Since controlled fusion has not yet been achieved, and may never be, only a brief mention of this potential source of energy will here be made. Initially, the most promising fusion reaction is one involving both D and eLi. However, the total known and inferred supply of ®Li in areas outside the Communist countries amounts to only about 7 x 10s4 eLi atoms, whereas the deuterium in the oceans amounts to about 1.5 x 1048 atoms, or about 109 times the eLi supply.

The energy obtainable from the lithium-deuterium reaction based on the total supply of 6Li would be about 2.4 x 1023 joules, which is approxi­mately equal to that of the world’s supply of the fossil fuels. The energy obtainable from a deuterium-deuterium fusion would be of the order of a billion times larger.

For a more tangible figure, 1 cubic meter of seawater contains 1.03 x 1025 atoms of deuterium having a mass of 34.4 grams, and a potential fu­sion energy of 8.16 X 1012 joules. This is equivalent to the heat of com­bustion of 269 metric tons of coal or of 1,360 barrels of crude oil. The deuterium in 28 cubic kilometers of seawater would have an energy equiv­alent to the world’s coal supply.

Conclusion

From this brief review, it is evident that the fossil fuels will be suffi­cient to supply the major part of the world’s power requirements for only about three centuries. Water power is potentially of a comparable order of magnitude but possibly also short-lived because of the silting of reservoirs. Geothermal and tidal power are useful, but of small magnitudes. This leaves only nuclear energy as a source of sufficient magnitude to supply the world’s power requirement for a period of a few additional centuries.

Against this must be considered the world’s finite area and its finite supplies of other mineral resources, particularly the ores of industrial metals. On a long-term basis, provided the world’s human population can be reduced to, and stabilized at, some optimum number, and provided that its industrial activity also can be stabilized at some nonexponentially expanding level commensurate with the earth’s resources, it should be physically and biologically possible to achieve and sustain a state of well being for the earth’s human population for at least a few centuries into the future.

REFERENCES

Averitt, Paul. Coal resources of the United States January 1, 1967. Washington: U. S. Geological Survey Bulletin 1275,1969.

Bemshtein, L. B. Tidal energy for electric power plants. Jerusalem: Israel Program for Scientific Translations, 1961 (Russian); 1965 (English translation). Committee on Geologic Aspects of Radioactive Waste Disposal. Report to the U. S. Atomic Energy Commission. Washington: Division of Earth Sciences, National Academy of Sciences-National Research Council, May 1966. 92 pp. Also pub­lished in Hearings before the Subcommittee on Air and Water Pollution of the Committee on Public Works, U. S. Senate, 91st Congress, November 18, 19, and 20,1969, pp. 462-512.

Daniels, Farrington. Direct use of the sun’s energy. New Haven, Conn.: Yale Uni­versity Press, 1964.

Duncan, D. С., & V. E. Swanson. Organic-rich shales of the United States and world land areas. Washington: United States Geological Survey Circular 523, 1965.

Faulkner, Rafford L. Remarks at Conference on Nuclear Fuel Exploration for Power Reactors, Oklahoma City, Oklahoma. Washington: United States Atomic En­ergy Commission, May 23,1968.

Hubbert, M. King. 1956. Nuclear energy and the fossil fuels. In American Petroleum Institute, Drilling and production practice (1956), 1957, pp. 7-25.

——- . Energy resources: A report to the Committee on Natural Resources. Wash­ington, D. C.: National Academy of Sciences Publication 1000-D, 1962.

——- . Degree of advancement of petroleum exploration in the United States.

American Association of Petroleum Geology Bulletin, 1967, 51, 2207-2227.

-. Energy resources. In Resources and man. Washington: National Academy