COAL is the most important and abundant fossil fuel in India. It accounts for 55% of the country's energy need. The country's industrial heritage was built upon indigenous coal.

Commercial primary energy consumption in India has grown by about 700% in the last four decades. The current per capita  commercial primary energy consumption in India is about 350 kgoe/year which is well below that of developed countries. Driven by the rising population, expanding economy and a quest for improved quality of life, energy usage in India is expected to rise around 450 kgoe/year  in 2010. Considering the limited reserve potentiality of petroleum & natural gas, eco-conservation restriction on hydel project and geo-political perception of nuclear power, coal will continue to occupy centre-stage of India 's energy scenario.

                 With hard coal reserves around 246 billion tonnes, of which 92 billion tonnes are proven, Indian coal offers a unique ecofriendly fuel source to domestic energy market for the next century and beyond. Hard coal deposit spread over 27 major coalfields, are mainly confined to eastern and south central parts of the the country. The lignite reserves stand at a level around 36 billion tonnes, of which 90 %  occur in the southern State of Tamil Nadu.

Coal is a fossil fuel extracted from the ground either by underground mining, open-pit mining or strip mining. It is a readily combustible black or brownish-black sedimentary rock. It is composed primarily of carbon and hydrocarbons, along with assorted other elements, including sulfur. Often associated with the Industrial Revolution, coal remains an enormously important fuel and is the most common source of electricity world-wide. In the INDIA, for example, the burning of coal generates over half the electricity consumed by the nation.

^Top

Coal is thought ultimately to derive its name from the Old English col but this actually meant charcoal at the time; coal was not mined prior to the late Middle Ages; i.e. after ca. 1000 AD. Mineral coal was referred to as sea-coal since it was found on beaches occasionally having fallen from the exposed coal seams above or sea-coal as it was easier to transport the coal via the sea rather than travel on the very poor road system (in London there is still a sea coal road/lane where the coal merchants conducted their business).

Coal consists of more than 50 percent by weight and more than 70 percent by volume of carbonaceous material (including inherent moisture). Coal is formed from plant remains that have been compacted, hardened, chemically altered, and metamorphosed by heat and pressure over geologic time. It is suspected that coal was formed from ancient plants that grew in swamp ecosystems. When such plants died, their biomass was deposited in anaerobic, aquatic environments where low oxygen levels prevented their decay and oxidation (rotting and release of carbon dioxide). Successive generations of this type of plant growth and death formed thick deposits of un oxidized organic matter that were subsequently covered by sediments and compacted into carbonaceous deposits such as peat or bituminous or anthracite coal. Evidence of the types of plants that contributed to carbonaceous deposits can occasionally be found in the shale and sandstone sediments that overlie coal deposits, and with special techniques, within the coal itself. The greatest coal-forming time in geologic history was during the Carboniferous era (280 to 345 million years ago).

As geological processes apply pressure to peat over time, it is transformed successively into:

Lignite - also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for steam-electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Iron Age.

Sub-bituminous coal - whose properties range from those of lignite to those of bituminous coal and are used primarily as fuel for steam-electric power generation.

Bituminous coal - a dense coal, usually black, sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke.

Anthracite - the highest rank, used primarily for residential and commercial space heating.

Coal is primarily used as a solid fuel to produce heat through combustion.

World coal consumption is about 5,300 million short tons annually, using about 75% for electricity. The region including China and India uses about 1,700 million tons annually, forecast to exceed 3,000 million tons in 2025.  The USA consumes about 1,100 million tons of coal each year, using 90% of it for generation of electricity.

When coal is used in electricity generation, it is generally pulverized and then burned. The heat produced is used to create steam, which is then used to spin turbines which turn generators and create electricity. Approximately 40% of the Earth's current electricity production is powered by coal, and the total known deposits recoverable by current technologies are sufficient for 300 years' use at current rates (see World Coal Reserves, below).

^Top

In the past, coal was converted to make coal-gas, which was piped to customers to burn for illumination, heating, and cooking. At present, the safer natural gas is used instead. Gasification is also a possibility for future energy use, as it generally burns hotter and cleaner than conventional coal. South Africa still uses gasification of coal for much of its petrochemical needs.

