More good news about electric cars in the U.S.: the emissions associated with the electricity used to charge them have fallen.
Based on the latest data on powerplant emissions from the EPA, an electric car on the road in the U.S. now has average emissions as low as an 80-mpg car.
DON'T MISS: Electric cars cleaner than any gas-only car for 97% of U.S. drivers (Jun 2017)
That figure is sales-weighted, meaning it takes into account where electric cars exist today in the U.S.
But that 80-mpg average translates to emissions 10 percent lower than even last year's average, which was 73 mpg—demonstrating that every time any powerplant gets cleaner, so does every single electric car that plugs into the grid it supplies.
The data come from the Union of Concerned Scientists, who've run this analysis for several years now.
Electric-car wells-to-wheels emission equivalencies in MPG, May 2017 [Union of Concerned Scientists]
Electric-car wells-to-wheels emission equivalencies in MPG, Sep 2015 [Union of Concerned Scientists]
Electric-car wells-to-wheels emission equivalencies in MPG, Sep 2014 [Union of Concerned Scientists]
Electric-car wells-to-wheels emission equivalencies in MPG, Sep 2013 [Union of Concerned Scientists]
Their maps of "MPG equivalency" show pretty much continuous reductions in emissions on the different grids across the U.S.
The wells-to-wheels carbon footprint calculations look at the carbon dioxide emitted to generate the electricity used to recharge the electric car, plus the smaller amounts for its manufacturing and materials.
A higher MPG-equivalency number means less carbon dioxide is emitted for every mile driven by that electric car.
READ THIS: Electric cars in UK cleaner than best diesels in summer, not yet in winter
As UCS points out, 75 percent of U.S. residents live in place where an electric car is as clean as a 50-mpg gasoline car.
Because electric cars are somewhat concentrated in areas with cleaner-than-average grids (e.g. California), the average electric car is equivalent to an 80-mpg gasoline car.
No vehicle sold in the U.S. today gets an EPA rating anywhere near 80 mpg, of course. No car without a plug seems likely to reach that efficiency, ever.
Two 2018 Nissan Leafs with EVgo fast charger at NJ Turnpike Joyce Kilmer travel plaza, Feb 2018
Having an accurate measure of the carbon footprint per mile for electric cars is crucial in understand their role in reducing overall carbon emissions to stem global warming caused by the rapid increase in atmospheric carbon dioxide over the last two centuries of human industry powered by fossil fuels.
While the ideal scenario remains an electric car recharged entirely by renewable energy, even today's U.S. grids will reduce the carbon emissions of personal transport significantly as more plug-in electric vehicles hit the country's roads.
CHECK OUT: In Just One Year, Electric Cars Have Gotten Cleaner: How'd They Do That? (Dec 2014)
It's what you might call a win-win situation: more electric cars coming onto U.S. roads cut emissions, and each of them gets steadily cleaner each year as the grid slowly decarbonizes.
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