Most of the compounds that come out of the refining process are fuels. The rest make up
waxes, plastics, fertilizers, and other products. The fuels that come from crude oil, including
gasoline, diesel, and heating oil, are rich sources of energy that can be easily transported.
Because of this, fuels from oil provide about 90% of the energy used for transportation
around the world.
We get gasoline from refining oil. Like oil, gasoline is most commonly used for transportation
because it is a concentrated form of energy that is easily carried. Let’s consider how gasoline
powers a car. Like other fuels you have learned about, gasoline burns and releases most of
its energy as heat. When it burns, the gasoline turns into carbon dioxide gas and water
vapor. The heat makes these gases expand, like the heated air that fills a hot-air balloon.
The expanding gases create enough force to move pistons inside an engine, and the engine
makes enough power to move the car.
When a resource like gasoline is concentrated in energy; it contains a large amount of energy
for its weight. This is important because the more an object weighs, the more energy it
takes to move that object. If we could only get a little energy from a certain amount of
gasoline, a car would have to carry more of it to be able to travel very far. But carrying
more gasoline would make the car heavier, so moving the car would take even more energy.
So a resource with highly concentrated energy is a practical fuel to power cars and other
forms of transportation.
Unfortunately, using gasoline to power automobiles also affects the environment. The ex-
haust fumes from burning gasoline include gases that cause many different types of pollution,
including smog and ground-level ozone. These forms of pollution cause air-quality problems
for cities where large numbers of people drive every day. Burning gasoline also produces
carbon dioxide, which is a cause of global warming.
Natural Gas
Naturalgasisafuelthatisamixtureofmethaneandseveralotherchemicalcompounds. Itis
oftenfoundalongwithcoaloroilinundergrounddeposits. Theconditionsthatcreatenatural
gas are similar to those that create oil. In both cases, small organisms called plankton and
algae die and settle to the bottom of the sea. In both cases, the remains of these organisms
decay without oxygen being present. The difference is that natural gas forms at higher
temperatures than oil does.
The largest natural gas reserves in the United States is found are in the Rocky Mountain
states, Texas and the Gulf of Mexico region. California also has natural gas, mostly in
the northern Sacramento Valley and the Sacramento Delta. In that region, a sediment filled
trough formed aside an ancient convergent margin. Organic material buried in the sediments
hardened to become a shale formation that is the source of the gas.
Because it is a mixture of different chemicals, natural gas must be processed before it can be