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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.
Upstream
(grams CO2/mile)

This is the upstream CO2 emissions rate associated with the extraction of materials used for fuel as well as the production and distribution of electricity used to charge the vehicle. It is estimated using the sources and assumptions below and will vary based on where you live.

(For plug-in hybrid electric vehicles, the upstream CO2 emissions rate is also associated with the extraction of oil and subsequent refining and distribution of gasoline or diesel.)

Total
(grams CO2/mile)
Total emissions include the vehicle's tailpipe and upstream emissions.
Electricity Assumptions
Power Plant Emissions

Annual CO2 output emissions rates (lbs/MWh) for 27 U.S. subregions are taken from EPA's Emissions & Generation Resource Integrated Database (eGRID2021).

EPA's Power Profiler ZIP Code Tool (Version 12.1) 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 a regional grid loss factor per subregion from eGRID2021.
Emissions Prior to Power Generation

Greenhouse gas emissions are associated with the production and distribution of feedstock and fuel used to generate electricity (e.g., emissions due to mining coal and transporting it to the power plant) and vary by resource type. The electricity generation resource mix per subregion (%) is taken from eGRID2021.

Upstream CO2 emissions by resource type are taken from the GREET model developed by Argonne National Laboratory (GREET 2022) and applied to each resource type per subregion to get a CO2 emissions “upstream factor” per subregion.

Combined Emission Rates Power plant CO2 emission rates that consider grid losses are multiplied by upstream factors to get a CO2 emission factor per subregion (g/kWh).
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 U.S. average factor of 1.25 to account for emissions associated with upstream gasoline production: extraction, refining, and distribution. (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.
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 eGRID2021 and assuming a national average loss during transmission & distribution. A national average factor is also 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 eGRID2021), and upstream factors for each method from the GREET model developed by Argonne National Laboratory (GREET_2022). 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 28 mpg. A factor of 1.25 is applied to account for emissions from the extraction, refining, and distribution of gasoline.

Calculation
(8,887 grams CO2 / 28 mpg) x 1.25 = 400 grams/mile (rounded)

This website is administered by Oak Ridge National Laboratory for the U.S. DOE and the U.S. EPA.