An article in Fast Company (Ariel Schwartz, January 13,2011) summarizes a  MIT study (http://web.mit.edu/mitei/research/reports/transport-electrification.html) that tracks the sources of electricity that will power electric plug-in cars.  Plug-ins using alternate energy sources such as nuclear, biomass etc are estimated in the study to decrease emissions by 66 % compared to gas powered engines.  But, given coal as the source of energy for many states, what can be done to convert the apparent “clean” energy benefits to be realized ? The study suggests a pricing scheme that encourages “green power” derived from alternate energy sources that enable such emission savings to be realized.  Should such supply chain wide impact be “required” to be calculated and displayed by automakers – who can use GPS and other information sources to calculate emissions ?