Geography Reference
In-Depth Information
geology all suggest that vast quantities are waiting to be tapped in various parts of the world. The
potential reserves of Alaska alone, for example, are thought to be double that of the rest of the United
States.
Grades of coal
Coal exists in several varieties, or
grades,
the difference being determined by the degree
of carbon content.
Anthracite
, the highest grade, is almost pure carbon and therefore
burns very hot and gives off little smoke or soot.
Bituminous,
the next highest grade, has
somewhat less carbon content and a higher percentage of waste materials. As a result,
it burns less hot (but still hot enough for most industrial purposes) but dirtier, generating
more pollution.
Lignite
and
peat
are progressively lower grades, burning even less hotly,
while generating more air pollution.
In nature, sadly, the most pure form of any substance tends to occur in the smallest
quantity. Thus, all global coal reserves considered, anthracite accounts for the smallest
portion. Being so pure and burning so hot, it is also the most sought after variety. The
end result is that that particular kind of coal is mostly depleted. Thus, the vast majority of
the world's remaining supply consists of “dirty varieties” whose consumption poses chal-
lenges to environmental quality.
A global map of natural gas reserves, therefore, must be presented with the warning that significant
changes will be seen in a matter of decades (see Figure 16-4). For now, Russia is home to about 34
percent of all global natural gas reserves. Iran possesses another 15 percent. The United States pos-
sesses only about 3 percent of global reserves, but accounts for about 23 percent of annual worldwide
production. Thus, the U.S. consumes its reserves at a rapid rate. As noted, however, the prospects for
new discoveries are good.