Coal can also be converted into liquid fuels like gasoline or diesel by several different processes. The Fischer-Tropsch process of indirect synthesis of liquid hydrocarbons was used in Nazi Germany, and for many years by Sasol in South Africa - in both cases, because those regimes were politically isolated and unable to purchase crude oil on the open market. Coal would be gasified to make syngas (a balanced purified mixture of CO and H2 gas) and the syngas condensed using Fischer-Tropsch catalysts to make light hydrocarbons which are further processed into gasoline and diesel. Syngas can also be converted to methanol: which can be used as a fuel, fuel additive, or further processed into gasoline via the Mobil M-gas process.

A direct liquefaction process Bergius process (liquefaction by hydrogenation) is also available but has not been used outside Germany, where such processes were operated both during World War I and World War II. SASOL in South Africa has experimented with direct hydrogenation.

Yet another process to manufacture liquid hydrocarbons from coal is low temperature carbonization (LTC). Coal is coked at temperatures between 450 and 700*C compared to 800-1000* for metallurgical coke. These temperatures optimize the production of coal tars richer in lighter hydrocarbons than normal coal tar. The coal tar is then further processed into fuels. The process was developed by Lewis Karrick, an oil shale technologist at the U.S. Bureau of Mines in the 1920s.

All of these liquid fuel production methods release CO₂ carbon dioxide in the conversion process. CO₂ sequestration is proposed to avoid releasing it into the atmosphere. As CO₂ is one of the process streams, sequestration is easier than from flue gasses produced in combustion of coal with air, where CO₂ is diluted by nitrogen and other gases.

Coal liquefaction is one of the backstop technologies that limit escalation of oil prices. Estimates of the cost of producing liquid fuels from coal suggest that domestic US production of fuel from coal becomes cost-competitive with oil priced at around 35 USD per barrel , (break-even cost), which is well above historical averages - but is now viable due to the spike in oil prices in 2004-2005.

Among commercially mature technologies, advantage for indirect coal liquefaction over direct coal liquefaction are reported by Williams and Larson (2003). Estimates are reported for sites in China where break-even cost for coal liquefaction may be in the range between 25 to 35 US$/barrel of oil.

^Top

Main article: Coke (fuel)

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 2,000 °F (1,000 °C) so that the fixed carbon and residual ash are fused together. Coke is used as a fuel and as a reducing agent in smelting iron ore in a blast furnace. Coke from coal is grey, hard, and porous and has a heating value of 24.8 million Btu/ton (29.6 MJ/kg). Byproducts of this conversion of coal to coke include coal-tar, ammonia, light oils, and "coal-gas".

Petroleum coke is the solid residue obtained in oil refining, which resembles coke but contains too many impurities to be useful in metallurgical applications.

Combustion of coal, like any other carbon containing compound, produces carbon dioxide (CO₂), along with varying amounts of sulfur dioxide (SO₂) depending on where it was mined. Sulfur dioxide reacts with water to form sulfurous acid. If sulfur dioxide is discharged into the atmosphere, it reacts with water vapor and is eventually returned to the Earth as acid rain.

Emissions from coal-fired power plants represent the largest source of artificial carbon dioxide emissions, according to most climate scientists a primary cause of global warming. Many other pollutants are present in coal power station emissions. Some studies claim that coal power plant emissions are responsible for tens of thousands of premature deaths annually in the United States alone. Modern power plants utilize a variety of techniques to limit the harmfulness of their waste products and improve the efficiency of burning, though these techniques are not widely implemented in some countries, as they add to the capital cost of the power plant. To eliminate CO2 emissions from coal plants, carbon sequestration has been proposed but is not yet in large-scale use.

Coal also contains many trace elements, including arsenic and mercury, which are dangerous if released into the environment. Coal also contains low levels of uranium, thorium, and other naturally-occurring radioactive isotopes whose release into the environment may lead to radioactive contamination. While these substances are trace impurities, if a great deal of coal is burned, significant amounts of these substances are released.

