The environmental impact of plug-in electric cars is a hot topic right now, and a fiercely debated one at that.

A couple of weeks ago, Tesla Motors CEO Elon Musk pledged to dive into it himself.

Musk tweeted, "Am seeing many poorly argued attacks on 'true' CO2 impact of electric cars. Will rewrite attacks 4 max strength & try my best to rebut."

His studies, he followed up, "will address the whole system analysis from power gen to power use."

(The tweet and its follow-up since appear to have been deleted--or at least Twitter can't find them. Hmmmmmmm.)

The carbon impact of electric cars focuses on two areas: the carbon produced in generating the electricity that charges their batteries, and that produced during their manufacture.

The first area is largely settled.

Last year, a study by the Union of Concerned Scientists concluded that even in states with the dirtiest electric grids, the carbon impact of driving electric cars is no worse than that the most fuel-efficient gasoline cars.

In states like California, with its much cleaner electric grid, an electric car is responsible for far less carbon than a 50-mpg Toyota Prius--the most fuel-efficient gasoline car sold in the U.S.

A 2007 study by the Electric Power Research Institute and the Natural Resources Defense Council came to similar conclusions.

So did an analysis of his own Tesla Model S by our author David Noland, who analyzed the myth that a Model S is worse than an SUV on overall emissions.

Lately, attention has shifted to the manufacturing impact of electric cars.

Elon Musk signs new 2013 Tesla Model S at Tesla Store opening, Austin, Texas [photo: John Griswell]

Elon Musk signs new 2013 Tesla Model S at Tesla Store opening, Austin, Texas [photo: John Griswell]

Author Ozzie Zehner has a new book out suggesting that the environmental burden of mining the materials for and manufacturing lithium-ion cells, electric motors, and other electronics for electric cars exceeds those for gasoline cars to a degree that offsets their tailpipe emission savings.

In a recent cover story in IEEE Spectrum magazine, Unclean at Any Speed, Zehner summarized the case made in his book.

As Zehner notes, “the seemingly simple question ‘Are electric cars indeed green?’ quickly gets complicated.”

The magazine was soon swamped with more than 500 comments on the article, many of countering his assertions and placed the future evolution of electric-car manufacturing into a broader context.

This author was asked to provide that broader context for an op-ed, Electric Vehicles Need More Study, Less Emotion, in the most recent issue of Spectrum.

The magazine also published a further article, A Rebuttal: EVs Are Clean at Every Speed, by Mark Duvall of EPRI.

The essential conclusions? More study is needed, but plug-in electric cars show great promise for reducing the overall carbon burden of transportation.

If you're interested in the topic, we suggest reading all the links above to educate yourself on the complexities of the issue--and there are many.

But Musk's promise, if it's still active, may bring new public attention to the issues.

Tesla's CEO is not only respected as an entrepreneur now running three startup companies--not only Tesla but also SpaceX and Solar City--but as a scientist as well.

Should he dive into the topic, his conclusions will be widely disseminated and discussed by a far wider audience than the hundreds of thousands of electrical engineers who are IEEE members.

For that reason, we hope Musk makes good on his promise.

[hat tip: Brian Henderson]


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