Coal can be classified by its age or by its calorific value in four large categories: anthracite, bituminous coal, sub-bituminous coal, lignite and peat, the richest one being the oldest one and the one with the higher carbon percentage. Many countries and organizations use different classifications, so that, when in doubt regarding a compound, it is advisable to check its chemical composition, heat value, moisture, and coking properties. 

Coal started to replace wood as a fuel in the middle of the 18th century, as wood became less available for house heating. The development of James Watts’ steam engine (1782) boosted its use in both the industrial and transportation sectors. With the steady increase in international commerce, coal became the main fuel for ships and railway transport.

Large coal deposits began to be exploited worldwide; in the USA (Pittsburgh), in Great Britain (Cardiff and Newcastle), in Germany (Ruhr), in the USSR (Donetz) and in Poland (High Silesia).

 Its consumption reached its peak during the decade of 1910. From then on, as it began to be replaced in many uses by petroleum and natural gas, its consumption started a slow but steady decrease.

The most common use for coal is as fuel for thermal electric power plants. Another one of its uses, the production of metallurgical coke has registered a continuous decrease since the decade of 1960, as a consequence of the decline of the steel industry. The domestic use of coal has diminished drastically due to the growing use of other fossils fuels and electricity. 

The world's known coal reserves are enough to satisfy the requirements for the next two hundred years at its present rate of consumption. However, there exist serious objections to its use, such as its emissions of greenhouse effect gases, the impracticality of its use in transport, and its small profit.

Coal News from Platts.