Our modern materialistic world is so busy inventing and re-inventing itself in novel technological ways that we pay little attention to the reality of limits. As we continue to dig for the metals that we need to make our innumerable products, we hardly give a thought to the reserves of these vital and non-renewable resources.
Not everyone, however, has forgotten that we live on a finite planet. Armin Reller is a materials chemist from the University of Augsburg in Germany. He and his colleagues have been wondering how much longer our supply of metals will be able to feed the voracious appetite of a growing world population needing increasing quantities to support consumer lifestyles (New Scientist, May 26/07).
Consider indium, a rare metal that is used in making LCD flat screens for computers and TVs. In 2003, it was selling for $60/kg; by 2006, the price had skyrocketed to over $1,000/kg. Reller and his team calculate that, at present rates of consumption, we have 13 years of available indium before supplies are exhausted.
Even supplies of gold, the most ubiquitous of rare metals, may be coming to an end. We have already mined about 150,000 tonnes of it since the beginning of history, approximately half the estimated global supply. According to Reller's estimates, at present rates of mining and consumption, we could exhaust the rest in 45 years.
Or consider platinum, one of the scarcest and most expensive of the rare metals. In addition to other special uses, a few grams of it are in the catalytic converter in most car exhaust systems. It is also a key component in fuel cells. Should we reach a time when the world's cars are powered by such cells, the planet's platinum supplies would be depleted in 15 years. Indeed, at about $50,000/kg, platinum is now so valuable that street dust, with its traces of 1.5 parts per million from catalytic converters, is now being considered as one of the richest sources of the rare metal. In a new field for crime, thieves are now stealing catalytic converters from cars for the few grams of platinum contained in them.
The rising incidence of metal theft is a measure of its growing value. Electrical power companies such as BC Hydro are losing copper and aluminum from workyards and substations. Even powerlines have fallen victim to thieves. Copper wiring and piping are being stolen from buildings under construction. Bronze, brass, aluminum and other metals are commonly removed from public and private objects accessible to thieves.
While theft is a function, together with other social factors, of the price of metals, the price, in turn, is a function of supply and demand. As demand strengthens and supply weakens, metals become the target of criminals.
But demand does not always increase indefinitely. A study by Tom Graedel and his colleagues at Yale University (Ibid.) found that per capita consumption of iron in the US reached a plateau in 1980. But most metal consumption continues to rise, and they calculate that demand for copper will outstrip supply by 2100. And rare metals are being used in increasing amounts as we become more technologically sophisticated.
Estimates for the remaining supplies of metals do not look particularly threatening if we consider only the immediate future. At present rates of consumption, chromium supplies could last 143 years, platinum 360 years, phosphorus 345 years and aluminum 1027 years. But 90 years for nickel, 42 for lead, 46 for zinc, 40 for tin and 29 for silver are worrisome. A 59 year estimated supply of uranium has serious implications if nuclear power stations are to supply our future energy needs. But increasing demand could exhaust platinum supplies in a mere 15 years, indium in 10, silver in 20, zinc in 30 and uranium in 40 years.
Uranium, of course, gets consumed by its use. But many metals can be recycled. According to Reller and his team, the following are the present recycling rates for the obvious ones: copper 31%, nickel 35%, silver 16%, tin 26%, zinc 26%, gold 43%, aluminum 49%, lead 72% and chromium 25%. Phosphorus, platinum and indium are presently 0%.
Eventually, however, recycling of metals will not be optional; it will be critical and strategically imperative. All metals will be treated as "cradle-to-cradle" resources with no end use. Products will only "borrow" the metals they contain. Energy efficiencies will also demand recycling. Potential ecological damage will increasingly constrain mining activities in sensitive locations. Cities, with their vast stores of metals may be "mined" when replacement materials are available ‹ networks of copper piping could be replaced with plastic. Existing landfills might become future mining sites. Mine tailings, now considered waste, could be re-processed for their metals. Bacteria might extract metals from micro-deposits. And some metals may be recoverable from seawater.
Clearly, however, the rising demand for a finite supply of metals could thwart technological development, stress living standards and precipitate geo-political conflicts. We need to anticipate these consequences and accelerate preventative measures. Although the assessment by Reller and his colleagues may not be definitive, it is certainly thought provoking. And in a world of limits, add metals to the growing list of things that demand our attention.