Is buying a Toyota Prius actually good for the environment?
In 1865, William Stanley Jevons articulated an elegantly counterintuitive theory that now bears his name: the Jevons paradox. The paradox was based in Jevons’ observation that “technological efficiency gains — specifically the more “economical” use of coal in engines doing mechanical work — actually increased the overall consumption of coal, iron, and other resources, rather than “saving” them, as many claimed.”
The paradox shows up in the cases of common appliances and electronics, but it does not carry over to the case of the Toyota Prius.
The key to the Jevons paradox is that energy efficiency limits the ubiquity of certain technology and/or the extent of its use. Once efficiency is improved, the cost per unit decreases and demand rises rapidly. Production vastly increases to meet the demand, as in the case of household appliances after WWII, computers in the 1990’s, and smartphones today. As a result of the massive increase in ubiquity and extent of use, total energy consumption increases despite the efficiency gains from each device.
For a salient example, look at televisions. They are much more efficient today than in the 1950’s, but as total TV ownership has ballooned to 219,000,000 U.S. citizens (1997 estimate), we use immensely more energy to power our televisions now than back in the heyday of The Honeymooners. There’s also much more to watch, further driving up consumption.
Extending this to the Prius, the efficiency of the hybrid effectively lowers the price of gasoline per mile traveled. The price of gas per mile traveled is a limiting factor of how far people may commute, how far they may travel to run errands, how often they drive, and in the long run, how far apart people may live. As argued by Ed Glaeser in Triumph of the City, cars originally granted their owners tremendous freedom to move about their surroundings inexpensively, supplanting trains as a means of suburbanization. It was cars (and highway infrastructure) that made exurbs possible, and extending the range/efficiency of cars will likely continue this trend if current gas prices are the limiting factor to outward development.
At present, however, it seems to me that the real limiting factor to outward expansion, lower density, and longer commutes is the time required for transit, not the cost of fuel. As a result, higher fuel efficiency would not spark increased demand in fuel consumption because the pattern of travel would remain virtually the same.
I welcome critiques on this point, but should it hold, the Prius’ gains in fuel efficiency will remain gains for the environment on the whole.