Geology Reference
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13.6 Summary of the chapter
The authors have proposed the application of the Hubbert Peak Model to non-fuel
minerals, plotting their exergy over time instead of mass over time. In doing this,
the concentration factor, which is very important for the case of solid minerals is
taken into account.
The first case study aimed at assessing the exergy loss of a country due to mine-
ral extraction. Australia was chosen for this analysis because it is one of the most
important mineral exporting countries in the world. It is also unique in having regis-
tered ore grade trends for its main minerals. The commodities analysed throughout
their mining history up until 2007-2008 were gold, copper, nickel, silver, lead, zinc,
iron, coal, oil and natural gas. It has been observed, that the general production of
commodities has followed an exponential-like behaviour. Due to the extraction of
metals, Australia has degraded the equivalent of 2.4 Gtoe (in exergy replacement
cost terms). This corresponds to 5 times its oil reserves. Thus, Australia year on
year is degrading on average, as a result of metal extraction, the equivalent of 4
times its primary oil production.
The Hubbert Peak Model was satisfactorily applied to all analysed commodities,
with the exception of the lead-zinc-silver group, whose production patterns differ
from the rest, as they are extracted together. With limitations, the authors predict
that the theoretical peak has been already reached for zinc (2010), silver (2009),
gold (2007), oil (1996) and lead (1994). Copper is expected to reach its peak in
2026, natural gas in 2029, iron in 2030, nickel in 2039, and finally coal in 2048.
The natural exergy bonus loss of Australian minerals and fossil fuels throughout
the analysed period is dominated by the extraction of two commodities, coal and
iron. In 2007, the exergy degradation velocity exceeded 500 Mtoe/yr (the equiva-
lent of around 18% of current world oil consumption). Furthermore, it is likely to
continue its exponential growth for at least another 20 to 40 years, whereby the
peaks of iron and coal are reached.
A very practical representation of the mineral reserves available and the possible
extraction pattern of commodities not only for Australia can be found in the “Exergy
countdown” graphs, which place the different Hubbert Peak Models (in terms of
exergy replacement costs ) in a single diagram. This enables the reader to compare
Australia's past, present and possible future extraction rates, together with its
available reserves of fuel and non-fuel minerals. Using the exergy countdown, the
authors predict 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 should also reach exhaustion within that
timeframe, if no significant additional resources be found and should production
continue to increase exponentially.
The authors estimated, in addition, the monetary cost of the reserve depletion
in Australia due to mineral extraction in 2007. This was carried out via the conver-
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