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Viewing the periodic table through the
lens of sustainability
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The
chemical industry has a long tradition of innovation that have made chemical
processes safer, cleaner and more efficient when using raw materials and
other resources such as energy and water. Starting from the early processes
for making basic chemicals such as soda ash and sulphuric acid, the history
of technological development in the industry is replete with examples of
‘greener’ and more sustainable processes.
The
sustainability challenges for this industry has several aspects: the
feedstock used; the products made; and the manner in which these are done.
For the last several decades the industry has come to be dependent on
petroleum resources (such as oil, gas and coal), or mineral resources mined
from the earth to provide the basic raw materials needed for processing.
While
tomes have been written on when the world will run out of fossil fuels and
how a shift to alternate feedstock such as biomass is needed to migrate
chemical the industry to a more sustainable growth path, less is known about
the challenges of meeting the future requirements of several other elements
that modern society is dependent on.
Relooking the periodic table
The
periodic table is well known to chemists and engineers. It lays out the
elements of nature (and some manmade) in the order of its atomic number –
bringing to the fore commonalities in properties, including trends in
chemical behaviour.
But
the periodic table can be viewed through the prism of availability of the
elements in the long-term and such an analysis is revealing as it turns
conventional thinking on its head. First a clarification: unlike petroleum,
the elements of the periodic table cannot theoretically run out, because,
apart from helium, which can escape into space and uranium, which is fissile,
elements are essentially indestructible. However, human activity is
increasingly taking these elements from relatively concentrated deposits
(ores) and distributing them so thinly in myriads of products and
applications that they are no longer easily recoverable.
An
effort to augment the periodic table to show which elements run the risk of
becoming endangered was made in 2011 by Mike Pitts and his colleagues at the
Chemistry Innovation Knowledge Transfer Network. This table shows 44 elements
whose supply is at risk. For some, the risk is more serious than for others –
but there are nine elements for which there is a possible serious threat to
their supply within the next 100 years, and a further seven for which there
is a rising threat due to increased use. Included are all of the rare earth
elements, as well as rhodium, indium, zinc, gallium, germanium, helium,
silver, and even phosphorus.
Rare earths
Particularly
at risk are rare earth elements widely used in cell phones and to power
‘green’ technologies. Each iPhone contains dozens of these. Every new
megawatt of wind power installed requires nearly a tonne of rare earth
permanent magnets. The battery of the world’s most popular hybrid, the Toyota
Prius, contains 10-15 kg of lanthanum (a rare earth) alone.
Though
not particularly rare, the rare earths are not very economic to recover, as
they are not concentrated enough in any one place. The Chinese have a
monopoly with 95% of world supply, and have sold these metals at such low
prices so as to drive other mines around the world out of business. As a
consequence, the world is now almost entirely dependent on one country for
all of its supply – a highly uncomfortable state of affairs, especially as
supply has become ensnared with geopolitics. Interestingly, India has the
potential to emerge as a sizeable supplier, as it is well placed on the
minerals, but it has been unable to capitalize on this strength.
Helium
Helium
is a surprising candidate for the list of endangered elements considering
that it is the second most abundant element in the universe. But its scarcity
is due to wanton usage and its ephemeral nature. The US, which produces 75%
of the world’s helium and maintains one of the largest stores, sets prices
for the element, and these need to go up, scientists say, by as much as fifty
fold, to ensure the inert gas is used more efficiently and reserved for
scientific endeavours like cryogenics and medical research.
Phosphorus
Phosphorus,
a vital fertilizer for modern agriculture, is also listed as a potential future
risk. Availability of rock phosphate – the ore from which most phosphatic
fertilisers are produced – is restricted to just a few places in the world,
with 85% of global reserves in just three countries, led by Morocco. As a
consequence, the fertilizer is increasingly becoming expensive for farmers in
the poorest countries, which has all sorts of adverse implications for soil
fertility and agricultural productivity.
But
the good news on phosphorus is that humans can take control of the phosphorus
cycle and through not-to-complex technological intervention recover &
reuse at least a portion of the element that flows out from animals via urine
and faeces.
Rhodium
Rhodium
is one of the rarest elements in the Earth’s crust – present at a level of
just 0.00002%. 83% of the global production is used in the making the
three-way catalytic converters that tackle harmful emissions of carbon
monoxide and unburned hydrocarbons from automobiles. Other important
industrial uses include catalysts for the manufacture of nitric acid and
hydrogenation of organic compounds; as well as an alloying agent for
hardening & improving the corrosion resistance of platinum and palladium.
Annual word production of rhodium is estimated at about 16-tonnes, and at
current patterns of consumption, there is just about enough to last anywhere
between five and fifty years!
Indium
Indium,
which is produced as a by-product of tin processing, is seeing a spurt in
demand driven by its use to make transparent coatings of indium tin oxide for
use in liquid crystal displays – which accounts for about half of global
indium demand – flat panel displays, touch screens, photovoltaic cells,
‘smart’ windows etc. As it is co-produced with a basic metal like tin, which
markets are growing slower, there is little possibility to ramp up production
to meet rising demand. This makes for very volatile market conditions.
At
the small levels of usage of indium in millions of dispersed units,
recycle and recovery is highly challenging – technically and commercially.
Zinc
Zinc
is the 23rd most abundant element in the earth’s crust, and
its inclusion in the endangered list may also seem surprising. While it makes
up an average of 65-grams of every tonne of the earth’s crust and
commercially exploitable reserves are estimated to exceed 100-mt, its rising
use implies that the world could run out in 5-50 years. One of the biggest
uses of zinc – accounting for nearly half of global consumption – is for
galvanizing of steel to impart corrosion resistance. In addition, zinc is used
in a variety of chemistries and as a catalyst in the form of zinc oxide.
Tin
Tin
has many important uses including its well-known use as a solder for
electronics, and the lesser-known use for making coatings for metals to
combat corrosion. In the chemical industry, tin is used as a catalyst and for
the manufacture of marine anti-fouling agents. Global reserves are largely in
Indonesia and to a lesser extent in China, and will be able to accommodate
just another 15-25 years of use.
Recovery and redesign – new approaches needed
Remarkable
developments in electronics and digital technologies are causing a
substantial dematerialization of modern society. But this trend is
counterbalanced by a marked increase of personal device ownership, most of
which have a dramatically expanded use of chemical elements. Together, these
trends portend cause for concern.
While
the elements of concern will not disappear from the Earth, there will come a
point when supply will be dwarfed by demand, or we will reach the point where
it no longer becomes economically viable to extract or use a particular
element for a particular application. Either way this has the potential to
cause major disruptions in the availability of the many devices that we now
take for granted and for several industrial products and processes, including
many in the chemical industry.
One
way out is for product designers to factor in these concerns in their
innovation programmes and redesign products using alternatives that are more
abundantly available. Far-sighted end-users, aware of the potential risks
from restricted availability of endangered elements, will support such
alternative technologies. Tesla Motors, to cite an example, has deliberately
avoided use of rare earth metals in their all-electric Model S car.
Market
forces – especially strong price signals – can play a role in expansion of
the supply base (as has been seen in the case of shale oil), in developing
substitutes and promoting recycling technologies.
Viewing
the periodic table through the lens of sustainability is an exercise for the
chemical industry too!
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- Ravi Raghavan
CHWKLY
28FEB17
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