Coal

As a fossil fuel, coal has been a major source of energy for centuries, powering industrial activities and electricity generation. Here’s an in-depth look at coal: 

Formation and Types of Coal 

Coal forms through a process called coalification, which transforms plant material into carbon-rich deposits through several stages. This process typically takes place in swampy areas where plants accumulate and are buried by sediment, then subjected to heat and pressure over geological time. 

Types of Coal (by Rank) 

Coal is classified into several ranks, which reflect the degree of carbon content, hardness, and energy content. The main ranks include: 

1. Peat: Although not technically coal, peat is the precursor to coal. It consists of partially decayed plant material and has low carbon content and energy. 

1. Lignite (Brown Coal): The lowest rank of coal, lignite has a carbon content of 25-35% and a relatively high moisture content, which results in lower energy output. It is primarily used in electricity generation and has a soft, crumbly texture. 

1. Sub-Bituminous Coal: Higher in carbon (35-45%) than lignite, sub-bituminous coal has a higher energy content and is widely used in power generation. It has a dull, black appearance. 

1. Bituminous Coal: Bituminous coal has a carbon content of 45-86% and is the most common type used worldwide for both electricity generation and steel production. It is harder and shinier than lower ranks and has a high energy content. 

1. Anthracite: The highest rank, anthracite, has a carbon content of 86-97%. It is hard, lustrous, and burns cleaner and more efficiently than other types of coal. Anthracite is primarily used for heating and industrial purposes due to its high energy output and low impurities. 

 

Major Uses of Coal 

1. Electricity Generation: Coal is one of the leading sources of global electricity. It is burned in power plants to produce steam, which drives turbines connected to generators. Despite growing renewable alternatives, coal remains a primary source of electricity in many countries. 

1. Steel Production: Bituminous coal is a vital ingredient in steel production through a process called coking. Coal is converted into coke, which is used as a reducing agent to extract iron from its ore, producing steel. 

1. Cement Manufacturing: Coal is used to heat kilns in cement production, where its high temperature allows for efficient production of clinker, a key ingredient in cement. 

1. Heating and Industrial Fuel: Anthracite and some bituminous coals are used for residential and industrial heating due to their high energy content and clean-burning properties. 

1. Chemical Industry: Coal can be processed into synthetic fuels, and coal derivatives are used in various chemical products, including dyes, plastics, fertilizers, and synthetic oils.