Fossil Fuels in Plain Language

The first of the 3 fossil fuels we will talk about is Petroleum.

Millions of years ago, even before the dinosaurs wandered the earth, the planet was covered with large trees, leafy plants, swamps and oceans. The algae plants that lived in the oceans contained a microscopic amount of oil. Algae use sunlight to convert carbon dioxide (CO2) into carbohydrates. Algae then store the carbohydrates as energy for growth.

When the ancient algae died, as all living things do, they sank to the bottom of the water and were buried by sand and sediment. The algae stayed buried for millions of years, through possible ice ages and earthquakes. Eventually miles of seawater and dirt covered the dead algae.

Whenever lifeless matter decomposes, heat is released. The heat that the algae released combined with the weight of miles of water and sediment on top of the dead algae created tremendous pressure and squeezed out the carbohydrates and oil from the algae. The oil was then trapped underground for millions of years during which it turned into a black substance, which we now call Petroleum. Petroleum is what we fuel our cars with today.


As the prehistoric forest trees and plant material died and produced heat, they were buried by surface matter that also created tremendous pressure. The weight caused incredible pressure which resulted in the creation of a carbohydrate-filled mixture that resembles dark paste. This substance is called peat. Over millions of years, the peat hardened into coal. Today, coal is burned and used mostly as a fuel to create electricity.

Fossil Fuels in Plain Language


Swamp matter decomposed even deeper down into the Earth than the oil (petroleum). It was so deep that there was no oxygen at all. The chemicals carbon and hydrogen were squeezed out of the lifeless swamp matter. Due to the very high heat and lack of oxygen, a chemical reaction occurred which changed the carbon and hydrogen into what is now called methane, also known as natural gas. Natural gas is a fossil fuel that is used for things like heating our homes and lighting stoves. Before the natural gas can be used as a fuel, it must undergo extensive processing to remove almost all materials other than methane.