Those electric cars? Not as clean as advertised.

From FOX News:

Study: Your all-electric car may not be so green
People who own all-electric cars where coal generates the power may think they are helping the environment. But a new study finds their vehicles actually make the air dirtier, worsening global warming.

Ethanol isn't so green, either.

"It's kind of hard to beat gasoline" for public and environmental health, said study co-author Julian Marshall, an engineering professor at the University of Minnesota. "A lot of the technologies that we think of as being clean ... are not better than gasoline."

The key is where the source of the electricity all-electric cars. If it comes from coal, the electric cars produce 3.6 times more soot and smog deaths than gas, because of the pollution made in generating the electricity, according to the study that is published Monday by the Proceedings of the National Academy of Sciences. They also are significantly worse at heat-trapping carbon dioxide that worsens global warming, it found.

The study examines environmental costs for cars' entire life cycle, including where power comes from and the environmental effects of building batteries.

"Unfortunately, when a wire is connected to an electric vehicle at one end and a coal-fired power plant at the other end, the environmental consequences are worse than driving a normal gasoline-powered car," said Ken Caldeira of the Carnegie Institution for Science, who wasn't part of the study but praised it.

The original paper is at PNAS: Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States