Where does electricity come from? When you flip a light switch on, you’re getting electricity from somewhere—maybe a spinning gas turbine, or maybe a battery storing excess electricity generated by wind or solar power. When you flip the light switch off, the grid responds by shifting its sources around, ensuring everyone connected is receiving a steady flow of electrons.

 

The complexity of the grid complicates how we measure greenhouse gas (GHG) emissions from an electric vehicle (EV). Charging an EV at different times of the day or in different locations may change the electricity source that charges the EV, resulting in different GHG emissions. This challenge gets at the heart of an ongoing debate between average and marginal electricity.

 

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