Hybrid and Plug-In Electric Vehicle Emissions Data Sources and Assumptions

The following sources and assumptions were used to calculate the emissions, fuel use, and electricity sources for conventional and electric drive vehicles on the hybrid and plug-in electric vehicle emissions page.

Electricity Sources and Annual Vehicle Emissions

The following sources and assumptions were used to show electricity sources and calculate the annual vehicle emissions for a conventional, hybrid electric, plug-in hybrid electric, or all-electric vehicle.

Parameter Value Source
Gasoline GHG/gal 24 Full fuel cycle (well to wheels) greenhouse gas emissions (GHG) factors derived from GREET 2 2014. Results in CO2 equivalents (model available at http://greet.es.anl.gov)
National Average Electricity GHG/kWh 1.66 Full fuel cycle (well to wheels) greenhouse gas emissions (GHG) factors derived from GREET 2 2014. Results in CO2 equivalents (model available at http://greet.es.anl.gov)
Electricity Prices   Electricity prices from http://www.ventyx.com
Electricity Fuel Mix   Mix of fuels derived from entered zip code by disaggregating EGRID2010 (Version 1.0), 9th Edition, available at http://www.epa.gov/cleanenergy/energy-resources/egrid/
National Average Electricity Cost $/kWh $0.110 EIA 2015 Annual Energy Outlook, Table A3, year 2014, Residential, Nominal dollars source: http://www.eia.gov/forecasts/aeo/?src=email
Conventional Vehicle mpg 24.3 CAFÉ Standard
HEV mpg 47.3 Sales weighted average: 2014 sales from spreadsheet "HEV Sales by Model" (http://www.afdc.energy.gov/data/vehicles.html); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)
PHEV mpg 39.3 Sales weighted average: 2014 sales from HybridCars (http://HybridCars.com); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)
PHEV kWh/mi 0.41 Sales weighted average: 2014 sales from HybridCars (http://HybridCars.com); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)
PHEV all-electric range 14 Sales weighted average: 2014 sales from HybridCars (http://HybridCars.com); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)
EV kWh/mi 0.324 Sales weighted average: 2014 sales from HybridCars (http://HybridCars.com); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)
Average Annual vehicle Mileage (miles) 11,804 TEDB #33, Table 8.1; Total vehicle miles traveled divided by vehicles in operation, 2012
Percentage of PHEV annual miles driven on electricity 50% Rough average based on data from 2001 National Household Travel Survey, Summary of Travel Trends, Table 29. Assuming that the vehicle owner plugs in at home every night he/she is home and that the PHEV all-electric range is 14 miles.

Emissions and Fuel Cost for a 100-Mile Trip

The following sources and assumptions were used to calculate the emissions and fuel costs for a 100-mile trip using a conventional, hybrid electric (HEV), plug-in hybrid electric (PHEV), or all-electric (EV) vehicle.

Parameter Value Source
Trip Length miles 100 Given
Gasoline GHG/gal 24 Full fuel cycle (well to wheels) greenhouse gas emissions (GHG) factors derived from GREET 2 2014. Results in CO2 equivalents (model available at http://greet.es.anl.gov)
National Average Electricity GHG/kWh 1.66 Full fuel cycle (well to wheels) greenhouse gas emissions (GHG) factors derived from GREET 2 2014. Results in CO2 equivalents (model available at http://greet.es.anl.gov)
Electricity Prices   Electricity prices from http://www.ventyx.com
Electricity Fuel Mix   Mix of fuels derived for the entered zip code by disaggregating EGRID2012 data available at http://www.epa.gov/cleanenergy/energy-resources/egrid/
Gasoline Cost $/gallon (national average for regular gasoline) $2.42 http://www.aaa.com on 7/29/2011
National Average Electricity Cost $/kWh $0.11 EIA 2015 Annual Energy Outlook, Table A3, year 2014, Residential, Nominal dollars source: http://www.eia.gov/forecasts/aeo/?src=email
Conventional Vehicle mpg 24.3 CAFÉ standard
HEV mpg 47.3 Sales weighted average: 2010 sales from spreadsheet "HEV Sales by Model" (http://www.afdc.energy.gov/data/vehicles.html); MPGs from 2010 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2010.pdf)
PHEV mpg 39.3 Sales weighted average: 2014 sales from HybridCars (http://HybridCars.com); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)
PHEV kWh/mi 0.41 Sales weighted average: 2014 sales from HybridCars (http://HybridCars.com); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)
PHEV All-Electric Range 14 Sales weighted average: 2014 sales from HybridCars (http://HybridCars.com); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)
EV kWh/mi 0.324 Sales weighted average: 2014 sales from HybridCars (http://HybridCars.com); MPGs from 2014 Fuel Economy Guide (http://www.fueleconomy.gov/feg/FEG2014.pdf)

Hybrid Electric Vehicle Emissions

To calculate HEV emissions, consider that during a typical 100-mile trip, an HEV averages 47.3 miles per gallon and uses about 2.1 gallons of gasoline. Gasoline contains about 24 pounds of CO2 equivalent per gallon (source: GREET), resulting in 51 pounds of CO2 emissions for the trip. At a gasoline cost of $2.42 per gallon, the trip costs $5.12.

Plug-In Hybrid Electric Vehicle Emissions

To calculate PHEV emissions, consider the emissions of both power sources: electricity from the grid and the fuel, such as gasoline.

  • Electricity (first 14 miles)—The electricity used depends on the vehicle's electricity consumption while in electric mode. If the vehicle uses 41 watt-hours to travel 1 mile, the vehicle will use 574 watt-hours—or 5.74 kilowatt-hours (kWh)—during the first 14 miles. The amount of emissions caused by generating 5.74 kWh of electricity depends on how that electricity was generated. Using the U.S. national average grid mix (source: GREET), 5.74 kWh of electricity results in 9.5 pounds of CO2. If the vehicle is charged from a non-polluting, renewable source, such as wind or solar, the emissions for this portion are zero. If electricity costs $0.11 per kWh (national average), this portion costs $0.63.

  • Gasoline (remaining 86 miles)—The amount of gasoline used depends on the vehicle's fuel consumption while using the gasoline engine. If the vehicle gets 39.3 miles per gallon, 86 miles requires about 2.2 gallons of gasoline. Gasoline contains about 24 pounds of CO2 equivalent per gallon (source: GREET), resulting in 52.5 pounds of CO2 for this portion. At a gasoline cost of $2.42 per gallon, this portion costs $5.30.

During a typical 100-mile trip, plug-in hybrid electric vehicles with a 14-mile all-electric range that starts with a full battery charge will use electricity for the first 14 miles before switching to gasoline.

All-Electric Vehicle Emissions

To calculate EV emissions, consider the electricity consumption (in watt-hours per mile) and the fuel used to produce the electricity. EVs produce no tailpipe emissions because the electricity consumed to drive the electric motor produces no emissions. However, producing the electricity that charges the vehicle's battery might produce emissions.

During a typical 100-mile trip, EVs with an electricity consumption of 32.4 watt-hours per mile require 3240 watt-hours (32.4 kWh) of electricity. Using the U.S. national average grid mix (source: GREET), 32.4 kWh of electricity results in 54 pounds of CO2 equivalent. If the electricity used to charge an all-electric vehicle comes from a non-polluting, renewable source, such as wind or solar, driving the vehicle produces no emissions. If electricity costs $0.11 per kWh (national average), the total electricity cost for the trip is $3.56.