San Diego Gas & Electric (SDG&E) has launched a pilot vehicle-to-grid project under which it will bid a group of energy storage systems and EV fleets as one resource directly into the California Independent System Operator’s (CAISO) energy markets. Utilities use storage resources like this to address short-term imbalances in electricity supply caused by such things as intermittent renewable energy.
“There is tremendous potential for dispatchable distributed energy resources to enhance reliability and achieve greater efficiencies,” said SDG&E Senior VP James P. Avery. “The key to unlocking that potential is to better understand how these resources provide value both at the customer site level and at the larger electric grid level. This project does just that.”
The project aggregates stationary storage systems together with EV fleets at five separate locations. The assets are remotely controlled using software that balances the participant’s charging needs and identifies opportunities to provide demand response services at the grid level. The project correlates charging activity with wholesale energy prices. By agreeing not to charge at peak hours, the aggregated resource is paid the marginal energy price in those hours, similar to a conventional generator.
“Creating a framework for small, aggregated resources to directly participate in energy markets is a natural evolution of SDG&E’s earlier, pioneering efforts at the San Diego Zoo and Borrego Springs Microgrid,” added Avery. “Those innovative projects demonstrated that aggregating diverse resources like solar, energy storage and EVs created efficiencies and enhanced reliability.”
“This pilot creates an important connection between actual grid conditions and customer response,” said CAISO’s Heather Sanders. “By having electric vehicles directly participate as a grid resource in the wholesale market, vehicles respond to signals from the grid operator to reduce when electricity is scarce, and continue or resume charging when renewable generation is plentiful. This capability helps maximize the use of energy from renewables while keeping the grid reliable.”
There are currently more than 13,000 EVs in SDG&E’s service territory.