Coal is a dark, combustible rock made mainly of carbon, along with small amounts of hydrogen, sulfur, oxygen, and nitrogen. It forms over millions of years from the remains of dead plants, typically found in ancient swampy regions, and is a type of fossil fuel.

Coal can be categorized into several types based on its carbon concentration and energy efficiency:

• Anthracite (highest carbon content, most energy-rich and cleanest to burn),
• Bituminous (commonly used for generating power and in industries),
• Sub-bituminous (moderate carbon content, lower energy output),
• Lignite (softest and least carbon-rich, often called "brown coal").

It is mainly burned to generate electricity, power industrial processes (such as in steel production), and serve as a raw material in chemicals. However, coal's use has been decreasing due to its high emissions of carbon dioxide and other pollutants, contributing to environmental issues.

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