If coal liquefaction or gasification is used to make petrochemicals, a great deal of carbon dioxide is produced in the process. If a carbon tax was introduced and sufficient CO² was not captured, the economics of such processes would be significantly less attractive. However, if sequestration or some other process were used to dispose of this by-product, fuels produced from this process would be less polluting. Some process do not have a much greater total impact on carbon dioxide levels than ones refined from petroleum. Others may be less polluting still. Research in this field is ongoing.

^Top

There are hundreds of coal fires burning around the world. Those burning underground can be difficult to locate and many can not be extinguished. Fires can cause the ground above to subside, 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. A grass fire in a coal area can set dozens of coal seams on fire. Coal fires in China burn 120 million tons of coal a year, emitting 360 million metric tons of carbon dioxide. This amounts to 2-3% of the annual worldwide production of CO² from fossil fuels, or as much as emitted from all of the cars and light trucks in the United States.

The Australian Burning Mountain was originally believed to be a volcano, but the smoke and ash comes from a coal fire which may have been burning for 5,000 years.

It has been estimated that, as of 1996, there are around one exagram (1 × 10¹⁵ kg) of total coal reserves economically accessible using current mining technology, approximately half of it being hard coal. The energy value of all the world's coal is well over 100,000 quadrillion Btu (100 zettajoules). There probably is enough coal to last for 300 years. However, this estimate assumes no rise in population, and no increased use of coal to attempt to compensate for the depletion of natural gas and petroleum.

^Top

The most economical method of coal extraction from coal seams depends on the depth and quality of the seams, and also the geology and environmental factors of the area being mined.

If the coal seams are near the surface, the coal is extracted by either:

strip mining, in which coal is exposed by the advancement of an open pit or strip. As the coal is exposed and extracted the overburden from the still covered coal fills the former pit, and strip progresses.

However most coal seams are too deep underground for open cast mining. Most coal is extracted by either:

bord and pillar, Here mining progresses along the seam, pillars are left to support the roof. These pillars may be removed on retreat allowing the roof to cave in. This method of mining is used principally in the U.S.A.

long wall mining, Here mining is conducted along the seam with the use of self-advancing hydraulic roof supports known as "chocks" or "shields". These supports are placed in a line (up to 400 meters long), known as a "long wall" and as coal is removed from in front of the long wall, the supports are advanced. As the long wall advances, the cavity created behind the longwall known as "the goaf" caves in. Longwall mining is the principle method of underground mining in Australia.

Other methods of mining include continuous highwall mining and highwall auger mining. These methods are generally applied in an open cast mine, once open cut mining becomes uneconomic.

Coal mining historically, has been a very dangerous activity. Open cut hazards are principally slope failure, underground mining roof collapse and gas explosions. Most of these risks can be greatly reduced in modern mines, and multiple fatality incidents are now rare in the developed world. Improvements in mining methods i.e. longwall mining, gas drainage and ventilation have reduced many of these risks. In lesser developed countries, thousands still die in coal mines. China in particular is the world leader in coal mining related deaths, with official estimates of around 6000 fatalities in 2004. Unofficial estimates place the figure much higher, at around 20,000 deaths. China is also the world leader in coal production and consumption.

Chronic lung diseases, such as pneumoconiosis are common to miners, causing a reduced life-expectancy for those in the occupation.

The oldest continuously worked deep-mine in Britain and possibly the world is Tower Colliery at the northern end of the south Wales valleys. This colliery was started in 1805 and at the end of the 20th century it was bought out by its miners rather than allow it to be closed.

Coal mining frequently causes significant adverse environmental impacts. Strip mining typically destroys most environmental value in the land through which it passes. All forms of mining are likely to generate areas where coal is stacked and where the coal has significant sulfur content, such coal heaps generate highly acidic metal rich drainage when exposed to normal rainfall. These liquors can cause severe environmental damage to receiving water-courses. In addition, the waste heaps are subject to slipping, as in the Aberfan disaster which killed 144 people in 1966.

^Top

| Mahakali Mata|Anandwan Ashram| CSTPS|Tadoba|   BILT|