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12.4: Fossil Fuel Formation

Difficulty Level: Basic Created by: CK-12
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Where is the energy coming from to power this bumper car?

Bumper cars usually run on electricity. Much of the electricity we use comes from fossil fuels. Coal or other fuels are burned in a power plant. This powers a generator and creates electricity. So the car is probably running on fossil fuels!

Formation of Fossil Fuels

Fossil fuels are made from plants and animals that lived hundreds of millions of years ago. The plants used energy from the Sun to form energy-rich carbon compounds. As the plants and animals died, their remains settled onto the ground and at the bottom of the sea. Layer upon layer of organic material was laid down. Eventually, the layers were buried very deeply. They experienced intense heat and pressure. Over millions of years, the organic material turned into fossil fuels.

Fossil fuels are compounds of carbon and hydrogen, called hydrocarbons (Figure below). An animated view of a hydrocarbon is seen here: http://www.nature.nps.gov/GEOLOGY/usgsnps/oilgas/CH4_3.MPG.

Ball and stick model of methane

Hydrocarbons are made of carbon and hydrogen atoms. This molecule with one carbon and four hydrogen atoms is methane.

Hydrocarbons can be solid, liquid, or gas. The solid form is coal. The liquid form is petroleum, or crude oil. The gaseous form is natural gas.

The solar energy stored in fossil fuels is a rich source of energy. But because they take so long to form, they are non-renewable.


  • hydrocarbon: A chemical compound containing hydrogen and carbon that is used for energy.


  • Hydrocarbons are molecules made of one carbon and four hydrogen atoms.
  • Ancient living organisms died and were buried quickly. Their remains were altered by intense heat and pressure. This formed fossil fuels.
  • Fossil fuels include solid coal, liquid petroleum, and liquid natural gas.


Use this resource to answer the questions that follow.


  1. Why is coal called a fossil fuel?
  2. During what period did coal formation begin?
  3. What is peat?
  4. What helps turn peat into coal?
  5. How long does it take for coal to form?


  1. Why are coal, petroleum, and natural gas called fossil fuels?
  2. How do fossil fuels form?
  3. Where did the energy in a fossil fuel come from originally?

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hydrocarbon Chemical compound containing hydrogen and carbon that is used for energy.

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Jan 04, 2013
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