An EV battery can do more than power a vehicle. With bidirectional charging, that same battery can provide backup power to a home or, in some applications, send electricity back to the grid. That turns EVs into a new type of distributed energy resource, with the potential to support the electric system during high demand.
EVs Can Keep the Lights On
A typical EV battery holds around 60 kilowatt-hours of energy, while the average U.S. household uses roughly 30 kilowatt-hours of electricity per day. The amount of backup power an EV can provide depends on the vehicle, household consumption, and which loads are connected, but a fully charged EV can provide substantially more energy than a typical home backup battery.
Ford and DTE Energy are putting that capability to work in Southeast Michigan through a vehicle-to-home pilot. Participants in the pilot use their vehicles to store electricity and can draw on that energy to power their homes during periods of high demand. DTE compensates participants for making their vehicle batteries available to support the system.
The same battery that gets the driver to work can serve another purpose while the vehicle is parked.
School Buses Can Support the Grid
Electric school buses offer a clear opportunity for vehicle-to-grid applications: They have large batteries, predictable schedules, and long periods when they’re not being driven. During the summer, those long periods of downtime align with the time of year when air conditioning can push electricity demand to its highest levels.
This summer, electric school buses participating in vehicle-to-grid programs from California to North Carolina sent electricity back to the grid during periods of high demand. The numbers are still small compared with the size of the electric system; fully deployed V2G projects involving about 230 electric school buses can currently supply roughly 8 megawatt-hours of energy at a given time, according to the World Resources Institute’s Electric School Bus Initiative.
That’s a fraction of what a regional grid needs during a heat wave, but it demonstrates what the technology can do. A vehicle that would otherwise be sitting parked can become a source of stored electricity when the grid needs it.
From EV Load to EV Resource
Scaling bidirectional charging will require the right vehicles and charging equipment, utility programs, interconnection processes, and compensation structures.
As more EVs and electric fleets connect to the grid, millions of batteries will sit parked for much of the day. Managed charging can control when those batteries consume electricity. Bidirectional charging can eventually allow some of them to provide electricity back to the grid. That creates value for both sides of the meter.
An EV can lower transportation costs for its owner, provide backup power during an outage, and, when the technology and programs are in place, provide valuable services to the electric grid.
Michigan Has an Opportunity to Lead
Michigan is already seeing this technology move from concept to real-world deployment through utility programs and fleet demonstrations. The opportunity is bigger than simply replacing gasoline-powered vehicles with electric ones. As the state’s EV market grows, Michigan can also build an energy system that utilizes the flexibility and storage capacity of those vehicles.
EVs can contribute new electricity sales that put downward pressure on rates. They can charge when the grid has more available capacity. With bidirectional charging, they can also contribute electricity when the grid needs it most.
This is the final installment in our series, EVs & the Grid: From New Demand to Grid Resource.