Nissan Leafs, Smart Cars, and other vehicles line in a lot in Hayward, California. Noah Berger/Reuters

There’s been a urban/rural divide on who gets cleaner air.

If you only listened to electric-vehicle evangelists like Elon Musk, Boris Johnson, or, heck, Justin Bieber, you might think EVs were the most eco-friendly machine since the waterwheel. The U.S., like China, Europe, and the U.K., has heavily incentivized EV purchases to speed electrification, fronting billions in subsidies to buyers and carmakers. In early November, the U.S. DOT dropped a few billion for a 25,000 mile-network of EV charging stations. All of these dangling carrots do seem to be working: EV purchases are currently on the rise. (Of course, there’s still only about 400,000 of them on U.S. roads, about 0.16 percent of all cars.)

But are all Americans breathing easier thanks to electric vehicles? And how much cooler does the planet stand to stay as a result of their adoption? These are questions of ongoing, heated debate. According to a new working paper published by the National Bureau of Economics, the answer is: It depends. The researchers looked at the air-quality costs and benefits of registered electric cars at the county level across the U.S., and further broke down those results by income and race. It seems some Americans are breathing much cleaner air than they would have been, but some Americans have been worse off—and the winners and losers largely fall along urban and rural divides.

The long tailpipe

How could anyone be on the suffering end of a gas-free electric vehicle, you ask? Individual EVs might not give off emissions, but that electricity comes from somewhere. Every time drivers plug in their cars, they’re tapping into power plants that might be burning coal, natural gas, or other fossil fuels. They may also be using juice from solar, wind, nuclear, or hydropower generation. Electric vehicles, then, could be said to have “long tailpipes.” They frequently rely on power plants located in rural areas, far from the urban centers where EV ownership is most heavily concentrated.

This also has implications for who wins and loses, across place, race, and income. How so? First, the study’s methodology: The co-authors, the economics scholars Stephen Holland, Erin Mansur, Nicholas Muller, and Andrew Yates, mapped out the costs and benefits of EV adoption in terms of the emissions they put into the air—not only carbon dioxide, but also pollutants that affect local air quality, such as sulfur dioxide, nitrogen, particulate matter, and volatile organic compounds. They added up all the emissions generated by electric vehicles purchased in counties across the U.S. (based on vehicle registration data), and compared them to the emissions that would have been generated by gasoline cars that EV drivers might have otherwise purchased. (To model those “forgone” gas guzzlers, researchers weighted the average of the emissions of the top-ten most frequently identified gasoline alternatives, based on market studies. They assumed each type of car was driven 15,000 miles.)

Unsurprisingly, the places with the greatest EV adoption rates got cleaner air as a result. Urban areas were clear beneficiaries, as a whopping 98 percent of EV registrations are in cities. But when they gained, some rural counties—especially the ones nearest to coal-burning power plants—really lost.

Pollution, imported and exported

Cartography drives this point home. In figure 1 below, the researchers show all the environmental benefits (blue) and costs (red) that EVs are generating within their own counties and exporting to others, a factor of reduced gas emissions and increased power plant activity. Figure 2 under it shows all emissions that EVs are generating within their own counties and importing from others, based on the same factors.

(NBER)

In the first map, you see a lot of the country is simply mapped in white; that’s because there are very few EVs in those parts of the country, so there’s no effect. Essentially the only pockets in blue are in cities on the West Coast and Mountain West; high rates of EV purchases in places like L.A., San Francisco, Denver and Phoenix are creating cleaner air for locals, and they’re not exporting much pollution, since so many Western states have shuttered coal plants in favor of renewable energy sources.

But that’s not the case for most cities, including Chicago, Dallas, and Atlanta, which appear in dark red. Even though those cities might have cleaner air locally, EVs are exporting emissions to other places that generate their required electricity. On balance, EVs in those urban centers are costing the country. That becomes abundantly clear in the the second map. Many of the counties that appeared white in the first map are now red; they’re importing more environmental costs than they are exporting or creating benefits.

