What, then, do the Marchetti curves predict? Nothing that genuine students of the field would find terribly surprising. In the US and the world, coal will continue its downward slide (primary fuels on their way down have always been insensitive to newcomers), declining to 1% of energy use by the year 2050. The energy source of the future is nuclear fission, but it, too, will go the way of all energy sources, peaking in the middle of the next century to make way for an as yet unknown energy source¾presumably nuclear fusion. The one surprise is that the share of nuclear energy will not be affected much by either coal or oil, but will slug it out with natural gas; the latter will peak about 2000 and then recede before nuclear energy.
The underlying reason why energy sources (and market penetration in general) follow these curves so well is not known. But we will offer a speculative explanation.
The analytical expression for these curves(*) occurs frequently in applied mathematics; it describes, for example, the spread of a disease or of a new idea (religion, ideology) among a population. In both these cases the reason is that it is the solution of a differential equation (that is, a relation between little increases of the variables) which says that the increase in the diseased (or converted) fraction of the population is¾
1) directly proportional to the number of people already infected or converted, because each acts as a new spreader of the disease or ideology; and
2) inversely proportional to the number of uninfected (unconverted) people, because fewer healthy people remain to be infected (converted).
The rest is calculus for beginners.
Now just because the development of two phenomena in time follows the same analytical formula, it does not at all follow that the mechanism causing the development is the same for both. But neither is it forbidden to search for similarities in trying to discover what makes it tick.
The second factor in the reasoning above obviously holds for energy sources: The fewer consumers are left to switch to a certain type of energy, the slower will be its growth because of the shrinking market.
But where is the analogy of the proselytizer, or of the contagiously infected, who not only switches himself, but causes others to switch, too?
If we were talking about miniskirts or left-wing radicalism, or even solar collectors, the answer might be simple aping of fashions, keeping up with the Joneses.
But that would hardly be the explanation for energy sources flowing by the thousands of megawatts at a time. The "proselytizing" effect here, instead, might well be caused by the supporting industries.
Consider just one aspect: transportation. As more and more oil flowed through the pipelines, they became cheaper; as less and less coal was transported by the railroads, they became more expensive. Since a single pipeline serves many consumers in one area, it (as well as the many other supporting industries) became the "proselytizer" lowering the price of oil for the undecided in its region of service.
This is, of course, only an hypothesis (part of one, at that) which would have to be verified quantitatively, checked out for counter-examples, and otherwise tested before it could be promoted to the rank of a "theory;" but we throw it out for our readers for what it is worth.
For what it is worth?
Probably $40,000 as a government-funded study on energy growth.
Make that $80,000 if you limit it to solar only.
* F(t) = 1/[1 + K exp(at)], where K and a are constants fixing the position and slope of the curve, respectively.
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Vol. 8, No. 1
Newsletter: Access to Energy Newsletter Archive Volume: Volume 8 Issue/No.: Vol. 8, No. 1 Date: September 01, 1980 04:03 PM Title: The next victim is decency
Copyright © 2004 - Access to Energy Newsletter Archive
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