Data Sources and Assumptions for the Electricity Sources and Fuel-Cycle Emissions Tool

The following data sources and assumptions were used to calculate the emissions, fuel use, and electricity sources for conventional and electric-drive vehicles in the Electricity Sources and Fuel-Cycle Emissions Tool.

Electricity Sources

These assumptions were used to show electricity sources.

Parameter	Value	Unit	Year	Source
Electricity fuel mix	varies by state	thousand MWh	2021	U.S. Energy Information Administration's Open Data API for Electricity Net Generation

Annual Vehicle Emissions

These assumptions were used to calculate the annual vehicle emissions for an average conventional, hybrid electric, plug-in hybrid electric, and all-electric vehicle.

Parameter	Value	Unit	Year	Source
Gasoline emissions	23.7	lbs. CO2e/gal	2019	Well-to-wheels greenhouse gas emissions factor derived from Argonne National Laboratory's GREET model
ICE gasoline efficiency	21.79	mi/gal	2019	Weighted average of projected vehicle sales from EPA Automotive Trends Report and mpg from the Fuel Economy Guide
HEV gasoline efficiency	39.78	mi/gal	2019	Weighted average of vehicle sales from U.S. HEV Sales by Model and mpg from the Fuel Economy Guide
PHEV gasoline efficiency	40.80	mi/gal	2019	Weighted average of vehicle sales from U.S. Plug-in Electric Vehicle Sales by Model and mpg from the Fuel Economy Guide
PHEV electric efficiency	3.03	mi/kWh
PHEV electric range	27.74	miles
BEV electric efficiency	3.60	mi/kWh
PHEV % electric VMT	56.3	% VMT	2010	SAE J2841, Appendix B, MDIUF based on PHEV electric range
Average annual VMT	11,579	miles	2019	Oak Ridge National Laboratory's Transportation Energy Data Book Edition 39, Table 4.3
Emissions from electric power	varies by state	million metric tons CO2e	2021	U.S. Energy Information Administration's Electric Power Annual
Energy generated from electric power	varies by state	thousand MWh

Average Emissions from Generated Electricity

The following equation is used to calculate average emissions from generated electricity at the state and national level:

$$\frac{{\mathrm{X\; million\; metric\; tons\; CO}}_{2}e}{\mathrm{Y\; thousand\; MWh}}x\frac{\mathrm{2,204.623}\mathrm{ lbs.}}{1\mathrm{ metric\; ton}}x\frac{1\mathrm{ MWh}}{\mathrm{1,000}\mathrm{ kWh}}=\frac{{\mathrm{Z\; lbs.\; CO}}_{2}e}{1\mathrm{ kWh}}$$ $$\mathrm{X}=\mathrm{Emissions\; from\; electric\; power}$$ $$\mathrm{Y}=\mathrm{Energy\; generated\; from\; electric\; power}$$ $$\mathrm{Z}=\mathrm{Average\; emissions\; from\; generated\; electricity}$$

The result of this equation is used to calculate annual vehicle emissions for BEVs and PHEVs.

All-Electric Vehicle Emissions

The following equation is used to calculate emissions for all-electric vehicles (EVs) also called battery electric vehicles (BEVs):

$$\mathrm{11,579}\mathrm{mi}x\frac{1\mathrm{ kWh}}{3.60\mathrm{ mi}}x\frac{{\mathrm{Z\; lbs.\; CO}}_{2}e}{1\mathrm{ kWh}}$$

Plug-In Hybrid Electric Vehicle Emissions

The following equation is used to calculate emissions for plug-in hybrid electric vehicles (PHEVs):

$$\left(\mathrm{11,579}\mathrm{mi}x\frac{56.3}{100}x\frac{1\mathrm{ kWh}}{3.03\mathrm{ mi}}x\frac{{\mathrm{Z\; lbs.\; CO}}_{2}e}{1\mathrm{ kWh}}\right)+\left(\mathrm{11,579}\mathrm{mi}x\frac{43.7}{100}x\frac{1\mathrm{ gal}}{40.80\mathrm{ mi}}x\frac{23.7{\mathrm{ lbs.\; CO}}_{2}e}{1\mathrm{ gal}}\right)$$

Hybrid Electric Vehicle Emissions

The following equation is used to calculate emissions for hybrid electric vehicles (HEVs):

$$\mathrm{11,579}\mathrm{mi}x\frac{1\mathrm{ gal}}{39.78\mathrm{ mi}}x\frac{23.7{\mathrm{ lbs.\; CO}}_{2}e}{1\mathrm{ gal}}=\mathrm{6,898}{\mathrm{ lbs.\; CO}}_{2}e$$

Gasoline Vehicle Emissions

The following equation is used to calculate emissions for gasoline vehicles also called internal combustion engine (ICE) vehicles:

$$\mathrm{11,579}\mathrm{mi}x\frac{1\mathrm{ gal}}{21.79\mathrm{ mi}}x\frac{23.7{\mathrm{ lbs.\; CO}}_{2}e}{1\mathrm{ gal}}=\mathrm{12,594}{\mathrm{ lbs.\; CO}}_{2}e$$