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Sources and Assumptions for the Electric and Plug-in Hybrid Vehicle Greenhouse Gas Emissions Calculator

To estimate your CO2 emissions rates and generate the bar graph, we used the following sources and assumptions.

Your CO2 Emissions Rates
Tailpipe (grams CO2/mile) This is the tailpipe CO2 emissions rate for combined city and highway driving that is shown on the fuel economy and environment label for the vehicle model you selected. It is the same regardless of where you live.
Total (grams CO2/mile) This includes the vehicle's tailpipe emissions and emissions associated with the production of electricity used to charge the vehicle. For plug-in hybrid electric vehicles, it also includes emissions associated with the production of gasoline. It is estimated using the sources and assumptions below, and will vary based on where you live.
Electricity Assumptions
Power Plant Emissions CO2 emissions rates (lbs/MWh) for 26 U.S. regions are taken from the Emissions & Generation Resource Integrated Database (eGRID2012 Version 1.0). EPA's Power Profiler ZIP Code Tool (Version 4.1) is used to map the user's zip code to the appropriate region. Click here for more information.
Transmission & Distribution Losses Some electricity is lost as it travels from the power plant to where it is used by the consumer (e.g., at the outlet). To adjust for these transmission & distribution losses, we apply five regional grid loss factors from eGRID2012 Version 1.0.
OtherEmissions Regional CO2 emission rates are multiplied by a region specific factor to account for greenhouse gas emissions associated with the production of feedstock used to generate electricity, e.g., emissions due to mining coal and transporting it to the power plant. Each region specific factor was determined based on the regional mix of electricity production methods (from eGRID2012 Version 1.0), and upstream factors for each method from the GREET model developed by Argonne National Laboratory (GREET1_2011, available here.)
Gasoline Assumptions
Combustion Emissions On average, 8,887 grams of CO2 are emitted from burning one gallon of gasoline.
Production Emissions Tailpipe CO2 emissions are multiplied by a national average factor of 1.25 to account for emissions associated with gasoline production, e.g., drilling, refining, and transportation, etc. (See 75 FR 25437, May 7, 2010)
Bar Graph
Your Results for this Vehicle Displays the total CO2 emissions for the vehicle model you selected in your region of the country.
National Average for this Vehicle This is an estimate of the total CO2 emissions rate for the vehicle model you selected using a national average electricity emissions factor from eGRID2012 Version 1.0 and assuming a 6.5% loss during transmission & distribution. A national average factor of approximately 10% is applied to account for greenhouse gas emissions associated with the production of feedstock used to generate electricity, e.g., emissions due to mining coal and transporting it to the power plant. It was determined based on the national average mix of electricity production methods (from eGRID2012 Version 1.0), and upstream factors for each method from the GREET model developed by Argonne National Laboratory (GREET1_2011). For emissions associated with the gasoline operation of plug-in hybrid electric vehicles, the assumptions are the same as those listed above.
Average Vehicle This is the estimated total CO2 emissions for the "average vehicle" as shown on the fuel economy and environment label. This gasoline-powered vehicle has a fuel economy of 23 mpg. A factor of 1.25 is applied to account for emissions from the production and transportation of gasoline.