The Exergy Evolution of Mineral Wealth - Thanatia: The Destiny of the Earth's Mineral Resources - page 427

With respect to fossil fuels, in exergy terms, oil has been the most consumed,
accounting for 42% of the total degradation in the 20th century (coal and natural
gas accounted for 38% and 20%, respectively). The total exergy depletion of con-
ventional fuels between 1900 and 2009 is estimated at 414 Gtoe, which is equivalent
to 46% of the total world's proven fuel reserves in 2009. It was consumed, in the
last decade, at an average velocity of 9 Gtoe/yr.
The Hubbert bell-shaped curves applied to the exergy production of fossil fuels
reveal that the theoretical peak oil has already occurred (2012) and that those of
coal and natural gas could appear in 2059 and 2024, respectively.
It should be emphasised, that the results obtained are estimations and hence the
numbers presented should be in no way taken as final. More reserves could be found
in the future, thereby prolonging the years until commodity depletion and peak
production. That said, the huge amount of energy and its equivalent in monetary
terms associated with the depletion of planetary mineral deposits, should alert the
reader as to the importance of resource conservation. This analysis demonstrates
that mineral scarcity will most likely be an issue in the coming decades, although
it is uncertain when and to what extent. The authors have reasons to believe that
demand will keep increasing and mineral suppliers will struggle to expand global
mineral output.
Possible solutions which could support the conservation of the mineral wealth
on Earth are discussed in the next, concluding part.