Geology Reference
In-Depth Information
Accordingly, from the Physical Geonomics position, the authors propose a new
stage in LCA's cradle-to-grave methodology, namely the grave-to-cradle approach,
leading to a closed material cycle: cradle-grave-cradle as depicted in Fig. 4.2.
Fig. 4.2 Closing the material's cycle: the cradle-grave-cradle approach. Reprinted from Valero D.
and Valero (2013)
For millions of years, Nature has formed and concentrated minerals through var-
ious geological activities such as magmatic separation, hydrothermal, sedimentary
and residual processes (Reservoir #0 to #1), forming the currently existing stock
in Nature or Reservoir #1. Its existence, allows society to save huge amounts of
energy, which would be otherwise used if one were to extract materials from the
common bedrock.
The difference between Reservoir #0 and Reservoir #1 is the bonus provided
by Nature and represents a hidden avoided cost that Man doesn't need to spend.
It can be assimilated by the grave-to-cradle stage of a LCA.
The stock in industry or Reservoir #2, meanwhile, consists of all the materials
which have already been extracted and are ready as raw materials for their later
transformation into products. The extraction, concentration and refining of mate-
rials in the cradle-to-gate stage (Reservoir #1 to #2) and referred to as beginning-
of-life (BoL) implies an obvious reduction of natural stock, with minerals extracted
from mines and fossil fuels burnt in the associated processes.
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