Energy value of coal

The energy value of coal, or fuel content, is the amount of potential energy coal contains that can be converted into heat.^[1] This value can be calculated and compared with different grades of coal and other combustible materials, which produce different amounts of heat according to their grade.

While chemistry provides ways of calculating the heating value of a certain amount of a substance, there is a difference between this theoretical value and its application to real coal. The grade of a sample of coal does not precisely define its chemical composition, so calculating the coal's actual usefulness as a fuel requires determining its proximate and ultimate analysis (see "Chemical Composition" below).

Chemical composition

Chemical composition of the coal is defined in terms of its proximate and ultimate (elemental) analyses. The parameters of proximate analysis are moisture, volatile matter, ash, and fixed carbon. Elemental or ultimate analysis encompasses the quantitative determination of carbon, hydrogen, nitrogen, sulfur and oxygen within the coal. Additionally, specific physical and mechanical properties of coal and particular carbonization properties

The calorific value Q of coal [kJ/kg] is the heat liberated by its complete combustion with oxygen. Q is a complex function of the elemental composition of the coal^{[citation needed]}. Q can be determined experimentally using calorimeters. Dulong suggests the following approximate formula for Q when the oxygen content is less than 10%:

Q = 337C + 1442(H - O/8) + 93S,

where C is the mass percent of carbon, H is the mass percent of hydrogen, O is the mass percent of oxygen, and S is the mass percent of sulfur in the coal. With these constants, Q is given in kilojoules per kilogram.

References

^ Vilakazi, L; Madyira, D (2024). "Estimation of gross calorific value of coal: A literature review". International Journal of Coal Preparation and Utilization: 1–15. doi:10.1080/19392699.2024.2339340. ISSN 1939-2699.

"Using Charcoal Efficiently." Food and Agriculture Organization of the United Nations. Retrieved 10 Nov 2011. [1]
"Combustion Training." (c)2011 E Instruments International, LLC.[2]^[usurped]

[1] Vilakazi, L; Madyira, D (2024). "Estimation of gross calorific value of coal: A literature review". International Journal of Coal Preparation and Utilization: 1–15. doi:10.1080/19392699.2024.2339340. ISSN 1939-2699.

[1]

v t e Coal
Coal types by grade (lowest to highest)	Xylit Peat¹ Lignite Sub-bituminous coal Bituminous coal Anthracite Graphite¹
Coal combustion	Ash pond Asian brown cloud Asthma Black coal equivalent Char Charcoal Coal combustion products fired power station gas phase-out pollution mitigation power in China power in the United States preparation plant seam fire tar Coke Coking Energy value Flue gas Fly ash Fossil fuel Fossil fuel phase-out Great Smog of London Greenhouse gas emissions Metallurgical coal NOx Smog Sulfur dioxide Toxic heavy metals
Coal mining	Blackdamp Black lung disease Coal dust Coalfields Coal gas homogenization liquefaction mining disasters in the United States mining region refuse slurry town Environmental issues in Appalachia Environmental justice and coal mining in Appalachia Firedamp Health and environmental impact of the coal industry Health effects of coal ash History of coal mining Hydrogen sulfide Mining regions Outbursts Peak coal Problems in coal mining Refined coal Whitedamp
Note: [1] Peat is considered a precursor to coal. Graphite is only technically considered a coal type.

Chemical composition

See also

References