Carbon dioxide (CO2) is the main greenhouse gas currently contributing to global climate change. New regulations have been set to require American (and foreign) car companies to modify their fleets to reduce CO2 emissions by increasing vehicle efficiency. Plug-in electric vehicles (PEV) have been the solution for many companies as PEVs can drive about 100 miles per charge and are thought to be zero emission environmentally friendly alternatives to conventional gasoline powered motor vehicles. When analyzing possible energy sources like coal and natural gas power plants that would provide the electricity to charge PEVs at individual homes, this study suggested the majority of those energy sources in the United States are coal powered and would emit more CO2 than a conventional motor vehicle's tailpipe emissions. As fuel economy regulations become stricter and companies consider producing more PEVs, the amount of CO2 emitted as a result of PEVs charging could increase past CO2 emissions from newer motor vehicles. Power plant modifications should be considered in conjunction with motor vehicle emission reductions to diminish CO2 contributing to climate change.