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Charging Electric Cars from the Grid: A Good Choice – or the Best Choice for Lowering Global Warming Emissions?

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Electric vehicles, hailed by some as the greenest cars on the planet, have also been dismissed by others as an expensive way to do little more than move vehicle emissions from the tailpipe to a smokestack. So who’s got it right? My colleague, Amine Mahmassani, who works in the Clean Vehicles program at UCS recently co-authored a new report on electric vehicles which clears the air on the issue. I interviewed Amine to see what I could learn about global warming emissions from charging vehicles on the electricity grid.

Given today’s vehicle market, is buying an electric vehicle really a good option for the climate conscious driver?

The answer is yes, but just how good depends on where in the country you live.

The global warming pollution emitted when charging your electric vehicle depends on how much of the electricity of your area is powered by coal, and how much comes from cleaner alternatives such as renewable sources and natural gas. Even on the most coal-heavy grids, EVs are on par with the most fuel-efficient conventional gasoline vehicles for global warming emissions – making them a good choice, though not necessarily the best. Only in areas where a greater share of electricity comes from cleaner sources do EVs compete with good gasoline-hybrids; in many cases beating even the most fuel-efficient hybrids on the road for global warming emissions.

Can one determine how electric vehicle emissions compare in different parts of the country?

The U.S. can be divided into 26 electric grid regions, each with a unique mix of power generation resources. We performed an analysis of the global warming emissions produced when charging an electric vehicle in each region, and then placed the regions into three categories—Good, Better, and Best—based on how the emissions compare to those of gasoline-powered vehicles. For example:

  • EVs in Good regions produce the same global warming emissions per mile as a gasoline vehicle with a fuel economy somewhere between 31 and 40 mpg. This means that their emissions are comparable to the best non-hybrid gasoline models available, such as the Ford Fiesta and the Hyundai Elantra.
  • EVs in Better regions produce the same global warming emissions per mile as a gasoline vehicle with a fuel economy somewhere between 41 and 50 mpg. This means that their emissions are comparable to the best gasoline hybrid models available, such as the Toyota Prius and Honda Civic Hybrid.
  • EVs in Best regions produce the same global warming emissions per mile as a gasoline vehicle with a fuel economy somewhere in excess of 50 mpg. This means that they outperform the best gasoline hybrid models available.

To make sure we are taking the fuel’s full life-cycle into account, our analysis includes emissions not just from burning fuel to power a car or to generate electricity, but also from producing the fuel. So we include emissions from pumping and refining oil into gasoline as well as mining and transporting coal, for example.

Check out the map to see how EVs in your region stack up. Click on the image for a larger version.

So what are the results? Where are the “Best” regions for charging an electric vehicle?

The analysis shows that 45% of Americans live in regions where electric vehicles are the “best” choice, producing less global warming pollution than any gasoline vehicle on the road, including the best hybrids. For those that don’t, EVs are at least a “good” choice, producing significantly less global warming pollution than the average new compact car.

So if you want to buy an EV and you live in a region with a “dirtier” electricity grid, what do you recommend?

Well first, it is important to note that the electricity grid has been getting cleaner as older coal plants are retired, and investments in cleaner power from renewables and natural gas increase. So even if an EV purchased today may not be the very best choice for cutting global warming pollution where you live right now, its emissions are likely to improve over its lifetime.

But there are definitely some things people can do right now to improve the environmental performance of EVs in their region. By participating in green energy programs offered by their utilities, supporting renewable energy standards for their state, or even producing their own renewable energy with rooftop solar panels if they own a home, individuals can help electric vehicles live up to their potential as the best choice everywhere.

 

Posted in: Energy, Global Warming, Uncategorized, Vehicles Tags: , , , , , ,

About the author: Laura Wisland is a senior energy analyst and an expert on California renewable energy policies. She holds a master’s degree in public policy. See Laura's full bio.

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  • Jeff S

    Could someone from UCS please address the following question:

    In this article, you said, “The global warming pollution emitted when charging your electric vehicle depends on how much of the electricity of your area is powered by coal, and how much comes from cleaner alternatives such as renewable sources and natural gas.”

    To what extent are some of the “Best” states able to achieve that ranking because of the use of Nuclear power? I will give one example of a state I happen to know has a very high percentage of nuclear in their mix: South Carolina. Right now, today, what states have nuclear power to thank for their “Best” ranking?

    • http://www.ucsusa.org/news/experts/laura-wisland.html Laura Wisland

      Dear Jeff S.,

      Thank you for your inquiry. Because nuclear power generation produces almost no global warming pollution, the use of nuclear power plants lowers a grid’s average emissions intensity. Some regions in the “Best” category, especially SERC Virginia/Carolina and RFC East, make extensive use of nuclear power and probably would not have attained their “best” rating without it. Other regions in the “Best” category, such as WECC California and WECC Northwest, make relatively little use of nuclear power and would have had “best” ratings even if coal power was used instead. The grid mix of each region can be found on page 8 of the technical appendix in the State of Charge report, found here: http://www.ucsusa.org/assets/documents/clean_vehicles/electric-car-global-warming-emissions-appendix.pdf

  • Bob Davey

    Solar panels on the roof plus an electric vehicle that contains a duel set of batteries that can be easily swapped out on a daily basis is the ultimate weapon to less reliance on coal and oil.
    That’s my longterm objective.
    I hope EV battery tech will advance to extend their range between recharges.
    In the meantime, and with the economy in a slump, my ’03 Honda Insight gets 60-70 mpg.
    That’s the best I can afford for now.

  • Marc

    I recently became the owner of a 100% Nissan LEAF…first one sold in Maine! I’ve begin trying to get the state to participate in the EV Network infrastructure development, but it does not appear that critical component is on their radar. Any suggestions from UCS in this regard?

    • http://ucsusa.org Rachel Cohen

      Rachel Cohen, Outreach Coordinator with the UCS Clean Vehicles program here. First off, congrats Marc on being a leader in bringing EVs to the streets across the US. We hope you’ll continue sharing your story with friends and family to help others learn about the benefits of driving an EV, including the fuel cost savings and global warming emissions benefits that we found in our report. We agree that expanding EV infrastructure is critical, and there are many ways to get this message to policymakers. Our action alert (http://www.ucsusa.org/clean_vehicles/what_you_can_do/unleash-electric-vehicles.html) makes it easy to write to your Governor in support of policies that lower barriers to EV ownership, and you can even add in your personal EV story and explain more about why you want your state to support charging infrastructure. After you take action and encourage others to do so as well, here are some resources to take it a step further by setting up and having a successful meeting with your state policy-makers (http://www.ucsusa.org/action/activist-resource-center.html). And remember, changing policies isn’t the only way to bring more EVs to the streets – reaching out to your company/employer, local businesses and community groups about installing charge stations is another great way to be an EV advocate.

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