The Real World Thorium Reserve

In 1956 M. King Hubbert foresaw the peaking of oil production. At the same time he believed that energy from thorium and uranium could be substituted for fossil fuels. He argued in his famous paper:

“[T]he fissioning of 1 gram of U-235 releases 2.28 x 104 kw-hr of heat, which is equivalent to the heat of combustion of 3 tons of coal or of 13 barrels of oil. One pound of U-235 is equivalent to 1400 tons of coal or 6000 barrels of oil. Within narrow limits the same values are valid for U-238 and for thorium.”

Using this information, Hubbert calculated that “[t]he energy of 358,000 metric tons . . . of uranium is equal to that of all the fossil-fuel reserves of the United States.”

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Hubbert then noted that even low grade uranium and thorium ores such as the phosphate rocks and the black shales have uranium content that ranges from 10 to 300 grams per ton.

Hubbert then stated, “such rocks are equivalent to 90 to 900 tons of coal or 390 to 3900 barrels of oil per metric ton for the phosphates, and to 30 to 300 tons of coal or 130 to 1300 barrels of oil per metric ton of rock, for the black shales. Even granite, as has been pointed out by Harrison Brown (1954) and by Brown and Silver (1955), contains about 13 grams of thorium and 4 grams of uranium per ton, which is equivalent to about 50 tons of coal or 220 barrels of petroleum per metric ton of granite.”

It is quite clear from Hubbert’s assessment that mining “so called low grade uranium and thorium orei would be highly profitable from an EOEI viewpoint.

In 1956 Hubbert believed that “Well-defined thorium deposits . . . are comparatively rare,” but in the early 1960’s geologists from Rice University, under contract from Oak Ridge National Laboratory set out to explore the thorium resources of the White Mountains of Vermont.

Geologists J. A. S. Adams, M.-C. Kline, K. A. Richardson, and J. J. W. Rodgers conducted the investigation. Their investigation centered on Conway Granite, an outcropping in Vermont, as much as a half mile thick, and 300 square miles in area. Their findings from drilling 3 holes onto the granite outcropping were that thorium concentrations were uniformly 56 plus or minus 6 ppm. Extrapolated to the whole mass, this meant that the Conway granite mass contained more than “3 X 106 metric tons per 100 feet of depth.” Using 1960’s leaching technology, ORNL scientists were able to extract 2/3 of the thorium from the rock. No doubt 21st century leaching technology would yield higher recovery totals, at lower costs.

The Rice geologists reported:
“The costs of extracting the uranium and thorium from the Conway granite are estimated by workers at the Oak Ridge National Laboratory to be less than $100/pound, or at most five to ten times the present costs of nuclear raw materials. This source of nuclear fuels, therefore, is currently uneconomic compared to the sources now being utilized. In terms of total energy content, however, the Conway granite represents an energy resource several orders of magnitude larger than the lower cost material. In the long-term future, when supplies of cheap uranium and thorium may start to be exhausted, sources such as the Conway granite may become increasingly important and necessary.”

They concluded:
“Thus the importance of the present work on the Conway granite lies in the indication that tens of millions of tons of thorium are available when the need for vast amounts of higher-cost nuclear fuel becomes pressing. These amounts may be compared to the few hundreds of thousands of tons of previously estimated thorium reserves. It is reassuring to know that the long-term future of nuclear power is not limited by the supply or by a prohibitively high cost of fuel. Furthermore, the Conway granite may become even more important considering the likelihood that improved extraction techniques may make the thorium available at costs well below the $100/pound estimated in preliminary laboratory experiments. It is also possible that larger amounts of lower-cost thorium might be realized by locating high-grade ore reserves such as the Lemhi Pass, Idaho, area may prove to be, or by finding a large granitic batholith more economic than the Conway.”

“Finally, it should be noted that the statistical and exploration techniques developed in the present work and described above, particularly the portable gamma-ray spectrometer, may make it possible to explore for thorium and develop reserves far more cheaply and rapidly than was the case for uranium.”

The 1962 Rice University report was submitted to PNAS (Proceedings of the National Academy of Sciences) by M. King Hubbert.

Conrad Windham has recently reported a confirmed thorium reserve of 600,000 tons, and a probable reserve of 3 million tones at Lemhi Pass on the Idaho/Montana border. 600,000 tons is twice the textbook reported US thorium reserve, and 3 million tones is larger than the total textbook world thorium reserve.

An Australian government reports on Australian thorium supplies states, “Exploration for thorium to date has been minimal and there are no comprehensive records of resources, mainly because of a lack of large-scale commercial demand.” What is true of Australia is also true of the United States, and indeed the rest of the world.

Since world uranium resources are practically limitless, and thorium is three to four times more plentiful than uranium, thorium can supply the world with a very large amount of energy for tens of thousands of years.

Update: The link to Conrad Windham's claims about the Lemhi Pass thorium reserve has been broken. Another report by Thorium Energy indicate a far more modest reserve.