Life Cycle Analyses

Over at Grist, the ever-mysterious Umbra responds to a question about whether electric cars are everything they're cracked up to be, environmentally speaking. Sure, a reader says, "They don't pollute the air where they are driven. But certainly when they are plugged in they use energy from a power plant, which does pollute and also contributes to global warming. Doesn't this just move the pollution from one area to another?" In the final analysis, are electric cars cleaner than those that run on gasoline engines? As usual, the answer is: That depends. (You'll have to read her answer for yourself, but here's a hint: It has to do with how the electricity is made.)

What I wanted to highlight here was Umbra's link to the ILEA. That's the Institute for Lifecycle Environmental Assessment, where they focus on breaking down those nagging questions that never seem to get a satisfying answer. Not just electric v. gasoline cars, but also things like paper v. plastic, cloth v. disposable diapers, and manufacture v. use of automobiles -- that is, is it better to buy a new, more efficient car or run your old one into the ground? According to a Carnegie Mellon life cycle analysis, the answer is: That depends -- in this case, on whether you're more concerned about energy use or toxic releases. Summarizing the findings, the folks at ILEA write:

...the bulk of environmental impacts from automobiles occur during the use stage. The implicit message is that if you can replace your car with one that is more energy efficient, chances are high that you truly will be reducing your overall environmental impact. However, if you are a person who considers toxic releases more important than energy use, then it is wiser to hold on to your existing car, in order to avoid promoting the manufacture of a new one.

Dang, if only they had stopped at 'however.'