Learn What Coal Is, How It's Formed and Where It's Found

Coal is a combustible, sedimentary, organic rock which is composed mainly of carbon, hydrogen and oxygen. It is formed from vegetation which has been consolidated between other rock strata, and altered by the combined effects of pressure and heat over millions of years to form coal seams.

It is a fossil fuel and is far more plentiful than oil or gas, with around 119 years of coal remaining worldwide. According to the World Coal Association, coal "is the altered remains of prehistoric vegetation that originally accumulated in swamps and peat bogs," and the energy we get from coal today comes from energy absorbed by plants from the sun. When plants die, they decay and release that energy. 

But coal has become very controversial in recent years. On the one hand, it is a plentiful resource and is considered to be a cheaper source of energy. But critics say byproducts — such as dust and runoff — and emissions from burning coal are harmful to the environment. 

Here are some key facts about coal. 

Types of Coal

From lignite to anthracite — and from power generation to domestic use — the different types of coal depend on the organic maturity of plant remains. This maturity occurred during the geologic ages and produced different types of coal that offer different characteristics such as color, hardness, oxygen, hydrogen and sulfur balance. These varieties of coal are consequently used for different purposes.

Starting from the peat, the first output of the conversion process is the lignite which is also known as "brown coal". The continuing effects of temperature and pressure might transform lignite into sub-bituminous coals. Sub-bituminous coal might become harder and blacker, which is then converted into bituminous coal or "hard coal".

Anthracite coal comes at the end of the evolution chain and contains the lowest rate of impurities.

Where is Coal Found?

According to the World Coal Association, coal reserves are available in almost every country worldwide. Recoverable reserves are found in as many as 70 countries.

  • There are more than 1.1 trillion tonnes of proven coal worldwide reserves.
  • The largest reserves are found in the United States, Russia, China and India. 
  • At current rates of production, coal reserves would last for about 150 years. In contrast, proven oil and gas reserves are equivalent to around 50 and 52 years at current production levels. 

How can coal reserves be extended?

  • Exploration through actual technology and process.
  • Exploitation of presently inaccessible — for technical and/or safety reasons — but identified resources, thanks to technological progress.
  • Optimization of coal use, increasing the energy ratio per ton of coal.

Coal Controversy

The impact coal has on the environment depends on who you ask. Because coal is considered a cheaper energy source, many countries are looking to use it to fuel their economies, so naturally, there are two sides to the debate of whether coal is actually a clean energy source. 

  • Proponents of "clean coal" believe it can be mined and burned with little to no environmental impact. Energy providers are able to use more environmentally-friendly ways of energy consumption as they expand their technology. This includes scrubbing or cleaning coal to reduce the amount of impurities and emissions it releases when burned. 
  • Using coal — a cheaper energy source — will give nations the ability to invest in alternative sources such as wind and solar. 

But critics of the fossil fuel are not convinced, saying: 

  • Air pollution associated with coal burning is believed to be related to various health problems — including asthma and cancer — especially for people living within the vicinity of coal mines. 
  • There is no such thing as "clean coal." The Union of Concerned Scientists says no matter how much coal is scrubbed, it still releases toxins into the environment. These can have long-lasting and harmful impacts such as global warming.