[Reader-list] Earth's natural wealth

[Nagraj Adve]

A not-ecent piece, but worth having a look at.
Naga


 Earth's natural wealth: an audit

   - New Scientist, 23 May 2007 by *David
Cohen*<http://www.newscientist.com/search?rbauthors=David+Cohen>

 "I GET excited every time I see a street cleaner," says Hazel Prichard.
It's what they collect in their sacks that gets her juices flowing, because
the grime and litter they sweep up off the streets is laced with traces of
platinum, one of the world's rarest and most expensive metals. The catalytic
converters that keep exhaust pollutants from cars, trucks and buses down to
an acceptable level all use platinum, and over the years it is slowly but
steadily lost through these vehicles' exhaust pipes. Prichard, a geologist
at the University of Cardiff in the UK, reckons that tonnes of the stuff is
being sprayed out onto the world's streets and highways every year, and she
is hunting for places where it is concentrated enough to be worth
recovering. One of her prime targets is the waste containers in
road-sweeping machines.

This could prove lucrative, but Prichard is motivated by something far more
significant than the chance of a quick buck. Platinum is a vital component
not only of catalytic converters but also of fuel cells - and supplies are
running out. It has been estimated that if all the 500 million vehicles in
use today were re-equipped with fuel cells, operating losses would mean that
all the world's sources of platinum would be exhausted within 15 years.
Unlike with oil or diamonds, there is no synthetic alternative: platinum is
a chemical element, and once we have used it all there is no way on earth of
getting any more. What price then pollution-free cities?

It's not just the world's platinum that is being used up at an alarming
rate. The same goes for many other rare metals such as indium, which is
being consumed in unprecedented quantities for making LCDs for flat-screen
TVs, and the tantalum needed to make compact electronic devices like
cellphones. How long will global reserves of uranium last in a new nuclear
age? Even reserves of such commonplace elements as zinc, copper, nickel and
the phosphorus used in fertiliser will run out in the not-too-distant
future. So just what proportion of these materials have we used up so far,
and how much is there left to go round?

Perhaps surprisingly, given how much we rely on these elements, we can't be
sure. For a start, the annual global consumption of most precious metals is
not known with any certainty. Estimating the extractable reserves of many
metals is also difficult. For rare metals such as indium and gallium, these
figures are kept a closely guarded secret by mining companies. Governments
and academics are only just starting to realise that there could be a
problem looming, so studies of the issue are few and far between.

Armin Reller, a materials chemist at the University of Augsburg in Germany,
and his colleagues are among the few groups who have been investigating the
problem. He estimates that we have, at best, 10 years before we run out of
indium. Its impending scarcity could already be reflected in its price: in
January 2003 the metal sold for around $60 per kilogram; by August 2006 the
price had shot up to over $1000 per kilogram.

Uncertainties like this pose far-reaching questions. In particular, they
call into doubt dreams that the planet might one day provide all its
citizens with the sort of lifestyle now enjoyed in the west. A handful of
geologists around the world have calculated the costs of new technologies in
terms of the materials they use and the implications of their spreading to
the developing world. All agree that the planet's booming population and
rising standards of living are set to put unprecedented demands on the
materials that only Earth itself can provide. Limitations on how much of
these materials is available could even mean that some technologies are not
worth pursuing long term.

Take the metal gallium, which along with indium is used to make indium
gallium arsenide. This is the semiconducting material at the heart of a new
generation of solar cells that promise to be up to twice as efficient as
conventional designs. Reserves of both metals are disputed, but in a recent
report Ren� Kleijn, a chemist at Leiden University in the Netherlands,
concludes that current reserves "would not allow a substantial contribution
of these cells" to the future supply of solar electricity. He estimates
gallium and indium will probably contribute to less than 1 per cent of all
future solar cells - a limitation imposed purely by a lack of raw material.

To get a feel for the scale of the problem, we have turned to data from the
US Geological Survey's annual reports and UN statistics on global
population. This has allowed us to estimate the effect that increases in
living standards will have on the time it will take for key minerals to run
out (see Graphs). How many years, for instance, would these minerals last if
every human on the planet were to consume them at just half the rate of an
average US resident today?

