Which fuel has lowest calorific value?

Which fuel has lowest calorific value?

The fuel with the lowest calorific value is hydrogen. Hydrogen is the lightest and most abundant element in the universe and has the highest energy content per unit of mass. It has a calorific value of 120MJ/kg, which is much lower than the calorific values of other fuels such as petrol, coal and natural gas. Hydrogen is also a clean fuel that does not produce any pollutants when burned.