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a set of actions serving as recommendations (corollaries), which effectively support
the principle. This is then complemented by the authors' personal reflections as
to how a resource e cient society should take shape. They are ordered as follows:
physical and engineering principles, biomimicry, industrial practices, sociopolitical
aspects, and finally the philosophy of Nature and ethics.
16.3 The principles
“Resource e ciency is an inexhaustible source of energy and imagination. Once
discovered, it is forever.” - Elias P. Gyftopoulos (2008).
Starting with the above motto as proposed through a personal communication
to the authors by Prof. Gyftopoulos 4 , the road towards resource e ciency is cons-
tituted by 12 underlying principles. Many of which are based on the empirical
endeavours of researchers and designers within the fields of Thermodynamics, En-
gineering, Economics and sustainability. The principles provide the philosophy of
an emerging science, Industrial Ecology. Industrial Ecology analyses the mate-
rial and energy flows through industrial systems, with the aim of closing loops, in a
very interdisciplinary way. Eco-design, eco-e ciency, industrial symbiosis, life-cycle
thinking, natural capital restoration and dematerialisation and decarbonisation are
some of the key themes. This new discipline forms an integral solution to sustainable
resource management.
Principle 1: Everything comes down to the Second Law
Energy is not lost, but degraded. What is lost however is its potential, its quality
namely its exergy. All natural processes are spontaneous and their exergy is lost
without producing useful effects. What goes up eventually comes down, that which
is concentrated disperses, what is warm cools and what is cool becomes warmer until
equilibrium with the ambient temperature is established. This loss in exergy is effec-
tively irreversibility. Notably, where mixtures are involved, it increases exponentially
as incremental increases in purity (separation) are demanded.
Corollary 1: Whatever you do, no matter how intelligent you think it is, the
entropy of a system and its surroundings will always increase. That is to say,
the total exergy will decrease.
Corollary 2: Instead of employing the property entropy as the accounting unit,
use exergy and exergy cost (or embodied exergy), since they are easier to un-
derstand.
4 Prof. Elias P. Gyfotopoulos (1928-2012), is considered by many to be one of the foremost
thermodynamicists of his time, Gyftopoulos was highly regarded for his significant contributions
to the fields of nuclear engineering and mechanical engineering, having held appointments in both
departments at Massachusetts Institute of Technology.
 
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