A Brief Overview of Coal: Part One – History, Origin & Formation and Distribution
Coal is two-faced. It gives warmth, heat and power, but with that comes appalling working conditions, death, despair and heavy-duty pollution. Archaeologists tell us that cavemen used coal for heat. The Chinese used coal to smelt copper for coinage around 1,000BC, and the Romans used it for heat around 400BC in England. It was being used for heat in England in the 14th century, and even then causing extensive air pollution. But much more was to come.
Coal drove the development of the steam engine, the harbinger of the industrial revolution, which in turn drove development of the coal industry. The first steam engine was developed to dewater coal mines, patented by Thomas Savery in 1698 (and refined by Thomas Newcomen in 1712). But it was James Watt’s steam engine patent in 1769 that ushered in the age of steam.
The industrial revolution was powered by steam; created by coal. The 18th and 19th centuries saw an explosion in coal production in the west. By the 20th century the United Kingdom was producing over 200 million tonnes per year, Germany 120 million tonnes, and the United States 350 million tonnes.
But coal’s dominance was nigh. In 1914, WW1 officially introduced the age of oil (see below for more information). Nonetheless coal consumption skyrocketed, particularly in the United States – the “Armoury of Democracy”. Coal production flattened out after the war, and was overtaken by oil as a primary energy source around 1960.
In the early 1990’s it looked as though coal use had peaked, but King Coal was only down, not out. By 2000 coal production rapidly escalated until today it is a comparable source of global energy consumption to oil, much of that due to the spectacular growth of the Chinese economy.
ORIGIN & FORMATION
Although land plants first formed about 500 million years ago (“mya”), and minor coal deposits formed around 400mya, the first significant coal deposits were not formed until the mid-Carboniferous Period, about 325mya. The main periods for coal formation have been 350 – 250mya, 200 – 65mya and 50 – 20mya.
It is well known that coal forms through the accumulation and then burial of plant debris, or peat. However, it requires specific conditions, over long periods of time to allow sufficient accumulation to form a meaningful coal seam. About 10 metres of peat is required to form a 1 metre coal seam, and deposition could take thousands of years.
Coal deposits have their origins in non-marine, wetland environments, such as swamps, where plant debris falls into water that is (usually) oxygen deficient, thus preventing decay and allowing carbonization and the formation of peat. However, for this to happen over many years the water depth must remain fairly constant to avoid drowning the plants or exposing the debris to the air. Today’s equivalent is a peat wetland or mire.
The peat is ultimately covered by sediments such as sand or silt. However, as the depositional environment changes more peat beds can be formed, interbedded with these non-coal sediments. Some characteristics of coal are influenced by the environment of peat deposition and include the types of plants from which it formed, temperature, bacteria, water acidity and others. Other coal characteristics relate to the depth, temperature and length of burial. This is discussed more fully in Part Two.
With the exception of Australia and South Africa, the vast majority of coal deposits are in the Northern Hemisphere. Peat predominantly formed in tropical latitudes. The current distribution of coal deposits is a result of continental drift. A large chain of coalfields stretches through North America and Eurasia. Although minor coal deposits exist in a number of countries in the Southern Hemisphere, the only large deposits are in Australia and Southern Africa.
There are a number of geological reasons why some regions of the world do not host viable coal deposits. For example:
- Deposits do exist, but are too deeply buried to be economic
- Deposits did exist, but have subsequently been eroded
- Regions where rocks younger than 325mya were never deposited
- Regions where rocks younger than 325mya were deposited, but in conditions not suitable coal formation.
Part Two – Rank and Uses
In the late 19th century Germany had forged an alliance with the Ottoman Empire. This included building a railway from Berlin to Baghdad, and mineral and oil rights. Oil had already been discovered along the route, in what is now Iraq.
The British saw this as a threat to their own oil security, especially as the British Navy was converted from coal to oil. They formed alliances with France and Russia and sought to destabilise the Ottoman Empire in the Balkans. They were successful and events there led to WW1. The resolution of this power struggle required a second war, out of which emerged two new great powers; Russia and the United States.