One of the primary reasons why hydrocarbons produce energy is the production of water during the combustion process.
I've been trying to find out why diesel is considered to have a higher energy density compared to gasoline and I can think of a couple of reasons:
- Higher molar mass (more carbon/hydrogen to burn)
- Easier to burn diesel since it is heavier (weaker bonds)
I think I'm on the right path but I don't have a clear picture of the situation.