated coal' refers to coal use that employs technologies to reduce greenhouse gas emissions. However, the definition can be ambiguous, as 'abatement' might involve capturing only a small percentage of emissions, leading to concerns about its effectiveness in meeting climate targets like those in the Paris Agreement.

What are the economic risks associated with coal?

The economic risks of coal include potential 'stranded assets' where coal-fired power stations become obsolete before their expected lifespan due to the energy transition. Investments in coal may lead to trillions of dollars in losses globally, and the social cost of carbon associated with coal use significantly impacts economies like India and the US.

What is the trend in coal subsidies?

Subsidies for coal production and use remain significant globally, with G20 countries providing billions of dollars annually. While some regions are phasing out subsidies, particularly for new plants, considerable financial support continues, influencing market trends and the energy transition.

What is the cultural significance of coal in some traditions?

In some cultures, coal has symbolic meaning. For instance, it's a tradition in some places for Santa Claus to leave a lump of coal in the stockings of misbehaving children. Conversely, in Scotland, coal is given as a lucky gift on New Year's Day, symbolizing warmth for the coming year.

What are the main types of coal based on their grade or rank?

Coal is classified into ranks based on its geological age and the degree of transformation it has undergone. The main types, from lowest to highest rank, are peat (a precursor), lignite, sub-bituminous coal, bituminous coal, and anthracite. Cannel coal is another variety known for its high hydrogen content.

What is the difference between thermal coal and metallurgical coal?

Thermal coal, also known as steam coal, is primarily burned to generate electricity through steam production. Metallurgical coal, or coking coal, is used at high temperatures to produce coke, which is essential for smelting iron ore in blast furnaces for steelmaking. Metallurgical coal is typically lower in sulfur and requires more processing, making it more expensive.

What are the primary chemical changes during carbonization?

Carbonization, a key part of coalification, primarily involves dehydration (loss of water), decarboxylation (loss of carbon dioxide), and demethanation (loss of methane). These processes reduce the oxygen and hydrogen content and increase the carbon saturation of the coal's structure.

How does coal mining contribute to methane emissions?

Coal mining can release methane, a potent greenhouse gas, into the atmosphere. This methane is often trapped within the coal seams and is released during the extraction process. Efforts to extract coalbed methane are sometimes undertaken to prevent mining accidents and potentially utilize this gas.

What are the main challenges for Carbon Capture and Storage (CCS) technology?

The widespread deployment of CCS technology faces challenges including high costs, the lack of clear long-term liability frameworks for stored CO2, and limited social acceptance. Consequently, many planned CCS projects for coal power plants have been canceled or failed to materialize.

What is the typical ash composition found in coal?

Coal ash typically contains a mixture of inorganic minerals, with the composition often discussed in terms of oxides. Common components include silicon dioxide (20-40%), aluminum oxide (10-35%), iron(III) oxide (5-35%), calcium oxide (1-20%), magnesium oxide (0.3-4%), titanium dioxide (0.5-2.5%), sodium and potassium oxides (1-4%), and sulfur trioxide (0.1-12%).

What trace elements are found in coal, and why are they a concern?

Coal contains trace elements such as mercury (around 0.10 ppm), arsenic (1.4–71 ppm), and selenium (around 3 ppm). While these are present in small amounts as minerals, they become mobile and can be released as volatile or water-soluble compounds during combustion, posing environmental and health risks.

Coal Wiki: Coal: The Earth's Buried Energy

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What is Coal?

Sedimentary Origin

Coal is a combustible, black or brownish-black sedimentary rock, formed in rock strata known as coal seams. It is primarily composed of carbon, with varying amounts of hydrogen, sulfur, oxygen, and nitrogen.

Fossilized Plant Matter

It is a type of fossil fuel, originating from dead plant matter in ancient wetlands. Over millions of years, the heat and pressure of deep burial transformed this organic material into coal.

Primary Fuel Source

Historically, coal's usage surged during the Industrial Revolution with the invention of the steam engine. Today, it remains a significant global energy source, supplying a substantial portion of the world's primary energy and electricity.

The Formation of Coal

Ancient Wetlands

Vast deposits of coal originate from ancient tropical wetland environments, known as coal forests, which covered much of the Earth's landmass during the late Carboniferous and Permian periods.

