Comparative energies of alternative fuels

In order to provide additional design data on candidate alternative fuels, a broad comparison is made of the net calorific values of a wide variety of gaseous, liquid and solid fuels, including a number of alternatives of current interest, against a background of conventional fuels, some of which may have alternative applications. In general, higher gravimetric calorific values are shown by the lighter of the gaseous and liquid fuels and the heavier of the solid fuels. Volumetric calorific values rise with fuel density, with the exception of the fuel gases. Despite a wide overall range in calorific values, the gravimetric energy content of a stoichiometric fuel-air mixture is seen to be virtually independent of fuel type. In such applications as the spark-ignition piston engine and the rocket, additional combustion parameters arise which tend to overshadow calorific value and are therefore adopted for performance assessment.