2012 Toyota Prius Plug-In Hybrid - production modelEnlarge Photo
This seems to be our time for debunking dumb stories about plug-in electric cars.
First, we had to educate a Forbes columnist (and oil-industry consultant) about how the auto industry works.
Now, it's time to offer some gentle guidance to all those journalists who covered last month's release of a study from the Norwegian University of Science and Technology that says, in essence, that plug-in cars are worse emitters of carbon dioxide on a wells-to-wheels basis than gasoline or diesel cars.
We were prompted by a piece on Jalopnik, but it was also covered in many other places.
(We note with amusement that the Popular Mechanics coverage hat-tips a gent who lists Chevron and Mobil as current employers. Uh huh.)
Data is good
In any case, we like data, we tend to like university studies, and we think that, if peer reviews of the Norwegian report hold up over time, it's a valuable contribution to the discussion.
But like all knowledge, there's some important context required to give media audiences a true sense of what it means.
The coverage of the Norwegian report highlights the reductionism often found in science coverage by quick-hit journalists, who take 20 minutes to cover the complex topics found at the intersection of energy policy and the global auto industry.
In almost all the coverage, there are a lot of qualifiers and caveats that reporters neglect in their eagerness to delineate the black and the white.
So here goes.
Norway: Not the U.S.
First, and by far most importantly, the study is more applicable to Europe than to the States.
Electric power plant outside Ithaca, New YorkEnlarge Photo
The study looks at "the present European energy mix," which is vastly different than the various mixes found in the U.S. (Norway has both a very positive attitude toward electric cars and strong government incentives for their adoption.)
Across Europe, the dominant fuel for electric grids is largely coal (with the exception of France, which has a huge amount of nuclear generation).
And in Europe, the baseline cars for comparison are much more efficient to start with: say, 40 mpg on average vs. 25 mpg for the States. Worse, differing test cycles between Europe and the U.S. make head-to-head comparisons quite challenging.
But about those grids: In the U.S., many electric utilities use more natural gas and--in some places--more renewables, including not only wind and solar but also hydro.
Thus the amount of carbon dioxide produced per kilowatt-hour across different U.S. grids varies by more than a factor of two, which makes it dangerous to generalize about the effect of electric cars.
Beware broad conclusions
And that's the biggest problem with the coverage, in our view: What's applicable in a comparison of far more fuel-efficient cars against electrics charged on European grids may be quite different from less efficient U.S. vehicles compared to plug-ins used in states with much cleaner grids.
A single coal plant in a particular grid may not make the plug-in emissions worse, but clearly electric cars are challenged in those states like North Dakota (the very worst) with 90-plus-percent coal.
On the other hand, California, which will buy more plug-ins than the next five states combined, has a grid that's somewhat cleaner than the U.S. average.
How Green Is My Plug-In, illustration by Holly LindemEnlarge Photo
So how green your plug-in car is will vary considerably depending on where you plug it in.
Your mileage may vary
Second, as a follow-on to the points above, how green your plug-in actually is depends not only on what grid you use, but what your comparison car is.
Jalopnik hedged somewhat in its piece by saying, "If you live somewhere with oil or coal-fired power plants, then having an electric car is actually far worse for the environment than a comparable gas or diesel car. This includes many areas of the U.S."
That's largely true, for some areas, if your comparison car is a 2012 Toyota Prius hybrid that gets a combined EPA gas mileage rating of 50 mpg.
It's not nearly as true if you're comparing to a more average U.S. vehicle, which gets 20 to 25 mpg.