Why is coal usually found in layers

Although coal is much maligned because of its byproducts from combustion, the factors responsible for coal accumulation also give us fossil treasures from the past. To stop coal mining would undoubtedly mean many good fossils remain in the ground. But the long-term health of our planet is a bigger priority. This is the first article in our series on the past, present and future of coal.

Look out for others in the coming days. Post any questions you have in the comments below. Portsmouth Climate Festival — Portsmouth, Portsmouth. Edition: Available editions United Kingdom. Become an author Sign up as a reader Sign in. Coal has provided us with some stunning fossils. Continued burial, resulting in increasing pressures and temperatures, causes this low quality lignite coal to be transformed into higher quality "black coals".

First lignite becomes sub-bituminous coal, then bituminous coal, and finally the highest quality anthracite coal. As these transformations occur, the amount of water and other compounds in the coal decreases and the coal becomes more dense.

Along with this comes a higher carbon concentration. Figure 2. General trends that produce coal with the different types of coal that exist. Energy, Environment and Climate , 2nd ed. New York, U. Affolter, J. May 11, Carbon dioxide is the primary emission. It is called a greenhouse gas because it absorbs and retains heat in the atmosphere, and keeps our planet at a livable temperature.

In the natural carbon cycle , carbon and carbon dioxide are constantly cycled between the land, ocean, atmosphere, and all living and decomposing organisms. Carbon is also sequester ed, or stored underground. This keeps the carbon cycle in balance. However, when coal and other fossil fuels are extracted and burned, they release sequestered carbon into the atmosphere, which leads to a build-up of greenhouse gases and adversely affects climate s and ecosystems.

Other Toxic Emissions Sulfur dioxide and nitrogen oxides are also released when coal is burned. These contribute to acid rain , smog , and respiratory illness es. Mercury is emitted when coal is burned. In the atmosphere, mercury is usually not a hazard. In water, however, mercury transforms into methylmercury, which is toxic and can accumulate in fish and organisms that consume fish, including people. Fly ash which floats away with other gases during coal combustion and bottom ash which does not float away are also released when coal is combusted.

Depending on the composition of the coal, these particulates can contain toxic elements and irritants such as cadmium, silicon dioxide, arsenic, and calcium oxide. Unfortunately, fly ash is often stored in landfills or power plants, and can drain into groundwater. As a response to this environmental hazard, fly ash is being used as a component of concrete , thereby isolating it from the natural environment.

Many countries do not regulate their coal industries as strictly as the U. Coal Fires Under the right conditions of heat, pressure, and ventilation, coal seams can self-ignite and burn underground. Lightning and wildfires can also ignite an exposed section of the coal seam, and smoldering fire can spread along the seam. Coal fires emit tons of greenhouse gases into the atmosphere. Even if the surface fire is extinguished, the coal can smolder for years before flaring up and potentially starting a wildfire again.

Coal fires can also begin in mines as a result of an explosion. Once coal catches fire and begins smoldering, it is extremely difficult to extinguish. Advantages and Disadvantages Advantages Coal is an important part of the world energy budget. It is relatively inexpensive to locate and extract, and can be found all over the world.

Unlike many renewable resources such as solar or wind , coal production is not dependent on the weather. It is a baseload fuel, meaning it can be produced 24 hours a day, 7 days a week, days a year.

We use and depend on many things that coal provides, such as heat and electricity to power our homes, schools, hospitals, and industries. Steel, vital for constructing bridges and other buildings, relies on coke for almost all production. Coal byproducts, such as syngas, can be used to make transportation fuels. Coal mining also provides economic stability for millions of people worldwide. The coal industry relies on people with a wide range of knowledge, skills, and abilities.

Jobs associated with coal include geologists, miners, engineers, chemists, geographers, and executives. Coal is an industry that is critical to countries in both the developed and developing world. Disadvantages Coal is a nonrenewable source of energy.

It took millions of years to form, and a finite amount of it exists on our planet. Although it is a consistent and reliable source of energy at this point in time, it will not be available forever.

Mining is one of the most dangerous jobs in the world. In addition to disease, thousands of miners die every year in mine explosions, collapses, and other accidents.

Burning coal for energy releases toxins and greenhouse gases, such as carbon dioxide. These have an immediate impact on the local air quality, and contribute to global warming , the current period of climate change. Surface mining permanently alters the landscape. In mountaintop removal, the landscape itself is obliterate d and ecosystems are destroyed. This increases erosion in the area. Floods and other natural hazards put these areas at great risk. Coal mining can impact local water supplies in several ways.

Streams may be blocked, increasing the chances for flooding. Toxins often leach into groundwater, streams, and aquifers. Coal is one of the most controversial energy sources in the world.

The advantages of coal mining are economically and socially significant. However, mining devastates the environment: air, land, and water. Clean coal usually refers to the process of carbon capture, where emissions are trapped and stored underground. Carbon Fiber Carbon fiber, used in everything from lightweight bicycles to bullet-protecting Kevlar vests, is a type of graphite, the highest rank of coal.

The open-pit mine has shipped more than 1. Top Coal Producers 1. China 2. United States 3. India 4. European Union leading producer: Germany 5. Acid rain can be manmade or occur naturally. Also called hard coal, black coal, and stone coal. Also called diesel oil and diesel fuel. Individual energy budgets are usually measured in calories.

Peat can be dried and burned as fuel. Also called black carbon. Also called leavings, mine dumps, and slickens. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited. Andrew Turgeon Elizabeth Morse. Mary Crooks, National Geographic Society. Jeannie Evers, Emdash Editing.

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