Page 156 - Synthetic Fuels Handbook

142 CHAPTER FIVE

in coal (dated to about 200 A.D.) has been found at the inland port of Heronbridge, near
Chester, and in the Fenlands of East Anglia, where coal from the Midlands was transported
for use in drying grain (Salway, 2001). Coal cinders have been found in the hearths of villas
and military forts, particularly in Northumberland, dated to around 400 A.D. In the west
of England contemporary writers described the wonder of a permanent brazier of coal on
the altar of Minerva at Aquae Sulis (modern day Bath) although in fact easily-accessible
surface coal from what is now the Somerset coalfield was in common use in quite lowly
dwellings locally (Forbes, 1966).
However, there is no evidence that coal was of significant importance in Britain before
1000 A.D. Mineral coal came to be referred to as sea coal because it came to many places
in eastern England, including London, by sea or because it was found on beaches (espe-
cially in northeast England) having fallen from exposed coal seams above or washed out
of underwater coal seam outcrops. By the thirteenth century, underground mining from
shafts or adits was developed (Britannica, 2004). It was, however, the development of the
industrial revolution that led to the large-scale use of coal, as the steam engine took over
from the water wheel.
The earliest use of coal in the Americas was by the Aztecs who used coal not only for
heat but as ornaments as well. Coal deposits were discovered by colonists in eastern North
America in the eighteenth century.
In the modern world, coal is primarily used as a solid fuel to produce electricity (approx-
imately 40 percent of the world electricity production uses coal) and heat through combus-
tion (Fig. 5.9).

Types of coal
Carbon/energy content of coal High
High Moisture content of coal

Low rank coals Hard coal
47% 53%
% of world reserves Lignite Subbituminous steam coal coking coal Anthracite
Bituminous
30%
52%
1%
17%
Thermal Metallurgical

Power generation
Manufacture
Uses Largely power Power generation cement manufacture of iron & steel Domestic/
industrial
generation cement manufacture
industrial uses industrial uses including
smokeless fuel
FIGURE 5.9 Uses of coal.
However, coal through the gasification process and the production of synthesis gas
opens the way to a very wide range of products that include liquid fuels (Fig. 5.10).
When coal is used for electricity generation, it is usually pulverized and then burned in a
furnace with a boiler. The furnace heat converts boiler water to steam, which is then used to