Types Of Fuels

Types Of Fuels

What is a fuel?

According to the law of conservation of energy, it can neither be created nor be destroyed, it can only be changed from one form to another. Thus, we cannot produce energy to do certain work. Therefore we use certain substances which help us transform one form of energy to another form.

For example, when we burn paper with a matchstick, light is produced by the flame. If we analyze this closely, light energy is not created over there, it has just been produced due to the transformation of heat energy provided by the matchstick into light energy. Thus, we always need a certain substance to convert one form of energy into another for accomplishing various jobs. We call such materials as fuels. In other words, any substance which upon combustion produces a usable amount of energy is known as fuel. Example: fossil fuels, biogas, nuclear energy,  etc.

Such materials can further be classified into:

   Renewable source of energy: one which is inexhaustible. Example: Solar energy.

   Non-renewable source of energy: one which is exhaustible. Example: Fossil Fuels.

Now, the energy produced by burning paper is not sufficient to run cars but energy produced by burning petrol is enough to do so. Thus, we can say that each fuel releases its own set of energy i.e. all of them do not release the same amount of energy upon combustion. The energy produced by combustion of one kg of fuel is known as its calorific value.

Thus, we can differentiate different fuels on the basis of their calorific value for their efficient usage. Furthermore, each of them has a different cost with respect to another. Some are cheaper while others are expensive. Therefore we categorize fuel as an ideal based on different criteria.

Some properties of ideal fuel are:

  • An ideal fuel is readily available.
  • An ideal fuel is cheap.
  • An ideal fuel burns easily in the air at a moderate rate.
  • It releases a large amount of energy.
  • It should not leave behind any undesirable substances which can be harmful to us.
  • It should not affect the environment adversely.

Types of Fuels:

Fuels can be generally classified into two factors:

  1. On the basis of their fuels state:
    • Solid Fuels

    • Liquid Fuels

    • Gaseous Fuels

  2. On the basis of their occurrence:
    • Natural Fuels

    • Artificial Fuels

Examples of Fuels:

Natural Fuels

Artificial Fuels

Solid Fuels

Oil Shale
Tanbark, Bagasse, Straw,

Liquid Fuels

Petroleum Oils from distillation of petroleum,
Coal Tar,
Alcohols, etc.

Gaseous Fuels

Natural Gas Coal gas,
Producer Gas,
Water Gas, Hydrogen,
Blast Furnace Gas,
Oil Gas

Solid Fuels

Solid Fuels

Fuels which are found in their solid state at room temperature are generally referred to as Solid Fuels. They were the first kind of fuel known to be used by man, basically wood to create fire. Coal was another one of the influential fuels known to man as it leads the way for the industrial revolution, from firing furnaces to running steam engines.


  • Easier transportation and storage.
  • Low production cost.
  • Moderate ignition temperature.


  • Large portion of energy is wasted.
  • Cost of handling is high and controlling is also hard.
  • Ash content is high & burn with clinker formation.

Liquid Fuel

Liquid Fuel

Most liquid fuels are derived from the fossilized remains of dead plants and animals by exposure to heat and pressure in the Earth’s crust. The fumes of the liquid fuel are flammable instead of the liquid.


  • Higher calorific value per unit mass.
  • Burn without ash, clinkers, etc.
  • Controlling the combustion is easier.
  • Transportation easier through pipes and stored indefinitely without loss.
  • Loss of energy is comparatively lower.
  • Require less furnace space for combustion.


  • Cost of liquid fuel is much higher compared to solid fuel.
  • Storage methods are costlier.
  • Greater risk of fire hazards.
  • Special burning equipment required for more efficient combustion.

Gaseous Fuel

Gaseous Fuel

Gaseous fuels occur in nature, besides being manufactured from solid and liquid fuels. Most gaseous fuels are composed of hydrocarbons, carbon monoxide, hydrogen or a mixture of them all.


  • Transportation through pipes is easy.
  • Sparking combustion is really easy.
  • They have a higher heat content.
  • Clean after use.
  • Do Not require any special burner technology.


  • Large storage tanks required.
  • As they are highly inflammable, the chance for fire hazards are extremely high and strict safety measures need to be followed.

What are fossil fuels?

Fossil Fuels

Fossil fuels are the dead and decayed remains of plants and animals subjected to decades of pressure and temperature under the earth’s crust. Primarily fossil fuels are hydrocarbons. They are convenient and effective. They provide the calorific value required to fulfill our needs. Even though they are available in plenty right now, they are a non-renewable source of energy. The burning of fossil fuels is responsible for a large section of the world’s pollution index.

Types of fossil fuels:

  • Coal

  • Oil

  • Natural Gas

Nuclear Fuel

Nuclear Fuel

Nuclear Fuel Element

Any material consumed to give out nuclear energy is a nuclear fuel. Technically speaking, any material can be made to give out nuclear energy. But looking at its practicality and feasibility, we pick materials which do not require extreme constraints to release nuclear energy.

Most nuclear fuels contain heavy fissile elements that are capable of nuclear fission. When these fuels are struck by neutrons, they are in turn capable of emitting neutrons when they break apart. This makes possible a self-sustaining chain reaction that releases energy at a controlled rate in a nuclear reactor or with a very rapid uncontrolled rate of a nuclear weapon.

Some common examples of nuclear fuel are uranium-235 (235U) and plutonium-239 (239Pu).

To learn more about different types of fuels, their calorific value and how they are harnessed, register with Byju’s and download Byju’s- The Learning App.

Practise This Question

Choose the correct statement about inflammable substances from the following. They have