Amid present concerns over a potential scarcity of
critical elements and raw materials that are essential for modern technology,
including those for low-carbon energy production, a survey of the present
situation, and how it may unfold, both in the immediate and the longer term, appears warranted. For elements such as
indium, current recycling rates are woefully low, and although a far more
effective recycling programme is necessary for most materials, it is likely
that a full scale inauguration of a global renewable energy system will require
substitution of many scarcer elements by more Earth-abundant material (EAM)
alternatives. Currently, however, it is fossil fuels that are needed to
process them, and many putative EAM technologies are insufficiently close to
the level of commercial viability required to begin to supplant their fossil
fuel equivalents, necessarily rapidly and at scale. As part of a significant
expansion of renewable energy production, it will be necessary to recycle
elements from wind turbines, and solar panels (especially thin-film cells). The
interconnected nature of particular materials, e.g. cadmium, gallium,
germanium, indium, tellurium, all mainly being recovered from the production of
zinc, aluminium and copper, and helium from natural gas, means that the
availability of such “hitchhiker” elements, is a function of the reserve size
and production rate of the primary (or “attractor”) material. Even for those
elements that are relatively abundant on Earth, limitations in their production
rates/supply may well be experienced on a timescale of decades, and so a more
efficient (reduced) use of them, coupled with effective collection and
recycling strategies should be embarked upon urgently.
Of all essential commodities, the fossil fuels may well run into production limits
during the next few decades, and indeed, the underpinning determinant
of how we extract resources, inducing those of energy, is the availability of
energy itself, and those resources that provide it. As we, inevitably, use up
high grade ores, and move on to poorer quality deposits, in which the desired
element is increasingly diluted by other materials, the energy input to the
whole extractive and processing mechanism increases: in terms of the production
of energy resources, this is expressed as declining Energy Return on Investment
(EROI). As the quality of mineral deposits declines, the volume of material
that needs to be exhumed from the Earth, and processed, enlarges relentlessly,
leading overall to increasing amounts of waste for each mass unit of metal, or
other element, recovered, and much more additional
energy is needed.
A coupling between the declining quality both of ores and energy sources can
only compound the situation.
It has been
indicated that there are insufficient,
proven, reserves (and resources too, in certain cases) of several metals
required to build a fully renewable energy system, to meet the global demand
for energy that is expected by 2050. For scarce
elements, recycling is indicated to be of limited value. It is possible that
incorporating potentially less efficient technologies (but based on elements
that are more widely available) might prove a viable strategy for reducing the
risks of supply constraints . The future development of
renewables may also rely on the recovery of materials from conflict zones and
other politically unstable regions, which could pose problems for its large
scale expansion. Moreover, how such a fully renewable energy system
might be maintained, beyond 2050, remains a serious open question. Meanwhile, major changes in our global demand
for energy are necessary, and it may be wise to spend the fossil fuel
equivalent of our remaining carbon budget on the extraction of metals required for
low-carbon energy technologies.
Current consumption of resources means that
the global materials base is unsustainable, and it is necessary to optimize our
use of energy, to close material cycles, and to curb irreversible material
losses, of all kinds. Mining of sand and gravel, used to furnish concrete, glass,
asphalt and electronic devices, has risen to the point that their supply too is
a matter of concern; levels of freshwater use are also now approaching newly
defined planetary boundary limits. Natural resources are being consumed on an
unprecedented scale, and currently, an annual 92 billion tonnes of raw
materials are being extracted, which corresponds to around 12 tonnes for every
person on the planet. The timescale of our intentions
regarding the use of resources is critical, and the question of whether
technology can solve our current problems, and meet future needs “sustainably”,
has yet to be answered fully. Perhaps such considerations of what is
sustainable only properly make sense, if societal viability over the duration
of a civilization (say, 500 years) is planned for; yet we have only the next
few decades, at most, to undertake the appropriate actions to establish this. In regard to the sustainable use and
regeneration of essential natural resources, it seems likely that the
Earth Stewardship scenario, with the design system of permaculture as a
creative response pathway toward achieving it, may be the most effective
option.
Keywords.
Endangered elements,
critical raw materials, conflict minerals, conflict resources, indium, Energy
Return on Investment, EROI, planetary boundary, low-carbon energy,
civilization, permaculture, circular economy, renewables, renewable energy,
fossil fuels, Earth stewardship, Earth-abundant materials, periodic table, wind
energy, solar energy, phosphorus, indium, fracking, sand, gravel, sand mining,
freshwater.
