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Electric Vehicles Are Not The Answer But Remain A Question


PHOTO (select to view enlarged photo)

A look back at an article by The Economist on why electric cars
are not greener than gasoline cars?

Comments By Josh Velson
Chemical Industry Consultant
December 25, 2014


The funny thing about science journalism is that if you have anything above a high school science education you're much better off reading the original paper instead of the opinion/spin of a journalist, who likely has less science education than you do. And this is an article about a lifecycle analysis (LCA). Funny thing about LCA studies is that you have to look at the underlying assumptions before you make any judgments about what they say, because the assumptions of the hypotheticals they use strongly influence their conclusions.

So I did both.

First, what is the paper really about? It's about PM2.5 emissions, not GHG emissions, which is valuable because it's different from the rest of the pack but confusing at the same time. The paper is fundamentally about differential health outcomes, not about GHG emissions, which is usually the benchmark "greenness" outcome.

Next, the Economist's spin*. What The Economist says is nothing new: electric cars are only as green as their electricity. Saying it for PM2.5 is no different for saying it for GHG emissions - and that fossil fuel technologies are worse in terms of PM2.5 emissions than green energy technologies is emphatically not surprising. That being said, I don't know how you got the conclusion that "electric cars are not greener than gasoline cars" - because nowhere in The Economist does it say that. They instead make the valid point that electric vehicles in China, which has 80% coal-based generation, will produce worse health outcomes than gasoline (though the generalization is a little irresponsible given that the study focused on the United States).

But wait! I was surprised by two things in particular: biofuels scored very low, and diesel scored high. The first of these didn't make any sense to me, especially when corn ethanol scored worse than stover ethanol - surely on a particulate matter basis, burning natural gas for electricity (as is typical in corn ethanol) is better than burning biomass residue (which has acknowledged problems with particulate matter)! And second, diesel fuel has over 10 times the particulate emissions of gasoline, well over its mileage increase, but was shown as better than the baseline gasoline scenario. Well, uh, let's look at the original study:

  • All particulate matter emissions from vehicles assumes a stringent vehicular particulate matter system: Well, that explains why diesel looks so good. That's not what exists right now, however, and is speculative in terms of assuming implementation by 2020. Why it didn't assume this same generous level of mitigation for coal power I don't know.
  • The Economist's coverage emphasizes the coal power uh-oh without reporting the paper's major conclusion: The paper says even in the abstract that EVs are just better for PM2.5 emissions unless you're on a 100% coal regime. And that makes sense! Even under a non-coal fossil fuel regime, you can better control particulate emissions in point sources rather than mobile sources. This is the fault of the Economist's coverage for not having the correct emphasis, but it didn't lie per se.
  • Biofuels are subject to a set of punishing assumptions: Basically, corn ethanol is used as a proxy for coal. Seriously! The study assumes that generation for corn ethanol production will come from coal-based power in Wyoming and West Virginia. As such almost all of the particulate emissions shown in the corn ethanol column are from coal power. Because of the study's assumptions, it intentionally portrays biofuels as shitty - intentionally, because I can think of no reason to not reflect the reality that coal power expansion in the United States in the period to 2020 is ridiculous, nor to reflect the fact that US Midwest electricity generation is already driven by natural gas.

    This is one of my pet peeves. I don't think the corn ethanol industry is a good long-term solution to our liquid fuels problems at all, but studies that intentionally penalize it have, time and time again, made me perversely leap to its defense.

So phooey. Elon Musk has nothing to learn here - you do.


*I've been a reader of The Economist since I was 16 years old. Call me a poseur, or whatever, it's still better journalism than most of the dross in the United States. Its coverage of energy issues is abysmal over the decade plus I've been reading it - they have never once unpacked the assumptions of a paper in reporting its conclusions, and I once called up people quoted in the article who flatly went against the conclusion they were cited to support - but I haven't ever read it for that.