More a Story About Coal Plants Than Electric Cars...A recent study by researchers at the University of Tennessee has been making the rounds on the web lately. Its conclusions are interesting, but they must be kept in context to stay valid. So what's the study about and what are its conclusions?
Researchers looked at the impact of electric vehicles in China (mostly e-bikes, which are very popular there, but also electric cars) on air quality, and more precisely on the particulate matter (PM2.5) emissions because these are the most likely to have health impacts. The finding that has many people talking is:
For most cities, the net result is that primary PM2.5 environmental health impacts per passenger-km are greater for e-cars than for gasoline cars (3.6× on average), lower than for diesel cars (2.5× on average), and equal to diesel buses. In contrast, e-bikes yield lower environmental health impacts per passenger-km than the three CVs investigated: gasoline cars (2×), diesel cars (10×), and diesel buses (5×). (source)
This shouldn't be shocking to anyone. The environmental performance of electric vehicles is highly dependent on their source of electricity, and China is almost the worst case scenario when it comes to air quality. Around 3/4 of their electricity comes from coal, their local coal is very dirty (which is why they import a lot of it form Australia), and their air-quality regulations are very lax and poorly enforced. Add to this the fact that China's coast is pretty densely populated and that many cities are located near very dirty coal plants, and that's a recipe for unhealthy air. Electric vehicles are dirtier in China, but so are TVs and toaster ovens and anything that runs on electricity.
Silver Lining in the Coal CloudThe good news is that, while China is at one extreme, the rest of the world mostly does much better when it comes to air pollution from electric power generation. Place like Norway and France gets almost all of their electricity from very clean sources, and electric vehicles there would not only be great when it comes to CO2 emissions (even in China they do pretty decently), but they would also do extremely well when it comes to air quality. Places like the US and most of Europe fall somewhere in the middle, but on average we can expect significant benefits from going electric (especially over time as power grids are cleaned up).
Another bit of forward-looking good news is that China's situation is not sustainable. Like the rest of the industrialized world before, it'll almost certainly tighten air quality regulations and should also - hopefully quickly - reduce its heavy dependence on coal. China's population might not have too much to say at the ballot box, but complaints about air quality are near the top of everybody's list, and even communist party officials don't want their families to breathe smog day in and day out...
So in short, these results make sense for China. They are specific to that country at this time and shouldn't be generalized to other places or to the future (unless nothing changes, which would be a sad scenario).