In the discussion of energy (or rather, how to curb our profligate use of energy), often the topic of energy efficiency comes up. And just as often, someone will say, "Energy efficiency doesn't work. Jevons paradox".
That's glib. A bit like saying, "Food stamps don't work. QED."
While we all know what "QED" means, maybe we should take a closer look at the Jevons paradox. This refers to the idea that, as technology improves the efficiency of a widget, that widget will get used more. A lot more. So much more, that the energy needed to run the widget for everyone is more than the energy needed before the innovation came along.
Jevons based this on his observations on the use of coal during the Industrial Revolution: As the newly invented steam machines quickly became more efficient, the price of coal went down. Economists like Jevons would say such a price decrease in energy encouraged the building of more steam machines, so you ended up with a higher total coal consumption than before, even as the amount of coal needed for each machine was reduced.
Let us put Jevons and his paradox in historical context: The Industrial Revolution was a period of feverish activity and invention. Manufacturing capacity was growing in leaps and bounds, fed by workers newly displaced from the countryside where Enclosure had just deprived them of their means to a livelihood. (Whatever Garrett Hardin may have claimed, the true tragedy of the commons occurred when England's aristocracy grabbed the land that used to be freely available for common use, to the immense loss of the common man).
The late 1800s was the time when industry enjoyed the kind of growth that stock markets today can only sigh over. I think Jevons missed that broader context when he formulated the paradox that bears his name: In his time, enormous growth in industrial activity would have taken place regardless of the price of coal. Perhaps the rate of growth would have been smaller if coal remained expensive, but growth would still have been robust anyway.
The Jevons paradox is still invoked today, and with a similar lack of context. One example is that of air conditioners, of which the efficiency has grown by 28% between 1993 and 2005, but of which the total energy use has grown by 37% over the same period. This narrow focus misses the fact that income has also increased (by 30%) over that same period. People with more disposable income can afford more luxuries, like air conditioning; and when they decide to buy one, very few people worry about the unit's efficiency.
Of course, Jevons paradox is invoked often when the topic of fuel efficiency is cars comes up, for instance by Alec Dubro who claims that advocating for fuel efficient cars doesn't make sense because we'd all just drive more.
I beg to differ for two reasons. First, the way fuel efficiency is achieved in the US right now is by selling hybrids and EVs. Those have higher up-front costs than conventional cars, which is a real deterrent. It appears that most people have a hard time looking beyond the purchase price.
Secondly, the people who do look beyond the purchase price do so because they are contemplating driving a lot. For instance, if you have a long commute to work every day, its cheaper to buy a fuel efficient car in the long run, because you expect the savings in gas to be more than the price difference between a gas sipper and a guzzler.
So rather than fuel efficiency pushing more use, it's the other way around: If you got a new job that's significantly farther away from home, you will seriously consider buying a more fuel efficient car. The reality is often, that while your commute may take you twice as far every day, it's hard to find a car twice as efficient as your old car. So overall your total use of gas does go up. But fuel efficiency is not the driver of your increased use.
Let's be careful about what causes what.
This is why it's crucial to look at the broader context: when I was a child, my mom worked on the other side of town. It wasn't a big town: her commute took less than 10 minutes by car and half an hour by bike. Still, I often heard relatives and friends remark on how mighty far away she worked from home. Remember, this was a time when people came home for lunch, and preferred to live around the corner from where they worked.
Things have changed. Today, the 50-mile commute is not extraordinary any more, and few people even commute by plane. One thing that that tells you is that the price of fuel is way low compared to the average income. Or it wouldn't pay to do that kind of commute. I mean, imagine paying for a 50-mile commute in one of those 1970s boats that get 10mpg.
Until we change the culture and infrastructure that encourages such crazy commutes, fuel efficiency is still the best, and certainly the quickest, way to reduce our overall energy use. Especially when coupled with the right incentives.
Let me offer a perconal case study: Our previous car was a 2001 VW Golf that got an embarrassing 19 mpg. Two years ago we traded it for a 2012 Golf TDI that gets 38mpg on average. So overnight, we doubled the efficiency of our family transportation. In these first two years, I averaged 8500 miles per year. For the previous car the average was 8000 miles per year. I atrribute the small increase to an increase in my children's activities as they grow.
If you believed Jevons I'd be driving more than 16,000 miles a year now. But where would I go? and where would I get the time to drive twice as much? Does CelloDad look at this car, with its 45 mpg highway efficiency, and suddenly say, "Hey, I could take a job in the city now"?
Heck no. He's got a cream puff job. He gets paid well enough, has extremely flexible hours, and can always make it to daytime school events. Besides, he has moved into the corner office since I put in the new windows and new floor for him, and painted the walls in the colour of his choice. He's all set. Since he started telecommuting, the stairs are the biggest obstacle in his commute. And me. I keep asking him for lunch dates.
A fuel efficient car can save you money and carbon emissions on your long commute. But if you don't commute at all you really save a bundle. And I'm sorry, but Jevons has entirely missed the happiness factor.