Timothy Lipman, Ph.D., Alissa Harrington, Adam Langton
Managedcharging of electric vehicleshas the potentialto help balance energy demand on the grid and manage intermittent renewables,save costs,andreducegreenhouse gas emissionstosupport California’s strategy to move to full decarbonization by 2045. Electric vehicles canhelp achieve this goal byactingasaflexibleresourcefor utility grids. They can curtail load when energy demand is high and accept load when energy demand is low and when there is excessgeneration.Shifting loadto lower-cost timescan alsoconferfinancial benefits to the vehicleowners.
The project examines several use cases for the interaction between driver plug-in/charging and driving behavior from 300 electric vehicle-driving households in the San Francisco Bay Area from 2017 through 2019. These cases range from avoiding electric vehicle home charging during peak evening hours, to shifting charging times and locations, to increasing charging during times of high renewable energy production, to more general goals of increasing the length of time that vehicles are plugged in, a key prerequisite for electric vehicle and grid interaction.
The project demonstrated a strong ability to shift electric vehicle charging loads through the various use cases, with the ability to shift up to about 20 percent of charging in any given hour to other times and the ability to add up to 30 percent of chargingin a givenhour. Optimization modeling using real-world driving and charging behavior revealed the ability to save about $56 per vehicle per year in reduced grid electricity supply costs by charging at lowest cost times, while meeting driver mobility needs. The modeling also demonstrated the potential to increase about 1,200 kilowatt-hours per vehicle per year in renewable energy use and about 300 kilograms per vehicle per year reduction in greenhouse gas emissions.