Power Down Day

Today was a lot of fun; I got to antagonize environmentalists! In coordination with student groups, my school sponsored a Power Down Day. The school turned off most of the lights in the school and encouraged people to cut back on use of electrical devices. As you can imagine, I immediately began trying to find a flaw with the idea. This is when I recalled a nifty economic theory (widely acceptable although hotly debated) called Jevons Paradox.

In economics, the Jevons paradox is the proposition that a technological advance which increases the efficiency with which a resource is used tends to increase (rather than decrease) the rate of consumption of that resource.

It was postulated by William Jevons in the 1800s after he observed that increased efficiency in coal-burning technology resulted in more coal usage, rather that less. This can be applied to any current technology, however. Take cars for instance. Although there are a lot of factors I am not taking into account, these are fairly indicative numbers. These graphs represent the Efficiency and the Consumption of fuel by passenger cars since 1960. Please note the scales of the horizontal axises.

Average MPG (image link broken)
Average fuel consumption (image link broken)
Data from infoplease.com.

This is a great illustration of the Jevons Effect. Even though fuel efficiency has been increasing, fuel consumption has increased as well (after the initial leap in car technology). This goes against the first intuition. The same goes for lightbulbs. Lightbulbs used to be rather rare. In the current day, we have numerous lights not only in every room of every building, but also in cars, on pens, even on shoes. Because lights are cheaper, we use them for more things; or everything.

Now, Power Down Day was not flawed in itself. Although you can use Jevons Paradox to argue that initiatives to increase efficiency are actually hurting the environment more than helping, it doesn’t apply to situation where you are just not using power. Using less power doesn’t necessarily decrease energy prices like more efficient electronics would. However, the whole conservationist effort stems from the same force that pushes for more fuel efficient cars and bans on incandescent lightbulbs. For instance, someone thought it would be a good idea to get a bunch of those useless rubber bracelets made with “Power Down Day” on them. It probably took more energy to make 500 of those wristbands than was saved by “powering down”.

The energy saving effort doesn’t actually save much money, despite that being a major argument point. That only works if you stick with the scheme in the long run. In a gymnasium, for example, there are 3 fluorescent bulbs per panel and the panels might be arranged in a 6 by 6 square. Assuming a wattage of 10 Watts per bulb, thats almost a kilowatt. Over the course of a day, that will save somewhere on the order of $2. With a majority of lights extinguished, that number could be brought up to maybe $50 a day. Which is not bad, but if you are going to keep the lights turned out all the time (thus actually making a legitimate amount in energy savings), you could have saved even more money by never installing them in the first place!


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