Chapter 8: Fossil Fuels - Coal, Oil and Natural Gas
Where Fossil Fuels Come From
There are three major forms of fossil fuels: coal, oil and
natural gas. All three were formed many hundreds of millions
of years ago before the time of the dinosaurs -
hence the name fossil fuels. The age they were formed is
called the Carboniferous Period. It was part of the Paleozoic Era.
"Carboniferous" gets its name from carbon, the basic element in coal and
other fossil fuels.
The Carboniferous Period occurred from about 360 to 286
million years ago. At the time, the land was covered with
swamps filled with huge trees, ferns and other large
leafy plants, similar to the picture above. The water and seas were filled with
algae - the green stuff that forms on a stagnant pool of
water. Algae is actually millions of very small plants.
Some deposits of coal can be found during the time of the
dinosaurs. For example, thin carbon layers can be found during
the late Cretaceous Period (65 million years ago) - the time of Tyrannosaurus Rex.
But the main deposits of fossil fuels are from the Carboniferous Period.
For more about the various geologic eras, go to
www.ucmp.berkeley.edu/help/timeform.html
As the trees and plants died, they sank to the bottom of the
swamps of oceans. They formed layers of a spongy material
called peat.
Over many hundreds of years, the peat was covered by sand
and clay and other minerals, which turned into a type of
rock called sedimentary.
More and more rock piled on top of more rock, and it weighed
more and more. It began to press down
on the peat. The peat was squeezed and squeezed until the
water came out of it and it eventually, over millions of
years, it turned into coal, oil or petroleum, and natural gas.
Coal
Coal is a hard, black colored rock-like substance. It is made up of
carbon, hydrogen, oxygen, nitrogen and varying amounts of sulphur.
There are three main types of coal - anthracite, bituminous
and lignite.
Anthracite coal is the hardest and has more carbon, which gives it a higher
energy content. Lignite is the softest and is low in carbon but
high in hydrogen and oxygen content.� Bituminous is in between.
Today, the precursor to coal - peat - is still found in many countries
and is also used as an energy source.
The earliest known use of coal was in China.
Coal from the Fu-shun mine in northeastern China may have
been used to smelt copper as early as 3,000 years ago.
The Chinese thought coal was a stone that could burn.
Coal is found in many of the lower 48 states of U.S. and throughout the rest of the world.
Coal is mined out of the ground using various methods. Some coal
mines are dug by sinking vertical or horizontal shafts deep under ground, and coal miners
travel by elevators or trains deep under ground to dig the coal. Other coal is mined in strip mines where
huge steam shovels strip away the top layers above the coal. The
layers are then restored after the coal is taken away.
The coal is then shipped by train and boats and even in pipelines.
In pipelines, the coal is ground up and mixed with water to make
what's called a slurry. This is then pumped many miles through
pipelines. At the other end, the coal is used to fuel power plants and
other factories.
Oil or Petroleum
Oil is another fossil fuel. It was also formed
more than 300 million years ago. Some scientists
say that tiny diatoms are the source of
oil. Diatoms are sea creatures the size of a pin
head. They do one thing just like plants; they can convert
sunlight directly into stored energy.
In the graphic on the left, as the diatoms died
they fell to the sea floor (1). Here they were
buried under sediment and other rock (2). The
rock squeezed the diatoms and the energy in their
bodies could not escape. The carbon eventually
turned into oil under great pressure and heat. As the earth
changed and moved and folded, pockets where oil and
natural gas can be found were formed (3).
Oil has been used for more than
5,000-6,000 years. The ancient Sumerians, Assyrians and
Babylonians used crude oil and asphalt ("pitch") collected
from large seeps at Tuttul (modern-day Hit) on the Euphrates
River. A seep is a place on the ground where the oil
leaks up from below ground.
The ancient Egyptians, used liquid oil as a medicine for
wounds, and oil has been used in lamps to provide light.
The Dead Sea, near the modern Country of Israel, used to be
called Lake Asphaltites. The word asphalt was derived is
from that term because of the lumps of gooey petroleum that
were washed up on the lake shores from underwater seeps.
In North America, Native Americans used blankets to
skim oil off the surface of streams and lakes.
They used oil as medicine and to make canoes water-proof.
During the Revolutionary War, Native Americans taught George Washington's troops how to
treat frostbite with oil.
