As policy decisions pave the way for more Electric Vehicles (EVs) on the road, there is expected to be a tremendous strain on the utility grid. Managing this strain requires careful planning for (and possibly control of) EV charging. This may include the utility firm managing intra-day demand variations using grid-scale batteries, and influencing the charging operations of some fraction of EVs (via active or passive managed charging program), including the possible use of Vehicle-to-Grid (V2G) technologies. A managed charging program must be carefully designed, accounting for EV users' driving patterns and range anxieties. In this paper, we take the perspective of an integrated energy system planner, who seeks to minimize generation and emissions costs arising from the electricity and transpotation sectors. Using a stylized analytical model that considers two periods per day (peak and off-peak), we derive optimal grid operations in the presence of a fraction of EV owners who sign up to a managed charging program. We characterize the optimal operating policy and show that EVs and grid-scale batteries can be substitutes or complements in the energy planner's portfolio. We demonstrate the validity of all our findings numerically using a higher fidelity 24-hour model calibrated to real data from the PJM interconnection. Our results suggest that a long-term outlook on navigating EV adoption should focus on managing more EV charging, rather than installing a lot of stationary battery capacity or promoting V2G.
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