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| Human World on Feb 22, 2012

Electric cars need a clean energy source, study suggests

You might assume that air quality and health impacts are lower for electric vehicles than for conventional vehicles. Not necessarily so, this study reveals.

Could it be that electric cars cause more overall pollution and are more harmful to health than conventional gasoline powered cars? In China, where electricity is generated primarily through the burning of fossil fuels, the answer appears to be yes. A research team from the University of Tennessee, Knoxville, has found in China the potential for a more negative overall impact – on pollution and health – from electric cars than from gasoline cars.

Study authors say their results point to electric vehicles being attractive if they are powered by a clean energy source. They also found that electric bikes had the lowest environmental impact in China.

The research team was led by Chris Cherry, assistant professor in civil and environmental engineering at UT Knoxville and graduate student Shuguang Ji. They looked at emissions and environmental health impacts for five vehicle technologies — electric car, electric bike, gasoline car, diesel bus, diesel car — in 34 major Chinese cities. They studied in China because electric car (e-car) use outnumbers conventional car use two to one. Also, electric bikes (e-bikes) are very popular in China, where over 100 million e-bikes were purchased in the last decade. For comparison, in the United States electric car technology hopes to catch on, but e-car and hybrid car purchases are predicted to remain below 10% of all auto purchases, through 2016.

This UT Knoxville study looked at the emission of fine pollution particulates including acids, organic chemicals, metals and soil or dust particles.

Cherry said in a press release:

An implicit assumption has been that air quality and health impacts are lower for electric vehicles than for conventional vehicles. 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 greenhouse gas emissions.

For electric vehicles, fine particulate emissions occur where electricity is generated rather than from the car’s engine, as is the case with a gasoline or diesel-powered vehicle. In China 85% of electricity is generated through the combustion of fossil fuels and 90% of that through burning of coal.

The study found that the power needed to operate electric vehicles in China results in pollution particulates at a far higher rate, although further away from population centers, than gas-powered vehicles.

Cherry said:

The study emphasizes that electric vehicles are attractive if they are powered by a clean energy source. 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.

Bottom line: Electric cars are only as environmentally friendly as their source of energy. Japan and other countries have utilized solar power to recharge electric cars. In the meantime, this troubling study finds that e-cars in China cause more pollution than conventional gas powered vehicles.

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