What is the principal gas contained in coal?

The principal gas contained in coal is methane (CH4). Coal deposits are formed from the remains of ancient vegetation that undergoes a process of decomposition and carbonization over millions of years. During this process, various gases, particularly methane, are released as the organic material breaks down.

Methane is not only significant as a byproduct of coal formation, but it is also a major component of the natural gas often found in association with coal seams. In the context of mining, understanding the presence of methane is crucial for safety, as it can create explosive atmospheres when mixed with air and is a common hazard in underground coal mines.

Carbon dioxide and nitrogen are present in smaller amounts in coal seams and do not represent the principal gas. Sulfur dioxide is primarily a combustion byproduct, resulting from the burning of sulfur-containing fossil fuels, rather than being contained within the coal itself.