As our country grew,
the demand for oil continued to increase as a fuel
for lamps. Petroleum oil began to replace whale oil in
lamps because the price for whale oil was very high.
During this time, most petroleum oil came from distilling
coal into a liquid or by skimming it off of lakes -
just as the Native Americans did.
Then on August 27, 1859, Edwin L. Drake
(the man standing on the right in the black and white picture to the right), struck liquid oil at his
well near Titusville, Pennsylvania. He found oil under ground
and a way that could pump it to the surface. The well pumped the
oil into barrels made out of wood. This method of drilling
for oil is still being used today all over the world in
areas where oil can be found below the surface.
Oil and natural gas are found under ground between folds of rock and
in areas of rock that are porous and contain the oils within the rock
itself. The folds
of rock were formed as the earth shifts and moves. It's
similar to how a small, throw carpet will bunch up in places on
the floor.
To find oil and natural gas, companies drill through the earth to the deposits deep
below the surface. The oil and natural gas are then pumped from below the
ground by oil rigs (like in the picture). They then usually travel through
pipelines or by ship.
Oil is found in 18 of the 58 counties in California. Kern
County, the County where Bakersfield is found, is one of the
largest oil production places in the country. But we only
get one-half of our oil from California wells. The rest
comes from Alaska, and an increasing amount comes from other
countries. In the entire U.S., more than 50 percent of all
the oil we use comes from outside the country...most of it
from the Middle East.
Oil is brought to California by large tanker ships. The
petroleum or crude oil must be changed or refined into other
products before it can be used.
Refineries
Oil is stored in large tanks until it is sent to various places to be used.
At oil refineries, crude oil is split into various types of products by heating the thick
black oil.
Oil is made into many different products - fertilizers for farms, the clothes you
wear, the toothbrush you use, the plastic bottle that holds your milk, the plastic pen
that you write with. They all came from oil.
There are thousands of other products that come from oil. Almost all plastic comes
originally from oil. Can you think of some other things made from oil?
The products include gasoline, diesel fuel, aviation or jet fuel, home heating oil, oil for
ships and oil to burn in power plants to make electricity. Here's what a barrel of crude oil can make.
In California, 74 percent of our oil is used for transportation -- cars, planes,
trucks, buses and motorcycles. We'll learn more about transportation energy in
Chapter 18.
Source: American Petroleum Institute (www.api.org). Figures
are based on 1995 average yields for U.S. refineries. One
barrel contains 42 gallons of crude oil. The total volume of
products made is 44.2 GALLONS - 2.2 gallons greater than
the original 42 gallons of crude oil. This is called
"processing gain," where other chemicals are added to the
refining process to create the products.
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Natural Gas
Sometime between 6,000 to 2,000 years BCE (Before the Common
Era), the first discoveries of natural gas seeps were made
in Iran. Many early writers described the natural petroleum
seeps in the Middle East, especially in the Baku region of
what is now Azerbaijan. The gas seeps, probably first
ignited by lightning, provided the fuel for the "eternal
fires" of the fire-worshiping religion of the ancient
Persians.
Natural gas is lighter than air. Natural gas is mostly made up of a gas called
methane. Methane is a simple chemical compound that is made up of carbon and
hydrogen atoms. It's chemical formula is CH4 - one atom of carbon along with
four atoms hydrogen. This gas is highly flammable.
Natural gas is usually found near petroleum underground. It is pumped
from below ground and travels in pipelines to storage areas. The
next chapter looks at that pipeline system.
Natural gas usually has no odor and you can't see it. Before
it is sent to the pipelines and storage tanks, it is mixed
with a chemical that gives a strong odor. The odor smells
almost like rotten eggs. The odor makes it easy to smell if
there is a leak.
Energy Safety Note! If you smell that rotten egg smell in your
house, tell your folks and get out of the house quickly.
Don't turn on any lights or other electrical devices. A
spark from a light switch can ignite the gas very easily.
Go to a neighbor's house and call 9-1-1 for emergency
help.
Saving Fossil Fuels
Fossil fuels take millions of years to make. We are using up the fuels that were
made more than 300 million years ago before the time of the dinosaurs. Once they are
gone they are gone.
So, it's best to not waste fossil fuels. They are not renewable; they can't really be
made again.
We can save fossil fuels by conserving energy.
Go To Chapter 9: Natural Gas Distribution System
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