[komadori]

I don't know, you make it sound like a pretty good analogy to me.

A coal power plant take a form stored energy which is relatively difficult to use because it has to be burnt with oxygen producing harmful waste products, and turns that energy into electricity which is easier to use in a variety of applications.

A mitochondria take a form of energy which is relatively difficult to use, sugars and fats, because they must be respired with oxygen producing harmful waste products, and turns that energy into ATP which is easier to use in a variety of applications.