The calculations are crude - they don't take into account any increase in
demand due to new technologies, and also assume that current production
equals consumption. Yet even based on these assumptions, they point to some
alarming conclusions. Without more recycling, antimony, which is used to
make flame retardant materials, will run out in 15 years, silver in 10 and
indium in under five. In a more sophisticated analysis, Reller has included
the effects of new technologies, and projects how many years we have left
for some key metals. He estimates that zinc could be used up by 2037, both
indium and hafnium - which is increasingly important in computer chips -
could be gone by 2017, and terbium - used to make the green phosphors in
fluorescent light bulbs - could run out before 2012. It all puts our present
rate of consumption into frightening perspective (see Diagram).

Our hunger for metals and minerals may not grow indefinitely, however. When
Tom Graedel and colleagues at Yale University looked at figures for the
consumption of iron - one of our planet's most plentiful metals - they found
that per capita consumption in the US levelled off around 1980. "This
suggests there might be only so many iron bridges, buildings and cars a
member of a technologically advanced society needs," Graedel says. He is now
studying whether this plateau is a universal phenomenon, in which case it
might be possible to predict the future iron requirements of developing
nations. Whether consumption of other metals is also set to plateau seems
more questionable. Demand for copper, the only other metal Graedel has
studied, shows no sign of levelling off, and based on 2006 figures for per
capita consumption he calculates that by 2100 global demand for copper will
outstrip the amount extractable from the ground.

So what can be done? Reller is unequivocal: "We need to minimise waste, find
substitutes where possible, and recycle the rest." Prichard, working with
Lynne Macaskie at the University of Birmingham in the UK, has found that
platinum makes up as much as 1.5 parts per million of roadside dust. They
are now seeking out the largest of these urban platinum deposits, and
Macaskie is developing a bacterial process that will efficiently extract the
platinum from the dust.

Other metals could be obtained in equally unorthodox places. Cities are huge
stores of metals that could be repurposed, Kleijn points out. Replacing
copper water pipes with plastic, say, would free up large quantities of
copper for other uses. Tailings from worked-out mines contain small amounts
of minerals that may become economic to extract. Some metals could be taken
from seawater. "It's all a matter of energy cost," he says. "You could go to
the moon to mine precious materials. The question is: could you afford it?"

These may sound like drastic solutions, but as Graedel points out in a paper
published last year (*Proceedings of the National Academy of Sciences*, vol
103, p 1209), "Virgin stocks of several metals appear inadequate to sustain
the modern 'developed world' quality of life for all of Earth's people under
contemporary technology." And when resources run short, conflict is often
not far behind. It is widely acknowledged that one of the key motives for
civil war in the Democratic Republic of the Congo between 1998 and 2002 was
the riches to be had from the country's mineral resources, including
tantalum mines - the biggest in Africa. The war coincided with a surge in
the price of the metal caused by the increasing popularity of mobile phones
(*New Scientist*, 7 April 2001, p 46).

Similar tensions over supplies of other rare metals are not hard to imagine.
The Chinese government is supplementing its natural deposits of rare metals
by investing in mineral mines in Africa and buying up high-tech scrap to
extract metals that are key to its developing industries. The US now imports
over 90 per cent of its so-called "rare earth" metals from China, according
to the US Geological Survey. If China decided to cut off the supply, that
would create a big risk of conflict, says Reller.

Reller and Graedel say urgent action is required. Firstly, we need accurate
estimates of global reserves and precise figures for consumption. Then we
need to set up an accelerated programme to recycle, reuse and, where
possible, replace rare elements with more abundant ones. Without all this,
any dream of a more equitable future for humanity will come to nothing.

Governments seem, at last, to be taking the issue seriously, and next month
an OECD working group will be convened to come up with some of the answers.
If that goes to plan, we will soon at least have a clearer idea of the
problem. Whether any solution to looming global shortages can then be found
remains to be seen.