How Green Are Electric Cars? Depends on Where You Plug In - NYTimes.com

Paul Stenquist, April 13, 2012
The U.C.S. report, which takes into account the full cycle of energy production, often called a well-to-wheels analysis, demonstrates that in areas where the electric utility relies on natural gas, nuclear, hydroelectric or renewable sources to power its generators, the potential for electric cars and plug-in hybrids to reduce carbon dioxide emissions is great. But where generators are powered by burning a high percentage of coal, electric cars may not be even as good as the latest gasoline models — and far short of the thriftiest hybrids.