Electric vehicles (EVs) can effectively serve as mobile batteries that provide energy to the power grid when not being driven, improving the reliability of the grid, serving as a source of backup power and potentially reducing energy and EV ownership costs. So why have so few places adopted the vehicle-to-grid (V2G) model? A new study details the barriers to V2G adoption and outlines possible paths forward for this technology.

“Most people are unfamiliar with the idea of what V2G is or how it can benefit both them and the power system more broadly,” says Serena Kim, corresponding author of the study and an assistant professor in North Carolina State University’s School of Public & International Affairs. “EVs are parked 95% of the time, and when EVs are parked they’re essentially a battery on wheels.

“That battery storage can be used to feed energy back into the power grid – and EV owners can actually get paid if their vehicle is supplying energy to the grid,” Kim says. “This can be useful to the grid because the vehicle may be parked – and providing energy – during periods of high energy demand, which is normally during the late afternoon or early evening. Feeding energy into the grid can also be useful if the vehicle is parked overnight, when some renewable energy sources – such as solar panels – are not producing electricity.”

A video explaining how V2G arrangements work can be found at: https://www.youtube.com/watch?v=lEdOq3e9v6Y

Experts estimate that there are approximately 4 million electric vehicles on the road in the U.S., and electric vehicles make up a significant portion of new vehicle sales. But so far most V2G efforts for passenger vehicles remain in pilot mode.

“Where the technology is being deployed, it is often focused on electric school buses and other fleet vehicles rather than privately owned cars,” says Kim. “Utilities have not yet rolled out V2G programs at large scale for the cars and light trucks most consumers drive.

“We wanted to explore why V2G has not been adopted more widely,” Kim says. “We know that a lack of clear compensation mechanisms is a variable. We know that limited infrastructure plays a role. But we wanted to get a deeper understanding of all the factors in play, as well as which factors may be most important, in order to support stakeholder decisions that can promote V2G efforts in the future.”

For the study, researchers conducted interviews with 42 stakeholders representing a variety of relevant interests. These included power utilities, EV manufacturers, local and state governments, school districts, and EV owners who participated in V2G pilot projects.

The interviews were designed to collect information about the barriers to V2G adoption. What are the stakeholder perceptions of V2G? What have their experiences with V2G been? What do they view as the biggest obstacles? And what do they see as the best path forward for V2G?

“A key finding here is that V2G adoption is a coordination problem rather than a technology problem,” says Kim. “It’s really a chicken-and-egg issue.

“On the one hand, utilities want to see more V2G-capable vehicles before they invest in V2G infrastructure and programs to compensate EV owners,” Kim explains. “On the other hand, EV owners are unlikely to participate in V2G programs if they don’t know how they will be compensated. And potential EV buyers can’t plan on defraying the cost of buying an EV if there is no infrastructure in place to support V2G programs. It’s a complex problem. Essentially, utilities are likely to play a central role in coordinating these problems if V2G programs are going to move forward. But there is currently little incentive for those companies to make the investment, beyond the potential to improve grid resilience.”

The study also found that this challenge is compounded by a patchwork of regulations and policies that vary across jurisdictions, with relevant rules differing from state to state and even at the local government level. This makes it harder for automakers, companies that build and operate EV charging networks, utilities, and other stakeholders to plan and invest at scale.

“One key takeaway message, then, is that harmonizing technical standards and interconnection requirements is an essential step toward scaling V2G programs,” Kim says.

A paper describing the study, “Electric Vehicles as Grid Resources: Barriers to Vehicle-to-Grid (V2G) in the United States,” is published open access in the journal Utilities Policy. First author of the paper is Crystal Soderman, a Ph.D. student at the University of Colorado Denver (CU Denver). The paper was co-authored by Jen Yip, a Ph.D. student at NC State; and Manish Shirgaokar, an associate professor of urban and regional planning at CU Denver.

This work was done with support from the National Science Foundation under grant 2324421.