Common examples of fossil fuels include natural gas, oil, peat and coal. These fuels are organic biomass extracted from the remains of primitive organisms that roamed the planet millions of years ago.
Sources of energy are classified into two types: renewable and non-renewable. Renewable energy resources accumulate at an equal or faster rate than they are consumed, such as solar and hydroelectric power. Non-renewable energy resources are consumed at a much quicker rate than they are able to accumulate, such as fossil fuels. The rapid depletion of these bio-fuels continues through time.
Fossil fuels consist of hydrocarbons, which contain long chains of carbon and hydrogen atoms. When fossil fuels undergo combustion, the heat causes the breakdown of the chemical bonds that hold the hydrogen and carbon atoms together. The chemical reactions involved in the burning process release energy that is used by people in their daily lives.