Millions of tonnes of coal are used all over the planet every year. This valuable resource isn’t man made, and the process in which it is created happened before any of us were even here – way before.
Coal formed millions of years ago when the earth was little more than swampy forests. Plants such as ferns, reeds and mosses grew abundantly. When they died, they fell into the swamp waters. New plants took their place before ultimately suffering the same fate. Over time, a layer of dead vegetation grew. When the surface of the earth changed, and dirt and water washed in, the decaying process was halted in its tracks.
Layers upon layer of vegetation built up, creating an incredible weight upon the bottom layers. Physical changes occurred in the plant layers as the intense pressure also caused intense heat, forcing out oxygen, and leaving rich carbon deposits. That material slowly developed into coal.
Coal is classified into three main types; lignite, bituminous coal and anthracite. The classifications are based on the amount of carbon, oxygen and hydrogen present in the coal. In the process of transformation, or coalification, peat is altered to lignite, lignite to sub-bituminous, sub-bituminous coal is altered to bituminous, and bituminous coal is altered to anthracite.
Lignite: Is used mainly for generating electricity. Lignite is the lowest ranked coal due to its low heating value and low carbon content. Although it is firmer than peat, shipping it long distances causes it to crumble. It can also be used to generate synthetic natural gas and to produce fertiliser products.
Bituminous: Sometimes called soft coal; this intermediately ranked coal is made up of many layers. It has a high heating value but suffers from a high sulphur content. Its major uses are in the cement, food, paper, automobile, textile and plastic industries, but is mainly used to produce electricity.
Anthracite: its high heating value and high carbon content makes anthracite the highest ranked coal available. It is very hard, a deep black, and looks almost metallic. Primarily used to heat homes as it produces less soot and dust than other coal types which is why it is referred to as smokeless coal.