A Quick, Crude Review of Thermodynamics
Repeated observations over many years of energy transfer processes has led
to the formulation of three useful statements. Because of a lack of any known
exceptions to these principles, they have come to be known as the Laws of
Thermodynamics.
Formally stated, the three laws are the following:
I. Energy can be neither created nor destroyed. It is conserved.
II. For any spontaneous process, there is always an increase in the entropy
of the universe.
III. The entropy of any pure crystalline substance at absolute zero is
zero.
A spontaneous process is one which takes place without
outside help. A ball rolling down a hill is an example. Reaction of a fuel with oxygen in
the process we call combustion is another.
Entropy is a measure of randomness or disorder. The greater
the randomness, the greater the disorder. Consider a single molecule of a typical fuel.
It consists of a string of carbon atoms all bonded to each other in an ordered way.
After combustion, all the carbon-carbon bonds have been broken and each now exists
as a separate molecule of carbon dioxide. The system is more disordered; entropy has
increased.
Absolute zero is -273 C (-460 F). It is the temperature at
which matter has lost all its energy. Even molecular vibrations cease. It is as cold as
things can get.
The Three Laws of Thermodynamics can be stated in many ways.
Since we often need to consider them within the context of the energy we burn and the
things we make, the following rendering may be more appropriate (and admittedly, a
good deal more crude).
I. You can never win, you can only break even.
II. You can only break even at absolute zero.
III. You can never get to absolute zero.
The impact of these principles is that everything we do generates
waste products. Just being alive generates wastes. Just thinking generates wastes.
Everything we do uses energy, and no energy using process can ever be 100%
efficient.
The real key to energy use and its inevitable waste production is twofold.
First, we should work to make systems that are as efficient as possible to minimize
energy use and minimize waste production. Second, we need to manage the wastes
that are produced, not delude ourselves into thinking they can be avoided
outright.
We need to stop wasting all our rhetorical energies devising schemes to find
"The Zero Emission" Holy Grail. None of us is ever going to get a call from
Stockholm to accept an award for inventing a perpetual motion machine.