Coal and Petroleum

Fossil Fuels

Fossil fuels are non-renewable energy sources(which are present in a limited quantity). They are exhaustible, and will not last for a long period of time if not used judiciously. Although fossil fuels are continually formed by natural processes, but they are classified as non-renewable resources because they take millions of years to form. Fossil fuels were formed by the remains of terrestrial and marine flora and fauna that decayed millions of years ago and got buried in layers under huge amounts of pressure and heat. These sources are responsible for pollution to the environment because carbon is the main element present in fossil fuels such as coal and petroleum. 


Coal is a black coloured rock-like fuel in which the content of carbon can vary between 70-90%. It is formed by the decomposition of vegetation under heat and pressure. The process of formation of coal is called carbonisation and the time period during which this process takes place is called the carboniferous age. Coal is one of the most important fossil fuels used to generate electricity. Coal is taken out from the earth by the process of underground mining or surface mining. We burn coal to get energy. Coal is mostly used as a domestic fuel to make food in rural areas. When coal is burnt, it releases harmful smoke. Coal is formed when the buried vegetation is subjected to extremities of heat and pressure. The formation of coal takes place in four stages which are peat, lignite, bituminous, and anthracite. Coal mainly contains carbon, hydrogen, and oxygen. 

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Types of Coal

  1. Lignite

Lignite is the lowest rank of coal in terms of carbon content(60-70%). It is the youngest type of coal deposit. It is soft and ranges in color from black to shades of brown. As a result, lignite coal is sometimes called brown coal. Lignite is not used on a large scale because other types of coal are superior to it in terms of handling and storage stability. Lignite is used to generate electricity, synthetic natural gas, and to create fertilizer products like anhydrous ammonia and ammonium sulphate.

  1. Sub-bituminous  

When lignite is subjected to continued high temperature and pressure for millions of years, the oxygen and hydrogen content gets decreased and the carbon content increases up to 75%. This type of coal burns cleaner than the lignite variety, producing less greenhouse gas emissions. Sub-bituminous coal is also used in electricity generation and in industrial processes.

  1. Bituminous

Bituminous coal is blacker and harder than sub-bituminous coal. It contains a tar-like substance called bitumen. Hence, its name is bituminous. It has a carbon content of up to 85%. It accounts for a majority of the coal industry. Bituminous coal is used in energy generation and for heating purposes also. It is also used in the manufacturing of cement and other industrial uses. 

  1. Anthracite

Anthracite is the most superior form of coal or most mature form of coal deposit i.e it contains the highest carbon content (more than 85%). It is harder than bituminous. It is used to provide energy. It burns as a smokeless fuel in furnaces.


Petroleum is a black coloured liquid fossil fuel composed of a variety of hydrocarbons. It is highly viscous. It is a very useful energy source. However, the petroleum extracted from oil wells is not in a directly usable form. It is impure and, therefore called crude oil.

Through a process called fractional distillation, this crude oil is refined where different hydrocarbons separate to form different fractions. Petrol, kerosene, paraffin, diesel are some of its fractions. Petrol is used as fuel in vehicles. The fractions obtained by the refining of crude oil are used not just for transportation but also for the manufacture of a variety of products such as plastics, tires, and synthetic materials such as polyester. It is a dependable and portable source of energy. 

However, petroleum has some advantages as compared to coal. These are as follows:

  1. It is high-density fuel.

  2. Petroleum is easy to extract.

  3. Petroleum can be stored, shipped, and piped over long distances.

  4. Petroleum can be used in a wide variety of ways.

  5. Petroleum provides a stable energy resource.

However, the combustion of both coal and petroleum is detrimental to the environment.

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Conservation of Coal and Petroleum

As we already know, coal and petroleum are exhaustible sources of energy. If they are not used judiciously, they will not last for more than a few decades. Since they are widely used as sources of energy throughout the world, it is of utmost importance to think about their conservation. Conservation is the process of using a resource in a more careful way so that it can be made to last for a longer period of time. We can conserve coal and petroleum by switching to alternative or renewable sources of energy, such as hydel power, wind energy, geothermal energy, tidal energy, etc. Not only these alternatives will provide us more environmentally friendly options for sustainable development, but they will also help in delaying the energy crisis that the world is about to face very shortly.

FAQ (Frequently Asked Questions)

1. What are the problems caused by using fossil fuels?

Fossil fuels are used as a major energy source around the world today, but their overconsumption can lead to environmental issues such as air pollution, global warming, greenhouse gases emission. These greenhouse gases trap the incoming solar radiation and gradually increase the surface temperature of the earth. This can lead to the flooding of glaciers and submerging of coastal areas. Fossil fuels release carbon dioxide, sulphur dioxide, carbon monoxide, etc. which leads to serious health issues.

2. What is Peat?

When plant material does not fully decay in acidic and anaerobic conditions, peat is formed. Peat becomes coal over a period of time. The formation of peat is the first step in the process of carbonization. It has low carbon content (less than 60%). It is used for domestic heating in some places around the world.