1. Petrakis Gulf Research and Development
A Metric (51) Energy Scale C O ~ V ~ ~ S ~and O N CS O ~ ~ ~ ~ ~ S O N S
Company P.O. Drawer 2038 Pittsburgh, Pennsylvania 15230
The advent of the "energy crisis" has forced into prominence, among other items, a most interesting and often somewhat baffling collection of energy terms. This situation often obtains in the classroom with scientific courses of societal relevance, in the popular press, and even in scientific and technical discussions. To a chemist, steeped in the kilocalories per mole tradition, the number of BTU/scf that the engineer interested in the Hz economy uses is probably cause for pause. Similarly, the energy of the neutrons for a given reaction expressed in MeV has no readily apparent relation to the kilowatt-hour or footpoundal of other technologies. The confusion over the use of different units to describe mechanical, electrical, thermal and other forms of energy is further exacerbated somewhat by the existence and use of various definitions within each unit (e.g., BTU, IST BTU, Mean BTU, and 39°F and 60°F BTU!). This situation will eventually be cleared, of course, by the introduction and general acceptance of the Systeme International d' Unit6s (SI). The inexorability of this trend is underscored by, among others, the IEEE's having gone on record as advocating the phasing out of even such a venerable term as the kilowatthour. Unfortunatdy, many of the texts being written in the U S . still appear to be using the conglomoration of the old and diverse units. On the other hand, the editors of many U S . publications are making a determined effort to facilitate and accelerate the acceDtance of a rational, unified system of units. Evidence, f& example, the large number of articles in ioumals such as Science and thrs Journnl (1, 2). In this spirit, we have here constructed an Energy Scale in terms of the SI unit (Joule) which we feel can he of timely interest and utility in the many and diverse discussions of both the energy crisis and the SI. The Energy Scale: The scale is presented in terms of the Joule, which is the only acceptable energy term of the SI. The scale provides for the ready conversion of all traditional units employed in engineering, science and techENERGY IN
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nology to describe the various forms of energy. In addition, and in order to provide a sense of relative importance, the scale gives the energy associated with a series of physical phenomena that cover 101 orders of magnitude! On the low end of the scale, we have the alignment of a nuclear spin in a zero magnetic field; and on the other, we have the energy equivalent of the matter of universe. (Of course, there is controversy over such cosmic numhers. The number we have chosen here is one that, by an amazing coincidence, agrees with the one determined by Archimedes in his correspondence to King Gelon on the "Sand Reckoner" (3).) The scale also provides a whole series of energy equivalents of quantities associated with various present and potential energy sources. These include, in addition to fossil fuels, laser and magnetic containment fusion, fission, geothermal sources and direct and indirect (ocean temperature gradients) solar sources. Finally, the scale includes a series of items that provide some sense of importance of energy sources and consumption. It is realized, of course, that these numbers are presented again as points of reference without accepting them necessarily as the most accurate or the only estimates available. Therefore, we have given the sources (1, 4-7) from which these numbers have been derived and those interested in the details of the models and calculations are referred to these sources, and especially the series of excellent articles in Science (I). Literature Cited Reaovrces ofthe U.S.," U S . Geolopieal Survey Circular No. 650,and Bureau 01 Mines Infarmstion Circular 8549. (19721 as quoted in Science. 177. 1180 (1972); 178. 291, 598. 849. and 1079 119721; 119. 54 (1973); and 180. 155. 1267
(1) "En-
119731.
121 J. CHEM. EDUC.. 18.797 (19711 and rebrenees therein. (3) Harrimn, E. R.,Phyaiea Today, p. 30. IOecember. 19721. (5) "HandbmkafChemistry and Physics." 46th Ed., 1985. 161 Hammond. Metz. andMaugh, "Energy and the Future." AAAS, 1973. (7) Baez. A . V.. "The New College Physics: A Spiral Aw,p.oach."W. H. Freeman 61 ENERGY
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Volume 51, Number 7. July 1974 / 459
