But are they? New research looking at electric cars in China is now second guessing that assumption. In the study, published in Environmental Science & Technology, Christopher Cherry, an assistant professor of civil and environmental engineering at University of Tennessee, and his colleagues found that electric vehicles were actually more harmful to public health per kilometer traveled than gasoline-powered cars in terms of air pollution, especially in China.
“If we compare gasoline car emissions to electric car emissions, the electric cars look very, very bad,” said Cherry to Time. “So the point is that you have to consider the emissions exposure when the exposure source is far apart—the electrical power plant as opposed to the tailpipe of a car.”
How is this possible? Basically, Cherry says any claims of "zero emissions" for electric cars fail to take into account how their electricity is generated. In China, where about 85 percent of the country’s power is sourced by fossil fuels (about 95 percent of which is coal), electric cars are among the worst environmental polluters, spewing on average 3.6 times more fine particulate emissions per passenger-km than gasoline cars. According to the study, the impact of EVs was equal to diesel buses, with electric bikes representing the lowest environmental health impacts per passenger per kilometer.
Of course, not every country is as coal crazy as China. For example, in the U.S., our energy grid is a mix of 50 percent coal, 20 percent natural gas, 20 percent nuclear, and 10 percent hydro and renewables. While that's a great deal cleaner than China, it's still not as good as places like Germany, which gets about 20 percent of its energy from renewables and only relies on coal for about a third of its power. Studies like Cherry's show that electric cars are only as green as the energy source they come from—the greener we are, the greener they get.
Which brings us to the real reason to support electric cars. As countries continue to decarbonize their electricity grid and move towards renewables, EVs are only going to get better for the environment. In the meantime, they're doing exactly what they were designed for: to give us an alternative to gasoline-fueled vehicles. As Chris Paine, director of Revenge of the Electric Car, says in an interview with CleanTechnica: “The core reason of the electric car has nothing to do with the environment, it has to do with not importing oil."