Brace yourself, electric-car fans and advocates. It may be a bumpy ride for the next few days.

Yesterday afternoon, the Associated Press covered a new study put out by the University of Minnesota that calculates the environmental impact of manufacturing and refueling vehicles with various powerplants.

DON'T MISS: EPA's Coal-Plant Emissions Rules: This Will Be The Big Fight

The article carries the headline Study: Your All-Electric Car May Not Be So Green. The actual study can be found here.

The key word in that headline is "may."

Regrettably, headlines in other outlets have missed the verb that alludes to a possibility.

BMW i3 at DC fast-charging station

Instead, many of them state definitively that electric cars are not as green as gasoline cars.

Which is simply not what the study says.

Electric cars 'preferable' with clean power

Here's the actual preface, taken verbatim from the first page of the study (we've added paragraph breaks to make it easier to read):

We evaluate the air quality-related human health impacts of 10 ... options, including the use of liquid biofuels, diesel, and compressed natural gas (CNG) in internal combustion engines; the use of electricity from a range of conventional and renewable sources to power electric vehicles (EVs); and the use of hybrid EV technology.

Our approach combines spatially, temporally, and chemically detailed life cycle emission inventories; comprehensive, fine-scale state-of-the-science chemical transport modeling; and exposure, concentration–response, and economic health impact modeling for ozone (O3) and fine particulate matter (PM2.5).

Photovoltaic solar power field at Volkswagen plant in Chattanooga, Tennessee

We find that powering vehicles with corn ethanol or with coal-based or “grid average” electricity increases monetized environmental health impacts by 80 percent or more relative to using conventional gasoline.

Conversely, EVs powered by low-emitting electricity from natural gas, wind, water, or solar power reduce environmental health impacts by 50 percent or more.

Consideration of potential climate change impacts alongside the human health outcomes described here further reinforces the environmental preferability of EVs powered by low-emitting electricity relative to gasoline vehicles.

Put another way: Charge an electric car on anything except coal, and it's greener than a gasoline car.

Notice that last paragraph, by the way? Electric cars, charged by low-carbon sources--anything except coal--are "environmentally [preferable]...to gasoline vehicles."

Electric-car wells-to-wheels carbon-emission equivalencies in MPG [Union of Concerned Scientists]

Which is rather a long way from "electric cars aren't as green as gasoline cars."

Flipping the numbers

The key point here is that phrase "coal-based or 'grid average' electricity"--and it highlights one of the advantages of plug-in electric cars: They get cleaner, or lower-carbon, as soon as the grid used to charge them does.

Taking air pollution from manufacturing the car and power generation, the study concludes that if an electric car is recharged with electricity generated by the coal-heaviest grids in the U.S., it causes almost twice as many deaths from air pollution as a comparable gasoline vehicle.

(We might note that electric-car sales are low to invisible in the states with the dirtiest grids: Illinois, Ohio, North Dakota, West Virginia, and Wyoming.)

Two BNSF locomotives hauling coal trains meet near Wichita Falls, Texas

But if you switch to recharging the electric car on electricity produced from natural gas, the numbers flip. Now the electric car produces only half the pollution-related health problems as the gasoline car.

Recharge it on renewable energy--whether centrally provided or derived from home solar panels--and electric cars produce just one quarter of the health problems.

Hence the conclusion saying that electric cars are preferable when electricity can be lower-carbon. Which is to say, anything except coal.

Coal to phase out if EPA rules hold

And here's where the news comes in.

Under EPA regulations for carbon emissions of existing powerplants proposed last summer, much of the current U.S. coal generation capacity will be retired in the next 20 years.

Electric power plant outside Ithaca, New York

Those regulations will undoubtedly be fought hard in Congress, especially now that new Senate Majority Leader Mitch McConnell is from Kentucky, a coal-producing state.

But if the rules survive the next two years, the coal argument will become largely irrelevant over the next 10 to 20 years as natural gas generation supplants coal.

Coal is now less than 40 percent of overall U.S. generation mix (per the U.S. Energy Information Authority), and utilities are already moving up planned retirement dates for many coal plants.

Among them is the Tennessee Valley Authority, which will shutter several of its coal plants as part of an overall strategy to reduce coal usage from its current 38 percent to 20 percent, cutting the amount of coal burned nearly in half.

Fast Charging 2011 Nissan Leaf

If photovoltaic solar panel costs continue to fall, the transition may happen more quickly as utilities boost the proportion of their generation that comes from renewable sources.

The Edison Electric Institute, a think tank of sorts for the utility industry, has concluded that its century-old business model--in which it bundles the costs of providing electricity and maintaining the grid that does so--will be demolished within 10 or 15 years by widespread distributed renewable power.

That transition can only be aided by the falling costs of the lithium-ion cells used in electric-car batteries, which will also permit individual buildings not only to generate energy via solar or wind but also to store it.

The ability for a building to power itself for a few hours is hugely advantageous to utilities in reducing periods of peak demand--and it's something the utility may well pay for.

Photovoltaic solar power field at Volkswagen plant in Chattanooga, Tennessee

New debates focus on carbon

In just four years, a previous round of arguments about why electric cars will fail has essentially disappeared.

It used to be said that no one wanted electric cars, that they would leave you stranded, that their batteries would blow up, or that their batteries would fail after just four or five years.

Now the debate has migrated to the grounds of accepted climate science, and it looks in detail at the wells-to-wheels carbon footprint produced by using a vehicle over its full lifetime.

And as noted, cars powered by grid electricity have the delightful characteristic that they get cleaner as the grid does.

That's simply not the case for cars with combustion engines, which have the same carbon footprint per mile throughout their lifetimes.

Ford and Windy Energy Windy System clean-energy pilot program.

Read the actual study, perhaps?

And it's certainly not a point that those alarmist headlines are making today.

Former Green Car Reports writer Nikki Gordon-Bloomfield has a nice take on the study and the headlines.

On Transport Evolved, she writes, "When making academic papers and studies palatable for the masses, important facts are nearly always left by the wayside."

Indeed.

In other words: Read the actual study, not the headlines.

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