Harmful Products Due to Burning of Fuels: Effects & More - Embibe
  • Written By Shalini Kaveripakam
  • Last Modified 20-07-2022
  • Written By Shalini Kaveripakam
  • Last Modified 20-07-2022

Harmful Products Due to Burning of Fuels: Types, Calorific Value

You have landed on the right page to learn about Harmful Products Due to Burning of Fuels. Fuels are chemicals that can be used as energy sources. Fossil fuels are buried organic materials that can be transformed into crude oil, coal, natural gas, or any heavy oil by applying pressure and heat to the earth’s crust over hundreds of years.

In this article, we will discuss in detail about the burning of fuels leads to harmful products. Continue reading to know more.

What is a Fuel?

Substances that provide energy on burning in the air are called fuels.

Combustible substances like wood, coal, petroleum, kerosene, paraffin wax and natural gas are fuels. They release energy in the form of heat on burning. However, all combustible substances are not fuels. You know paper and cloth are combustible substances but do you burn paper or cloth to make food? Certainly not, for our heat energy requirements to cook food we have to select a fuel which gives regular and sufficient energy on burning.

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 A fuel need not burn itself. It may just support burning. All substances that burn cannot be used to obtain energy, but fuels are used to obtain energy utilised for various purposes like cooking food, driving a car, or running a machine.

Types of Fuels

Fuels can be solid, liquid, or gaseous and are used for a variety of purposes. Solid fuels, liquid fuels, and gaseous fuels are the three forms of fuels.

  1. Some examples of solid fuels are wood, charcoal, coal, coke, agricultural waste, cow dung cakes, etc.
  2. Examples of liquid fuels are petrol, diesel, kerosene and alcohol.
  3. Examples of gaseous fuels are petroleum gas, biogas, natural gas and coal gas.

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At home, in industry, and in transportation, we use various fuels for various purposes. Wood, LPG, charcoal, coal, and kerosene are some of the fuels used in homes. Coal and natural gas are two of the most commonly used fuels in industry. Diesel, petrol, and compressed natural gas (CNG) are the fuels used to power automobiles and vehicles.

Calorific Values of Different Fuels

Calorific value is the amount of heat energy released by the complete combustion of \(1\,{\rm{kg}}\) of fuel. When they burn, the heat generated by fuels is measured in joule or calories \(\left( {1\,{\rm{calorie}} = 4.18\,{\rm{joule}}} \right).\) The calorific value is expressed in \({\rm{kilojoule/kg}}\).

A fuel with more calorific value releases more energy than a fuel with a lower calorific value. The fuel with a higher calorific value is, therefore, more efficient. The table given below is some of the fuels with their calorific values.

FuelCalorific value \(\left( {{\rm{kj}}/{\rm{kg}}} \right)\)
Wood\(17,000 – 22,000\)
Coal\(25,000 – 33,000\)
Biogas\(35,000 – 40,000\)

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Burning of Fuels Leads to Harmful Products

  1. The burning of coal and oil causes the release of atmospheric pollutants such a carbon dioxide, sulphur dioxide, carbon monoxide and nitrogen oxides. These gases easily condense into smog, which pollutes the air. The principal greenhouse gas that contributes to global warming is carbon dioxide. The impact of oil drilling is another environmental issue related to the use of oil. The majority of oil wells are located beneath the sea. Accidents involving oil spills pose a serious hazard to marine organisms and birds.
  2. Carbon-containing fuels like coal and wood release unburnt carbon particles, which form soot and are responsible for causing respiratory diseases like asthma. During incomplete combustion, the unburnt carbon causes wastage of the fuel and pollutes the atmosphere by producing highly poisonous carbon monoxide gas. Carbon monoxide causes respiratory problems and may even prove fatal.
  3. The sulphur contained in coal forms sulphur dioxide when it burns. Harmful nitrogen oxides, heavy metals, and carbon dioxide are also released into the air during coal burning. The harmful oxides dissolve in rainwater to form acids like nitric and sulfuric acid, which fall to the ground as acid rain. This is harmful because it-
    1. Damages green leaves of plants and trees
    2. reach the sources of surface water and underground water, deteriorate the quality of water and
    3. causes damage to monuments.
  4. Coal mining results in the degradation of vast areas of land. Mining this fossil fuel is also challenging, and mineworkers’ lives may be put in danger. Coal mining is regarded as one of the most hazardous occupations in the world.
  5. Incomplete combustion of fuels (due to a lack of oxygen) produces carbon monoxide, a highly toxic gas. Carbon monoxide poisoning can be harmful if inhaled in excess. We should never sleep in a room with a coal fire burning inside and locked doors and windows. This is because a lot of carbon monoxide gas is produced when coal burns in an insufficient supply of air in the room (due to closed-door and Windows). The people sleeping in this room could all die if they inhale toxic carbon monoxide gas.

