EVs, it seems, have been resurrected. Witness the boom in next-generation all- or mostly-electric vehicles, including the Chevy Volt, the Tesla Roadster and sedan, CODA's EV sedan, Fisker's luxury EV sedan, the Nissan Leaf, and others  -- as well as the boom in companies that are hoping to get a piece of the EV infrastructure market.

Electric vehicles have benefitted greatly from the wide adoption of hybrid vehicles, especially in the wake of the last big gas price spikes in 2008. And the current gas spike certainly isn't hurting sales and interest in hybrids and EVs.

But new research from the Sightline Institute, a sustainability research institute based in Seattle, raises important questions about the overall greenness of the Nissan Leaf -- or any electric vehicle -- and that should put a wrinkle in corporate plans to widely adopt EVs for fleets.

Over on the Sightline blog, Clark Williams-Derry writes:

[I]f your main concern is the climate impact of your driving habits, how does the Leaf fare? The EPA label says that the car gets the energy equivalent of 99 miles per gallon -- 106 mpg in the city, 92 mpg on the highway. Pretty good, in other words!

But the EPA also says that the car emits "0" pounds of climate-warming emissions each year. And while this is technically true, it's also misleading. No, the Leaf doesn't have a tailpipe spewing carbon-laden exhaust. But the electricity the car runs on doesn't magically appear out of nowhere. And even in the Northwest, blessed as we are with lots of hydropower, some of the electricity that comes out of our sockets started out as coal or natural gas. So despite what the EPA label suggests, the Leaf does have some climate impact. 

How much of an impact? Williams-Derry has put together a great chart that spells out the difference between the average passenger vehicle in the United States, a standard Toyota Prius hybrid, and a Nissan Leaf that is drawing its power from a grid that's largely powered by coal, by natural gas, or by hydroelectric energy.

The numbers put the greenness of the Leaf into a bit of perspective:

Williams-Derry is writing from the Pacific Northwest, with its plentiful hydroelectric power, and he's writing from the perspective of the individual, rather than corporate, driver. So that throws a few more wrinkles into the mix.

First off, how many individuals really care about the carbon emissions of their daily drive? It's a not-insignificant number, but it's certainly dwarfed by people who care about how much their commute costs every week. And secondly, how many individuals know the generation mix of the energy that powers their home? Probably and even smaller slice of the already-small slice of climate-conscious drivers.

None of this is to downplay Williams-Derry's work; I simply think it will have more resonance in the C-Suite than on the cul de sac.

Because, as we report every day, a large and steadily growing number of companies are very concerned about their carbon emissions, and vehicle emissions will fall directly into a company's Scope 1 or Scope 2 emissions (Scope 2 if we're talking about electric vehicles, which we are...).

So if your company is looking at ways to reduce emissions, and settles on EVs as a strategy, whether for transportation for your sales or maintenance team or as incentives for employee commutes, it will be important for your future sustainability reports to factor Williams-Derry's figures in.

His takeaways from the research:

[I]f the electricity that powers the Leaf comes from a coal-fired power plant, then the battery-powered car performs far worse than a Prius. In fact, by these calculations, it's the equivalent of a car that gets about 30 mpg: better than the average car, but certainly not much to brag about.

I take two things away from all this. First, electric cars in the Northwest appear to be a pretty good deal for the climate. But second -- and more importantly -- coal-fired power negates all of the climate benefits of electric cars. If power companies in the US West were to build lots of coal plants in order to power a fleet of electric vehicles, electric car buyers will be doing the climate no favors. People might as well buy a small-and-efficient car that burns plain old gasoline.

So if you really want to drive green, you ought to focus on getting rid of coal, as fast as possible. What car you drive is important; but where your electricity comes from can make an even bigger impact on the climate.

Be sure to read his full blog post; he provides useful links and resources that, among other things, can help you calculate the emissions per kilowatt-hour from your own regional energy generation.

_{Leaf photo CC-licensed by Tom Raftery. Chart courtesy of Sightline.}