Transport Theory

How 'green' are electric vehicles?

Posting in Energy

A new study suggests that your EV may only be truly low-emissions if you live in a region that uses renewable energy to produce electricity.

Electric vehicle skeptics have long argued that EVs cannot truly be considered "zero emissions" because they use coal-generated electricity, which in itself produces harmful emissions.

Now, a new report from the Union of Concerned Scientists seems to lend credence to that view. In a report to be published Monday, according to The New York Times, the advocacy group compares the emissions of a baseline electric vehicle, the Nissan Leaf, in different parts of the country.

The report, titled "State of Charge: Electric Vehicles' Global Warming Emissions and Fuel Cost Savings Across the United States," found that given similar driving conditions and distances, a hypothetical Nissan Leaf in Denver would generate significantly more emissions than the same hypothetical car in Los Angeles.

California uses clean energy for much of its electricity. As a result, the Leaf in the Los Angeles part of the comparison would emit greenhouse gases at around the same level as a gasoline-powered car that got 79 miles per gallon. In Denver, where electricity is coal-dependent, the same car would produce the same level of greenhouse gas as a gasoline-powered Mazda 3, which gets only 33 miles per gallon.

In regions where renewable energies are used to generate electricity, the study shows, electric vehicles can reduce emissions significantly. "But where generators are powered by burning a high percentage of coal," said The New York Times, "electric cars may not be even as good as the latest gasoline models — and far short of the thriftiest hybrids."

While Nissan CEO Carlos Ghosn maintains that even EVs powered by electricity generated from coal are better than conventional gasoline-powered cars, Nissan's supporting studies indicate that EVs only perform better than cars with fuel efficiency of between 27 and 36 miles per gallon.

Here's one way to look at it, according to The New York Times:

If one region were completely dependent on coal for power, its electric cars would be responsible for full-cycle global-warming emissions equivalent to a car capable of 30 m.p.g. in mixed driving. In a region totally reliant on natural gas, an electric would be equivalent to a 50 m.p.g. gasoline-engine car.

So if you are considering buying an electric vehicle, your geographic location may help you decide if it is worth the investment. See The New York Times' info graphic to see to see how different parts of the country compare:

Photos: Nissan, The New York Times

via [The New York Times]

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Channtal Fleischfresser

Contributing Editor

Contributing Editor Channtal Fleischfresser has worked for The Economist, WNET/Channel 13, Al Jazeera English, Wall Street Journal and Associated Press. She holds degrees from the University of Pennsylvania and the Columbia University Graduate School of Journalism. She is based in New York. Follow her on Twitter. Disclosure