Mineral resources are sub-divided, in order of increasing geological confidence, into inferred, indicated and measured categories. It allows for dilution and losses which may occur when the material is mined. Appropriate assessments and studies will have been carried out, and include consideration of realistically assumed mining, metallurgical, economic, marketing, legal, environmental, social and governmental factors. It is commonly asserted that because "the resources of the earth are finite", therefore we must face some day of reckoning, and will need to plan for "negative growth".
All this, it is pointed out, is because these resources are being consumed at an increasing rate to support our western lifestyle and to cater for the increasing demands of developing nations. The assertion that we are likely to run out of resources is a re-run of the "Limits to Growth" argument Club of Rome popularised by Meadows et al in Limits of Growth at that time. It also echoes similar concerns raised by economists in the s, and by Malthus at the end of the 18th Century.
In recent years there has been persistent misunderstanding and misrepresentation of the abundance of mineral resources, with the assertion that the world is in danger of actually running out of many mineral resources. While congenial to common sense if the scale of the Earth's crust is ignored, it lacks empirical support in the trend of practically all mineral commodity prices and published resource figures over the long term.
In recent years some have promoted the view that limited supplies of natural uranium are the Achilles heel of nuclear power as the sector contemplates a larger contribution to future clean energy, notwithstanding the small amount of it required to provide very large amounts of energy.
Uranium supply news is usually framed within a short-term perspective. It concerns who is producing with what resources, who might produce or sell, and how does this balance with demand? However, long-term supply analysis enters the realm of resource economics. Such a focus on sustainability of supply is unique to the long view. Normally-functioning metals markets and technology change provide the drivers to ensure that supply at costs affordable to consumers is continuously replenished, both through the discovery of new resources and the re-definition in economic terms of known ones.
Of course the resources of the earth are indeed finite, but three observations need to be made: first, the limits of the supply of resources are so far away that the truism has no practical meaning. Second, many of the resources concerned are either renewable or recyclable energy minerals and zinc are the main exceptions, though the recycling potential of many materials is limited in practice by the energy and other costs involved. Third, available reserves of 'non-renewable' resources are constantly being renewed, mostly faster than they are used.
What then does sustainability in relation to mineral resources mean? The answer lies in the interaction of these three things which enable usable resources Some licence is taken in the use of this word in the following, strictly it is reserves of minerals which are created effectively to be created. They are brought together in the diagram below. Numerous economists have studied resource trends to determine which measures should best reflect resource scarcity Tilton, J.
On Borrowed Time? Their consensus view is that costs and prices, properly adjusted for inflation, provide a better early warning system for long-run resource scarcity than do physical measures such as resource quantities. Historic data show that the most commonly used metals have declined in both their costs and real commodity prices over the past century.
Such price trends are the most telling evidence of lack of scarcity. An anecdote underlines this basic truth: In two eminent professors, fierce critics of one another, made a bet regarding the real market price of five metal commodities over the next decade.
Paul Ehrlich, a world-famous ecologist, bet that because the world was exceeding its carrying capacity, food and commodities would start to run out in the s and prices in real terms would therefore rise. Julian Simon, an economist, said that resources were effectively so abundant, and becoming effectively more so, that prices would fall in real terms. He invited Ehrlich to nominate which commodities would be used to test the matter, and they settled on these chrome, copper, nickel, tin and tungsten.
In Ehrlich paid up - all the prices had fallen. However, quantities of known resources tell a similar and consistent story. To cite one example, world copper reserves in the s represented only 30 years of then-current production 6. Many analysts questioned whether this resource base could satisfy the large expected requirements of the telecommunications industry by The reserve multiple of current production remained the same.
Another way to understand resource sustainability is in terms of economics and capital conservation. Under this perspective, mineral resources are not so much rare or scarce as they are simply too expensive to discover if you cannot realise the profits from your discovery fairly soon.
Simple economic considerations therefore discourage companies from discovering much more than society needs through messages of reduced commodity prices during times of oversupply. Economically rational players will only invest in finding these new reserves when they are most confident of gaining a return from them, which usually requires positive price messages caused by undersupply trends.
If the economic system is working correctly and maximizing capital efficiency, there should never be more than a few decades of any resource commodity in reserves at any point in time. The fact that many commodities have more resources available than efficient economic theory might suggest may be partly explained by two characteristics of mineral exploration cycles.
First, the exploration sector tends to over-respond to the positive price signals through rapid increases in worldwide expenditures which increases the rate of discoveries , in particular through the important role of more speculatively-funded junior exploration companies. Exploration also tends to make discoveries in clusters that have more to do with new geological knowledge than with efficient capital allocation theory.
As an example, once diamonds were known to exist in northern Canada, the small exploration boom that accompanied this resulted in several large discoveries — more than the market may have demanded at this time. These patterns are part of the dynamics that lead to commodity price cycles.
New resource discoveries are very difficult to precisely match with far-off future demand, and the historic evidence suggests that the exploration process over-compensates for every small hint of scarcity that the markets provide. Another important element in resource economics is the possibility of substitution of commodities.
Many commodity uses are not exclusive — should they become too expensive they can be substituted with other materials. Even if they become cheaper they may be replaced, as technology gains have the potential to change the style and cost of material usage. For example, copper, despite being less expensive in real terms than 30 years ago, is still being replaced by fibre optics in many communication applications.
