Coal

Coal is the largest source of fuel for the generation of electricity, as well as the largest worldwide source of carbon dioxide emissions. Carbon dioxide is a greenhouse gas and the major contributor to an increase in global average temperature and related climate changes. Gross carbon dioxide emissions from coal usage is slightly more than that from petroleum about double the amount from natural gas. World coal consumption is about 6.2 billion tons annually. China produced 2.38 billion tons in 2006 and India produced about 447.3 million tons in 2006. 68.7% of China's electricity comes from coal. The USA consumes about 1.053 billion tons of coal each year, using 90% of it for generation of electricity. The world in total produced 6.19 billion tons of coal in 2006. //Liquefaction// processes convert coal into a liquid fuel that has a composition similar to that of crude petroleum. Coal can be liquefied either by direct or indirect processes. However, because coal is a hydrogen-deficient hydrocarbon, any process used to convert coal to liquid or other alternative fuels must add hydrogen. Four general methods are used for liquefaction: (1) pyrolysis and hydrocarbonization, in which coal is heated in the absence of air or in a stream of hydrogen; (2) solvent extraction, in which coal hydrocarbons are selectively dissolved and hydrogen is added to produce the desired liquids; (3) catalytic liquefaction, in which hydrogenation takes place in the presence of a catalyst; and (4) indirect liquefaction, in which carbon monoxide and hydrogen are combined in the presence of a catalyst.
 * Coal **
 * Who Uses It? **
 * How Coal is Used?**


 * Advantages || Challenges/Disadvantages ||
 * Relatively cheap || Major contributor to green house gases ||
 * Ways to transport it has already developed || Coal mining is dangerous for the workers ||
 * Fuel for electricity and heat || Takes geological time to form (non-renewable) ||
 * Coal liquefaction - backstop technology for high oil prices ||  ||
 * In certain places, such as China, there is an abundance of the resource, and it is cheap. || When burned, emitts carbon monxide, which contributes largely to pollution. ||

= Coal =  = What is it? =  Coal is a [|fossil fuel] formed in [|ecosystems] where [|plant] remains were preserved by water and [|mud] from [|oxidization] and [|biodegradation], and which its chemical and physical properties have been changed as a result of geological action over time. = How do we get it? =  ·   Mining the coal Coal miners use giant machines to remove the coal from the ground by using two methods. There are surface mining and underground mining which is also called deep mining. Surface mining is used when the coal is buried less than 200 feet underground. Underground mining is used when the coal is buried several hundred feet below the surface. ·  Processing the coal After coal is removed from the ground, it is conveyed to the plant that is located at the mining site. The plant then cleans the coal and processes coal to remove dirt, rock, ash, sulfur, and other unwanted materials, increasing the heating value of the coal. ·  Types of coal After being processed, coal is classified into four main types or ranks which are lignite, subbituminous, bituminous, and anthracite judging on the amounts and types of carbon it contains. Also, coal is judged on the amount of heat energy it can produce. ·   How is coal used? Coal is basically used for electric power, industry, and production of steel. ·   Advantages and Disadvantages of Coal Even though, coal is really cheap it has a devastating environmental impact. When burning coal it emits harmful substances like methane and CO2.