Geoscience Reference
In-Depth Information
D I S C O V E R . . .
FOssIL FUELs
From a scientific perspective, geology is a fascinating dis-
cipline because it provides important insights into the evo-
lution of Earth. It also has many practical applications that
are important to our industrial way of life. An excellent ex-
ample of geology's relevance is our dependency on organic
sedimentary rocks. These rocks are particularly important to
humans because they are the source of fossil fuels—coal,
natural gas, and petroleum—which are the overwhelming
source of power for industrial activities.
If you use electrical devices of any kind, the “juice” used
to power them was most likely derived from burning coal at
your local power plant. The amount of coal consumed to
power the electrical grid is staggering. For example, a typi-
cal 500 MW power plant requires over 3000 tons of coal per
day to sustain operations. Another way to look at is that if
you were to burn one 100 watt light bulb 24 hours a day for
a year, the nearby power plant would require over 300 kg
(~700 lbs) of coal to power that light! Natural gas is another
important fuel source because it is also used to generate
electrical power. In fact, most power plants in the United
States built since the 1990s are powered by natural gas.
You are probably most familiar with this fuel source because
you use it to cook and heat your home. On the other hand,
did you know that the typical American family probably con-
sumes over 2800 m
3
(100,000 ft
3
) of natural gas per year to
keep their home comfortable?
World Energy Consumption by Type
Renewables
Nuclear
Oil
Coal
Natural Gas
A typical coal-fueled power plant. Look at the amount of coal re-
quired to keep this plant humming.
How many times have you purchased refined petroleum in your
life so far?
due to the thick accumulation of overlying sediments or be-
cause they are deeply buried by crustal processes. Another way
that alteration occurs is through
contact metamorphism
, which
occurs when rocks are heated dramatically when they come into
contact with invading magma in batholiths, dikes, or sills such
as those illustrated in Figure 12.6. Whatever kind of alteration
