Energy Conservation and Its Relation to Work Obtainable

Much stuff and nonsense have been written about the conservation of energy in physics and electrical engineering.

The primary and master law of conservation of energy is this:  Energy cannot be created or destroyed.  But it certainly can be converted in form!

Let us be rigorous.  We have great difficulty in trying to define energy.  It isn't the "capacity to do work," because it isn't capacity. Having capacity and identically being capacity are two quite different statements! 

Ultimately energy represents a change in a potential (potential state, condition, vacuum, whatever) which, however, is itself a collection of energy and thus just a form of energy.  So, we can also reverse ourselves and interpret the potential as a change in the energy state.  Regardless of how we proceed, effectively we just wind up stating that energy—whatever it might be—can always be changed in form. Perhaps the closest approach to defining energy can be taken from general relativity, where it can be argued on one hand that energy is a curvature in spacetime, and on the other hand that energy causes a curvature in spacetime, and on yet another hand that energy is whatever acts upon uncurved spacetime to curve it.  And there is about where the matter rests.  As Nobelist Feynman { [39] } stated,

" It is important to realize that in physics today, we have no knowledge of what energy is."

Along with Feynman, we have to admit that no one really knows what energy is, and this author does not claim to be an exception. We just know a lot of things that energy does.  However, we do know what work is, once we assume energy as a given.  Work identically is the changing of the form of energy, rigorously. 

So a standard question I always ask new researchers is this:  "Suppose we have one joule of collected energy.  What is the maximum work we can do with that joule of energy?"

Almost invariably the answer is, "One joule of work."  That is quite wrong.

If we change the form of all that joule of collected energy, we have done one joule of work.  But afterwards we still have precisely one joule of energy remaining!  It's just in a form differing from the form it was in when we started.  Energy is never consumed, and never destroyed.  Use it to do work, and we just have all of it left in a different form. 

But we've done one joule of work from our original joule of energy, and we've still got one joule of energy remaining.  If we then change the form of that joule of energy yet another time, we get yet another joule of work.  And so on, as long as we can design an "energy-form changing" system that will not just let the energy completely escape after each transformation of the form of the energy. [14]

In theory, a single joule of energy can do any number of joules of work, if we change its form repeatedly and if we continue doing that indefinitely.

In short, energy can be—and is—recycled and reused, over and over without end. [15]

In the prevailing Big Bang theory, every joule of energy in the universe was there shortly after the big bang began.  Since then, every joule of that energy has been doing joule after joule of work.  And all of it is still here, and still doing more work! 

There is no conservation of work law!  All that means is that there is no limit on the number of times a given joule of energy can be changed in form or "transduced".  Run some energy through a resistor, and produce heat.  Retroreflect all the heat somewhere into some chemicals, and change it all into chemical energy.  Let that chemical energy do some more work on some plates, and get some more electrical energy.  And so on.  Such serial form-converting reactions producing more than one joule of work from one joule of energy do not violate the conservation of energy law, the laws of physics, and the laws of thermodynamics.  One is permitted indeed to get more than one joule of work from one joule of energy. [16]

But not in a single energy-form conversion!  In only one conversion, one can only get one joule of work from one joule of energy—but one also still has a joule of energy remaining .  If one does not further convert that remaining joule, that's the end of it.  In short, one then collects a joule of energy, does a joule of work with it, and then one wastes (dissipates) the joule of energy remaining in its different form.

Most of our professors in university were not quite clear on this subject, although at least some of them understood it.  But many did not, and many still do not today.