Bituminous coal is a black, hard, solid sedimentary rock that was formed by the carbonization of plant remains ( coalification ) and consists of more than 50 percent by weight and more than 70 percent by volume of carbon . This is a collective term for higher quality coals . The coal is also called black gold . It is a fossil fuel and is mainly used to generate electricity and heat through combustion and to produce coke for iron smelting. Residues from incineration are used in the construction industry. Due to the substantial contribution of hard coal combustion to climate change , an exit from coal by switching to alternative energy sources is increasingly being sought. Ways are being discussed how the emissions caused by the burning of hard coal can be partially compensated by means of CO 2 separation and storage .
The origin of hard coal lies in geological time about 250 to 350 million years ago. In the Carboniferous and Permian gediehene Urfarne , Calamites and sealing and shed trees formed large swamp forests. The optimal growth conditions for the plants led to a strong overproduction of biomass, which accumulated in swamp soils, similar to a recent peat bog . These layers were partially covered at regular intervals by other sediments such as clays and sand, e.g. B. by river sediments. Such recurring, cyclical sedimentation conditions ( cyclothemes ) are characteristic of the formation of hard coal in the Upper Carboniferous and gave rise to several coal seams deposited on top of one another . The swamp soils were compressed and drained by the sediment cover and, over millions of years, the process of coalification finally resulted in hard coal. The organic starting material was compressed and converted under exclusion of air, high pressure and high temperatures, and a solid bond of carbon , water and incombustible inclusions in the form of ash was created . Therefore, hard coal is characterized by a black, solid ground mass in which plant fossils can often be found. The hard coal occurs mainly in layer-bound deposits , the seams.
More recent research suggests that hard coal formation was particularly favored due to the lack of wood-decomposing organisms . Only with the appearance of the white rot fungi about 300 million years ago, i.e. at the end of the Carbon Age , could the resistant wood component lignin be dissolved by means of the enzymes of these fungi.
When and where coal was first discovered and mined in today's Germany is not known. Natural resources were already being used in the Neolithic Age . In the Saarland and in the triangle between Belgium , the Netherlands and Germany , on the Inde and Wurm , coal production has been documented since the Celtic settlement. As early as the 7th century BC BC coal was mined in the " Heinitzer Keltengrub" in the Neunkirchen district , as revealed by the palnyological examination of a carved coal bead that was found in 1982 as a grave in a burial mound from the Hallstatt period in Rubenheim in the Saar-Palatinate district .
Around 400 BC The Celts mined iron ore and later limestone on the Korkus in the south of Eschweiler , and it can be assumed that they also mined hard coal, which was openly exposed there in many places; as in the Wurmtal near Herzogenrath , where it can still be seen today. Finds in the Propsteier Villa and in the Korkus in the southern Limburg- Eschweiler area show that the Romans also used coal . Hard coal finds in Roman dwellings in Saarbrücken , Brebach and Beckingen prove that the Romans also operated mining in this part of the province of Germania; the near-surface “wild dig” for hard coal in the Saarkohlenwald-Revier was finally dammed in the 14th and 15th centuries by the sovereigns.
There is written evidence of coal mining in the High Middle Ages . The annals of the Klosterrath Abbey reported in 1113 that the abbey acquired land in the places where the coal occurred with a view to the combustible earth material.
Around 1370 it was also dismantled in what is now the western Ruhr area. Mining was not known in today's sense, but called coal digging, as the farmers shoveled for coal in simple pits when there was nothing to do in agriculture due to the season.
With the end of the Middle Ages , Europe experienced a tremendous economic and trade boom. Due to the enormous increase in production, wood became scarce, which is why other forms of heat energy were sought more intensively. Mining was particularly popular in England from around 1550 onwards, but also in many areas of Germany: for example in the Westphalian town of Unna , where the salt boiler benefited greatly from coal burning and new combustion technologies, or in the Osnabrück area , where the coal was used for lime kilns .
In England in the 17th and 18th centuries, hard coal formed the basis of the industrial revolution and thus the basis for the development of technology in industrialization .
According to the removal of volatile components (gases), hard coal is divided into:
- Flame coal (40 to 43 percent)
- Gas flame coal (35 to 40 percent)
- Gas coal (28 to 35 percent)
- Fatty coal (19 to 28 percent)
- Fatty coal is a dense coal , usually black, sometimes dark brown, often with easily recognizable light and matt stripes, and is mainly used as fuel in energy production.
- A large part is also used to generate heat in industry or to produce coke . Fatty coal is the most common type of coal in the Ruhr area and is particularly suitable for coking. Their moisture content is usually below 20 percent. Their carbon content is around 88 percent in anhydrous coal. The sulfur content is up to one percent. Another characteristic of the fatty coal is its high proportion of volatile components. Therefore, charcoal burns with a long, bright and sooty flame.
- Edible coal (14 to 19 percent)
- Lean coal (10 to 14 percent)
- Anthracite (less than 10 percent)
- Anthracite is considered the highest quality type of coal. It has great hardness. During the coalification process, vegetable raw materials are transformed under exclusion of air and high pressure , with increasing carbon content . The carbon content of anthracite can be over 90%. Because of the high energy content, the hot flame and the almost residue-free combustion, anthracite is highly valued as a fuel . Anthracite was extracted in Germany in the Sophia-Jacoba colliery and in the Ibbenbüren mine.
Annealed hard coal or annealed coal is called "Zinder" (mask.) (Cf. English Cinder : ash).
In 2006 the Federal Institute for Geosciences and Natural Resources (BGR) estimated the reserves that can be extracted worldwide at current prices and with today's technology at 736.1 billion tons of hard coal. Of this, the United States accounted for 29.0% (213.3 billion tons), the People's Republic of China for 22.7% (167.0 billion tons) and India for 13.0% (95.4 billion tons). With constant production (5.356 billion tons in 2006) and constant use, the demand could be met for about 130 years. However, global demand for coal continues to rise, according to an estimate by the International Energy Agency (IEA) by 2.3% annually.
