Abstract
Plug-in electric vehicles propelled by stored electrical energy do not directly emit greenhouse gas emissions during operation, but indirect emissions can occur when electricity is generated to recharge the vehicle batteries. Determining the mix of power plants that would supply this electricity is difficult due to the technical complexity inherent in grid modeling. This paper describes best practices for projecting future grid emissions and uses these best practices to forecast grid emissions in the United States. These projections indicate that plug-in electric vehicles can significantly reduce transportation sector emissions even when accounting for the emissions associated with vehicle electrification.