Facts about coal
Coal formation
Five-metre thick seams of coal, such as found in Svea on Svalbard, were once 50–60-metre thick layers of peat. The formation of a peat layer this thick takes about 40 000 years under good growing conditions. The land areas we now call Svalbard had higher temperatures in pre-historic times, making such plant growth possible.
Peat is converted into coal by the layers of peat being covered by sediment and then pressed down into the earth’s crust, where high pressure and temperatures start a process called coal formation. Coal formation takes many millions of years. It should not be confused with coal charring, which is a quicker process under different pressure and temperature conditions.
Types of coal
Based on the carbon content, we differentiate between three main types, or ranks, of coal: lignite, bituminous and anthracite. It is largely the age of the coal and its depth in the earth’s crust that determines the carbon content. Coal with a high carbon content has a higher energy content and is “cleaner” in use, because the content of water and other substances is lower.
Lignite
Lignite, or brown coal as it is often called, is a young type of coal with a lower carbon content. Lignite is soft with a matt surface, and the coal deposits are usually near the surface. The energy content in lignite is lowest of the three types. Since lignite also contains more sulphur than older coal, it emits more pollution when burned.Bituminous
Bituminous coal has a higher carbon content than lignite. It therefore contains less moisture than lignite, is harder and has a lustrous surface. Bituminous coal is divided into two categories, subbituminous and bituminous, with bituminous the most high-energy value category.Anthracite
Anthracite is the “oldest” type of coal. It is hard, dark grey and with a high lustre. It has the highest carbon content of all the coal types. Anthracite requires a high temperature to ignite, and because of this people struggled to make use of it right up until the industrial age.
Coal on Svalbard
Coal is found only in sedimentary rock, of which there is little on the Norwegian mainland. The only workable coal deposits in Norway are on Svalbard, where sedimentary rock dominates. We find a lot of coal in particular in rock dating from the Carboniferous Period (300–360 million years old) and the Tertiary Period (2–65 million years old).
At Pyramiden in Billefjorden and on the island of Bjørnøya, there has been mining of coal from Carboniferous deposits, but most of the other coal deposits on Svalbard are from the Tertiary. The mining operations in Ny-Ålesund, Barentsburg, Grumant, Svea and Longyearbyen have all been based on such deposits.
The coal deposits on Svalbard lie in almost horizontal strata in the rock, like the filling in a sponge cake. In the rocks from the Older Tertiary Period (60–65 million years old) there are here five coal seams in total. These are the Svea seam, the Todal seam, the Longyear seam, Svarteper and Askeladden. Currently only the Longyear seam and the Svea seam are economically workable. In the mining fields along the valley of Adventdalen it is the Longyear seam that has formed the basis for mining operations. The Svea seam is currently mined in the Svea Nord mine.
Uses of coal
The most important uses for coal are as a fuel in energy production and in the process industry, and as a reducing agent in the manufacture of steel.
Coal was the world’s most important source of energy up until the 1960s, when oil took over the role. Coal is nevertheless still the most important fuel in the production of electricity. Over 40 per cent of the world’s electricity is generated in coal-fired power plants, and 25 per cent of all human-generated energy today is based on coal.
The other main area of use for coal is in various chemical processes, of which iron and steel manufacture are the most important. Coal is usually refined into coke first, by the driving off of volatile matter in a separate process. The coke is then used as a reducing agent in the purification of iron ore and the refining of iron into steel.
Coal is also used in the manufacture of cement, artificial fertilisers, plastics, tools and pharmaceutical products, and as an additive in the casting of various metal alloys.
World production of bituminous coal in 2008 totalled 5.8 billion tonnes, while lignite production totalled 950 million tonnes. In 2009, Store Norske produced 2.5 million tonnes of coal.
On a global basis, coal is the largest fossil energy reserve. Known coal reserves are spread throughout more than 100 countries, with the largest reserves in the USA, the former Soviet Union, China, Australia and India. At current production levels, the world’s coal reserves will last for approximately 200 years.
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