(This was published in Chemistry and Industry, 25th August 2008, p21).
(This was published in Chemistry and Industry, 25th August 2008, p21).
By Chris Rhodes.
We live on a planet with finite resources, and yet consume them with alacrity in the false assumption of limitless expansion. Demand for metals rises inexorably due in large part to roaring economic growth in China and India, at a level that production of them struggles to meet. In consequence, the price of copper and iron ore has doubled during the past two years. The price of rhenium, used for highly fuel-efficient aircraft engines, has jumped to a record $11,250 per kilogram, which is almost twelve-times its price in 2006. Indeed, it is now only half the price of gold, which is a major boon to the main countries that mine rhenium-ore: Chile and Kazakhstan. Reserves of indium, used for solar cells and LCD's along with those of hafnium, an essential component of computer-chips and also employed as a thermal-neutron absorber in nuclear control-rods, may literally run-out within 10 years.
Some salient points about potential metals shortages1 are apparent from the list of elements in Box 1, which gives the world total reserve of each, the expected time of exhaustion based on current rates of production and their principal uses. The figures therein are based on known reserves, noting that more might be found if they were explored for with sufficient assiduousness. However, emerging new technologies and a growing world population, mean that some key-metals are likely to be exhausted more quickly, as indicated in Box 2.
The reserve lifetime of a resource (also known as the R/P ratio) is defined as the known economically recoverable amount (R) divided by the current rate of use (P) of it, hence the values in Box 1 and Box 2. Economics predicts that as the lifetime of a reserve shortens so its price increases. Consequently, demand for that reserve decreases and other sources, once thought too expensive, enter the market. This tends to make the original reserve last longer, in addition to the volume of the new reserves. For example, there is enough bauxite reckoned to provide aluminium for 70 years, but the latter is an abundant element and there are many alternative known sources of it, thought to add-up to over 1000 years worth. In practice many other factors are involved, particularly geopolitical situations, but the basic geological fact remains: reserves are limited and hence their present patterns of consumption and growth are not sustainable over the longer term. While some elements are very plentiful compared to the total amount of them required, the rate at which they can be recovered sets a limit on how quickly a given reserve can be exploited. Recovering platinum to make fuel-cells is a good such example2.
The majority (88%) of the world's platinum is produced from just two mines in South Africa and most of the rest (8%) from one other mine in Russia. Since platinum is recovered at a rate of about 200 tonnes per year, even if all of it were used to make fuel-cells, this is only enough to equip 2 million fuel-cell powered cars, or just 5.7% of the world's current road-fleet of 700 million vehicles by 2028, by when conventional crude-oil production will be reduced to perhaps half its present level and the cost of a barrel of oil is anyone's guess. The previous sum assumes that humanity would be prepared to turn-over all its "new" platinum annually for making fuel cells, thus sacrificing the creation of any new jewelry or catalytic converters to clean emissions from existing oil-powered engines, each of which accounts for 40% of the current world platinum market. Hence the real number of fuel cells made would be far less. The process of separating pure platinum from its ore (at a yield of 3 grammes per tonne) is complex and exacting and it is unlikely that it can be recovered much faster than now.
Peak Oil - Peak Minerals.
According to the Hubbert theory3, all resources are finite and will ultimately be extracted only to the limit where it is feasible to do so, whereupon either financial costs or those of energy dictate that to proceed further only yields diminishing returns. The Hubbert theory was originally applied to oil, in which the production curve "peaks" at the point of maximum output (when half the original resource has been used), beyond which it falls remorselessly. Similar fits can also be made to gas and coal production data and a recent analysis was reported using the approach to a study4 of 57 different minerals by Ugo Burdi and Marco Pagini. These authors have fitted both logistic and Gaussian functions to mineral production data from the United States Geological Survey (USGS), and it is interesting that for mercury, lead, cadmium and selenium, there is good accord found between the "ultimate recoverable resources" URR determined from the curve-fitting to the data and those reported as remaining in the USGS tables (plus the amount of each already extracted). For tellurium, phosphorus, thallium, Zircon(ium) and rhenium, the agreement is quite close but tends to smaller values than are indicated from the figures for cumulative production plus the USGS reserves. For gallium, the figure obtained from the fitting analysis is significantly lower than the USGS estimate (by about a factor of seven).
Evidence of peaking is found for a number of minerals, e.g. mercury around 1962; lead in 1986; Zircon in 1990; selenium in 1994; gallium in 2000. The results for gallium are significant, both in that the peak occurred seven years ago and in the size of its total reserve, which when compared with the amount used worldwide by the electronics industry implies that we may run short of gallium any time soon. Tellurium and selenium are two other minerals that underpin the semiconductor industry and it appears that their fall in production may also impact negatively on future technologies that are entirely reliant upon them, since there are no obvious substitute materials with precisely equivalent properties.
For vanadium, although a production peak is indicated in 2005, the data in the "mineral commodities handbook" show a later and sudden surge in production, which is not fully explained but thought may potentially relate to uncertainties in reporting from countries like China. So, there may be a real and ongoing upsurge in production from e.g. the Chinese economy which is quoted as being "out of sync" with the rest of the world, such is its massive expansion, or it might be a red herring.
Interestingly, copper, zinc, tin, nickel and platinum show an almost exponential increase in production; however, as I have noted, the stocks of some metals may be insufficient to supply the technological demands of the modern developed world into the far (or even near) future. There is also the issue of how quickly a rare and difficultly extractable metal such as platinum might be produced in comparison with an overall demand for it. Copper production can be fitted with an exponential function up to 2006, while a logistic function provides about the same quality of fit, yet indicates a peak in about 2040. The latter agrees reasonably well with the USGS estimated copper reserves of 0.5 - 1.0 Gigatons, while the fit gives 2 Gigatons. Notably, the world price of copper has skyrocketed during the past few years, which is again attributed to demand in China, as was the cost and shortage of wood earlier in the year.
