Coal is a black or brownish-black, firm sedimentary rock, which resulted from Carbonisierung of Pflanzenresten (Inkohlung) and to more than 50 per cent of the weight and more than 70 per cent of the volume consists of carbon. The hard coal is also called "black gold".

Coal is a source of energy and by humans as fossil fuel is used.

Emergence

The raw material from coal is mainly vegetable origin as for example ferns (tree ferns). In the carbon, a very warm and damp climate with a pronounced plant growth prevailed to the earth-history time of origin of the today degradable hard coal. When dying individual plants these sank to normal aerobes in the sump and so the decomposition process were extracted. It developed for peat.

With sea break-downs these sumps were covered with sediments. Under the increasing pressure and increased temperature the process of the Inkohlung began. The pressure pressed the water from the peat and it developed first for brown coal. At this time the still low pressure pressed only little water from the coal. With the deposit of further layers the pressure increased and ever more waters from the coal was pressed. Gradually hard coal became and with again more pressure anthracite coal from the brown coal. Therefore the economic quality of the coal is better, which lies deeply underground and is older.

In particular during the carbon before approximately 280 to 345 million years developed powerful hard coal stores, which rank today among the world-wide most important energy suppliers. Brown coal stores are substantially recent date and in the Tertiary period before 2,5 to 65 million years developed.

Intended purpose

Coal is used predominantly as solid fuel, in order to produce warmth by burn. Develop carbon dioxide, water vapour and other gases such as sulfur dioxide. In order to produce electricity, by means of the warmth water vapour is produced, which propels again turbines. In order to compare, which can be won energy quantity with which coal, one serves itself usually of the hard coal unit.

2003 was produced world-wide for 24.4% of the primary energy and 40.1% of the electric power by the industrielle use of coal as fuel. Hard coal and brown coal are represented thereby in approximately same strongly.

Modern coal-fired power stations use a multiplicity of techniques, in order to limit the injurious character of the waste products and to increase the efficiency of the burn process at the same time. In some countries these techniques are however not far common, particularly since they increase the capital outlays of the power station.

A not inconsiderable part of the coal is used after its coking (see also coke) for the reduction of ores, mainly iron ore, in blast furnaces.

Starting from that 19. Century found the coal also to use for the production of town gas, which for the road lighting and cooking as well as heating was used. In gas works one won town gas by the Trockendestillation from the coal - a by-product was the coke. In 20. Century was replaced to a large extent town gas by the natural gas.

In 18. Century was used brown coal under the name Umber or earth as Farbpigment.

Environmental problems

During the firing of coal very much climaticharmful CO2 develops. In particular brown coal power stations with their comparatively low efficiency discharge very much of it. The CO2-Freisetzung is principle-conditioned and cannot not be prevented, but only by a better efficiency of the power stations and thus smaller coal consumption in masses to be reduced.

The sulfur dioxide, which develops particularly with the burn of brown coal, is jointly responsible for the acid rain. With modern stone and brown coal power stations the exhaust gases in flue gas desulphurating plants (see also REA, flue-gas desulphurization gypsum) by sulfur dioxide, by catalytic (SCR) or not-catalytic (SNCR) denitrification by nitrogen oxides and in electrical separators are cleaned by dust.

The production of brown coal in the open mining is connected with an immense land consumption. In order to be able, become to win stores as completely as possible sometimes whole villages resettled, which can lead to Konfliktpotenzial with the population (see also list of abgebaggerter localities). Perhaps also ecologically valuable areas are destroyed - a current example (conditions January 2006) is the Lacomaer pond landscape and the village Lacoma/Lakoma, which is to yield the open mining Cottbus north operated by Vattenfall Europe.

In brown coal day building similarly as with, develop for dry fields in the agriculture large dust quantities can widening. Therefore the employment of efficient dust suppression technology is essential.

A further aspect is the sinking of the ground-water level on a level underneath the deepest promotion sole in the brown coal open mining. This happens with submerged pumps in specially wells created for it. A sinking of the ground-water level can have negative effects on the Flora, since upper Bodenschichten can drying-fall. Also the sinking leads drying traps of nearby wells, which refer their water from the groundwater leader concerned to.

Turned around a quiet putting of an open mining leads to the increase of the ground-water level, as soon as the submerged pumps are turned off. This can lead with the buildings built in the environment to large damage. A well-known example of it is the environment of the city Korschenbroich, whose inhabitant since the gradual quiet putting of the open mining Garzweiler I with the rising ground-water level to fight to have. Unfortunately the owners of house are alone left on the part of the open mining operator RWE, so that at each individual enormous expense come.

Supplies

The promotable reserves became 2004 on world-wide 783.1 billion t SKE coal estimated. Likewise of it are allotted 27% to the USA, 16% to Russia, 12% to China, 12% to India, 7% to the European union (EU-25) and 7% to Australia. With equal lasting consumption (2004: ) The need could be covered for 3.8 billion t SKE coal still for approximately 206 years.

In Germany at present about 77 billion t brown coal stores, by which 53% (approx. 41 billion t) with the conditions of the today's technology would be profitable. Thus the supplies became when constant promotion (2004: 181.9 Mill. t) still for 225 years are sufficient.

From the German hard coal supplies approximately 24 billion t applies as profitable. In view of a current promotion ratio of 25,7 Mill. t (2004) a theoretical range of over 900 years results. Due to unfavorable geological conditions however only one part of these supplies is internationally competitively promotable.

Representatives of the German coal economy number therefore while maintaining the present deliveries the range of the German coal on approximately 400 years.

Articles in category "Coal"

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