One worry a lot of people have before buying an electric car is that they won’t be able to find a place to charge their vehicle. This can be a problem if you park on the street and don’t have a dedicated charger, need to charge while out running errands, or if you’re going on a trip and have anxiety over finding a charging station.
According to Statista, as of January 2022, there were 46,290 electric vehicle (EV) charging stations and 113,558 charging outlets in the US. At least 41,300 public and private outlets were found in California, which is by far the state with the most EVs. While the US has come a long way with EV charging infrastructure, it is still outpaced by countries like China, which according to Statista has about 800,000 EV chargers. As the US expands its charging footprint, one challenge is where those EV chargers should be placed.
Researchers at North Carolina State University have tried to make EV charging station placement better by developing a computational model. This not only can determine where to put EV charging facilities, but also how powerful the chargers can be based on the local power grid. Ultimately, the model can be used to develop EV charging infrastructure in different ways, whether it’s helping commuters charge their cars or serving interstate travelers, according to Leila Hajibabai, who wrote a paper on the model and is an assistant professor at NC State’s Fitts Department of Industrial and Systems Engineering.
When the average person needs to charge their EV, it might be challenging to find a charging station nearby or in a convenient location along a trip or commute route. This model could help solve that problem. “Our model can find locations for charging stations that are more convenient for users based on their travel patterns,” Hajibabai said. “In another study, we have also incorporated into our models charging prices, waiting times to get served, among other user-centric factors to ensure the charging solutions account for people’s preferences.”
While developing the model, Hajibabai and other researchers found a common problem was that there was often a mismatch between the optimal placement for EV charging stations based on travel patterns, and the power network requirements. Because of this mismatch, they instead decided to study the EV network design and power aspects together, while also factoring in people’s route choices.
Ultimately, there are a variety of ways the models can be used to plan EV charging infrastructure.
“We hope our models will be used by stakeholders such as the utility companies, charging network operators, municipalities and departments of transportation,” said Hajibabai.
One particular challenge for EV owners is finding charging stations at the right spots on long drives, and also finding fast chargers so they don’t have to stop for several hours waiting for the battery to be full enough to continue. This a concern in the US, but also in other countries where people might want to go on a road trip that covers hundreds of miles.
Hajibabai said that they took this challenge into account, and that their model is designed to support long-distance travel and trip chains. Stakeholders will need to account for travel origins and destinations and points of interest, like shopping centers, restaurants and workplaces, when they plan to deploy charging facilities, she said.
“One challenge that could also be thought of as an opportunity would be matching travel plans with the location of chargers (e.g., getting lunch while charging en-route),” Hajibabai said. “Chargers may not be necessarily installed at optimal locations, but at least they can be placed at near-optimal sites that can maximize the benefits from both power and transportation networks in terms of receiving the required energy amount and proximity to people’s travel preferences.”
Adding to the complexity of where to put chargers, there are other factors like pricing and usage duration, she adds. Some common problems EV users report include going to a charging station and finding there isn’t the right plug for their vehicle or the charger doesn’t work, and having the right payment method.
With more and more people buying electric cars, the charging infrastructure will need to expand. The model from Hajibabai and other researchers will help ensure that they are in the places people need them most.