Reducing Marginal Emissions of an Electric Vehicle Fleet through Smart Charging and Vehicle-to-grid

Marginal greenhouse gas emissions are a crucial metric in the electrical system. They measure the amount of avoided or induced CO
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-equivalent by controlling demand at the margin. In this work, we present a new method for calculating instantaneous marginal emission factors and assess the potential for reducing emissions of a fleet of electric vehicles (EVs) through unidirectional smart charging (V1G) and vehicle-to-grid (V2G) at the electrical system level. Based on actual driving profiles, results show that an optimal V1G strategy could potentially reduce marginal emissions from broadly 15% to 40%. An optimal V2G strategy yields even better results as EVs may displace highly emitting power production by discharging over-stored low-carbon energy. These range from 20% to 60%, with some instances exceeding 100% reduction, thus over-reimbursing the carbon footprint of the energy charged for driving purposes.