Which of the following fuel has the highest calorific value ?

Question

Accepted Answer

Hydrogen is the correct answer because it has the highest calorific value among the given options. The calorific value of a fuel is the amount of energy released during its complete combustion. It is typically measured in units such as kilojoules per gram (kJ/g) or megajoules per kilogram (MJ/kg).

1. **Hydrogen (Option 4)**: Hydrogen has an exceptionally high calorific value, approximately 120-142 MJ/kg. This is because hydrogen is a very light element and releases a significant amount of energy when it reacts with oxygen to form water. The high energy content per unit mass makes hydrogen an efficient fuel, especially for applications where weight is a critical factor, such as in aerospace.

2. **Petrol (Option 1)**: Petrol, also known as gasoline, has a calorific value of about 44-47 MJ/kg. While it is a widely used fuel for internal combustion engines due to its energy density and ease of use, its calorific value is significantly lower than that of hydrogen.

3. **LPG (Option 2)**: Liquefied Petroleum Gas (LPG) has a calorific value of approximately 46-50 MJ/kg. LPG is a mixture of propane and butane and is commonly used for heating, cooking, and in some vehicles. Although it has a higher calorific value than petrol, it still falls short compared to hydrogen.

4. **CNG (Option 3)**: Compressed Natural Gas (CNG) has a calorific value of about 45-55 MJ/kg. CNG is primarily composed of methane and is used as a cleaner alternative to other fossil fuels. Despite its advantages in terms of emissions, its calorific value is lower than that of hydrogen.

In summary, hydrogen stands out as the fuel with the highest calorific value among the options provided. Its ability to release a large amount of energy per unit mass makes it the most efficient choice in terms of energy content, justifying why Option 4 is the correct answer.