Electric Vehicles in China More Polluting Than Gasoline Vehicles.
KNOXVILLE, Tennessee, February 16, 2012 (ENS) - Electric vehicles in China cause more harmful particulate matter pollution than gasoline-fueled cars, when emissions from the generating stations that power them is factored in, new research shows.
In China, 85 percent of electricity production is from fossil fuels, and about 90 percent of that is from coal. The generation of electricity to operate EVs emits fine particles at a much higher rate than petrol-powered vehicles, finds a team of researchers from the United States and China.
BYD electric buses in Shenzen, China. The Shenzen government plans to have all public transportation on electric power in the next five years. (Photo courtesy BYD)
Chris Cherry, assistant professor in civil and environmental engineering at the University of Tennessee, and graduate student Shuguang Ji, analyzed the emissions and environmental health impacts of five vehicle technologies in 34 major Chinese cities, focusing on dangerous fine particles.
"An implicit assumption has been that air quality and health impacts are lower for electric vehicles 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," he said. "Prior studies have only examined environmental impacts by comparing emission factors or greenhouse gas emissions."
Cherry worked with Ye Wu from Tsinghua University in Beijing and scientists from the University of Minnesota.
The study was conducted in China because of the popularity of electric bikes and electric cars and the country's rapid growth.
E-bike and bus in Shanghai (Photo by electricbicycle.net)
Electric vehicles in China outnumber conventional vehicles 2:1. E-bikes in China 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.
For electric vehicles, says Cherry, combustion emissions occur where electricity to power them is generated rather than where the vehicle is used.
"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.
Coal-fired power plant in Guangdong, southern China (Photo by Panaramio)
The impact of electric cars was found to be 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 type of air pollution measured for the study - particulate matter - includes acids, organic chemicals, metals, and soil or dust particles. It is also generated through the combustion of fossil fuels.
Cherry said the research highlights the importance of considering exposures and the proximity of emissions to people when evaluating environmental health impacts for electric vehicles and the impact of moving air pollution out of cities. For electric vehicles, about half of the urban emissions are inhaled by rural populations, he said.
This study is funded by the U.S. National Science Foundation. The findings are published in the journal "Environmental Science and Technology."
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