Geology Reference
In-Depth Information
into exergy ones and their value is an indication of quality. Nevertheless, when non-
fuel minerals come into play, exergy measured in terms of its chemical component
(as is done with fossil fuels) does not inform as to the quality of the flow. Moreover,
when compared to the exergy of fossil fuels, that of non-fuel minerals is signifi-
cantly lower meaning that the results obtained could lead to the wrong conclusion.
Something similar happens when material bifurcations occur, a moment at which
one needs to allocate costs. If this is done with exergy, one would again obtain
inconsistent results. All such issues related to the application of Thermoeconomics
in the mining and metallurgical industry, when material commodities are analysed,
can be solved by using exergy replacement costs instead of exergy. Keeping this in
mind, the general rules applied for the thermoeconomic analysis of power plants are
equally valid, details of which can be found in Valero et al. (1986) and Lozano and
Valero (1993). Accordingly, the next subsections describe the considerations that
apply in the analysis of mining and metallurgical systems.
9.7.1 Cost of input mineral resources
Generally speaking, the cost of an output product is equal to the expenditures
involved in its manufacture and that of input resources. At the same time, any
resource can be considered as an output of a previous manufacturing process, thus
its cost is equal to the sum of previous process expenditures coupled with the
costs of its preceding resources and so on and so forth until one meets Nature. As
Nature “herself” does not assign prices to natural goods, nobody reimburses Nature
but instead people is paid. This explains why the norm in conventional economic
thinking is to pay the extracting company which in turn may use some of this
money to pay people through environmental taxes and restoration programmes, for
example, to reverse the deterioration. This view is typically an “Over the Rainbow -
OTR” one, since it only accounts for Man's effort involved in the production process
from the cradle. The effort that Nature made to concentrate the mines and natural
assets that society uses meanwhile is taken for granted because Nature could never
accept money. “She” only understands actions and reactions. Therefore, following
this reasoning, Man's accounts can never really be measured in physical units, since
natural costs are either unknown, deliberately ignored or replaced by costs and
prices as dictated by Economics.
Nevertheless and in contrast to the conventional paradigm, one can use exergy
replacement costs to measure the extent of which Man fails to reimburse Nature.
Accordingly, the exergy cost of a manufactured product is equal to the exergy ex-
penditures involved in its manufacture and the exergy replacement cost of input
resources, thus taking Nature into account and adding the DTR view. The value
of a product only depends on the effort required to form it from the grave (Tha-
natia) to the cradle - the part ascribed to Nature- and from the cradle to its final
commercial output - the part ascribed to Man. The exergy cost of a product is thus
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