Peat Formation

When dead plant matter in these wetlands was protected from oxidation, typically by mud or acidic water, it began to decay and accumulate, forming peat. These peat bogs trapped immense amounts of carbon.

Coalification Process

Over millions of years, these peat deposits were buried deeply. The increasing heat and pressure from this burial gradually drove out water, methane, and carbon dioxide, concentrating the carbon content and transforming the peat into various ranks of coal.

The process, known as coalification, is influenced by temperature, pressure, and time. Higher temperatures and pressures generally lead to higher ranks of coal. Factors like the evolution of lignin-degrading fungi and tectonic mountain ranges also played roles in the extensive coal formation during the Carboniferous period.

Coal's Composition

Elemental Makeup

Coal is a complex mixture. Bituminous coal, for instance, typically consists of about 84.4% carbon, 5.4% hydrogen, 6.7% oxygen, 1.7% nitrogen, and 1.8% sulfur by weight.

Ash and Impurities

A significant portion of coal is ash, an undesirable non-combustible mixture of inorganic minerals. Sulfur and nitrogen are often strongly bound within the hydrocarbon matrix, releasing pollutants like SO₂ and NO_x upon combustion.

Ash composition varies but commonly includes oxides like SiO₂ (20-40%), Al₂O₃ (10-35%), and Fe₂O₃ (5-35%), along with smaller amounts of calcium, magnesium, titanium, sodium, and potassium oxides. Trace elements like mercury, arsenic, and selenium are also present.

Macerals

Coal also contains macerals, which are coalified plant fragments retaining some original morphology. Key macerals include vitrinite (from woody parts), lipinite (from spores/algae), and inertite (from burnt woody parts).

Diverse Applications

Electricity Generation

The predominant use of coal is as thermal coal for electricity generation. Pulverized coal is burned in boilers to produce steam, which drives turbines connected to generators.

Coal power plants convert the chemical energy in coal into electrical energy. The efficiency of this conversion varies, typically ranging from 25% to 50%. Integrated Gasification Combined Cycle (IGCC) plants offer higher efficiency and reduced local pollution by gasifying coal into syngas first.

Industrial Processes

Metallurgical coal, or coking coal, is essential for steel production. It is heated in ovens to produce coke, which acts as a fuel and reducing agent in blast furnaces for smelting iron ore.

Chemical Feedstock

Coal can be gasified to produce syngas (a mixture of carbon monoxide and hydrogen), which serves as a building block for various chemicals, including methanol, ammonia, and fertilizers. It can also be liquefied into synthetic fuels.

Historical Significance

Ancient Use

The intentional use of coal dates back thousands of years, with evidence found from the Stone Age. Early civilizations in China and Europe utilized coal for smelting metals and heating.

Industrial Revolution

Coal's importance dramatically increased with the Industrial Revolution, powering steam engines and driving unprecedented industrial growth. It became the primary energy source, transforming economies and societies.

By the 18th century, Britain was a leading coal producer. The widespread adoption of coal fueled advancements in manufacturing, transportation (steam locomotives and ships), and urban development, fundamentally reshaping the modern world.

Modern Trends

While coal remains significant, global trends show a gradual shift towards renewable energy sources and natural gas, driven by environmental concerns and technological advancements. Many nations are implementing coal phase-out plans.

Environmental & Health Impacts

Air Pollution

Burning coal releases significant pollutants, including sulfur dioxide (SO₂), nitrogen oxides (NOx), particulate matter (PM2.5), heavy metals like mercury, and greenhouse gases like carbon dioxide (CO₂).

Climate Change

Coal is the largest anthropogenic source of carbon dioxide, a primary driver of global warming and climate change. Its combustion contributes substantially to the greenhouse gas emissions warming the planet.

In 2020, burning coal released approximately 14 billion tonnes of CO₂, representing about 40% of total fossil fuel emissions. Meeting climate targets necessitates significant reductions in coal consumption.

Health Consequences

Coal mining and combustion contribute to severe health issues, including respiratory diseases (like black lung from coal dust), cardiovascular problems, asthma, and premature deaths. Air pollution from coal plants is linked to millions of early deaths globally each year.

Water & Land Contamination

Coal mining can contaminate water sources and affect water tables. Coal combustion produces vast amounts of ash containing toxic heavy metals and radioactive elements, which can pollute land and waterways if not managed properly.

