Epilogue - Thanatia: The Destiny of the Earth's Mineral Resources - page 500

17.2.5 Cradle-to-grave technologies constitute only half of a
material cycle
Only on a geological timescale will element cycles ever close. On the contrary, on
a human timescales all elements will be dispersed. This is because regardless of
how many minerals are stored in the crust, their demand will increase. Even in
the most optimistic case that recycling becomes a highly e cient and more com-
monplace technology, sooner or later all elements will eventually become dispersed
and degraded. The reader has seen that for element recovery, either in a natural or
urban mine, the required energy input in extraction increases exponentially as its
concentration decreases, in such a way that an infinite amount of energy is needed
for infinite recovery. It is Economics not Physics that decides the limits of recov-
ery. Therefore, before reaching infinity, a significant amount of waste material will
become un-recycled and finally dispersed.
As seen throughout the topic, in the cradle-to-grave process many materials
are left at the wayside. Mining leaves rocks containing minor ore grades and tail-
ings. Metallurgy and refining expels gases, particulate matter, wastewaters and
solid residues that can hardly be expected to be recovered, even should increas-
ingly stringent legislation be passed. These two processes -mining and metallurgy-
are essentially separating and chemical isolating processes. In such processes, pro-
duct entropy decreases at the cost of increased environmental entropy with this rise
taking the form of aquatic and atmospheric pollution, solid wastes, ecosystem de-
terioration and energy degradation. All of which fall under the umbrella of exergy
destruction. Manufacturing and fabrication processes, whereby an element or com-
pound is now combined, alloyed, doped, welded, glued, fixed, etc with another to
form a product for a given customer's specifications, are in essence processes that
create entropy. This is because both the entropy of the material and that of the
environment increases in the form of e uents and energy degradation. Finally, no
matter how long the life of a product, it will always eventually oxidise, fatigue, de-
teriorate, degrade, become obsolete or simply un-useful. Its end-of-life commences,
either by landfilling (in which case urban mining could be undertaken) or by start-
ing a new life with recycling. In terms of entropy generation, the recycling process
resembles metallurgy whilst urban mining, natural mining.
McDonough and Braungart (2002) call this overall cycling process “cradle to
cradle”. Cradle-to-cradle is a nice message about the need to extend the life of
materials and recycling. Whilst the authors agree with this message in essence, in
reality any material that is not recycled will disperse into Thanatia. Therefore they
object to the idea that recycling should be considered cradle-to-cradle, seeing that
it is actually a gate-to-gate process, occurring in the technosphere. Technology con-
centrates all efforts on improving the situation and must shine strongly if humanity
is to continue to thrive. This is why cradle-to-grave processes are referred to by the
authors as “over the rainbow” because they constitute only half of the cycle.