Physicist Richard A. Muller wrote this essay for MIT Technology Review June 14, 2002. This is the source of the energy-productivity statistics I quoted in Winning the Oil Endgame. Fortunately I recalled the figures correctly!
Prof Muller has written a series of essays for the MIT journal that are all worth reading. More Muller essays are referenced in A Third Way On Climate.
I have friends who otherwise like me but consider me morally depraved for thinking that the population bomb is not going to kill us all. It is an unpopular time to be an optimist. But a recent discovery in population dynamics, and a fascinating discovery I call "Rosenfeld’s Law," may eventually drive the world toward a happier conclusion. …
Yet when I do the math, I cannot be pessimistic. I find hope in a discovery that I call Rosenfelds Law. Arthur Rosenfeld is a former professor of physics at the University of California at Berkeley, founder of Berkeleys Center for Building Sciences, a former senior advisor to the Department of Energy on energy efficiency, and currently a California energy commissioner. He is one of the worlds true experts on conservation, and in a recent study of the history of energy use, he made a rather remarkable discovery. From 1845 to the present, the amount of energy required to produce the same amount of gross national product has steadily decreased at the rate of about 1 percent per year. This is not quite as spectacular as Moores Law of integrated circuits, but it has been tested over a longer period of time. One percent per year yields a factor of 2.7 when compounded over 100 years. It took 56 BTUs (59,000 joules) of energy consumption to produce one (1992) dollar of GNP in 1845. By 1998, the same dollar required only 12.5 BTUs (13,200 joules).
Past conservation growth wasnt completely constant. During the oil crisis of the 1970s, conservation improved at 4 percent per year. Rosenfeld believes that with a little government encouragement, we can sustain a 2 percent rate per year indefinitely. Energy companies that dont want the public to reduce consumption have tried to persuade us that this much conservation would mean discomfort. Rosenfeld did the opposite. Conservation means not putting on a sweater, he entitled one of his presentations. Turn up the thermostat, if you like it warm! But, at the same time, reduce your energy bills by putting better insulation into your walls. If you dont want to invest the money, let someone else pay for it. It wont be hard to find someone. The yield on conservation investment is 20 percent per year, tax free!
Past conservation efforts have been far more successful than many people appreciate. It was conservation that liberated us from the control of the oil cartel in the 1970s. The members of the Organization of Petroleum Exporting Countries were more addicted to U.S. dollars than we were to oil. A little bit of extra conservation on our part (3 percent per year during the crisis period) drove down their income and forced them to increase production.
The steady pace of conservation would do little good if population outraced it. But there is encouraging news about population growth. The United Nations now estimates that the population of the world will peak, sometime in this century, at about ten billion. That sounds badit is much higher than the current levelbut it is a peak. After that, the population will decrease slowly. The predictions are now believed to be quite robust, as a paper in Nature last August documented (Vol. 412, pp 543-545, 2001). Malthuss population bomb is fizzling. The year 2026 will pass without a singularity.
What is happening? Where was Malthus wrong? At a United Nations conference last March, demographers discussed many possible explanations. The most appealing one was that the declining growth is a consequence of the expanding worldwide rights of women. Others attribute it to poverty reduction. Wealthy people have fewer children, for reasons we dont fully understand. Western TV is also cited: people see happy families with small numbers of children. I get the sense that scientists are groping, putting forth plausible explanations for an observed fact that they didnt predict. Fertility is declining far faster than expected in many regions, even in nations with no government family planning efforts (e.g., Brazil).
The happy news comes when we combine limited population with conservation growth. The conservation bomb wins. Rosenfeld points out that at 2 percent growththe 2 percent solutionconservation outruns population by a large factor. Two percent compounded over 100 years reduces energy use by a factor of 7.2. By 2100, with a world population of 10 billion people, everyone can be living at the current European standard of living and yet expending half the energy we are using today.
The solution may lie in making the developing world wealthy. What a delightful vision! Economicsthe glorious science. Wealth reduces population growth; conservation wins; the environment is cleaner; the world is happier. If we allow conservation to putter along at 1 percent, on the other hand, then in 2100 we will be using 40 percent more energy than today. That may be acceptable, but there is a catch: if the United States standard of living continues to increase, and the developing world wants to match that increase too, then the energy requirements may continue upward. The two percent solution is painless and preferable, but to achieve it probably requires conscious government-led efforts to develop cleaner, more energy-efficient technologies in areas like power generation, transportation, manufacturing and environmental control. Cancellation of research programs in these areas is self defeating. The solution to pollution is conservation.
The increasing efficiency isn’t just applied to a static standard of living, of course; much of it is eaten up in upgrading (increasing) devices which require it, or which generate $1 of GDP. It would be interesting to combine these numbers with some of the new accounting initiatives, which greatly expand the factors taken into account in computing GDP-like figures.
BTW, for ease of computation, there is something called the Rule Of 72. Divide 72 by either the compounding rate or the number of periods to get the other required to double a starting figure. E.g.: 2%/annum doubles in 36 years; 12% doubles in 6 years, etc.