Which of these fuels has the highest calorific value?
The calorific value of a fuel is expressed in kilojoule per kg (kJ/kg).
The calorific values of coal, CNG, hydrogen and petrol are as follows:
Coal: 25,00033,000 kJ/kg
CNG: 50,000 kJ/kg,
Hydrogen: 150,000 kJ/kg
Petrol: 45,000 kJ/kg
Living Science (2020, 2021)