Bjorn Lomborg at a conferenceCredit: Simon Wedege/Wikimedia CommonsWhen Bjorn Lomborg wrote “Green Cars Have a Dirty Little Secret” for The Wall Street Journal earlier this month, he based his argument—that electric vehicles (EVs) are no better for the environment than internal combustion engine vehicles (ICEVs) due to the manufacturing process—on a 2012 study published by the Journal of Industrial Ecology (JIE). He made a convincing case, and I must admit: I was taken in.

But the convenience and even wide-spread belief of something doesn’t necessarily make it true. Spurred on to seek out the truth by a very helpful Reason reader, I took a hard look at the JIE study from Hawkins et al. I wasn’t the first to do this, but I hope to be one who cares more about the facts than an agenda.

As it turns out, the JIE study that Lomborg points to contains a number of problems that should raise a quizzical scientific eyebrow. In fact, Hawkins et al. were forced to issue a correction to their report in January.

In the JIE correction, EVs come out much greener than they do in Lomborg’s op-ed. While Lomborg states that “unless the electric car is driven a lot, it will never get ahead environmentally,” Hawkins et al. come to a different conclusion:

We find that EVs powered by the European electricity mix reduce GWP [global warming potential] by 26% to 30% relative to gasoline (originally 20% to 24%) and 17% to 21% relative to diesel (originally 10% to 14%).

Even in the original study, EVs came out ahead over an estimated lifespan of 90,000 miles, despite being loaded down with lithium-ion batteries that scientific advancements have not yet made kind to Mother Nature. Still, reducing emissions by up to 30% without necessitating any changes to our current energy consumption habits can hardly be called “never getting ahead.”

Cutaway view of a Nissan Leaf, showing the batteriesCredit: Tennen-Gas/Wikimedia CommonsAnd that’s assuming that Hawkins et al. have actually reached a reasonable conclusion now that they have corrected their estimates of the required production inputs for a Nissan Leaf—their representative EV for the study. Instead of assuming, however, let’s take a look at another study.

This UCLA report prepared for the California Air Resources Board, Lifecycle Analysis Comparison of a Battery Electric Vehicle and a Conventional Gasoline Vehicle, compares EVs (which they refer to as BEVs, or battery electric vehicles) to ICEVs (which they call CVs, or conventional gasoline vehicles). On pages 18 and 19, the authors report average expected CO2 emissions over a lifetime of 180,000 miles for an ICEV to be more than twice those expected for an EV.

In sum: both the JIE and the UCLA studies reach very similar conclusions. Hawkins et al. find EVs to be up to 30 percent cleaner than ICEVs over 90,000 miles and the UCLA study estimates 64 percent lower CO2 emissions over 180,000. (Keep in mind: this is with current battery technology as well as current energy mixes, which rely primarily on fossil fuels.)

And yet Lomborg dismisses this still-fledgling technology as doing “virtually nothing.” He’s right that EVs are not “zero emissions,” of course. But if the chief goal of a buyer is to reduce greenhouse gas emissions, they are a step in the right direction.

That having said, a reduction in greenhouse gas emissions isn't grounds for thousands of dollars in subsidies from Uncle Sam. Let the market decide if it's worth driving an electric car to be green, not the government.

UPDATE (3:00 pm): Bjorn Lomborg reached out to me via email with this response that I think is worth posting:

I do know of the correction to the Hawkins study, but it just changes the outcome about 6% (they're very explicit about it not changing much). However, the US electricity grid is also significantly more co2-intensive than the EU average, which was why I kept their estimate of 24% less emissions if driven 90,000 miles in my WSJ. It is not surprising, that if the car is driven twice that at 180,000 miles, it will emit even less. 

My point with the WSJ article, however, was also to point out that if you can only drive 73 miles at a time (and likely much less, both because you want to avoid being stranded, like NYTimes reporter John Broder, and because the range declines to 55 miles in five years), it is much less likely that you will drive even 90,000 miles and certainly 180,000 miles before you change your battery and hence increase your co2 emissions again.

Moreover, if you buy a car with a longer range (just drove a fantastic Tesla with almost 300 miles range)—its batteries will obviously have emitted so much more co2 in production that it is unlikely the car will ever earn it back.

So, I don't think these points serve to undermine my argument, but rather simply show that the numbers are pretty clear. If you drive little (50,000 miles or less), you'll emit more co2. If you drive rather much (90,000 miles) you'll probably emit 76% of a gasoline car (with average US electricity), and if you drive your electric car exceptionally far (180,000 miles) you might just emit half of a gasoline car.

All that remains to think about is how far will most future purchasers of a Nissan Leaf actually drive their car. Most will buy it as their second car for short, infrequent trips. 

This is an excellent point. In writing this post, I focused solely on rebutting the idea that EVs can't make up for their manufacture with lower greenhouse gas emissions over time (and miles). I stand by what I've written above—they can even with current technology. If you drive them long enough.

However, Lomborg's point that many will buy these as second cars and use them only rarely and for short trips is probably very true. If you're buying one of these cars to reduce your emissions, you better actually drive it a lot (instead of your ICEV) and hold onto it for as long as possible. Otherwise they're just a wasteful fashion statement—like pretty much every other car on the road.