Fossil fuels are formed by geological processes acting on the remains of living organisms from millions of years ago. As organic material from deceased plants and animals becomes buried deeper and deeper underground, that material is exposed to increasing amounts of pressure and heat. This heat and pressure transforms underground plant and animal material into coal, natural gas or oil. The form that the ancient remains take depends on the type of organic matter involved, the amount of time its been buried and the degree pressure and temperature. For example, plankton and algae can naturally transition from kerogen to petroleum if given enough time.

In the 21st century, fossil fuels are burned to meet most human energy needs. They also serve as the base for common plastic products, such as shopping bags, car parts, containers, electronics, and clothing. Our reliance on fossil fuels is increasing the net amount of heat energy in the planet’s atmosphere, causing global average temperatures to rise. The resultant greenhouse gases from burning these fuels also contribute to ocean acidification, air pollution, and water pollution.

Fossil Fuels Definition

Fossil fuels are organic substances that are removed from the Earth’s crust and used for energy. The remnants of decomposing organic material naturally create carbon- and hydrogen-plentiful compounds (also known as hydrocarbons) as they become buried, compressed and heated over millions of years. Hydrocarbon deposits are then extracted from underground sources by way of mining, hydraulic fracturing, and drilling. Burning hydrocarbons produces heat energy which powers engines, generates electricity and supports industrial processes.

The energy in fossil fuels comes from the hydrocarbon within them. Those hydrocarbons come from photosynthetic organisms (life forms that use sunlight to synthesize nutrients like oxygen and sugars from water and carbon dioxide). Hydrocarbons are molecules consisting of bonded hydrogen and carbon atoms. The stored energy in fossilized hydrocarbon compounds releases energy in the form of heat when burned. Hydrocarbon combustion, the chemical reaction in which hydrocarbons interact with oxygen, also produces water and carbon dioxide.

Fossil Fuels Used For

Fossil fuels have a diverse range of uses across sectors in civilization. Oil specifically, has byproducts that are used in pesticides and fertilizers. Natural gas is sometimes used to for refrigerating and cooling equipment, and to heat buildings. Coal, perhaps the most abundant fuel source, is critical for the generation of electricity. Fossil fuels may continue to dominate our energy economy because strategies and technologies for their extraction continue to improve.