Environmental Engineering Reference
In-Depth Information
Table 1.2
Estimated Future Global Supply of Some Common
Metals
Source: Data from Richards (2009).
Metal
Estimated supply
(years)
Metal
Estimated supply
(years)
Iron ore
178
Lead
19
Aluminum 219
Copper 35
Zinc
19
Nickel
51
Manganese 43
Uranium 65
Hubbert's theory of diminishing reserves on exploiting a finite resource
beyond a certain level might also be used to estimate how long rare metal
resources might last. Unlike base metals such as iron and copper, the rare
metals show a peak in the production versus time curves. Some, such as
mercury, zircon, selenium, and gallium, have already peaked by year 2000.
Metals such as indium, hafnium, gallium, germanium, and arsenic are
estimated to deplete within two decades! Indium is used in solar panels as
well as in liquid crystal displays, while hafnium is used in computer chips
and in nuclear engineering. A majority of the metals in short supply are
expected to deplete within the next 100 years (Rhodes, 2008).
However, such estimates will be approximations for a variety of reasons.
First, the resource base is not constant as new supplies are being added to
the reserve base each year and the annual demand for metals also changes
with time. Secondly, the rate of exploitation being demand-sensitive is
highly variable. Physically running out of these materials is unlikely in the
medium term; more intensive and increasingly polluting new technologies
will ensure their supply. The United States is heavily dependent on foreign
may also play a role in their future supply. Despite these observations, the
next century is unlikely to be an austere metal resource-strapped world
as more of the Earth's crustal reserves will probably be exploited more
intensively and with even better technology. Learning to use less of the
scarce materials and substituting for them will be a slower process, and
changes in technology may ultimately shift the demand away from the
scarce metals.
