Carbon dioxide emissions indirectly generated from United States plug-in electric vehicles

Plug-in electric vehicles (PEVs) are marketed as zero-emission alternatives reducing air pollutant emissions like greenhouse gases contributing to climate change. Coal and natural gas are the largest contributors to the electric power sector, making up about 45% and 24% of power generation, respectively; they are the main sources of electricity for consumers charging their eco-friendly vehicles like PEVs from the local grid. Combustion equations for coal, methane and gasoline were used to analyze the carbon dioxide (CO2) emissions generated by PEVs and cars (with average fuel economy of 22 miles per gallon (mpg) as of 2010) to estimate if PEVs generate less CO2. Based on recent federal regulations, new vehicles powered by gasoline will have to average 35.5 mpg by 2016; therefore, if the average vehicle is driven 12,000 miles per year, the current fleet will emit 10,680 pounds of CO2 per vehicle and new vehicles will emit 6,600 pounds of CO2 annually. Considering the number of kilowatt hours to power a PEV, consumers plugging into a grid powered by a coal plant to charge PEVs will generate about 14,235 pounds of CO2 annually while grids powered by natural gas will emit approximately 4,400 pounds of CO2 annually. Given coal currently makes up a larger percent of electric power sources compared to natural gas, PEVs may be responsible for a larger amount of CO2 emitted. Future regulations should consider the type of power plants generating electricity for PEV charging to quantify the total CO2 emissions generated by these vehicles correctly.