In some Chinese cities, the environmental impact of EVs is worse than that of gas vehicles, due to old coal power plants that lack modern pollution controls.

What vehicles are best for the environment: gas, diesel, or electric? That’s the question that researchers from three universities tried to answer with a study of 34 cities in China. Their paper, published in Environmental Science & Technology, gives no simple answer – the authors found that there are so many local variables that impacts can be totally different from one city to another. “The net result for China is that it is unclear a priori whether EVs are an environmental health benefit or disbenefit relative to [internal combustion vehicles].”

One conclusion that may dismay us EV evangelists: In some Chinese cities, the environmental impact of EVs is worse than that of gas vehicles. This is because 77 percent of China’s electricity comes from nasty coal, much of it from old power plants that lack modern pollution controls. In the US (45% coal) or in nuclear-powered France, the picture is surely different, but this report underscores an obvious fact: phasing in EVs without phasing out coal power plants may do little to cut carbon emissions. On the other hand, the report notes that power-plant emissions tend to happen away from population centers, while tailpipe emissions happen right where people have to breathe the stuff – so when it comes to health, EVs don’t look so bad.

Another point that may surprise some folks: in terms of local air pollution, diesels fare much worse than gas engines (or EVs). Diesels emit less CO2, but more of other pollutants that cause health problems.

Here’s one finding that won’t surprise anyone: the greenest vehicle of all is an electric bicycle. The Chinese have bought 100 million of them in the past decade, and they now out number cars two-to-one.

Like it or not, here’s what the authors said:

“Our findings show that replacing gasoline cars with e-cars will result in increased CO2 from combustion emissions and all-cause mortality risk…in most cities. Chinese policy makers should carefully proceed with deployment of plug-in vehicles and consider aggressive improvements in the power sector to realize anticipated gains in emissions and health.”

Image: mckaysavage