CNG Burning Harmful Effects

CNG (Compressed Natural Gas) is being used to replace petrol and diesel as fuel in automobiles (vehicles). This is because CNG produces a small number of hazardous chemicals as it burns. CNG is a clean fuel because it does not produce smoke when burned. The usage of CNG as a fuel in automobiles has reduced air pollution in our cities since it produces far less hazardous chemicals and smoke when burned.

Harmful Effects of Burning Wood

Wood has been used as a domestic and industrial fuel for centuries. People still use wood as a fuel in many rural parts of our country due to its low cost and easy availability. The burning of wood as a fuel has, however, many disadvantages. Some of the disadvantages of burning wood as fuel are as follows:

  • (i) Wood burning produces a lot of smoke, which is extremely toxic to humans. Respiratory illnesses are caused by smoking.
  • (ii) Trees supply us with a variety of beneficial substances. All of the beneficial substances derived from trees are lost when trees are cut down to obtain timber for use as fuel.
  • (iii) The cutting down of trees to obtain fuelwood leads to deforestation, which is very harmful to the environment.

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Coal and other fuels, such as LPG, have mostly replaced wood. LPG is a better domestic fuel than wood due to the following reasons:

  • (i) Because LPG has a much higher calorific value than wood, it provides significantly more heat when burned.
  • (ii) LPG burns without producing any smoke, but wood-burning produces a lot of smoke.
  • (iii) LPG burns entirely without leaving any solid residue but wood leaves behind a lot of ash on burning.


The ecosystem, air quality, climatic conditions, and human health can all be affected by burning fossil fuels. According to every recent scientific study, the burning of fossil fuels for energy, such as coal, oil, and gas, is the primary contributor to the fast-rising level of carbon dioxide that is driving climate change. The climatic situation will alter, and the temperature will rise as the use of fossil fuels grows. The mining, processing, and combustion of fossil fuels can have detrimental health consequences for communities. This article learns about fuel, types of fuel, calorific value, burning of fuels leads to harmful products.


Q.1. What harmful products are formed by the burning of fuels?
Sulphur dioxide, carbon monoxide, carbon dioxide, nitrogen oxides, lead and particulate matter, are the harmful products of burning fuels.

Q.2. What are the harmful effects of using fossil fuels?

(i) Many respiratory disorders, such as asthma, are caused by unburned carbon particles created by fossil fuels such as wood, coal, and petroleum.
(ii) Carbon monoxide \(\left( {{\rm{CO}}} \right)\) is a very deadly gas produced by the incomplete combustion of carbon (fossil) fuel. It can kill people who are asleep in a room with carbon monoxide.
(iii) Carbon dioxide produced by burning fossil fuels contributes to global warming, which is defined as an increase in the temperature of the earth’s atmosphere. Polar ice melts as a result of this.
(iv) Sulphur dioxide and nitrogen oxides are released when fossil fuels such as coal, diesel, and gasoline are burned. These fumes are exceedingly corrosive and suffocating.
Acids are formed when sulphur and nitrogen oxides dissolve in rainwater. Such rain is called acid rain. Acid rain is extremely destructive to crops, buildings, and soil.

Q.3. What are the harmful by-products obtained by burning coal and petroleum?
Suffocating and corrosive gaseous oxides of nitrogen are produced when diesel and coal are burned, and petrol engines emit gaseous oxides of nitrogen. Acid rain is caused by sulphur and nitrogen oxides dissolving in rainwater.

Q.4. How does burning fuel affect the environment?
Nitrogen oxides are released into the atmosphere when fossil fuels are burned, contributing to smog and acid rain production. Nitrogen oxides are a group of nitrogen-related chemicals emitted into the air due to human activity.

Q.5. Explain how the use of CNG in automobiles has reduced pollution in our cities.
The use of CNG in place of petrol and diesel reduce pollution in the following ways:

  1. It produces less carbon monoxide gas.
  2. It produces less carbon dioxide gas.
  3. It produces less amount of sulphur dioxide and nitrogen dioxide, which cause acid rain.
  4. No residue remains after combustion.

Q.6. What is fuel? Give some examples of a fuel.
The combustible substances which produce heat and sometimes light on combustion are called fuel. Fuel may be solid, liquid and gas.
Wood, charcoal, petrol and kerosene are some of the examples of fuel.

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