Geology Reference
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less economically attractive. Sometimes a drop in material weight can be at the ex-
pense of using others with a greater energy and environmental rucksack (materials
rebound effect - Sec. 14.8). In construction for instance, light-weighting involv-
ing glass, aluminium or steel structures instead of concrete, whilst decreasing the
amount of materials, greater energy losses during the utilisation phase could occur.
Therefore, a life cycle optimisation of materials and energy use in buildings and
systems should be undertaken, including considerations into end-of-life recycling.
Unfortunately such optimisations are rarely done. Ashby (2009) and Allwood et al.
(2011) propose a “back to the future” scenario with stone and wood acting as good
candidate substitutes for concrete and steel with reduced embodied energy
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.
Substitution can be particularly important in the case of metals. Wäger et al.
(2012) distinguish two types: first, the substitution of critical metals for ones that
are less scarce or those with a lower embodied energy and environmental impact.
Such substitutions need to be carefully planned, as they could entail losses in func-
tionality and e
ciency, as is the case of replacing copper wire with aluminium. The
second type, involves a change in the product but not functionality to reduce en-
vironmental impact. This case is demonstrated in the substitution of asphalt with
special cements for roads. Asphalt is obtained from usually imported heavy oil frac-
tions of petroleum processing whilst cement can be obtained using non-imported
coal, biomass and/or recycled waste.
Reflection 3: If the end-of-life is important and needs radical changes, the
beginning-of-life, i.e. mining, beneficiation and refining present huge opportuni-
ties in resources e
ciency. As opposed to the end-of-life which depends on many
social actor interactions, improvements in the beginning-of-life strongly depend on
a few decision makers and technology developers. Blasting, for instance, consumes
less energy than crushing and grinding, and new grinding technologies can be imple-
mented. Many opportunities for improving leaching processes exist such as the reuse
of water, dry processing, the use of less aggressive chemicals, and the implementa-
tion of biometallurgical processes as mentioned in Wäger et al. (2012) and already
explained in Chap. 8. However, intensive capital investment for R&D is needed. The
metals industry particularly, requires large investments with a low capital return,
which serves to slow down any sectorial technological evolution. Also, these kinds
of industries are frequently located in remote areas and are considered “dirty”. The
lasting result is a limited attraction for young researchers, not to mention mining
and metallurgical engineers.
The recovery of metals from low grade minerals and coal from dumps heralds
great prospects. It must be as important and necessary as urban mining. Tail-
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See for instance CIRCE Building of the University of Zaragoza, which was built according to
the guidelines promoted by the Institut für Baubiologie und Ökologie. The idea was to create
a Life Cycle Zero-Emission Building. In its construction the embodied energy of each building
block was calculated and minimised where possible. Most of the building materials are completely
recyclable. Constructors also used noxious emission free materials. Heating and cooling losses
were optimised. http : ==www:fcirce:es. Accessed Jan. 2014.
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