Coal and Coke
Coal has been used for centuries to provide energy, for domestic heating and also for industrial use. It has various forms that can be used in different circumstances: some coal is only suitable for industrial use or power generation, while higher grade coal can be used for domestic heating (such as solid fuel central heating) or space heating in commercial settings. Coke is a variant of coal that undergoes processes that eliminate most of the smoke-producing components, so while both coal and coke may be used in coal stoves, coke is preferred in areas with strict regulations on smoke reduction.
Anthracite Coal
Anthracite is the highest grade of coal used for general industrial and domestic purposes. It is sometimes known as smokeless coal as it burns ‘cleaner’ than the softer bituminous coal: the reason for this is that it has a higher carbon content and less impurities. This produces fewer emissions when the coal is burned. It is the coal that has traditionally been used for domestic heating (including solid fuel heating), and also in some commercial settings. Due to its high quality it is usually more expensive than other types of coal.
Bituminous Coal
Bituminous coal is of a lower grade than anthracite. It is commonly referred to as thermal coal due to the fact that it is used extensively in power generation. One of its variants, coking coal, is the main form of coal used to produce coke.
Lignite
Lignite is a still lower grade of coal that is also used in the generation of power. It is also called brown coal due to its colour: this colour is due to the greater amount of impurities lignite contains compared to anthracite or bituminous coal.
Clean Coal
Clean coal is not a different variety of coal, rather it represents an advance in the technology used when coal is burnt in power stations. Carbon capture technology is used to ensure that a proportion of the waste products emitted in the burning of coal is captured and then sequestrated in a long-term storage area. The theory is that the waste carbon is not released into the atmosphere but returned to a more natural state, thus making the use of coal more acceptable long term. Environmental activists often disagree, saying that clean coal is expensive, and perhaps even a ruse, preferring to concentrate on the development of renewable energy.
Coke
Coke is a form of coal which has been processed by baking in a vacuum in order to leech off the majority of its impurities. As a result of this, it burns cleaner and with much less smoke than other varieties of coal. Due to this property it has been popular in domestic heating, whether in fireplaces, coke stoves or solid fuel boilers. It is also extensively used in steel production.
Coal Reserves
Though coal reserves are being depleted, depending on the source consulted it is estimated that there are between 100 and 150 years of coal left if consumption is continued at present rates. The question is whether the quickening industrialisation of emerging economic giants like China, India and Brazil will lead to an increase in coal production, or the advance of renewable energy in developed economies will lead to an overall decrease.
Coal Prices
As with any other globally-traded commodity, coal prices rise and fall in response to market conditions. Though demand is expected to increase, in the near future it is expected that the trend for coal prices will be downwards due to improvements in extraction technologies and probable decreases in transportation costs.