to make a point about energy production (and "concentrating" it).
The second law of thermodynamics is an expression of the universal principle of increasing entropy.
Wikipedia:
http://en.wikipedia.org/wiki/Second_law_of_thermodynamicsOr, I use to say to my college classrooms... "All of this pales in insignificance when compared to the impending heat death of the universe". Which I'm sure is a quote by someone else, but I can't find the attribution right this instant.
But the point I was making is that all of matter is energy, as we all know. Releasing that energy is difficult, BUT possible. We simply have to hold on (as a race with a functioning technology base) long enough to get there.
In other words, when those engineers are using economic models to describe what's possible, they neglect to take into account the "Eureka!" discovery moments. Moments that do, in fact, happen, but can't be predicted. When we DO have that moment with matter to energy conversion, we will no longer face either an energy crises or an environmental crises... in fact, our ability to control our environment will increase significantly.
For planning purposes, by all means, look at what is available today, or is possible with evolutionary progress. But to totally discount revolutionary discovery is also wrong.