Coal

Coal is a black or brown rock that can be ignited and burned to produce energy in the form of heat. Coal's chemical makeup is a complex mix of elements that include sulfur, carbon, oxygen, hydrogen and nitrogen, as well as small quantities of aluminum, zirconium and many other minerals.

Throughout history, coal has been a useful resource for human consumption. It is primarily burned as a fossil fuel for the production of electricity and/or heat, and is also used for industrial purposes such as refining metals.

The burning of coal can produce acid rain when sulfur impurities are burned. This burning of sulfur creates SO 2 (sulfur dioxide) which reacts with water to create a relatively weak acid called sulfurous acid (H 2 SO 3 ). Also, catalysts such as dust particles in the air help react the SO 2 with O 2 to to create sulfur trioxide (SO 3 ). The SO 3 then reacts with water to create sulfuric acid (H 2 SO 4 ). Hence, acid rain is created.



Uses: 1. electric generation 2. steel production 3. cement manufacture 4. steam coal - power generation 5. coking coal - steel production

Coal is primarily used as a solid fuel to produce electricity and heat through combustion. World coal consumption was about 6.75 billion short tons in 2006 and is expected to increase 48% to 9.98 billion short tons by 2030. China produced 2.38 billion tons in 2006. India produced about 447.3 million tons in 2006. 68.7% of China's electricity comes from coal. The USA consumes about 14% of the world total, using 90% of it for generation of electricity. The proved reserves worldwide data for coal at the end of 2008 is 19,400EJ. And the energy from coal used in United States is 24.5EJ in 2007. Different kinds of coal have different energy contents.

Energy density
The energy density of coal, i.e. its heating value, is roughly 24 megajoules per kilogram. The energy density of coal can also be expressed in kilowatt-hours, the units that electricity is most commonly sold in, per units of mass to estimate how much coal is required to power electrical appliances. One kilowatt-hour is 3.6 MJ, so the energy density of coal is 6.67 kW·h/kg. The typical thermodynamic efficiency of coal power plants is about 30%, so of the 6.67 kW·h of energy per kilogram of coal, 30% of that—2.0 kW·h/kg—can successfully be turned into electricity; the rest is waste heat. So coal power plants obtain approximately 2.0 kW·h per kilogram of burned coal. As an example, running one 100-watt lightbulb for one year requires 876 kW·h (100 W × 24 h/day × 365 day/year = 876000 W·h = 876 kW·h). Converting this power usage into physical coal consumption: For a coal power plant with a 40% efficiency, it takes 325 kg (714 lb) of coal to power a 100 W lightbulb for one year. One should also take into account transmission and distribution losses caused by resistance and heating in the power lines, which is in the order of 5–10%, depending on distance from the power station and other factors.

Carbon intensity
Commercial coal has a carbon content of at least 70%. Coal with a heating value of 6.67 kWh per kilogram as quoted above has a carbon content of roughly 80%, which is , where 1 mol equals to NA (//Avogadro Number//) atoms. Carbon combines with oxygen in the atmosphere during combustion, producing carbon dioxide, with an atomic weight of (12 + 16 × 2 = 44 kg/kmol). The CO 2 released to air for each kilogram of incinerated coal is therefore . This can be used to calculate an emission factor for CO 2 from the use of coal power. Since the useful energy output of coal is about 31% of the 6.67 kWh/kg(coal), the burning of 1 kg of coal produces about 2 kWh of electrical energy. Since 1 kg coal emits 2.93 kg CO 2, the direct CO 2 emissions from coal power are 1.47 kg/kWh, or about 0.407 kg/MJ. The U.S. Energy Information Agency's 1999 report on CO 2 emissions for energy generation, quotes a lower emission factor of 0.963 kg CO 2 /kWh for coal power. The same source gives a factor for oil power in the U.S. of 0.881 kg CO 2 /kWh, while natural gas has 0.569 kg CO2/kWh. Estimates for specific emission from nuclear power, hydro, and wind energy vary, but are about 100 times lower.

Environmental effects
   Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event There are a number of adverse health and environmental effects of coal burning especially in power stations, and of coal mining. These effects include:
 * Coal-fired power plants shortened nearly 24,000 lives a year in the United States, including 2,800 from lung cancer
 * Generation of hundreds of millions of tons of waste products, including fly ash, bottom ash , flue-gas desulfurization sludge, that contain mercury , uranium , thorium , arsenic , and other heavy metals
 * Acid rain from high sulfur coal
 * Interference with groundwater and water table levels
 * Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
 * Impact of water use on flows of rivers and consequential impact on other land-uses
 * Dust nuisance
 * Subsidence above tunnels, sometimes damaging infrastructure
 * Uncontrollable underground fires which may burn for decades or centuries.
 * Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure
 * Coal-fired power plants emit mercury, selenium, and arsenic which are harmful to human health and the environment
 * Release of carbon dioxide, a greenhouse gas, which causes climate change and global warming according to the IPCC and the EPA . Coal is the largest contributor to the human-made increase of CO 2 in the air

** Total Global Coal Production ** (including hard coal and lignite)
 * 7229Mt (2010e)
 * 6823Mt (2009)
 * 4677 (1990)

Top Ten Hard Coal Producers (2010e)

 * ~ PR China || 3162Mt ||~ Russia || 248Mt ||
 * ~ USA || 932Mt ||~ Indonesia || 173Mt ||
 * ~ India || 538Mt ||~ Kazakhstan || 105Mt ||
 * ~ Australia || 353Mt ||~ Poland || 77Mt ||
 * ~ South Africa || 255Mt ||~ Colombia || 74Mt ||