Coal Essay ⋆ Environment Essay Examples ⋆ EssayEmpire

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The industrial revolution in 18th-century Europe and North America was propelled by a black rock called coal. Modern industrial civilization still continues to depend heavily on this rock. The word coal is of Anglo-Saxon origin from the word col, which means charcoal. Historians note that coal was already under use during the Bronze Age (around 2000 B.C.E.) in Britain. By 200 C.E., coal was being widely traded in Britain and used for fires to heat villas and military forts and also to dry grain. However, before 1000 C.E., the trade and use of coal was on a small scale. It was not until 1000 C.E. that coal began to be a prominent commodity in Britain. Initially, exposed coal seams were exploited, but by the 13th century these were exhausted, necessitating the development of underground mining from shafts.

Coal is a fossil fuel formed from prehistoric vegetation that originally accumulated in swamps and peat bogs and then consolidated between other rock strata. Silt and other sediments buried these swamps and peat bogs at great depths. This subjected the plant matter to high temperatures and pressure, which in turn transformed the vegetation into peat and then into coal. It is believed that coal formation began during the Carboniferous period about 360-290 million years ago. In Europe, Asia, and North America, the Carboniferous coal was formed from tropical swamp forests, which are sometimes called the coal forests. Southern hemisphere Carboniferous coal was formed from the Glossopteris flora, which grew on cold periglacial tundra when the South Pole was far inland in Gondwanaland.

Through the process of coal formation (coalification) over millions of years, various states of coal have been formed, resulting in different types of coal and coal seams that can be extracted via deep or underground mines or open pit mining. There are four main types of coal that range from high water content to high carbon content: peat (lignite or brown coal), sub-bituminous, bituminous, and anthracite. Peat and sub-bituminous coal are ranked as low coal, as they have high water content and low carbon content, while bituminous and anthracite are ranked as hard coal with a very high carbon content and therefore high energy output. The term dirty black rock comes from the highly ranked hard coal with a black luster, while the low-ranked coal is softer with a brown or earthy appearance.

Carbon accounts for more than 50 percent by weight and more than 70 percent by volume of coal, depending on the rank. Highly ranked coals contain 95 percent purity of carbon with less hydrogen, oxygen and nitrogen. Coal also contains incidental moisture, which is why coal is mined wet and stored wet. Low-ranked coals, such as lignite, contain considerable amount of moisture and other volatile materials known as macerals. These macerals are byproducts of the long process of coal formation from carbohydrate material into carbon over millions of years. Examples of macerals are vitrinite (fossil woody tissue, often charcoal from forest fires); fusinite (made from peat); exinite (fossil spore casings and plant cuticles); resinite (fossil resin and wax); and alginite (fossil algal material). Coal may also contain other mineral matter such as silicate, carbonate minerals, iron sulfide minerals, and sulfate minerals. Methane gas is also a major valuable byproduct for natural gas, but also an extremely dangerous component, as it often causes coal seam explosions in underground mines. The presence of these extraneous materials in coal seams determine the chemical composition of coal and therefore its utility for various tasks.

The different types of coal are used for various purposes. For example, lignite, the lowest rank of coal, is used largely for steam-electric power generation. Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal, are used primarily for steam-electric power generation and for other industrial purposes such as cement manufacturing. Bituminous coal, a coal that is usually black and dense with well-defined bands of bright and dull material and is highly ranked, is often used for steam-electric power generation, the manufacturing of cement, and other industrial uses. More importantly, it plays an essential role in the production of iron and steel as a metallurgical coking coal. The highest-ranked coal, anthracite, is harder, glossy, and black in character and is primarily used for residential and commercial space heating. It is preferred for domestic use due to its smokeless characteristics.

Coal is primarily used as a solid fuel for the generation of electricity and heat through combustion. To generate electricity, coal is usually pulverized and then burned in a furnace with a boiler. The furnace heat converts boiler water to steam, which is then used to spin turbines, which in turn create electricity. Coal accounts for more than 40 percent of electricity production in the world.

About 66 percent of the world’s steel production is based on coal. Coke is a solid carbonaceous residue derived from low-ash, low-sulfur bituminous coal from which the volatile constituents are driven off by baking in an oven without oxygen at temperatures as high as 1,832 degrees F (1,000 degrees C) so that the fixed carbon and residual ash are fused together. To make iron and steel, the raw materials-iron ore, coke and fluxes-are fed into the top of the 2,192 degrees F (1,200 degrees C) blast furnace. The burning coke produces carbon monoxide, creating a chemical reaction that reduces iron ore to molten iron.

Сoal can also be readily converted into a variety of fuels (gas and liquids), with a number of key advantages such as fuels that are sulfur-free, low in particulates, low in nitrogen oxides and low in CO2 emissions. As the world demand for petroleum-based fuels has increased due to the escalating use of automobiles, the coal-to-liquids industry is becoming a more viable alternative. South Africa has produced commercial coal to liquids fuels since 1955. It is estimated that about 30 percent (160,000 barrels per day) of South Africa’s gasoline and diesel requirements are produced from locally available coal.