For an example of where they’re being coming from, look at the Atlanta metropolitan area, which dominates Fulton County, Georgia. More new electric vehicles are purchased in there than any other region, thanks to sizable state and federal subsidies and other local incentives. As a result, Fulton County itself is breathing cleaner air, with fewer tailpipe emissions; it’s bright blue in the second map, but the counties surrounding it are red. Atlanta’s EVs are essentially shoving pollution onto other counties, especially up into the Carolinas, where coal-fired plants are powering those cars and widely dispersing pollutants. That’s why in the first map, Fulton County is dark red.

“Atlanta receives cleaner air because of people in Fulton County, but it is also making the rest of the country worse off,” says Yates, an environmental economist at UNC Chapel Hill and one of the co-authors. “That's really the urban story.”

The rural/urban divide on EV’s environmental impacts is apparent in much of the country, which carries implications across race and class. Yates and his co-authors found that, because wealthier Americans are more concentrated in urban areas, they tend to enjoy more of the benefits of EVs, while poorer Americans bear the costs. And because they represent a larger share of rural populations, white and black populations also suffered more on average, per capita, than Hispanic and Asian populations.

The future looks brighter

Perhaps some of this research sounds familiar; my former colleague Eric Jaffe covered a very similar study by the same authors in summer 2015. That paper looked hypothetically at county-level trade-offs between electric and gas-powered cars, and found that EVs driven in counties with dirty power plants hurt air quality more than gasoline cars would have. It was extremely controversial among CityLab commenters, so Jaffe wrote a follow-up that dove deep into the paper’s caveats, which overlap with this new one.

Namely: This study used the latest, fully vetted EPA data on power plant emissions—which comes from 2010-2012. Outdated data is inevitable in this domain of research. “ Scientific databases move slowly,” Jaffe wrote. But it’s important to realize that the situation reflected in this data represents the past, not the present. States across the country are rapidly cleaning up their grids, thanks to cap-and-trade programs, investments in renewable energy, tightened air quality standards, and more coal plants put to sleep. As soon as recent emissions data becomes available, the map won’t look so red for rural America.

This research also does not include any analysis of “upstream” emissions of either type of vehicle—oil extraction, refinement, and distribution for gas cars, and battery production for EVs. Different studies have drawn opposing conclusions on which type of vehicle has a cleaner “lifecycle” overall, based on existing emissions data. This is an incredibly contentious issue. At least one peer-reviewed study has concluded that, with all the upstream emissions accounted for, EVs that get their power from coal plants are worse for the environment than gasoline cars; others, including one notable report by the Union of Concerned Scientists, have found EVs to compare favorably.

The study also says nothing about the future of automobiles, which is much brighter for EVs than it is for gas-powered cars. That’s because, again, a lot of the country is switching to natural gas and renewables to power the grid—and this only stands to improve over time. “If you own an EV for a decade … it has the potential to get cleaner every year as the electricity grid gets cleaner—in a sense, updating itself in real-time,” Jaffe wrote. Fuel economy for gas-powered cars is also getting better on the whole—particularly with President Obama’s ambitious 54.5-mpg-by-2025 target—but an individual gas-powered car won’t get any more efficient once you buy it.

(NBER)

As long as electric cars and the grid that powers them keeps getting cleaner—and they probably will, despite Donald Trump—rural Americans won’t be absorbing their emissions to the same degree. At the same time, “that doesn’t make the inequity go away,” says Yates. Cities will still receive more benefits more, even if rural areas aren’t getting hurt. That might have implications for where state and federal subsidies are directed. As the above map shows, they’re currently heavily concentrated in the urban centers that are already enjoying cleaner air. This study does not mean we should scrap electric vehicles—far from it. It’s just that, like anything else, the distribution of their benefits will likely never be totally fair.

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