Epilogue - Thanatia: The Destiny of the Earth's Mineral Resources - page 510

Using the exergy countdown diagram, the authors have predicted that about
64% of the principal mineral commodities produced in Australia could be depleted
by 2050. Moreover, except for coal, iron and nickel, more than 85% of the mineral
reserves are also expected to reach exhaustion within that timeframe, if no sig-
nificant additional resources be found and should production continue to increase
exponentially.
In order to provide a monetary estimation of what it would cost to replace the
depleted Australian mineral endowment, a preliminary analysis was carried out via
the conversion of exergy replacement costs into their monetary equivalent through
conventional energy prices. The results show that for 2007 Australia would have
lost up to A$142 billion of its mineral wealth. This figure is equivalent to about
12% of the nation's 2007 GDP, which highlights the importance of depletion and
the need to take it fully into account. This issue becomes even more alarming when
one considers that the mineral resource sector contributes to less than 10% to the
nation's GDP. That said, it should be stressed that the conversion of exergy into
monetary costs is not free of arbitrariness, especially given the volatility of prices.
However, it does provide useful information and an order of magnitude as to the
important role that mineral extraction has in the economy.
17.3.3.2 Case study: the world
An assessment taking into account the entire globe was a huge challenge as a signif-
icant amount of historical information was required but not available. In order to
overcome this, many assumptions had to be made at the expense of an important
loss of accuracy. Hence, the obtained results are a crude estimate of the depletion
in planetary mineral wealth since the beginning of the 20th century.
Some 54 non-fuel mineral commodities were analysed with the results showing
that their depletion due to extraction was equivalent to at least 100 Gtoe (more than
half of all current world oil reserves). The mass use of iron, aluminium and copper
has meant that these commodities have contributed the most to the degradation of
the planet's mineral endowment. Yet these three minerals are not the most depleted
ones. Instead it are those of mercury, silver, gold, tin, arsenic, antimony and lead.
With respect to conventional fossil fuels, the obtained exergy loss in the analysed
period has been around 400 Gtoe. Of all, oil has been the most consumed (42%)
followed by natural gas (38%) and coal (20%).
The Hubbert Peak Model was also applied to a good number of commodities,
assuming a minimum value, which corresponds to the published reserves and a
maximum one, which in turn corresponds to world resources. According to the
results, the theoretical peaks of the former have already been reached for mercury
(1960), arsenic (1971), tin (1979), lead, (1989), gold (1994), silver (1995), cadmium
(1996), antimony (1998), zinc (1999), zirconium (2003), manganese and wolfram
(2007), copper and oil (2012). The theoretical peak for world resources meanwhile,
may have been reached for mercury (1965), tin (1986) and gold (2001). The exergy