The Club of Rome view is that the future of humanity will be dismal. Yet a glance at the earth's mineral resources show that several important resources are available in great abundance, enough to make their use sustainable for the period of human habitation on the earth. The question then becomes whether there are enough of the right sort of resources to sustain an advanced materially oriented civilization over a long period of time. I intend to argue that the answer is yes.
Extracting minerals from the Earth's crust would not be possible without energy, and it is my contention that the energy present in the earth's crust in the form or Thorium, and Uranium is sufficient to last us to the end of our days as living beings on earth. Nor would it take a great deal of energy to extract thorium from the earth's crust. We have don it already in abundance and thrown it away. The World nuclear Association notes:
In Victoria, 65 million tonnes of brown coal is burned annually for electricity production. This contains about 1.6 ppm uranium and 3.0-3.5 ppm thorium, hence about 100 tonnes of uranium and 200 tonnes of thorium is buried in landfill each year in the Latrobe Valley. Australia exports 235 Mt/yr of coal with 1 to 2 ppm uranium and about 3.5 ppm thorium in it, hence up to 400 tonnes of uranium and about 800 tonnes of thorium could conceivably be added to published export figures.1200 tons of Thorium a year would be sufficient to provide the United States with all the energy it needs to power its economy. The world's fly and bottom ash mountain has already been mined, so extracting it from the earth would not require any energy. Thorium and uranium can be recovered from ash piles at highly favorable Energy Returned on Energy Invested, using acid extraction techniques. The world's economy can be operated at energy levels found now in Western Europe with the energy from 12000 tons of thorium. Thus twice the energy the world needs to assure every man woman an child on this planet a satisfactory level of material comfort is being thrown away every year in the form of thorium left in cola ash waste.
Other coals are quoted as ranging up to 25 ppm U and 80 ppm Th. In the USA, ash from coal-fired power plants contains on average 1.3 ppm of uranium and 3.2 ppm of thorium, giving rise to 1200 tonnes of uranium and 3000 tonnes of thorium in ash each year (for 955 million tonnes of coal used for power generation). Applying these concentration figures to world coal consumption for power generation (7800 Mt/yr) gives 10,000 tonnes of uranium and 25,000 tonnes of thorium per year.
Coal ash waste is hardly the only out of ground source of now wasted thorium. Recoverable concentrations of thorium, millions of tons. are found in phosphate mine tailings, uranium mine tailings, and tin mine tailings. There is an enormous amount of Thorium in granite at a concentration that can be recovered at a very favorable EROEI. Granite used in construction and for decorative purposes in building typically has a thorium content of around 17 ppm. Thorium at that concentration is recoverable with quite favorable EROEI. Huge granite formation contain thorium at concentrations of about 50 ppm. We could supply all of the world's energy needs at abundant levels for hundreds of years without any mining. All we need to do is to recover the thorium that we now treat as waste.
I might add that Uranium is also present in recoverable amounts from the sources I have mentioned, and a Uranium based energy economy would be sustainable as well. I favor thorium because the thorium fuel cycle is more efficient than the uranium fuel cycle - efficiency as measured by its neutron economy - and hence the thorium cycle solves the problem of nuclear waste without resorting to expensive, technically difficult and potentially dangerous nuclear technology.
In 1968 the USAEC estimated the amount of thorium in the United States that could be recoverable if the price of thorium were $500 a pound to be 3 billion tons. Five hundred 1968 US dollars would be the equivalent of two thousand 2008 US dollars. Lest the reader think that this cost is extremely expensive, two thousand dollars today would buy 20 tons of coal, while the pound of thorium would containthe same amount of energy as 1500 tons of coal. Thus thorium has the potential to be a very low cost energy source.
Lowering the cost of energy from the thorium cycle would be a reason for choosing LFTR technology.
What can we do with low cost energy from thorium?
A little over a generation ago Alvin Weinberg together with H. E. Goeller set out to investigatethe Club of Rome's claims about the impending doom of human civilization. In a little noted paper, titled "Age of substitutability: or what do we do when the mercury runs out", they argued that what was needed to maintain civilization was "an
inexhaustible source of energy".
Most of the minerals that man uses - iron ore, carbon dioxide, and alumina - are found in nature 'in an oxidized state, or more generally, in a state of relatively hish entropy. To reduce these materials, i.e., to extract iron, to convert C02 t o cellulose, or to change alumina to aluminum, ,.. requires energy (more accurately, free energy). Thus man's economicGeoller and Weinberg pointed to one "inexhaustible" sources of energy, the breeder reactor, and by breeder they were not referring to the Liquid Metal Fast Breeder, they were refeering to what they would have called the Molten Salt Breeder, that is a Liquid Fluoride Thorium Breeder reactor.
transaction with nature involves expenditure of free energy; and as his high-grade resources dwindle, he expends more energy.
Geoller and Weinberg pointed out an absurdity of The Limits of Growth, the claim that
"The effect of exponential growth is to reduce the probable period of availability ofYet the supply of Aluminum in the earths crust was inexhaustible in human terms as can be seen above. Quoting geologist Dean F. Frasche, Geoller and Weinberg
aluminum from 100 years to 31 years.''
"Total exhaustion of any mineral resource will never occur. Minerals, and rocks that are unexploited will always remain in the earth's crust. The basic problem is how to avoid reaching a point where the cost of exploiting those mineral deposits which remain will be so costly, due to depth, size, or grade, that we cannot produce what we need without completely disrupting our.socia1 and economic structures."
There would be three stages of progressively greater resource scarcity, Geoller and Weinberg argued.
In Stage one, our present patterns of non-renewable resources would continue, but would run its course sometime between 2005 and 2025.
In Stage two fossil fuels would be increasingly exhausted, and the use of more exotic metals would decline with steel alloiys playing an increasingly important role.
In Stage II fossil fuels would be exhausted and the material basis of society would rely on inexhaustible resources.
In Stage III, inexhaustible resources will be substituted for exhausted resources.
insofar as limits to mineral resources can be discerned, the condition of life in Stage 111, the Age of Substitutability, will not be drastically different from our preserlt condition of life: we have the physical possibility of living in the Age of Subititutability without "completely disrupting our social and economic structure". To reach this state without immense social disruption will, however, require unprecedented foresight and planning.They add
Let 'us now state the Principle of "Infinite" Substitutability: with two notable exceptions - phosphorous and energy-producing fossil fuels, i.e, CH, the society can subsist with relatively little loss of living standard on infinite or near-infinite minerals. Such a civilization would be based largely on glass, plastic, wood, cement, iron, aluminum, and magnesium: whether it will be anything like our present society will depend upon how much of the ultimate raw material , energy, we can produce - and how much energy will cost, both economically and environmentally.Thus a high standard of living is possible for all people on earth with the long term resources that humans will have at their disposal over the millions of years. There are however, implications for agriculture:
With regard to the trace elements 'which are present in the soils and are needed only at low concentrations, modern agriculture slowly depletes soil of these elements. In the near term, shortages can undoubtedly be supplied from inorganic sources; in the long run, we will be forced to return agricultural and animal wastes to the soil, particularly for the trace elements with limited resources such as copper, zinc, and cobalt.The gap between preferred materials and available resources thus can be resolved in two ways:
1. By recycling
2. By substitution.
The survival of Civilization would not be sustainable without be possible without unlimited energy, and As I have already pointed out Alvin Weinberg believed that the best source of sustainable would be found in the use of the thorium fuel cycle, in the Liquid Fluoride Thorium Reactor.
Tomorrow I hope to explain why, in Weinberg's view, the LFTR was greener than the Sun.