Epilogue - Thanatia: The Destiny of the Earth's Mineral Resources - page 498

are not well defined thermodynamic systems but fuzzy. They are in no way in
equilibrium nor homogeneous and their properties are approximate. In spite of
this, their intensive properties need to be identified. To use an example, the relevant
properties for the exergy calculation of a mine are composition, concentration (ore
grade) or improbability, amongst others.
For calculating exergy resources, the reference environment (R.E.) deserves spe-
cial attention. The previously published reference environments focused on well
defined system states and their exergy losses, rather than on natural resources and
their degradation (Sec. 10.4). For the latter the problem is conceptually deeper.
Therefore the core issue in finding an appropriate R.E. for resource assessment is
related to the question of: how to stipulate the consistency of an entropic soup
which most reliably depicts the current geological reality and forecasts that of the
future?
Unfortunately when one attempts to answer this question, one finds that the
composition of the Earth's crust is not equal to the average concentration of all
chemical elements in the biosphere, nor for a few kilometers below that. Further-
more, the Earth is not uniform and is divided up not just into the crust but also into
the hydrosphere and atmosphere which are likewise potential providers of material
resources. Besides, one must distinguish between what is solely bedrock and that
which represents a potential mine in a determined location. Finally, temperature,
as it varies on location, according to climatic conditions and climate change, needs
to be defined since it plays a major role in exergy calculations.
17.2.3 Thanatia is a coherent baseline for mineral exergy
calculations
In this topic, the authors proposed an imaginary degraded Earth, Thanatia, as the
baseline for exergy calculations. Thanatia represents an imaginary ultimate state
of the present evolutionary Man-induced degradation path, in which the crust, the
hydrosphere and the atmosphere have reached maximum dissipation of all their ma-
terials, taking into consideration the natural conditions on Earth (given its distance
from the Sun and its internal heat). In Thanatia no commercially exploitable mines
exist with all materials having been dispersed and degraded and having reached
the composition of the bare rocks commonly found in the crust; the hydrosphere
contains no poles and is nearly entirely composed by standard saltwater; whilst the
atmosphere has arrived at the state predicted by long term climate change models,
where greenhouse gases are at a concentration of 683 ppm due to the complete
combustion of fossil fuels. Thanatia is by no means in equilibrium state but in a
conceivably geological steady state that can be characterised by a reasonably short
set of physicochemical parameters.
Thanatia constitutes a coherent baseline to evaluate the loss of mineral endow-
ment on Earth and the speed of its exhaustion. It does not consider the end of the
world or represents a dead planet but rather its commercial climax. Whilst it is