The Physics
An encyclopedia of scientific essays

Energy Density of Coal

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Bibliographic Entry Result
(w/surrounding text)
Energy Conversion. Energy Conversion: Typical Heat Values of Various Fuels. Tad W. Patzek. University of California, Berkeley.
Firewood (dry) 16 MJ/kg
Black coal (NSW & Qld) 24-30 MJ/kg
Black Coal (SA & WA) 13-20 MJ/kg
Natural Gas 39 MJ/m3
13-30 MJ/k
Bioenergy Archive. Re: Optimizing Fuel Volume Density. Weststeijn, A. "COAL
loose bulk density = 850 kg/m3 (in pile)
energy density CV = 24 MJ/kg = 24 GJ/ton"
24 MJ/kg
B.R. Cooper and W.A. Ellingson. The Science and Technology of Coal and Coal Utilization, 1984. [see table below] 14.6-32.5 MJ/kg
Fuel Densities. Biomass Energy Foundation. "Brown Coal - 1120 860 62.5 2 8.0 9.0
Black Coal - 1450 940 8 22 24.0 34.8"
8.0-24.0 MJ/kg
Lin, Bruce. Rules of Thumb. 13 September 1999. "Also, note that 1 tonne of oil equivalent ('toe') is equal to 11630 kWh or 11.63 MWh)
0.444–0.646 tonnes of oil equivalent per tonne, energy density of coal"
18-27 MJ/kg

Coal is a hard, black substance found in deposits of sedimentary rock. Coal is a fossil fuel. It is formed from the remains of ancient life that was buried deep in the earth millions of years ago. The main use for coal is to produce energy but it can also be used to manufacture steel and is an important source of some of the chemicals used in pharmaceuticals, pesticides and fertilizers. Coal has a relatively high energy density of approximately 24 MJ/kg. Energy density can be defined as the amount of energy per mass. Its SI units are J/kg but MJ/kg is more common.

Eighty six percent of the coal burned in the United States is used by power plants to make energy for electricity. When the coal is burned by the power plants, energy produced is in the form of heat. When coal is used by the steel industry, it is first heated and turned into a substance called coke, which is almost pre carbon. The coke is then combined with other ingredients, heated and turned into steel.

Currently coal deposits can be found in almost every region of the world. Areas with significant coal amounts are Europe, Asia, Australia and North America. In 1997 world coal resources were estimated to be 9.98 trillion metric tons. United States coal reserves are locates in six different regions. These include the Appalachian Basin, West Virginia, Kentucky, Ohio, Alabama and Tennessee. In 1996, estimates of total US coal reserves were approximately 17.6 billion metric tons.

ASTM class ASTM group MJ/kg
Lignite Lignite A <14.6
  Lignite B 14.6–19.3
Sub-bituminous Sub-bituminous C 19.3–22.1
  Sub-bituminous B 22.1–24.4
  Sub-bituminous A 24.4–26.7
  High volatile C 24.4–30.2
Bituminous High Volatile B 30.2–32.5
  High Volatile A >32.5
  Medium volatile >32.5
  Low volatile >32.5
Anthracite Semi-anthrcite >32.5
  Anthracite >32.5
  Meta-anthracite >32.5

Juliya Fisher -- 2003

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