I am analyzing the energy of different fuels. I have several fuels and for each fuel I have the energy density and the energy that is released from heat of combustion. The way I understand energy density is the energy that a substance has per unit so ethanol for example has an energy density of 28000kJ/kg which means for every kilogram, there is 28000kJ of energy. Is my understanding of this correct?
Anyway, the heat energy released from combustion is always more than the energy density. Why is this so? I would have thought it would have been the other way around.
Thanks for your replies