Environmental Engineering Reference
In-Depth Information
Table 1.6
Uranium (U) Resources for 2001
Resources with production costs
Total
US$40/kg U
US$40-130/kg U
Resources
1.57 Mt
a
5.67 Mt
b
7.24 Mt
3620 EJ
Speculative resources
12.52 Mt
12.52 Mt
6260 EJ
Note:
a Reasonable assured resources; b reasonable assured resources and estimated
additional resources
Source:
BGR, 2002
When dealing with energy reserves, proven reserves are most important.
These are reserves available with certainty, which have been proven by
exploration through drilling and measurement and which are technically and
economically exploitable. Additionally, unproven reserves of uncertain extent
exist, but are hard to estimate. Dividing the proven reserves of an energy
carrier by the present annual demand provides the statistical duration of the
reserve. This duration will decrease if the energy demand rises and will increase
if new reserves are exploited.
The Earth's uranium reserves for operating nuclear power stations are
limited as well. The estimated global reserves are less than 20 million t, of
which 12.52 million t are only speculative. Table 1.6 shows the uranium
reserves. At present, only about 5 per cent of the global energy demand is
provided by nuclear energy. If the total world primary energy demand in 2000,
about 1.1
•
10
14
kWh
~
400 EJ, had been provided by nuclear power, the
reasonably assured, economically exploitable reserves would have lasted only
about 2 years. Breeder reactors can increase this time by a factor of about 60.
However, nuclear power on the basis of nuclear fission is no real long-term
alternative to fossil fuels due to the very restricted reserves of uranium.
Only a limited number of today's technologies will survive the 21st century
due to very limited reserves of conventional energy carriers. This fact is a
sufficient reason to switch our present energy supply to non-fossil and non-
nuclear energy sources. This development should be completed before the
conventional energy reserves are depleted. The next two sections will describe
two additional motivations for a change in energy policy: the greenhouse effect
and the risks of nuclear power.
G
REENHOUSE
E
FFECT
Without the protection of Earth's atmosphere, the global mean ambient
temperature would be as low as -18°C. Particular gases in the atmosphere
such as carbon dioxide (CO
2
), water vapour and methane capture parts of the
incoming solar radiation, acting like a greenhouse. These gases have natural as
well as anthropogenic, or human-induced, sources. Figure 1.6 illustrates the
anthropogenic greenhouse effect.
