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MIT study offers data on optimal placement of EV charging stations

A new study by MIT researchers offers guidance on the placement of charging stations to help encourage wider adoption of electric vehicles.

Placing charging stations on residential streets, rather than just in central locations such as shopping malls, could have an outsized benefit, the researchers found.

It is critical to look at high impact approaches “rather than haphazardly putting a charger at the grocery store or at the mall or any other public location,” Jessika Trancik, MIT associate professor of energy studies and one of the authors of the report, said in a statement. Charging stations in public places such as malls are useful, “but public planning should be aiming to expand accessibility to a greater part of the population,” she said.

The other authors are Wei Wei, a graduate student; Sankaran Ramakrishnan, a post-doc student, and Zachary Needell, a former doctoral student.

The study also highlights the importance of making overnight charging available to more people. Many people do not have their own garages and use public parking. “It’s really important to provide access — reliable, predictable access — to charging for people, wherever they park for longer periods of time near home, often overnight,” Trancik says.

The study, Personal vehicle electrification and charging solutions for high-energy days, also found that adding high-speed charging stations along highways and making supplementary vehicles more available to people who need to travel beyond the single-charge range of an electric vehicle could greatly increase the spread of electric vehicles.

The report was published in Nature Energy.

While the vast majority of people’s daily driving needs can be met by the range provided by existing lower-cost electric cars, there are typically a few times when people need to drive much farther or make more short trips than usual in a day with little time to recharge. Those “high-energy days,” the researchers said, may only happen a handful of times per year, but they can be the deciding factor in people’s decision making about whether to go electric.

In the report, the researchers developed a methodology to identify charging solutions that would conveniently fit into people’s daily activities, using data collected from GPS tracking devices in cars, as well as survey results about people’s daily driving habits and needs.

The report used general data from the United States, as well as more detailed data from the Seattle area. In analyzing driving habits in Seattle, the researchers found that the impact of either adding highway fast-charging stations or increasing availability of supplementary long-range vehicles for up to four days a year meant that the number of homes that could meet their driving needs with a lower cost electric vehicle increased from 10 percent to 40 percent. The number rose to above 90 percent of households when fast-charging stations, workplace charging, overnight public charging, and up to 10 days of access to supplementary vehicles were all available, the researchers said.

“Real-world driving data can not only guide infrastructure and policy planning, but also optimal EV charging management and vehicle purchasing and usage decisions,” Lynette Cheah, an associate professor of engineering systems and design at Singapore University of Technology and Design, who was not associated with this work, said in a statement.

The study should help to provide some guidance to policymakers at all levels who are looking for ways to facilitate the reduction of greenhouse gas emissions, since the transportation sector accounts for about a third of those emissions overall, the study’s authors said.

“If you have limited funds, which you typically always do, then it’s just really important to prioritize,” Trancik said, noting that this study could indicate the areas that could provide the greatest return for those investments. Being strategic about infrastructure expansion will continue to be important even as fast chargers fall in cost and new designs begin to allow for more rapid charging, she added.

The American Public Power Association provides an EV activities tracker to its members. The tracker summarizes key efforts undertaken by members including incentives, electric vehicle deployment, charging infrastructure investments, rate design, pilot programs, and more.