Energy

Where it is

The favourable environment for the formation of coal includes the vast coastal, lagoon or swampy plains where in the past the hot and humid climate developed a rich vegetation. The low sinking of the soil led the vegetal organisms to be quickly buried by sand and clay carried by rivers. Underground, in the absence of oxygen, the vegetal matter pressed by the weight of sediments and owing to the heat undergoes a process of compression and slow transformation into materials progressively poorer in water and rich in carbon. Peat is the first result, i.e. an accumulation of partially decomposed vegetal organism full of water. Then lignite, a brown and soft type of coal containing 70% carbon. Then lythanthrax, the most commonly coal used to produce electric energy containing the highest carbon percentage (from 93% to 98%). It is the best and less polluting coal (with a high calorific value), but is not widely used because it is hard to find and consequently very expensive. The formation of coal fields required from millions to hundreds of million years, according to the final product. 95% of coal fields are in the northern hemisphere (almost 60% shared between China, USA and former USSR). In Europe, the belt of large fields covers central-northern countries: Great Britain, northern France, Belgium, Holland, Germany, Poland and Russia. Italy has small quantities of “poor coal” (lignite). That unequal distribution depends on the fact the formation of great masses of vegetal rests calls for dry land and ad hoc climate. In the Palaeozoic age (from 530 to 245 million years ago), the regions of today’s central Europe were occasionally invaded by shallow seas: the optimum condition to develop abundant vegetation and slowly transform it into coal. On the contrary, today’s regions of southern Europe date back to the Mesozoic age (from 245 to 65 million years ago) or are more recent, and formed in the sea far away from the coats: that is why they contain small unimportant coal fields.