Question

Which among the following has the highest calorific value?
A. Petrol
B. Kerosene
C. Ethanol
D. Wood

Answer 1

Hint: The calorific value of a fuel is the quantity of heat produced by its combustion - at constant pressure and under a condition known as " normal " of temperature and pressure (i.e. to 273.15K and under a pressure of 1,013 mbar).

Complete step-by-step solution:
The combustion of a fuel product generates water vapor. Certain techniques are used to recover the quantity of heat contained in this water vapor by condensing it.
The Higher Calorific Value (or Gross Calorific Value - GCV) supposes that the water of combustion is entirely condensed and that the heat contained in the water vapor is recovered.
The Lower Calorific Value (or Net Calorific Value - NCV) supposes that the products of combustion contain the water vapor. The heat contained in the water vapor is not recovered. This is the more standard means of measurement when compared to HCV/GCV.
Now that we have established what the calorific value of a substance really means, lets analyse the calorific value for each of the given options.
a) Petrol – LCV: 44.9MJ/kg b) Kerosene – LCV: 43.1MJ/kg
c) Ethanol – LCV : 26.7MJ/kg d) Wood – LCV: 15.4 MJ/kg
Therefore, from this data, the answer to this question is a) Petrol.

Note: Please make sure you compare LCVs of the different fuels rather than the HCVs so as to ensure that your calculations are correct and that you have compared the right metric with each other.