A hard, black, stone-like substance, coal has been a critical source of energy and heat for thousands of years. Coal was the fuel which powered the industrial revolution of the 17th and 18th centuries, and it continues to be a vital source of energy today. The attraction to coal is its low cost, accessibility and abundance when compared to the other fossil fuels. Currently, coal is used primarily for making steel (about 70% globally) and for generating heat within other industries such as electric power plants (about 35% globally).

However, not all coal is created equal. Higher densities of carbon and decreased levels of moisture increase the hardness and energy value of coal. As a result, coal is classified into four rankings:

• Anthracite is the hardest and most energy valuable rank of coal.
• Bituminous is the second rank of coal and accounts for half of the coal production in Canada. It is the primary type of coal that is used in making steel and for thermal electricity generation.
• Sub-bituminous is the third rank of coal and accounts for about a third of Canada's coal production. It is used for thermal electricity generation.
• Lignite, the final rank of coal, has the lowest energy value and is also used for thermal electricity generation.
  

All of these rankings reflect different stages of coal development. The more time, pressure and heat that the ancient plants deposits are subjected too, the harder, drier and more energy rich the resulting coal will become.

Mining, Extraction and Refinement

The thought of coal mining often evokes images of the coal streaked faces of miners as they work deep within dark mining shafts. These images are real part of Canadian heritage, but many technological advances have been made since then to improve the safety and efficiency of coal mining. These technologies are tailored to how close coal deposits or seams are to the earth's surface. In some cases these deposits are shallow and even exposed, in other cases they lie deeper within the earth.

Deep deposits of coal are accessed using vertical or horizontal shafts that aid the movement of miners, equipment and coal. Coal deposits that are closer to the surface are excavated using either open pit or strip mining techniques, depending on the shape of the deposit. In spite of these advancements, shaft coal mining continues to be expensive and dangerous.

Coal can then be refined in order to improve its value. For instance, coal can be cooked at high temperatures in the absence of air within “cokers” to remove moisture, tars, oils and gases. The coke that comes from this process is used for making steel. In addition, coal can be processed to produce other types of fossil fuels including gasoline, diesel and kerosene.

Pollution and Environmental Impact

Coal is considered the dirtiest of the fossil fuels and contributes significant amounts of pollutants that affect our health, environment and economy. The most obvious example of this was the London Smog of 1952 in which thousands of people died because of poor air quality caused by the burning of coal and compounding climatic conditions. Even today, coal powered industries continue to be a major source of particulate matter (PM), sulphur dioxide (SO2), nitrogen oxides (NOx), mercury and greenhouse gases such as carbon dioxide emissions.

A variety of technologies are in place to reduce the amount of pollution being produced by the combustion of coal. For instance, most of the fly ash (suspended particulate matter) that comes from the burning of coal is collected using electrostatic precipitators. This fly ash is then shipped to dumping sites, used as backfill for the mine, or is made available as material for cement making factories. The heavier bottom ash, collected at the bottom of furnace, is transported as waste to dumping sites.

Sulphur dioxide is also a major pollution concern for the combustion of coal and an integral component of acid rain. Similar technical advancements such as scrubbers located in furnace stacks are able to clean the emissions before they are released to the atmosphere. This pollution concern can also be addressed by burning cleaner, low sulphur coal. For example, coal found in Alberta and British Columbia has a much lower sulphur content than coal coming from the eastern provinces.

Another important concern for coal mining, more so than for the other fossil fuels, is the physical disturbance of the environment. Large tracts of land must be cleared and excavated to access coal deposits particularly for surface mines. This can have a significant environmental impact on wildlife and vegetation. Many efforts are being made to minimize this disturbance and to reclaim the disturbed areas.