According to the principle of energy conservation it is not possible to create or destroy energy. Remarkably, PubMed database queries using the terms (mitochondria AND "energy generation") or (mitochondria AND "energy production") reveal that a substantial number of authors in the scientific literature states that mitochondria generate or produce energy.
In my opinion this is misleading: mitochondria synthesize energy rich ATP but not energy per se.
The Chemiosmotic Theory by Peter D. Mitchell states that mitochondria are organelles of energy conversion but not of energy generation or production.
What do you think?