Sub-bituminous coal

Sub-bituminous coal is a lower grade of coal that contains 35–45% carbon. The properties of this type are between those of lignite, the lowest grade of coal, and those of bituminous coal, the second-highest grade of coal.^[1] Sub-bituminous coal is primarily used as a fuel for steam-electric power generation.

Properties

Sub-bituminous coals may be dull, dark brown to black, soft and crumbly at the lower end of the range, to bright jet-black, hard, and relatively strong at the upper end. They contain 15-30% inherent moisture by weight and are non-coking (undergo little swelling upon heating).^[2] The heat content of sub-bituminous coals range from 8300 to 11,500 BTu/lb or 19.3 to 26.7 M J/kg. Their relatively low density and high water content renders some types of sub-bituminous coals susceptible to spontaneous combustion if not packed densely during storage in order to exclude free air flow.

Reserves

A major source of sub-bituminous coal in the United States is the Powder River Basin in Wyoming.

Application

Sub-bituminous coals, in the United States, typically have a sulfur content less than 1% by weight, which makes them an attractive choice for power plants to reduce SO₂ emissions under the Acid Rain Program.

Sub-bituminous coals release large quantities of greenhouse gases when burned, compared to higher grades of coal.^[3]

References

^ "Coal explained". Energy Information Administration. Retrieved 2020-09-26.
^ The Babcock & Wilcox Company (2005). Steam: its generation and use. The Babcock & Wilcox Company. pp. 36–5. ISBN 0-9634570-1-2.
^ Bond, Jordan (14 July 2021). "NZ imported more than a million tonnes of 'dirty' coal last year". RNZ. Retrieved 24 September 2023.

[1] "Coal explained". Energy Information Administration. Retrieved 2020-09-26.

[2] The Babcock & Wilcox Company (2005). Steam: its generation and use. The Babcock & Wilcox Company. pp. 36–5. ISBN 0-9634570-1-2.

[3] Bond, Jordan (14 July 2021). "NZ imported more than a million tonnes of 'dirty' coal last year". RNZ. Retrieved 24 September 2023.

[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.

Properties

Reserves

Application

See also

References