What are Fossil Fuels: Definition, Types, Extraction, Uses and Environmental Impact

Coal, natural gas and oil are the fossil fuels that are limited resources that run modern civilization. They supply about 80% of the world's total energy and are used in transportation, power generation, cooking and for many other things. These limited resources are found in earth's crust and contain carbon and hydrogen. Let’s understand what fossil fuels are, how they formed, how they are used and what consequences their use carries for our environment.

Table of Contents 

• What are Fossil Fuels
• Types of Fossil Fuels
• Fossil Fuels Comparison Table
• How are Fossil Fuels Formed
• Extraction of Fossil Fuels
• Environmental Impact of Extraction
• Uses of Fossil Fuels
• Frequently Asked Questions about Fossil Fuels

What are Fossil Fuels 

Fossil fuels are non-renewable natural resources such as coal, oil and natural gas, that formed over millions of years from the remains of ancient plants and microorganisms. They are the compounds formed from only two elements, carbon and hydrogen. Fossil fuels are used to produce energy. In the home they are burned to produce heat, in large power stations they are used to produce electricity and they are also used to power engines.

Types of Fossil Fuels 

The three primary types of fossil fuels are: coal, oil and natural gas.

• Coal: Coal is a material usually found in sedimentary rock deposits where rock and dead plant and animal matter are piled up in layers. It is a black and brown fossil fuel found in rock layers formed from ancient vegetation. It is the most carbon-intensive of all fossil fuels, meaning it releases the most carbon dioxide per unit of energy produced.

• Natural Gas: Natural gas is usually found in pockets above oil deposits. It can also be found in sedimentary rock layers that don't contain oil. Natural gas is a fossil fuel in gaseous form that is composed of methane and other small hydrocarbons. It is known to be the cleanest of the three fossil fuels as it generates less carbon dioxide per unit of energy compared to coal or oil.

• Oil: It is originally found as a solid material between layers of sedimentary rock, like shale. This material is heated in order to produce the thick oil that can be used to make gasoline. Oil or petroleum, is a liquid fossil fuel that consists of a variety of hydrocarbons. It is found one to two miles below the Earth's surface, whether on land or under the ocean and is extracted by drilling.
  
  

Fossil Fuels Comparison Table

Feature	Coal	Oil (Petroleum)	Natural Gas
Physical state	Solid	Liquid	Gas
Formed from	Ancient land plants	Marine plankton and organisms	Marine plankton and organisms
Main component	Carbon	Hydrocarbons	Methane (CH₄)
Extracted by	Mining	Drilling	Drilling and fracking
Primary use	Electricity generation	Transport, plastics	Heating, cooking, electricity
CO₂ emissions	Highest	Medium	Lowest of the three
Formation period	359 to 299 million years ago	Millions of years	Millions of years

How are Fossil Fuels Formed 

Fossil fuels such as coal, petroleum and natural gas are not simply buried rocks or liquids. They are the chemically transformed remains of ancient plants and marine organisms, locked away through slow geological processes that took place over millions of years. As these organic matter decomposed under intense heat and pressure deep within the earth, they transformed into carbon-rich, combustible energy sources like coal, oil and natural gas.

Extraction of Fossil Fuels

Getting fossil fuels out of the ground requires fundamentally different techniques depending on the fuel type. For example, solid coal is extracted by mining.

• Extraction of coal is done through two primary methods - underground mining and strip mining. In underground mining tunnels are dug into the earth while in strip mining layers of earth above coal seams are removed. It is also known as surface mining.
• Accessing natural gas involves drilling a well. The natural gas is found deep in the earth in shale beds and other sedimentary rock formations and is extracted through a process called hydraulic fracturing or fracking.

Environmental Impact of Extraction 

The environmental costs of fossil fuel extraction are significant and span the entire production chain. Coal mining results in land damage and releases pollutants including sulfur dioxide and mercury into surrounding ecosystems. Oil extraction carries the constant risk of spills that contaminate both freshwater and marine environments. Fracking fluids have been found to leach into drinking water aquifers.

Uses of Fossil Fuels

Fossil fuels touch nearly every aspect of modern life. This is the energy that is used to generate heat and provide electricity to homes and businesses. It is also used to run cars and factories. Fossil fuels, such as coal, oil and natural gas, are burned with air or oxygen to generate heat, which can be used directly or to produce steam that drives generators for electricity. In large power stations they are burned in the presence of oxygen. The bonds between the hydrogen and carbon atoms store energy. By burning the compounds in the presence of oxygen, the bonds are broken and the stored energy is converted into heat energy, releasing carbon dioxide in the process.