Fuels

What is a Fuel?

A fuel is a substance that can be burned to produce heat or power. Fuels are typically classified based on their origin and physical state, and they release energy in the form of heat or light during combustion.

Fuels are essential for activities such as heating, cooking, transportation, and electricity generation.

Types of Fuels

Fuels can be classified into two main categories based on their origin and form:

• Primary Fuels: Fuels that are found in nature and require little to no processing, such as coal, wood, and natural gas.
• Secondary Fuels: Fuels that are manufactured by processing primary fuels, such as petrol, diesel, and LPG (Liquefied Petroleum Gas).

Solid Fuels

Solid fuels are the most commonly used form of fuel in industries, particularly in power generation. Some examples of solid fuels include:

• Coal: A fossil fuel formed from the remains of plants that lived millions of years ago. Coal is widely used for electricity generation and industrial processes.
• Wood: A renewable fuel source used for heating, cooking, and in some industrial applications.
• Peat: An early stage of coal formation used as a fuel in some parts of the world.

Liquid Fuels

Liquid fuels are widely used for transportation and industrial purposes. Some examples include:

• Petrol (Gasoline): A liquid fuel derived from petroleum, primarily used in internal combustion engines (cars, motorcycles, etc.).
• Diesel: A heavier liquid fuel used in diesel engines for vehicles, generators, and industrial machines.
• Liquefied Petroleum Gas (LPG): A mixture of propane and butane, used as fuel for heating, cooking, and in some vehicles.

Gaseous Fuels

Gaseous fuels are used in various applications, such as cooking, heating, and generating electricity. Some common gaseous fuels include:

• Natural Gas: Mainly composed of methane, natural gas is widely used for heating, cooking, and electricity generation.
• CNG (Compressed Natural Gas): A form of natural gas used as an alternative to gasoline and diesel in vehicles.
• Biogas: A renewable gaseous fuel produced from organic matter like agricultural waste, used in rural areas for cooking and lighting.

Calorific Value of Fuels

The calorific value of a fuel is the amount of energy released when a unit mass or volume of the fuel is completely burned. It is typically measured in kilojoules per kilogram (kJ/kg) or kilojoules per cubic meter (kJ/m³).

Fuels with a higher calorific value are more efficient and release more energy per unit of fuel. The calorific value of some common fuels is as follows:

• Coal: Around 24,000 – 30,000 kJ/kg
• Wood: Around 15,000 – 20,000 kJ/kg
• Petrol: Around 45,000 kJ/kg
• Diesel: Around 45,000 kJ/kg
• Natural Gas: Around 55,000 kJ/kg

Renewable and Non-Renewable Fuels

Fuels can also be classified based on their sustainability:

• Renewable Fuels: These are fuels that can be replenished naturally within a short period. Examples include biogas, ethanol, and solar energy.
• Non-Renewable Fuels: These fuels are finite and cannot be replenished on a human timescale. Examples include coal, petroleum, and natural gas.

Previous Year Questions

• RRB JE 2019: Which of the following is a non-renewable fuel?
• Coal
• SSC JE 2020: What is the main component of natural gas?
• Methane (CH₄)
• HSSC 2021: Which fuel has the highest calorific value?
• Natural Gas

Conclusion

Fuels are an integral part of modern life, driving industries, transportation, and providing essential energy for daily activities. With increasing concerns over environmental sustainability, renewable fuels are gaining importance as alternatives to conventional non-renewable fuels. Understanding the types, properties, and applications of fuels is crucial for energy conservation and reducing environmental impact.