These changes to materials usage and commodity demand provide yet another dimension to the simple notion of depleting resources and higher prices. In summary, historic metals price trends, when examined in the light of social and economic change through time, demonstrate that resource scarcity is a double-edged sword. The same societal trends that have increased metals consumption, tending to increase prices, have also increased the available wealth to invest in price-reducing knowledge and technology.
These insights provide the basis for the economic sustainability of metals, including uranium. Whatever minerals are in the earth, they cannot be considered usable resources unless they are known. There must be a constant input of time, money and effort to find out what is there. This mineral exploration endeavour is not merely fossicking or doing aerial magnetic surveys, but must eventually extend to comprehensive investigation of orebodies so that they can reliably be defined in terms of location, quantity and grade.
Finally, they must be technically and economically quantified as mineral reserves. That is the first aspect of creating a resource. See section in paper for mineral resource and reserve categories. For reasons outlined above, measured resources of many minerals are increasing much faster than they are being used, due to exploration expenditure by mining companies and their investment in research. Simply on geological grounds, there is no reason to suppose that this trend will not continue.
Today, proven mineral resources worldwide are more than we inherited in the s, and this is especially so for uranium. Simply put, metals which are more abundant in the Earth's crust are more likely to occur as the economic concentrations we call mineral deposits. They also need to be reasonably extractable from their host minerals. By these measures, uranium compares very well with base and precious metals.
Its average crustal abundance of 2. Many common rocks such as granite and shales contain even higher uranium concentrations of 5 to 25 ppm. Also, uranium is predominantly bound in minerals which are not difficult to break down in processing. As with crustal abundance, metals which occur in many different kinds of deposits are easier to replenish economically, since exploration discoveries are not constrained to only a few geological settings.
Currently, at least 14 different types of uranium deposits are known, occurring in rocks of wide range of geological age and geographic distribution. There are several fundamental geological reasons why uranium deposits are not rare, but the principal reason is that uranium is relatively easy both to place into solution over geological time, and to precipitate out of solution in chemically reducing conditions.
This chemical characteristic alone allows many geological settings to provide the required hosting conditions for uranium resources. Related to this diversity of settings is another supply advantage? Unlike the metals which have been in demand for centuries, society has barely begun to utilise uranium. As serious non-military demand did not materialise until significant nuclear generation was built by the late s, there has been only one cycle of exploration-discovery-production, driven in large part by late s price peaks MacDonald, C, Rocks to reactors: Uranium exploration and the market.
Proceedings of WNA Symposium This initial cycle has provided more than enough uranium for the last three decades and several more to come. Clearly, it is premature to speak about long-term uranium scarcity when the entire nuclear industry is so young that only one cycle of resource replenishment has been required.
It is instead a reassurance that this first cycle of exploration was capable of meeting the needs of more than half a century of nuclear energy demand. Related to the youthfulness of nuclear energy demand is the early stage that global exploration had reached before declining uranium prices stifled exploration in the mids. The significant investment in uranium exploration during the exploration cycle would have been fairly efficient in discovering exposed uranium deposits, due to the ease of detecting radioactivity.
Still, very few prospective regions in the world have seen the kind of intensive knowledge and technology-driven exploration that the Athabasca Basin of Canada has seen since This fact has huge positive implications for future uranium discoveries, because the Athabasca Basin history suggests that the largest proportion of future resources will be as deposits discovered in the more advanced phases of exploration.
Another dimension to the immaturity of uranium exploration is that it is by no means certain that all possible deposit types have even been identified. Any estimate of world uranium potential made only 30 years ago would have missed the entire deposit class of unconformity deposits that have driven production since then, simply because geologists did not know this class existed. It is meaningless to speak of a resource until someone has thought of a way to use any particular material.
In this sense, human ingenuity quite literally creates new resources, historically, currently and prospectively. That is the most fundamental level at which technology creates resources, by making particular minerals usable in new ways.
Often these then substitute to some degree for others which are becoming scarcer, as indicated by rising prices. Uranium was not a resource in any meaningful sense before By any reasonable definition, nuclear breeder reactors are indeed renewable. However, billion-year sustainability does require advances in seawater uranium extraction , reactor construction performance , and public acceptance.
We have developed breeder reactors in the past , but they remain a small minority of our current fleet. We are talking about all primary energy here rather than just electricity. The rest is for transportation, industrial heat, etc.
This is available for free on Windows, Linux, and Mac. Because non-breeders are x less fuel efficient than breeders, it has long been considered impractical to use low-grade uranium resources like seawater or crustal nuclear fuel in non-breeders. The energy to get the material out is too high given the return. Breeders with mined, seawater, and erosion resources, assuming about half the erosion resource will reach the sea:. Assuming big gigawatt-scale reactors, we find:.
Another nearly unbelievable fact HT reddit user paulfdietz is that if you dig up an average crustal rock, it will have 20x more nuclear energy in it than a piece of pure coal of the same mass. With crustal abundances of 2. Two technologies could greatly extend the uranium supply itself. Neither is economical now, but both could be in the future if the price of uranium increases substantially.
First, the extraction of uranium from seawater would make available 4. Second, fuel-recycling fast-breeder reactors, which generate more fuel than they consume, would use less than 1 percent of the uranium needed for current LWRs. Breeder reactors could match today's nuclear output for 30, years using only the NEA-estimated supplies. Editor's Note: This question was submitted by G. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue.
0コメント