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Coal

Saturday, 04 February 2006

Coal was made out of the ancient plants, 300 million years ago, even before dinosaurs, when huge plants started sedimentation in swamps. In millions of years that followed, mud was frothed over remains, transforming in that process huge heat in to a pressure, and all these factors combined gave ideal conditions for coal’s "birthing place". Today coal is located mostly below the layers of rocks and mud, and to get to it, mines are excavating. Coal is important particularly because of  the two reasons: steel production and electrical energy. Coal is giving about 23% of the world’s total primary energy. 38% of the world’s generated electrical energy is gained from coal. For 70% of the world’s steel production, coal is needed as the key ingredient.

Coal, besides being the mostly spread of all the fossil fuels, also has the longest use in history. Archaeologists have found proofs which are pointing to the fact that Romans in England were using coal in second and third century. In northern America, Indians in the 14th century were using coal for cooking, heating and ceramic. In 18th century English discovered that coal combusts cleaner and in higher temperature than the charcoal. Industrial revolution was first real agitator of coal's use. James Watt invented engine on steam (steam engine), which made it possible for machines to do the work that was before done by humans or animals. James Watt used coal for manufacturing steam which motioned the engine. During the 19th century ships and trains were main transporting vehicles, and were using steam engine for propulsion. In these steam engines coal was used for manufacturing the steam. In year 1880, coal had been used for the first time ever for electrical energy's production.

Ecology and methods of coal’s purification

Coal
Mostly, coal is made of carbon (black) and hydrogen (red). It also has small amounts of sulfur (yellow) and iron (green)

Ecologically, coal is most dangerous source of energy. Coal and all other fossil energy sources are mostly made of carbon and hydrogen. Inside coal, there is some dirt captured as well, like sulfur and nitrogen. When coal combusts, this dirt gets released in to an atmosphere. Up in the atmosphere these substances are connecting with steam (for instance in clouds) and are forming drops in the process, which fall down on the ground in the form of weak sulfuric acids as well as azotic acids - acid rains. Inside the coal, there are also small mineral particles. These particles do not combust, therefore not creating dust that remains after combustion. One group of these particles gets captured in the whirlpool of the gases and together with steam forms the smoke that is coming out of the coal power plants. Some particles are so small that when combining them 30 in the line, that line would be barely as long as width of the human hair. Coal is mostly made out of carbon. When coal is combusting, carbon mixes with oxygen from air forming carbon dioxide in the process. Carbon dioxide is a gas without color and scent, and one of the greenhouse gases in atmosphere.

Most scientists believe that global temperature increase is direct consequence of release of carbon dioxide in to an atmosphere. From all that was said before, it seems that coal is a "dirty" energy source. Many years ago it was indeed dirty, but in the last 20 years scientists found the way of capturing large part of dirt before they can slip to an atmosphere. Today there are technologies that can purify 99% of small particles and remove 95% of dirt which are causing acid rains. There are also technologies that can decrease emission of the carbon dioxide to an atmosphere using more efficient coal combustion. These technologies were mostly financed by governments of USA and Canada, because of the problems they’ve had with acid rains.

Gas, Coal power plant
One of the "cleanest" coal power plants is Tampa Electric's Polk Power Station in Florida, and works on gas gained from coal.

Transformation into a gas is the cleanest method for gaining the energy from a coal. Inside the big metal bucket, coal gets heated and then showered with water. On this way mixture of carbon monoxide and hydrogen is gained, and that mixture is the gas. This procedure is efficient in removing majority of dirt, so when combusting there’s no big environment pollution.

As an example of coal’s purification, elimination of sulfur may come handy. Amount of sulfur in the coal depends a lot about its finding place. Some finding sites have about 10% of sulfur in the coal, and there are also some sites with less than 1% of sulfur. One of the methods for the purification is fragmentation and simple washing. All sulfur however, can’t be removed because one part of his atoms is joined together with carbon. This part can be removed, but available technologies are too expensive for mass use. Because of this reason all modern coal power plants have devices that are removing the sulfur from gases after combustion, and before they’re released to an atmosphere. Despite all purification procedures, one part of dirt still gets to an atmosphere destroying the nature in process.

Coal production, consumption and its reserves

Coal production and consumption
Country’s production and consumption of coal. China is traditionally relying on coal, and USA is high because of large consumption of all fossil fuels, including coal.

Lately, there’s nothing new in coal’s consumption. That is understandable because exploiting technologies have reached its peak, so there’s no big possibility of progress. According to the rough predictions, there’s still enough coal for the next 200 years if we continue today’s tempo of its exploitation. That means that in our close future won’t be problems with coal’s supply, but could be problems because of economical and ecological aspects of this energy’s use.

Geographically, South America is the continent that has the smallest number of coal reserves-only 2.2%, Africa too is in bad position with only 6%, and of this poor 6% South Africa alone has 90% reserves. North America and Asia have each 25% of coal reserves. Europe together with Russia has 35% confirmed coal reserves. Europe’s reserves are dominantly divided to Germany 21% and Russia 50%.

Largest progress in coal production and consumption in the end of the 20th century happened in China. In 1997 China produced 1268 millions tons of coal. In 1999 small decrease happened, below 1000 millions tons, but despite that China still leads coal production and consumption. USA increased its production up to a 975 millions of tons, but the amount of its exportable coal is constantly getting smaller. USA liquidates its own production deficit with bilateral contract with Canada. USA is also importing coal from Colombia because of its cheap transportation to harbors.

 
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