Exergy evolution of the mineral capital on earth - circe

<strong>Exergy</strong> <strong>evolution</strong> <strong>of</strong> <strong>the</strong> <strong>mineral</strong> <strong>capital</strong> on earth
Alicia Valero Delgado
Thesis submitted in partial fulfilment <strong>of</strong> <strong>the</strong> requirements for
<strong>the</strong> degree <strong>of</strong> Doctor <strong>of</strong> Philosophy
University <strong>of</strong> Zaragoza, Spain
Abstract
The 20th century has been characterized by <strong>the</strong> economic growth <strong>of</strong> many industrialized
countries. This growth was mainly sustained by <strong>the</strong> massive extraction
and use <strong>of</strong> <strong>the</strong> earth’s <strong>mineral</strong> resources. The tendency observed worldwide in <strong>the</strong>
present, is that consumption will continue increasing, especially due to <strong>the</strong> rapid
development <strong>of</strong> Asia, <strong>the</strong> desire for a higher living standard <strong>of</strong> <strong>the</strong> developing world
and <strong>the</strong> technological progress. But <strong>the</strong> physical limitations <strong>of</strong> our planet might
seriously restrain world economies. In fact, many <strong>mineral</strong> commodities such as oil
or copper are already showing signs <strong>of</strong> scarcity problems, and consequently <strong>the</strong>ir
prices are increasing sharply.
Our society is based on an inefficient use <strong>of</strong> energy and materials, since <strong>the</strong>re is a
lack <strong>of</strong> awareness <strong>of</strong> <strong>the</strong> limit. If resources are limited, <strong>the</strong>ir management must be
carefully planned. But it is impossible to manage efficiently <strong>the</strong> resources on earth,
if we do not know what is available and at which rate it is being depleted.
Therefore, <strong>the</strong> aim <strong>of</strong> this PhD has been <strong>the</strong> assessment <strong>of</strong> <strong>the</strong> physical stock on
earth and <strong>the</strong> degradation velocity <strong>of</strong> our <strong>mineral</strong> resources due to human action.
This has been accomplished through <strong>the</strong> exergy analysis under <strong>the</strong> exergoecological
approach. This way, <strong>the</strong> resources are physically assessed as <strong>the</strong> energy required
to replace <strong>the</strong>m from a complete degraded state to <strong>the</strong> conditions in which <strong>the</strong>y
are currently presented in nature. The main advantage <strong>of</strong> its use with respect to
o<strong>the</strong>r physical indicators is that in a single property, all <strong>the</strong> physical features <strong>of</strong> a
resource are accounted for. Fur<strong>the</strong>rmore, exergy has <strong>the</strong> capability <strong>of</strong> aggregating
heterogeneous energy and material assets. Unlike standard economic valuations,
<strong>the</strong> exergy analysis gives objective information since it is not subject to monetary
policy, or currency speculation.
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