Waste heat, H waste ; is the measure of Q in reference to reversible heat extracted, the
upper limit,
H waste ¼ Q rev À Q
and correspondingly,
Free heat is the measure of Q in reference to spontaneous heat extracted, the lower
limit,
Free heat ¼ Q À Q spon
Both concepts offer useful perspectives for the reversible limit. Reversibility
means either achieving the elimination of waste heat or the maximization of free
heat, i.e., the reversible free heat. Waste heat versus free heat is the alternative of the
“glass is half empty” versus the “glass is half full”, and both are the manifestation of
the degree of success in the management of the EGP. Again, it is worthwhile to
repeat that waste heat in a process is neither directly measured by its discarded heat,
e.g., heat discarded by a Carnot cycle is not waste heat; nor, in an adiabatic process
which discards no heat, necessarily means that it involves no waste heat, e.g., in the
case of free expansion the adiabatic process incurs waste heat (see Problem 8.4).
8.7.2 Kinds of EGP’s: Stock EGP and Natural (Ongoing) EGP
In the context of their management, EGP can be distinguished into two kinds:
1. Entropic drive of the latent or stock kind (which may be referred to as the stock
spontaneity or stock EGP).
1:a. The usual EGP that we call energy systems
1:b. Pure EGP, the special kind of stock EGP that have potential for producing
work without energy degradation as considered in Sects. 5.10 and 8.4.
2. Entropic drive of the ongoing kind (ongoing spontaneity, i.e., natural EGP).
The most common examples of spontaneity of the former kind are fossil fuels.
Examples of the latter kind are sun and wind, etc. The usefulness of sun and wind is
not due to their materiality but to their existence as phenomena of exergy transfer
processes, which is identified with ongoing entropy growth processes.
While stock energy leads to entropy growth only after its consumption, ongoing
EGP phenomena are associated with entropy growth as ongoing processes
regardless whether they are “consumed” or not. Entropically speaking, the “consumption” of the latter is of entirely different matter from the consumption of stock
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8 The Second Law: The Entropy Growth Potential Principle …
upper limit,
H waste ¼ Q rev À Q
and correspondingly,
Free heat is the measure of Q in reference to spontaneous heat extracted, the lower
limit,
Free heat ¼ Q À Q spon
Both concepts offer useful perspectives for the reversible limit. Reversibility
means either achieving the elimination of waste heat or the maximization of free
heat, i.e., the reversible free heat. Waste heat versus free heat is the alternative of the
“glass is half empty” versus the “glass is half full”, and both are the manifestation of
the degree of success in the management of the EGP. Again, it is worthwhile to
repeat that waste heat in a process is neither directly measured by its discarded heat,
e.g., heat discarded by a Carnot cycle is not waste heat; nor, in an adiabatic process
which discards no heat, necessarily means that it involves no waste heat, e.g., in the
case of free expansion the adiabatic process incurs waste heat (see Problem 8.4).
8.7.2 Kinds of EGP’s: Stock EGP and Natural (Ongoing) EGP
In the context of their management, EGP can be distinguished into two kinds:
1. Entropic drive of the latent or stock kind (which may be referred to as the stock
spontaneity or stock EGP).
1:a. The usual EGP that we call energy systems
1:b. Pure EGP, the special kind of stock EGP that have potential for producing
work without energy degradation as considered in Sects. 5.10 and 8.4.
2. Entropic drive of the ongoing kind (ongoing spontaneity, i.e., natural EGP).
The most common examples of spontaneity of the former kind are fossil fuels.
Examples of the latter kind are sun and wind, etc. The usefulness of sun and wind is
not due to their materiality but to their existence as phenomena of exergy transfer
processes, which is identified with ongoing entropy growth processes.
While stock energy leads to entropy growth only after its consumption, ongoing
EGP phenomena are associated with entropy growth as ongoing processes
regardless whether they are “consumed” or not. Entropically speaking, the “consumption” of the latter is of entirely different matter from the consumption of stock
220
8 The Second Law: The Entropy Growth Potential Principle …