primary energy
Noun
Meaning
English Wikipedia has an article on:primary energyWikipedia
primary energy (plural primary energies)
Energy in a form that has not been processed or is not processed before utilization.
Examples
It's so logical and so simple. Fat is the backup fuel system. The role it plays in the body is that when there's no carbohydrate around, fat will become the primary energy fuel. That's pretty well known.