The Exergy Evolution of Mineral Wealth - Thanatia: The Destiny of the Earth's Mineral Resources - page 381

900 0.05

Exergy cost Ore grade

0.045

800

0.04

700

0.035

600

0.03

500

0.025

400

0.02

300

0.015

200

0.01

100

0.005

0 0

1967 1972 1977 1982 1987 1992 1997 2002 2007

Year

Fig. 13.7 Ore grade and exergy replacement cost of Australian nickel mines

Fig.13.8TheHubbertPeakappliedtoAustraliannickelreserves

regression factor is very low (RF = 0:57), considering that the reserves expressed
in exergy replacement costs are R 1884 = 36:0 Mtoe. The theoretical peak was
envisioned to occur in 2009 (see Fig. 13.10), yet empirical data suggests otherwise
(ABARE, 2011). However, silver is a special case since it is extracted only as a
byproduct of other minerals such as copper, lead, zinc and to a lesser extent, gold