When we think of an electric vehicle (EV), we might envision a car receiving power from the electric power grid before driving off. Along the way, its battery will deplete, so it will need to be plugged in to charge again. In other words, there is a one-way relationship between the grid and the EV: The car gets electricity from the grid so it can drive.
But what if the relationship could be bidirectional? What if, when plugged in and parked (which cars are most of the time), EVs could communicate with the grid and act as a spare battery. Not only would they be receiving power to charge but also supplying it back.
This idea — known as vehicle to grid (V2G) — is being explored in laboratories and pilot programs across the world. And don’t worry, you wouldn’t come back to a car with a dead battery — with many cars being used at the same time, the amount of power taken from any one would likely be small. You may even be compensated for the power your vehicle supplies.
The possibilities of V2G are vast. For example, EVs could be charged with renewable energy during the day and then send power back to the grid later, when electricity demand is high and renewable resources less readily available. At a broad level, V2G could help optimize and stabilize the grid and add value to EVs by giving them an additional use.
Medium- and heavy-duty EVs, in particular, are being eyed for their V2G potential. Electric buses, utility trucks and other large vehicles have much bigger batteries than light-duty vehicles, making them even more encouraging for grid applications.
Nissan is one manufacturer that has been pursuing these possibilities. Over the past several years, the company has worked with utilities and other industry partners to conduct V2G tests and pilots in Denmark, Italy, Chile and elsewhere. In the U.S., V2G projects are underway at the University of California San Diego and in Delaware and Virginia, which is also home to Dominion Energy’s electric school bus initiative that has a V2G component.
One concern with V2G is the possibility that it could harm EV batteries. The thought is that the frequent cycling (i.e., switching between charging and discharging) required for V2G could degrade batteries more quickly. Degradation is not a guarantee, though, and under some circumstances, battery performance could actually improve.
Along with V2G, other EV-grid applications are being studied and implemented. One is vehicle to home (V2H), which, as it sounds, is when an EV battery supplies power to individual homes. This system could be useful when navigating peak periods or emergencies, with the battery acting as a backup generator. Furthermore, with smart or managed charging, utilities can help direct EV charging so that it occurs when demand is lower, such as overnight and during other off-peak times. This type of demand response capability would help utilities optimize the grid, improve reliability, better integrate renewables and reduce costs for all.
The future of V2G and its kin is exciting, especially with the continued growth of EVs. As more vehicles hit the road and with additional tests, policy developments and technological advancements, the next few years should shed more light on the potential and possibilities of these applications. If they work on a large scale, the grid might have a new tool to support its energy balancing act: a giant battery made up of thousands of EVs.