Both Neoclassical and Post Keynesian economic models have been "energy blind": postulating output from inputs of Technology, Labor and Capital, but ignoring energy (and matter, for that matter...). In this lecture I show how tautological and wrong the Cobb Douglas Production Function is, and that incorporating energy into it does enormous damage to the Neoclassical paradigm. On the other hand, the empirically-based Leontief Production Function only needs to acknowledge that what has been called the "Capital-Output Ratio" is in fact the inverse of "the efficiency with which machinery turns energy into useful work", and Post-Keynesian economic models are now energy-aware.
If you are not already aware of it, consider some of Daniel Nocera's thoughts and calculations for world energy usage, GDP, and population. For one fairly succinct presentation of this see https://www.youtube.com/watch?v=zXBQjhXCydg. He goes into more detail in other presentations.
Friede Gard Prize Lecture 05 Energy In Production Functions
If you are not already aware of it, consider some of Daniel Nocera's thoughts and calculations for world energy usage, GDP, and population. For one fairly succinct presentation of this see https://www.youtube.com/watch?v=zXBQjhXCydg. He goes into more detail in other presentations.