Coal is a dark, flammable rock primarily composed of carbon, along with minor quantities of hydrogen, sulfur, oxygen, and nitrogen. It is formed over millions of years from the decomposed remains of ancient plants, typically found in prehistoric swampy areas, and is classified as a type of fossil fuel.

Coal can be classified into various types based on its carbon content and energy efficiency:

• Anthracite (highest carbon content, most energy-dense and cleanest for combustion),
• Bituminous (commonly utilized for electricity generation and in industrial applications),
• Sub-bituminous (moderate carbon content, lower energy yield),
• Lignite (softest and lowest in carbon content, often referred to as "brown coal").

It is primarily burned to produce electricity, power industrial processes (such as steel manufacturing), and act as a raw material in chemical production. Nevertheless, the use of coal has been declining due to its significant emissions of carbon dioxide and other pollutants, which contribute to environmental challenges.

• Indonesian Coal 5,500 Kcal/kg
• South African Coal RB1 - RB4
• Colombian coal