Do All-electric Cars Provide Global Warming and Pollution Reductions If They Get Their Energy from Power Plants That Use Natural Gas or Coal?

Ask a Scientist - October 2010

G. Kalland from Los Osos, CA, asks "With the introduction of all-electric cars, is there a real benefit for smog and global warming emissions reductions if the energy comes from power plants that produce electricity from natural gas and coal?" and is answered by Patricia Monahan, Deputy Director of the UCS Clean Vehicles Program

This is a great question as there are a number of new electric car models coming out soon—and they’re not what people might picture when they think of electric cars. I had a chance to test drive one model recently and sit in another. Electric vehicles are really fun to drive. The ones I tested out seat five and have a good amount of storage—in short, good family cars. But what’s their environmental benefit if you’re just swapping out one fossil fuel—gasoline—for electricity powered by other fossil fuels, such as coal or natural gas?

Well, electric vehicles are clearly more energy efficient than conventional cars. An electric car can travel more than three times further than today’s conventional gasoline car per unit of energy (i.e. electricity or gasoline) consumed. Electric vehicles also reduce global warming emissions. A recent study by Argonne National Labs found that, on average, plug-in hybrid electrics cut global warming emissions by 20 to 25 percent compared to today’s average car, and pure battery electric cars can achieve even greater reductions.

What gets more complicated is when you compare electric vehicles to hybrid-electric vehicles, such as the Toyota Prius or the Ford Fusion. That’s where the environmental benefit really depends on where you get the electricity. Some studies find that plain old hybrid vehicles can be cleaner than plug-in vehicles, especially if the plug-in is powered by electricity coming from dirty coal. The Electric Power Research Institute found that plug-in hybrid electric vehicles that are powered by coal release up to 11 percent more global warming emissions than hybrid-electrics. But, if you’re plugging your electric vehicle into a grid that relies heavily on natural gas, it is likely cleaner than a hybrid. And if the electricity is primarily from renewable energy, like wind or solar, your carbon footprint is very small. So ultimately, how much environmental benefit you get from an electric vehicle really depends on where you get your electricity.

That’s why the Union of Concerned Scientists would like to see pollution standards for vehicles that account for all sources of global warming emissions—from the power plant to the tailpipe.

UCS supports electric vehicles because they are more efficient than the conventional vehicles we have today and, if paired with a clean electricity grid, can dramatically cut pollution. In the long run, we’re going to need major changes in both the transportation and energy sectors to see the kinds of global warming emissions reductions that scientists say we need to avoid the worst effects of climate change.

Patricia Monahan is the director of the California office and deputy director for Clean Vehicles at UCS. She has a master's degree in energy analysis and policy from the University of Wisconsin at Madison and has published numerous studies on the benefits of reducing pollution from cars, trucks, buses, and heavy equipment.

The Union of Concerned Scientists is the leading U.S. science-based nonprofit organization working for a healthy environment and a safer world. Founded in 1969, UCS is headquartered in Cambridge, Massachusetts, and also has offices in Berkeley, Chicago and Washington, D.C. To subscribe or visit go to:  http://www.ucsusa.org