Aug 15 - Coal is used to produce 40 percent of the world's
electricty, most of its steel and the cement in its buildings
and shows no sign of losing popularity.
It is made of old organic matter which has been compressed
by rocks over millions of years and there are several types
found around the world of varying moisture content and energetic
value, factors which largely determine how it is used.
Burning coal produces more carbon dioxide than any other
fossil fuel, the main manmade gas blamed for global warming.
Coal quality is determined by pressure, temperature and how
long it has been forming, with the oldest and hardest coals
drier and more energetic than younger, damper deposits.
Organic matter in peat bogs first transforms over millions
of years into lignite or 'brown coal.'
Over millions more years lignite transforms into the range
known as `sub-bituminous' coals.
Further blackening and hardening during 'coalification'
forms `bituminous' or hard coals. Eventually, under the right
conditions, the hardest of coals, anthracite, is formed.
Below is a summary of the different types of coal and what
they are used for.
For information on the producers and users of coal, click
LOW QUALITY COALS - Softer, wetter, duller, earthier, lower
LIGNITE - Mostly used to generate power. Demand expected to
grow by 1 percent a year through to 2030.
SUB-BITUMINOUS - Power generation, cement making and
industries like chemicals and pharmaceuticals.
Coal is not only an ingredient in cement but is also used in
large quantities to fire the kilns which bake the material used
in many of the world's buildings.
It is also needed to make carbon fibre which is used for
strong, light-weight products from bicycles to tennis rackets.
HARDER COALS - Darker, drier, shinier, more energetic
Thermal Steam Coal - used for power generation, cement and
other industrial uses. Thermal steam coal demand is expected to
grow at at 1.5 percent a year until 2030.
Metallurgical Coking Coal - used to make iron and steel.
Demand expected to grow at 0.9 percent a year until 2030.
ANTHRACITE - Relatively clean burning and lightweight for
its energy content but expensive. Most often used in domestic
coal fires and businesses needing smokeless fuel.
Source: World Coal Institute.