Sub-bituminous coal

Sub-bituminous coal is a type of coal whose properties range from those of lignite to those of bituminous coal and are used primarily as 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).^[1] The heat content of sub-bituminous coals range from 8300 to 11,500 BTu/lb or 19,306 to 26,749 kJ/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.

Current use

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.

See also

• Types of Coal
• Acid Rain Program
• List of CO2 emitted per million Btu of energy from various fuels

References

1. ↑ The Babcock & Wilcox Company. Steam: its generation and use. The Babcock & Wilcox Company. pp. 36–5. ISBN 0-9634570-1-2. 

Coal
Coal types by grade (lowest to highest)	Peat1 Lignite Sub-bituminous coal Bituminous coal Anthracite Graphite1
Coal combustion	Black coal equivalent Char Clean coal Coal preparation plant Coal seam fire Coke Coal tar Energy value Flue gas Fly ash
Coal mining	Coalfields Coal dust Coal gas Coal slurry Coal homogenization Coal liquefaction Environmental impact of the coal industry History Mining regions Peak coal Refined coal Coal town
Note: [1] Peat is considered a precursor to coal. Graphite is only technically considered a coal type.