China's pollution related to E-cars may be more harmful than gasoline cars, researchers find

Electric cars have been heralded as environmentally friendly, but findings from University of Tennessee, Knoxville, researchers show that electric cars in China have an overall impact on pollution that could be more harmful to health than gasoline vehicles.

Chris Cherry, assistant professor in civil and environmental engineering, and graduate student Shuguang Ji, analyzed the and environmental health impacts of five vehicle technologies in 34 major Chinese cities, focusing on dangerous fine particles. What Cherry and his team found defies conventional logic: cause much more overall harmful particulate matter pollution than gasoline cars.

"An implicit assumption has been that air quality and health impacts are lower for than for conventional vehicles," Cherry said. "Our findings challenge that by comparing what is emitted by vehicle use to what people are actually exposed to. Prior studies have only examined environmental impacts by comparing emission factors or ."

Particulate matter includes acids, , metals, and soil or . It is also generated through the combustion of fossil fuels.

For electric vehicles, combustion emissions occur where electricity is generated rather than where the vehicle is used. In China, 85 percent of is from fossil fuels, about 90 percent of that is from coal. The authors discovered that the power generated in China to operate electric vehicles emit fine particles at a much higher rate than gasoline vehicles. However, because the emissions related to the electric vehicles often come from power plants located away from population centers, people breathe in the emissions a lower rate than they do emissions from conventional vehicles.

Still, the rate isn't low enough to level the playing field between the vehicles. In terms of impacts, electric cars are more harmful to public health per kilometer traveled in China than conventional vehicles.

"The study emphasizes that electric vehicles are attractive if they are powered by a clean energy source," Cherry said."In China and elsewhere, it is important to focus on deploying electric vehicles in cities with cleaner electricity generation and focusing on improving emissions controls in higher polluting power sectors."

The researchers estimated health impacts in China using overall emission data and emission rates from literature for five vehicle types—gasoline and diesel cars, diesel buses, e-bikes and e-cars—and then calculated the proportion of emissions inhaled by the population.

E-cars' impact was lower than diesel cars but equal to diesel buses. E-bikes yielded the lowest environmental health impacts per passenger per kilometer.

"Our calculations show that an increase in electric bike usage improves air quality and environmental health by displacing the use of other more polluting modes of transportation," Cherry said. "E-bikes, which are battery-powered, continue to be an environmentally friendly and efficient mode of transportation."

The findings also highlight the importance of considering exposures and the proximity of emissions to people when evaluating impacts for electric vehicles. They also illuminate the distributional impact of moving pollution out of cities. For electric vehicles, about half of the urban emissions are inhaled by rural populations, who generally have lower incomes.

The findings are published in the journal Environmental Science and Technology.

Cherry worked with Matthew Bechle and Julian Marshall from the University of Minnesota and Ye Wu from Tsinghua University in Beijing. The scientists conducted their study in China because of the popularity of e-bikes and e-cars and the country's rapid growth. Electric vehicles in China outnumber conventional vehicles 2:1. E-bikes in are the single largest adoption of alternative fuel vehicles in history, with over 100 million vehicles purchased in the past decade, more than all other countries combined.

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Provided by University of Tennessee at Knoxville
Citation: China's pollution related to E-cars may be more harmful than gasoline cars, researchers find (2012, February 13) retrieved 20 May 2019 from
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Feb 13, 2012
what a load of crock....

Feb 13, 2012
gee...i wonder if the dept at this university has received any OIL MONEY lately?

Feb 13, 2012
Funny how worldview comes first, facts second...even on a "science site"....

Feb 13, 2012
lol. why is UTK doing research on vehicle emissions in China?
all they really are saying is that coal electrical efficiency might be worse than gasoline.

Feb 13, 2012
I think this goes to show that even though the intent on electric is great, unless the base source of energy to power them is renewable than all we are doing is shifting the physical location of the pollution and not actually eliminating it. I'd like to see more studies on this in countries with a high percentages of renewable energy

Feb 13, 2012
"focusing on improving emissions controls in higher polluting power sectors."

That's the key here. China's power generation from coal is so unregulated that emissions are staggeringly high. This wouldn't be true in other countries with strict emissions limits on power generation.

Feb 13, 2012
The article is quite incomplete. Nowhere does the environmental impact of the manufacture and disposal of the batteries get mentioned. (...let alone the impact of the lack of pollution control on the coal-fired plants as noted above)

Feb 13, 2012
Of course, the E-cars pollution is much higher for classical cars, because the fossil fuel energy is used in E-cars with fifteen percent efficiency - not to say about pile of disposed battery waste. It's trivial calculation: 60% of energy is lost during conversion into electricity, another 40% during recycling of batteries and cars itself. Whereas gas engines are using fossil fuel with twenty percent efficiency.

Feb 13, 2012
In addition, the consumption of neodymium in China's own car production effectively lead to end of neodymium export into another countries, namely USA and Japan. The neodymium magnets are crucial for construction of wind plants, for example.

Feb 13, 2012
Excuses and more excuses.... What else could be done to prevent the consumer from owning low maintenance low energy consuming vehicles... Like many have posted already, China certainly was the best place to do a study about how electric vehicles "pollute" via Coal plants... Shame on you UTK

Feb 13, 2012
What a load of crock is right, considering that the article tries to tie actual vehicle emission to inhaled pollutants. Bad form, that..

For electric vehicles, combustion emissions occur where electricity is generated rather than where the vehicle is used.

Well, yes. Yes it does. The same can be said for handheld electric torches*. Unless China generates electricity for their e-cars in facilities that are separate from those used to generate electricity for other uses, then I really don't see the point of this research.
Is the point that poorly regulated coal-burning power plants are bad? I think we knew that, but tying that to electric cars is just odd, in my opinion.

Feb 15, 2012
Is the point that poorly regulated coal-burning power plants are bad? I think we knew that, but tying that to electric cars is just odd, in my opinion.

Even if that's where they get the power to run on from? You can't have your cake and eat it.

Feb 18, 2012
I thought it was already well known that cars (Toyota Pirius for one) cause more damage to the environment throughout their life cycle than the equiv Landrover Discovery. The environmental cost of mining the resource for batteries and the like far out weight the use of petroleum. So its not just the use of electricity or petrol that must be taken into account, its the who life cycle from mining to disposal that should be looked at. And when it is, petrol run gars are still less damaging to the environment.

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