The above analyses rest upon the case that the determined "peaks" represent actual global production maxima. Indeed, more reserves of all minerals may yet be found if we look assiduously enough for them; but herein lies the issue of underpinning costs, both in terms of finance and energy. It is the latter that may determine the real peaking and decline of minerals, which extend beyond the simple facts, say, of mining and refining a metal from its crude ore. There is also the cost-contribution from the energy needed to garner energy-materials such as oil, gas, coal and uranium, and thence to turn them into power and machinery; and since fossil fuels are being relentlessly depleted, it takes an inexorable amount energy to produce them, resulting in a cumulative and rising energy demand overall.
The whole "extractive system" is interconnected through required underpinning supplies of fossil fuels, and it is perhaps this that explains why the production of so many minerals seems to be peaking during the period between the latter part of the 20th century and the start of the 21st, in a virtual mirror-image of the era when troubles in the production of fossil fuels were experienced across the globe. Hence, it may be the lack of fossil fuels which determines the real amount of all other minerals that can be brought onto the world markets4.
The Role of Recycling.
In the face of resource depletion, recycling looks increasingly attractive. In this stage of development of the throw-away society, now might be the time to begin "mining" its refuse. A recent analysis has shown part-per-million (p.p.m.) quantities of platinum in road-side dust1, which is similar to the 3 p.p.m. concentration in South African platinum ore. It is suggested that extracting platinum from this dust, which originates in catalytic converters, might prove lucrative and would expand the limited amount of platinum available, which even now does not meet demand for it. Discarded cell-phones too, might be a worthwhile source. For metals such as hafnium and Indium, recycling is the only way to extend the lifetime of critical sectors of the electronics industry. This is true also of gallium, tellurium and selenium, since all of them are past their production peak, which forewarns of imminent potential production shortages and escalating prices. While recycling of base-metals from scrap is a mature part of an industry worth $160 billion per year, current efforts to recover and recycle rare-metals are far less well advanced. However, in view of its present high-price, rhenium is now recovered from scrap bimetallic catalysts used in the oil refining industry. I expect to see an expansion of this top-end of the metals-market since rising demand for rare-metals will confer highly lucrative profits. It might be argued that we will never "run-out" of metals because their atoms remain intact, but the more dispersion that occurs in converting concentrated ores into final products, the more difficult and hence energy intensive it becomes to reclaim those metals in quantity. In a sense the problem is the same as deciding which quality of ore to mine in the first place: we now need to either find richer sources to recycle from or arrange how we use these materials in the first place to facilitate recycling. Ultimately, recycling needs to be deliberately designed into an integrated paradigm of extraction, use and reuse, rather than treating it as an unplanned consequence.
(1) D.Cohen, "Earth Audit", New Scientist, 26th May 2007, p. 35.
(2) C.J.Rhodes, "Energy Balance": http://ergobalance.blogspot.com
(3) M.K.Hubbert, “Nuclear Energy and the Fossil Fuels.” Presented before the Spring meeting of the Southern District, American Petroleum Institute, Plaza Hotel, San Antonio, Texas, March 7-9, 1956.
(4)"Peak Minerals", By U.Bardi and M.Pagani. http://www.theoildrum.com/node/3086.
Box 1. Metals under threat: the world total reserve of each, and the expected time of exhaustion based on current rates of production and their principal uses.
Aluminium, 32,350 million tonnes, 1027 years (transport, electrical, consumer-durables)
Arsenic, 1 million tonnes, 20 years (semiconductors, solar-cells)
Antimony, 3.86 million tonnes, 30 years (some pharmaceuticals and catalysts)
Cadmium, 1.6 million tonnes, 70 years (Ni-Cd batteries)
Chromium, 779 million tonnes, 143 years (chrome plating)
Copper, 937 million tonnes, 61 years (wires, coins, plumbing)
Germanium, 500,000 tonnes (US reserve base), 5 years (semiconductors, solar-cells)
Gold, 89,700 tonnes, 45 years (jewelry, "gold-teeth")
Hafnium, 1124 tonnes, 20 years (computer-chips, nuclear control-rods)
Indium, 6000 tonnes, 13 years (solar-cells and LCD's)
Lead, 144 million tonnes, 42 years (pipes and lead-acid batteries)
Nickel, 143 million tonnes, 90 years (batteries, turbine-blades)
Phosphorus, 49,750 million tonnes, 345 years ( fertilizer, animal feed)
Platinum/Rhodium, 79,840 tonnes, 360 years for Pt (jewellery, industrial-catalysts, fuel-cells, catalytic-converters)
Selenium, 170,000 tonnes, 120 years (semiconductors, solar-cells)
Silver, 569,000 tonnes, 29 years (jewellery, industrial-catalysts)
Tantalum, 153,000 tonnes, 116 years, (cell-phones, camera-lenses)
Thallium, 650,000 tonnes, 65 years (High Temperature Superconductors, Organic Reagents)
Tin, 11.2 million tonnes, 40 years, (cans, solder)
Uranium, 3.3 million tonnes, 59 years (nuclear power-stations and weapons)
Zinc, 460 million tonnes, 46 years (galvanizing).
Box 2. It is predicted that the growth in world population, along with the emergence of new technologies will result in some key-metals being used up quite rapidly, e.g.
Antimony, 15 - 20 years.
Hafnium, 10 years.
Indium, 5 - 10 years.
Platinum, 15 years.
Silver, 15 - 20 years.
Tantalum, 20 - 30 years.
Uranium, 30 - 40 years.
Zinc, 20 - 30 years.