Sunday, July 10, 2005

Deffeyes's Reprise

I have just (July 9, 2005) finished reading Kenneth Deffeyes's new book "Beyond oil: The view from Hubbert's Peak" (2005) .

I almost didn't buy this book. I assumed it would not add much to what I had learned from Deffeyes's earlier book on the same subject, "Hubbert's Peak: The impending world oil shortage". What a mistake that would have been!

"Hubbert's Peak" remains an extremely valuable book for those who want to understand *why* Hubbert's hypothesis may be correct, but "Beyond Oil" is much better at explaining the hypothesis and showing us that the data supports it overwhelmingly. The great new value in "Beyond Oil" is to be found in Chapter 3, The Hubbert Method.

In "Hubbert's Peak", Deffeyes presented only qualitative and graphical descriptions of Hubbert's theory in the main text. He describes what the theory means and why it was important. Reader's may believe him because the rest of the book makes his credentials unmistakable: Professor Emeritus of Geology at Princeton, obvious encyclopedic knowledge of petroleum geology, 50 years in the oil business or consulting to it, friendship and collegial association with Hubbert himself. But his editor did not let him put any equations in the main text. When he does get to the equations in the notes at the back, their presentation is too concise, they require too much math knowledge for most readers, and lack the associated explanation that would make their relationship to the theory easy to understand, even for many readers who have the necessary math knowledge. It's all there, but you have to be committed and sophisticated to dig it out.

In this new presentation, Deffeyes has performed a brilliant act of creation in constructing a quantitative explanation of Hubbert's theory that can be completely understood by anyone who can read graphs and do elementary high school algebra. (The success of Hubbert's Peak must have persuaded his editors to let him put a few equations in the text of this book.) Instead of understanding merely the results of Hubbert's theory, and accepting them on Deffeyes's authority, you can understand, completely, the sequence of thought that leads from data to theory and back to data to check the support for the theory. The effect is compelling. Hubbert did not seem to understand his own theory this clearly until a decade of so after his early publications in the 1950s, and he never explained it simply. His early arguments depended on educated guesses about the total volume of oil that could eventually be recovered from the oil provinces in question. To this day, his detractors criticize the theory incorrectly on the assumption that it depends on a separate and independent estimate of the size of the ultimately recoverable resource in order to predict the date of the peak of production. Hubbert removed this dependence, but his papers are apparently so hard to read that those who are looking for a way to refute the theory miss the improvement. The revised theory *generates* a robust estimate of the ultimately recoverable resource from historical production data. As history approaches the predicted peak, as now, the prediction of the peak becomes utterly compelling.

Deffeyes's renders Hubbert's theory transparently clear. It's essence is a guess, verified by appropriate analysis of historical production data, that the rate of oil production has depended and will depend mainly and linearly on the fraction of the ultimately recoverable resource that remains to be produced. The maximum possible production rate at any level of cumulative production is proportional to the product of the remaining fraction and the cumulative production. This dependence on the fraction of oil remaining is manifested by an ingeniously selected plot of the historical production rate data and the historical cumulative production data.

The theory's disregard of other factors on which production must depend, such as the price of oil, technological improvements in extraction, accidents of history, and geopolitical incentives and constraints, infuriates the detractors of the theory. The answer is that the production rate does indeed depend on these other factors, but the data demonstrates compellingly that it depends on them much less than it depends on the fraction of the ultimate total that remains to be extracted. The reasons for this dominance of the single factor is well understood by geologists. "Hubbert's Peak" explains this dominance much better than "Beyond Oil", so you'll need both books to argue against committed detractors. But anyone who takes the trouble to first understand Hubbert's hypothesis and what the data says about it will be looking to these explanations mainly to find reasons for the obvious empirical truth of the hypothesis.

Economists (and those who have been stupefied by economists' assertions) do not accept the hypothesis that the maximum production rate depends mainly on the remaining fraction, even though historical data provides overwhelmingly powerful support for the hypothesis and geological reasoning explains this support. I am convinced that the economists have the mistaken impression that Hubbert's theory is merely qualitative and descriptive and as such cannot defeat their own simplistic qualitative ideas about resource quality pyramids and supply and demand. Everyone who gives evidence of actually understanding Hubbert's theory seems to accept it. Those who repudiate it seem always to give evidence of not understanding it, or even of not caring to understand it.

Much loud opinion misrepresents Hubbert's theory, or gives it a status roughly equivalent to that of, say, the opinions of Wall Street analysts. It seems likely that Deffeyes saw that his "Hubbert's Peak" had not produced the popular understanding he had hoped for, that Hubbert is sound science. Thank goodness he has taken this second shot in "Beyond Oil".