The process of converting coal into liquid fuels can be done through direct or indirect liquefaction. Direct liquefaction involves dissolving the coal in a solvent at high temperature and pressure, and then further refining the liquid products to achieve highgrade fuel characteristics. Indirect liquefaction involves gasifying the coal to form a syngas, which is a mixture of hydrogen and carbon monoxide. The syngas is then condensed over a catalyst to produce high quality, ultra-clean products. Through these processes, various other products can be produced from coal, including ultra-clean petroleum and diesel, synthetic waxes, lubricants, and alternative liquid fuels such as methanol and dimethyl ether. Liquefaction of coal into fuel liquids has great potential for countries that heavily depend on imported oil but have large reserves of unused coal. It is one of the backstop technologies that could potentially limit the escalation of oil prices and mitigate the effects of transportation energy shortages. Projects to utilize these benefits are currently underway in import oil-dependent countries such as China, India, Australia, and the United States.

Cement and Other Industries

Another major use of coal is in the cement industry, in a process that requires large amounts of energy. Approximately 16 million tons of cement are used globally every year. The manufacturing of cement involves the mixing of limestone, silica, iron oxide, and alumina. This mixture is heated by coal to very high temperatures of more than 2,642 degrees F (1,450 degrees C), transforming the mixture into a pebble-like substance called clinker, which is then mixed with gypsum and ground to a fine powder to make cement. It is estimated that for every 900 grams of cement produced, 450 grams of coal are used. There are other byproducts that are derived from the burning of coal, such as fly ash, bottom ash, boiler slag, and flue gas desulferisation gypsum. These can be recycled as primary raw materials to replace or supplement cement in concrete.

Coal is also used in other important industries such as alumina refineries, paper manufacturers, and the chemical and pharmaceutical industries. Several chemical products can be produced from the byproducts of coal. Refined coal tar is used in the manufacture of chemicals, such as creosote oil, naphthalene, phenol, and benzene. Ammonia gas recovered from coke ovens is used to manufacture ammonia salts, nitric acid, and agricultural fertilizers. From this “dirty black stone,” thousands of different products are manufactured, including soap, aspirins, solvents, dyes, plastics, and fibers such as rayon and nylon. Coal is also an essential ingredient in the production of specialist products such as activated carbon (used in filters for water and air purification and in kidney dialysis machines); carbon fiber (an extremely strong but lightweight reinforcement material used in construction, mountain bikes, and tennis rackets); and silicon metal (used to produce silicones and silanes, which are in turn used to make lubricants, water repellents, resins, cosmetics, hair shampoos, and toothpastes).

Greatest Use: Electricity

While coal may have multiple uses, its greatest use-about 75 percent of all mined coal (about 5.8 billion tons)-may be in the generation of electricity. The United States, China, and India consume 2.8 billion tons every year (48 percent of annual global consumption). With China’s growing economy, India and China alone may soon need about 3 billion tons annually. As of 2005, estimates indicated that there are more than 909 billion tons of proven coal reserves throughout the world. The largest reserves of coal are found in the United States, Russia, China, and India. It can also be found in sizable quantities in 66 other countries. Fossil fuels are finite; however, with current usage levels, the lifetime for coal could be extended 157 years and beyond through new discoveries, advances in mining techniques, and efficiency improvements.

However, there is a dark, flip side to the use of coal as a source of energy. The burning of coal produces many byproducts that are harmful to human and environmental health. The use of coal produces carbon dioxide (CO2) and nitrogen oxides (NOx), along with varying amounts of sulfur dioxide (SO2). Sulfur dioxide reacts with oxygen to form sulfur trioxide (SO3), which then reacts with water to form sulfuric acid, which falls to the ground as acid rain. Emissions from coal-fired power plants represent the largest source of carbon dioxide emissions, now known to be the primary source of global warming gases. Coal mining and abandoned mines also emit methane, another cause of global warming. Other coal waste products, including fly ash, bottom ash, boiler slag, and flue gas desulferization, contain heavy metals, including arsenic, lead, mercury, nickel, vanadium, beryllium, cadmium, barium, chromium, copper, molybdenum, zinc, selenium, and radium. These heavy metals are extremely dangerous to human, animal, and plant health when spewed into the environment. Other impurities include low levels of uranium and thorium, which could potentially lead to radioactive contamination. U.S. environmental groups claim that coal power plant emissions are responsible for tens of thousands of premature deaths annually in the United States alone. Technologies to mitigate the harmful effects of coal burning are available, but these are rarely installed in power plants as they would add to their building costs and make them less profitable.

The useful aspects of coal notwithstanding, this fascinating, simple black rock that has shaped our modern civilization now threatens it. It is undeniable that coal has transformed societies, expanded our frontiers, and sparked social movements, and continues to power electric generation. However, coal’s world-changing powers have come at a tremendous price, including centuries of blackening skies and lungs, particularly the lungs of those involved in its mining. Many believe that the increasing burning of coal in power generation plants around the world is resulting in global warming and is changing the earth’s climate. Scientists caution that before we plunge ourselves into reviving the coal industry as an alternative to oil from the Middle East, we need to take a step back and carefully examine the tragic legacy of coal that has claimed millions of lives and ravaged the environment. Due to the proven deleterious environmental consequences of coal, The Economist recently dubbed the burning of coal “Environmental Enemy No.1.”

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