Up to 2003, around 24 billion tons of German hard coal reserves were considered recoverable. Given a production rate of 23.5 million tons (2006), the theoretical range would be over 1000 years. Due to unfavorable geological conditions, however, only a part of these reserves can currently be extracted in an internationally competitive manner. Representatives of the German coal industry therefore put the range of German coal at around 400 years while maintaining the current production rates. However, on the grounds that speculative reserves would no longer be recorded, the reserves that can be extracted at current prices and with today's technology increased in its "Energy Study 2004" by 99 percent to 183 million tons, in 2005 to 161 million tons and in 2006 to 99 Millions of tons (calculated range from 2006: four years) reduced.
Following government resolutions, coal production in Germany expired in 2018. The last hard coal was mined on December 21, 2018 at the Prosper-Haniel colliery . This decision was to be checked again in 2012 according to the updated profitability forecasts, but the Federal Government decided on November 17, 2010 to delete this check without replacement. This was in line with the European Union, which considered a subsidy only permissible until 2014 for reasons of competition law.
Around 7.153 billion tons of hard coal were mined worldwide in 2014. The People's Republic of China funded more than half with 52.1%. In Europe, the largest mining areas are in Russia , Poland and the Ukraine . In Germany, most recently even in two mines RAG German hard coal AG coal mined (Prosper-Haniel in Bottrop and anthracite Ibbenbüren). Both were shut down in 2018.
Coal from countries such as Australia , Colombia , the USA and South Africa can be mined more cheaply than coal from Germany, which is due both to the deposits and the wage structures of the countries. There, hard coal can often be mined in open-cast mining, which is much cheaper than underground mining. The German hard coal subsidy existed until 2018 so that only coal from abroad was not used in Germany .
(in million t )
(in million t)
|1||People's Republic of China||3,725.0||11||Ukraine||65.0|
|7th||South Africa||253.2||17th||United Kingdom||11.6|
The global export volume of hard coal amounted to around 105.4 billion in 2018. Australia was the most important international export nation with an export volume of 39.8 billion euros. For Australia coal was the most important export good in the same period with a share of 18.5% of the national exports.
|#||country||Exports (in billion €)|
|9||People's Republic of China||0.7|
Hard coal is mainly used as a solid fuel to generate heat through combustion. This creates carbon dioxide , water vapor and other gases such as sulfur dioxide . In order to generate electrical energy , water vapor is generated using the heat , which in turn drives turbines . In order to compare which amount of energy can be obtained with which coal, one usually uses the hard coal unit (SKE). A large part of the coal is also refined into hard coal coke . Coal coke is used as fuel and as a reducing agent in iron production in blast furnaces. The hard coal serves as a raw material for the chemical industry , here the by-products such as tar , benzene, toluene etc. are of particular interest. The importance of hard coal as a chemical raw material declined in favor of crude oil since the middle of the 20th century . The coal liquefaction is not economically viable at present compared to the petrochemical industry.
The price for imported coal at the German border is regularly determined and published by BAFA ( Federal Office for Economics and Export Control ). The previous high was in the third quarter of 2008 at EUR 131.80 / tce . The previous maximum results in a price per kWh th of around 1.61 euro cents. For comparison: With a previously maximum crude oil price of $ 147 / barrel (equivalent to 82 euros), the price per kWh th is around 5.2 euro cents. Lignite , on the other hand, is much cheaper and costs around 40 euros / t TCE. The following table shows the third country coal purchases reported by the power plant operators in accordance with Section 6 (2) of the Hard Coal Financing Act and the average free German border prices for power plant hard coal. For a modern hard coal power plant such as Units D and E of the Westfalen power plant , with a process efficiency of 46% with the current table value, fuel costs for 2018 and an energy tax of 0.12 ct / kWh th of around 2.8 ct / kWh e result .
[Euro / t SCE]
When coal is burned, various residues are created. Steam coal contains up to 12% non-combustible solid components, which are referred to as ash content. Together with the water content, they make up the ballast content, which is around 20%. The exhaust gas consists mainly of carbon dioxide , as well as nitrogen oxides and can contain sulfur dioxide as well as trace elements such as mercury and dust. In modern coal-fired power plants, the exhaust gases are cleaned of sulfur dioxide in flue gas desulphurisation systems , nitrogen oxides by catalytic or non-catalytic denitrification and dust (fly ash) by means of electrostatic filters . This essentially leaves the greenhouse gas carbon dioxide, which is released into the atmosphere. Hard coal filter ash (like lignite filter ash ) is used as an additive in concrete production and u. a. used as backfill in the custody of closed mines .
By coal fires in shallow coal seams, the same as in exhaust gases of combustion in power plants arise additionally carbon monoxide due to the incomplete combustion. Coal fires have significant local effects, but can be neglected on a global scale: in China, around 25 million tons of hard coal are lost to coal fires every year. This corresponds to around one percent of the Chinese annual production of around 2.5 billion tons.
The coal mining causes land use and mining-related subsidence mining damage . These consist of building damage in built-up areas and the need to regulate flowing waters to ensure flow. Furthermore, areas for heaps and day-care facilities are used during the operating time of a mine and often for a long time beyond . In Germany, tailings piles have had to be designed as landscaping structures since the 1980s, which are re-used as recreational areas or otherwise after the end of their operating hours. The daytime facilities are to be dismantled or re-used. In old mining in particular , often without a legal successor, there are still a large number of brownfield sites with a high need for renovation. In almost all of the former mining areas, the rise in pit water must be monitored and regulated.
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