Economic Landscape

Global Market

China is the world's largest producer and consumer of coal, followed by India. Major exporters include Indonesia, Australia, and Russia. Market trends are heavily influenced by national energy policies and global demand.

Subsidies and Costs

Significant government subsidies continue to support coal production and consumption globally. However, the economic viability of coal is increasingly challenged by the falling costs of renewable energy and the substantial external costs associated with its environmental and health impacts.

The true cost of coal includes not only extraction and generation but also the immense societal costs of pollution, healthcare, and climate change mitigation. Many coal-fired plants are becoming economically uncompetitive compared to cleaner alternatives.

Stranded Assets

The global energy transition poses a risk of coal-related infrastructure becoming "stranded assets"—investments that lose value prematurely due to market shifts, regulatory changes, or technological obsolescence.

Political Dimensions

International Agreements

Countries heavily reliant on coal face international criticism for hindering global climate goals, such as those outlined in the Paris Agreement. Efforts to phase out coal are central to international climate negotiations.

Policy Debates

The future of coal is a subject of intense political debate, involving energy security, economic development, environmental protection, and public health. Policies range from phasing out coal power to exploring "clean coal" technologies.

The term "clean coal" often refers to technologies aimed at reducing emissions, such as scrubbers or carbon capture and storage (CCS). However, critics argue that these technologies do not fully mitigate coal's environmental impact, and the term can be misleading, implying coal itself can be inherently clean.

National Policies

Governments worldwide are navigating the complex transition away from coal, balancing energy needs with climate commitments. This involves significant policy decisions regarding subsidies, regulations, and investments in alternative energy sources.

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References

Ayuso-Fernandez I, Ruiz-Duenas FJ, Martinez AT: Evolutionary convergence in lignin-degrading enzymes. Proc Natl Acad Sci USA 2018, 115:6428-6433.

The travels of Marco Polo the Venetian. 1914. pp.214-215.

Human Impacts on Atmospheric Chemistry, by PJ Crutzen and J Lelieveld, Annual Review of Earth and Planetary Sciences, Vol. 29: 17â45 (Volume publication date May 2001)

A full list of references for this article are available at the Coal Wikipedia page

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This content has been generated by an AI and is intended for educational and informational purposes only. It is based on data from Wikipedia and may not reflect the most current information or all nuances of the topic.

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Coal: The Earth's Buried Energy

💡 Dive in with Flashcard Learning! 💡

What is Coal? ⚫

💎 Sedimentary Origin

⏳ Fossilized Plant Matter

🔥 Primary Fuel Source

The Formation of Coal 🌱➡️🔥

🌳 Ancient Wetlands

💧 Peat Formation

🌡️ Coalification Process

Coal's Composition ⚛️

🧪 Elemental Makeup

🌫️ Ash and Impurities

🌿 Macerals

Diverse Applications 💡

⚡ Electricity Generation

🏭 Industrial Processes

⚗️ Chemical Feedstock

Historical Significance 📜

🏺 Ancient Use

⚙️ Industrial Revolution

📉 Modern Trends

Environmental & Health Impacts ⚠️

💨 Air Pollution

🌡️ Climate Change

😷 Health Consequences

💧 Water & Land Contamination

Economic Landscape 💰

📈 Global Market

💸 Subsidies and Costs

⚠️ Stranded Assets

Political Dimensions 🏛️

🌍 International Agreements

⚖️ Policy Debates

🏛️ National Policies

Teacher's Corner 🧑‍🏫

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References

📜 References

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Disclaimer ⚠️

📜 Important Notice

Dive in with Flashcard Learning!

What is Coal?

Sedimentary Origin

Fossilized Plant Matter

Primary Fuel Source

The Formation of Coal

Ancient Wetlands

Peat Formation

Coalification Process

Coal's Composition

Elemental Makeup

Ash and Impurities

Macerals

Diverse Applications

Electricity Generation

Industrial Processes

Chemical Feedstock

Historical Significance

Ancient Use

Industrial Revolution

Modern Trends

Environmental & Health Impacts

Air Pollution

Climate Change

Health Consequences

Water & Land Contamination

Economic Landscape

Global Market

Subsidies and Costs

Stranded Assets

Political Dimensions

International Agreements

Policy Debates

National Policies

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice