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Fossil Fuels

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  • Last Updated : 02 Jun, 2021

The primary source of energy is derived from natural resources obtained from the Earth. What kind of fuel does your vehicle use? These are classified as natural resources since they are entirely hydrocarbon-based, thus the name fossil fuels. Let us learn about the significance of these nonrenewable resources and draw important conclusions regarding fossil fuels and their management.

What is Energy? 

The capacity to do work or the overall power generated from our natural resources is referred to as energy. Energy comes in a variety of ways and can be transformed from one to another. Energy in usable form is dissipated as a less usable form into the environment.

Conventional Sources of Energy:

The traditional sources of energy are generally termed as conventional sources of energy, which are being used for a very long time. The primary conventional sources of energy are wood & fossil fuels like coal, petroleum, etc.  Also, the fuels derived from coal such as charcoal, coke are also called conventional sources of energy. 

Sources of Energy

A source of energy is one that can consistently provide enough usable energy for a long period of time. Energy comes primarily from natural sources such as the sun, oceans, fossil fuels, wind, and so on, and is transformed into electrical energy that we use for our everyday needs and benefits.

A good source of energy should be:

  • It is both safe and easy to use. Nuclear technology, for example, can only be used by highly qualified engineers with the assistance of nuclear power plants. It is not suitable for our domestic use.
  • It is easy to transport Gas, petrol, diesel, LPG, and other fuels, for example, must be transported from the point of origin to the point of consumption.
  • It is simple to store. Huge storage tanks, for example, are needed to store petrol, diesel, LPG, etc.

Classification of Sources of Energy

  1. Renewable Sources of Energy: Renewable energy sources are inexhaustible, meaning they can be replaced and used to produce energy again and again after we use them. In nature, there is an infinite number of these, and they evolve in a relatively short period of time. e.g. Solar Energy, Wind Energy, etc. 
  2. Non-Renewable Source of Energy: Non-renewable energy sources are those that are exhaustible and cannot be replaced once used. These resources have accumulated over millions of years in nature. e.g. Fossil fuels, etc.

Let’s discuss the fossil fuels in detail as:

Fossil Fuels

A natural fuel formed by dead animals plants deep under the earth in the presence of high pressure, and the high temperature gets converted into fossil fuels over a long time. The plants and animals that are died millions of years ago are buried in the earth and get mixed with rocks, sand, mud over a long period of time in the absence of oxygen. Due to the unavailability of oxygen, the effects of high pressure, high temperature, and bacteria convert the buried remains of dead plants and animals into fossil fuels.

Fossil fuels are buried combustible geologic deposits of organic things, such as dead plants and animals, that have been accumulated underneath thousands of feet of sediment. Due to the intense heat and pressure within the earth’s crust, these deposits decomposed over time and were changed to natural gas, coal, and petroleum.

Coal, crude oil, natural gas are obtained from the earth’s crust in the form of fossil fuel. Fossil fuels are used for over a very long time in the home for cooking food. Also, fossil fuels are still being used for generating electricity from thermal power plants. 

Formation of Fossil Fuels

Looking back millions of years, the earth’s landmass was dominated by seas and wetlands. Huge trees and various green plants began to develop in these marshes. Furthermore, the ocean’s surface was coated with algae, which were little plants. After these plants and algae died, they fled to the bottom strata of the seas and wetlands.

With the passage of time, this layer of organic materials was covered by clay, sand, and other minerals. Later, as the weight of this layer of clay and sand rose, the moisture or water in the organic stuff was forced out, and ultimately fossil fuels were produced. This time is known as the Carboniferous epoch and is thought to have occurred roughly 300 million years ago.

Fossil fuels are produced by the compression of dead organic matter buried deep beneath the earth for millions of years. An entire organism or its sections are often buried in sand or mud during its development. Then they decompose and disappear, leaving no trace of their presence. In reality, after an organism’s death, the hardest parts of the organism settle down, are covered by sediments, and are exposed to intense pressure and temperature, or the Earth turns them into fossil fuels, a process known as fossilization

Advantages of Fossil Fuels

  • Fossil fuels have the ability to generate a large amount of electricity from a single source.
  • They are fairly easy to locate.
  • They are inexpensive.
  • Oil and gas can be transported quickly and easily using pipelines.
  • Over time, they’ve become safer.
  • Despite being a limited resource, there is plenty of it.

Disadvantages of Fossil Fuels

  • Fossils are non-renewable energy sources that cannot be restocked once used.
  • The combustion of fossil fuels pollutes the atmosphere.
  • The Earth’s fossil fuel reserves are finite and could be depleted too.

Types of Fossil Fuels

Fossil fuels are basically categorized into three main types of fuels, that are:

  1. Coal is mined and used to power 1/3 of the world’s electricity (the largest consumers are China, India, and the US).
  2. Petroleum oil is drawn up through the earth and refined into various oils that we use for fuel (like gasoline, diesel, kerosene, etc.).
  3. Natural gas primarily methane found near oil resources, which prompted the controversial fracking procedure.

Types of Fossil Fuels


Carbon, hydrogen, nitrogen, oxygen, and Sulphur make up this hard, black material. Anthracite, bituminous, and lignite are the three main forms of coal. The hardest variety of coal, anthracite, has a higher carbon content. The oxygen and hydrogen content in lignite is high, but the carbon content is low. Coal is processed in the industrial sector to produce products such as coke, coal tar, and coal gas.

Coal is a black substance with a rock-like feel. It consists of carbon, nitrogen, oxygen, hydrogen, and sulphur. It is important to understand that there are three varieties of coal: anthracite, lignite, and bituminous.

The formation of Coal is explained as:

  • Coalification is the term for the process of coal creation.
  • Millions of years ago, the lush forest in the low-lying wetland was buried by the ground.
  • Soil continued to accumulate on top of them, compressing them.
  • They encountered extreme temperatures and pressure as they moved deeper and deeper into the cave.
  • As a result, the chemicals were gradually transformed into coal.

Some of the main uses of Coal are:

  1. Initially, coal was used to generate steam in railway engines.
  2. It’s used to prepare food.
  3. Thermal power plants use it to generate energy.
  4. It is utilized as a fuel in industries.


Petroleum is an oily, transparent liquid that’s frequently green or black in colour. It smells weird and is made up of petroleum gas, diesel, paraffin wax, petrol, lubricating oil, and other substances. Because of its extensive range of applications in a variety of industries, it is also known as Black Gold.

Petroleum is a naturally occurring liquid found in rock formations. This is a complicated combination of hydrocarbons with varying molecular weights, as well as other organic molecules. Some chemical compounds derived from petroleum are also derived from other fossil fuels.

The formation of Petroleum is explained as:

  • Sea animals and plants died, and their bodies sank to the ocean’s depths.
  • The layers of sand and clay squeezed them.
  • When they come into contact with high temperatures and pressure, they turn into petroleum.
  • In a refinery, a series of operations remove the petroleum from the crude oil. Petroleum refining is the term for this process.

Some of the main uses of Petroleum are: 

  1. In the form of gasoline, it is utilised to power internal combustion engines.
  2. It’s utilised in roofing, road pavements, and as a water repellent, among other things.
  3. It’s used to make detergents, plastics, fibers, and polythene, among other things.

Natural gas

Natural gas is a non-toxic and non-polluting fossil fuel. It’s odorless and colorless, and it’s easy to transport through pipelines. It is compressed and stored under high pressure as compressed natural gas (CNG). It is a fossil fuel that is both less polluting and less expensive. The most important natural gas is methane.

Natural gas is found deep beneath the earth’s crust, either alone or in conjunction with oil above the petroleum reserves. Natural gas is created underneath the soil by the decomposition of organic matter that has been submerged in water. In the absence of oxygen, this breakdown is carried out by anaerobic bacteria.

The formation of natural gas is explained as:

  • Sink in the ocean’s bottom combine with organic debris to generate mud that is rich in organic matter.
  • The mud purifies when it is buried behind further strata, forming an organic shale. This keeps it from being exposed to oxygen. This is done to prevent microorganisms from decomposing the organic materials.
  • As the pressure and temperature rise, the shale transforms into a waxy substance called kerosene.
  • Kerosene is converted to natural gas at temperatures of 90-160 °C.

Some of the main uses of Natural gas are:  

  1. Compressed Natural Gas (CNG) is utilised to generate electricity.
  2. It is used in autos as fuel.
  3. It can be utilised in the kitchen at home.
  4. Chemicals and fertilizers use it as a starting material.

Sample Problems

Problem 1: What are the disadvantages of burning fossil fuels?


The disadvantages of burning fossil fuels are:

  • The combustion of fossil fuels often produces byproducts, which pollute the air.
  • Coal and petroleum combustion emit toxic carbon, nitrogen, and sulfur dioxides, which pollute the environment and contribute to acid rain and the greenhouse effect.
  • The biggest contributor to global warming is gases released by the burning of fossil fuels.

Problem 2: Compare fossil fuels and the sun as direct sources of energy.


Fossil fuels are derived from the remains of dead plants and animals in the earth’s crust. They are similar to coal and petroleum in that they are readily accessible. There are non-renewable energy sources that cannot be replaced.

Solar energy or the sun as direct sources of energy, on the other hand, is plentiful in nature and can be replenished.

Problem 3: What is fossilization?


Fossil fuels are produced by the compression of dead organic matter buried deep beneath the earth for millions of years. An entire organism or its sections are often buried in sand or mud during its development. Then they decompose and disappear, leaving no trace of their presence. 

In reality, after an organism’s death, the hardest parts of the organism settle down, are covered by sediments, and are exposed to intense pressure and temperature, or the Earth turns them into fossil fuels, a process known as fossilization.

Problem 4: Why Fossil Fuels are non-renewable?


While natural processes create fossil fuels on a continuous basis, they are classified as non-renewable resources because they take millions of years to form and known viable reserves are exhausted much faster than new ones are created.

Problem 5: Discuss what is LPG?


Liquefied petroleum gas (LPG) is made up mostly of propane, butane, propylene, butylene, and isobutane. LPG is a highly combustible combination of various hydrocarbon gases that is frequently used as a fuel in domestic cooking. It’s also utilised as a fuel in some cars. Propane and butane are the primary active components of LPG.

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