Fossil Fuel Energy

Fossil fuel energy is a term used to describe a group of energy sources that were formed when ancient plants and organisms were subject to intense heat and pressure over millions of years.


What is Fossil Fuel Energy?

Fossil fuel is a term used to describe a group of energy sources that were formed from ancient plants and organisms during the Carboniferous Period, approximately 286 – 360 million years ago1, prior to the age of dinosaurs.

At that time, the land was covered with swamps filled with microorganisms, marine organisms, trees, ferns and other large leafy plants. As the organisms and plants died, they sank to the bottom of the swamps and oceans and formed layers of a spongy material called peat. Over millions of years, the peat was covered by sand, clay, and other minerals, which converted the peat into sedimentary rock. Over time, different types of fossil fuels formed, depending on the combination of organic matter present, how long it was buried, and what temperature and pressure conditions existed when they were decomposing. 2

There are three major types of fossil fuels:3

  • Coal is formed from ferns, plants and trees which hardened due to pressure and heat
  • Oil is formed from smaller organisms, like zooplankton and algae. Intense amounts of pressure caused this complex organic matter to decompose into oil
  • Natural Gas undergoes the same process as oil; however the process is longer and subject to higher amounts of heat and pressure, causing further decomposition.



Fossil fuels are the world’s dominant energy source, making up 82% of the global energy supply.4 Non-OECD countries hold the majority of proven reserves for all fossil fuels.5 These energy sources have powered, and continue to power, the industrialization of nations. They have a variety of applications, from electricity production to transport fuel.  Moreover, fossil fuels are necessary for the production of a variety of common products, such as paints, detergents, polymers (including plastics), cosmetics and some medicines.

Some fossil fuels, such as coal, are an abundant and cheap form of energy. Others, like oil, have a variable cost depending on geographic location. For this reason, geopolitical issues arise due to the geographic allocation of these highly valuable resources.

Fossil fuels are non-renewable resources, as they have taken millions of years to form. Once these resources are used, they will not be replenished. Moreover, fossil fuels are the largest source of carbon dioxide, a greenhouse gas which contributes to climate change, and their production causes both environmental and human health impacts. These concerns are triggering the world to look at alternate sources of energy that are both less harmful and renewable. Additionally, the gradual depletion of conventional fossil fuel reserves has led companies to develop more challenging reserves.  These unconventional resources usually have higher production costs and a greater risk of environmental impact. 


  1. California Energy Commission. (n.d.) Where fossil fuels come from. Retrieved 17th January, 2015.
  2. United States Department of Energy (n.d.). Fossil.
  3. United States Oil Properties (n.d.) Oil and natural gas: What are they and what makes them different?” Accessed June, 2012. 
  4. International Energy Agency. (2014) Key World Statistics.
  5. BP PLC. (2014) BP Statistical Review of World Energy.