I’ve just noticed an interesting article on the recently re-launched ‘History & Policy‘ site which suggests – by looking at the historical evidence –  that our chances of reducing energy consumption without sanctions or limits being imposed is, frankly, wishful thinking. Even though we have in the past achieved the energy efficiency gains needed now to reduce CO2 emissions dramatically, energy consumption has kept on increasing.

The article is by Paul Warde of Keele University, who contributed a review of historical evidence to the Stern Review.

I’m going to pull out a couple of sections here which capture the thread of his argument (as so often, the whole thing is well worth reading).

Prior to the Industrial Revolution:

human society was subject to a ‘photosynthetic constraint’, based on the efficiency by which plants undertook this process, and in turn the efficiency with which we used plants. Examination of western European economies suggests that none could really get by with under 10 gigajoules per person per year from this process, and on an organic basis it was pretty well impossible to breach a consumption level of 20 gigajoules per person per year. It was possible to intensify energy production a little bit, but basically to expand the economy, you needed to expand the territory exploited.

In the modern world, energy consumption is around ten times higher per person per year, at about 200 GJ. (For reference: A gigajoule of electricity is enough power to keep a 60W light burning for six months).

One consequence of this is a staggering calculation about how much fuel we’d need if we went back to getting our energy from plants (which is basically what biofuels set out to do), given that population levels are also three times higher than in 1750:

Supplying the total energy required today from this source would mean that each European hectare of land would have to be thirty times more productive than it was two hundred years ago.

And the other half of the story is just as dismal. Even though the energy efficiency of the UK economy is far greater than it was in Shakespeare’s day, we’re using far more of the stuff:

Despite big efficiency gains, in the 1920s total energy use was roughly static; in the 1950s it rose by 27%; between 1960 and 1980 by 22%; and in the 1980s by 3%. Why did this happen? It is partly because of what economists call ‘take-back effects’: we simply used the energy saved by efficiency improvements elsewhere, and as we got rich at a faster rate than our energy use got more efficient, per capita consumption of energy went up. We are over 3 times more energy efficient than we were in the 1880s, but we each consume about a third more energy. Although we need a lot less energy to produce each unit of income, we are all very much richer than we were over a century ago.

And since labour costs continue to grow faster than energy costs, it continues to make sense to substitute energy for labour wherever possible – thus making the ‘decoupling’ of economic growth from overall energy consumption unlikely. Warde concludes that if we want to restrict energy use to reduce emissions, investment in renewables will have to be coupled with rationing.

The function of History & Policy is to work for better public policy through an understanding of history. Maybe a subject for another post on another day.