Distribution of EV Charging Infrastructure Across US is Unequal and Not Improving, First-time Nationwide Study Finds

The income gap for access to public EV chargers is now three times that of gas stations on a national scale.

Does access to electric vehicles vary by race or income? This is a pressing concern for just transitions as electric vehicle (EV) adoption has grown exponentially in the United States over the past decade. An electric mobility study in Applied Energy offers new insights into this question — the first to quantify income and racial inequalities in EV adoption and charging infrastructure distribution (compared to conventional vehicles and gas stations) at local, regional, and national levels based on current and historical trends. In the process, a novel way of quantifying the evolution of inequality has emerged that can be applied more broadly.

Through analysis of location-based changes in transportation over time, this study compares EV adoption and charging infrastructure with traditional vehicles and gas stations at the city, state, and national levels. The research team found that as EVs have gained popularity nationwide, income inequality has gotten worse, most significantly in the distribution of EV charging. The income gap for access to public EV chargers is now three times that of gas stations on a national scale.

While EV charging infrastructure surged 350% nationwide between 2015 and 2021, equality in the distribution of those chargers did not improve. Instead of being equally distributed across cities and states, new EV chargers were typically located in areas with similar socioeconomic characteristics to those that already had more chargers.

The study was led by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and co-authored by researchers at Boston University’s Institute for Global Sustainability (IGS), Rutgers University, and the Georgia Institute of Technology. For IGS, this research is part of an ongoing collaboration with NREL to support just transitions, including another joint EV study on the socioeconomic and perceptual barriers that was recently published in Energy and Climate Change.

The researchers also found wide variability in trends across states and municipalities. For instance, while one state may have an equal distribution of EV chargers by race, distribution by income in that same state may be uneven. The next state may have the inverse problem.

These findings can guide legislators, planners, and other leaders in supporting EV transitions that address disparities in adoption and charging while also benefiting inter-state travel and the environment.

“Transportation electrification is a key facet of slowing emissions and climate change,” said IGS Associate Director Cutler Cleveland, co-author of the new study. “EVs and charging infrastructure are unevenly distributed by race and income across the US, and these patterns differ significantly between states and cities. Solutions to address inequality must be coordinated at all levels to support nationwide adoption.”

“By the end of 2021, there were about two million plug-in EVs on the road across the US. With policy and market momentum, EV adoption will likely keep growing,” said IGS Director and study co-author Benjamin Sovacool. “We need to allocate chargers in ways that promote equal access and also allow people to use EVs for long-distance travel. To do that, we first need to understand where and how we’ve fallen short. This study helps us to do that.”

Study Highlights:

• New metrics to assess income and race inequality: To better study inequality at city, state, and national levels, the researchers developed two new metrics: Per-Capita Share of Low-Income Neighborhoods (PCS-LIN) and Racial Gap Index (RGI). Both measures are widely deployable and address gaps in existing metrics. Unlike the widely used Gini coefficient, PCS-LIN and RGI can be used to study small sample sizes and locales and for multi-dimensional variables like race.
• EV access is improving over time: Internal combustion engine vehicle ownership is almost evenly distributed across the country on a per-capita basis. EV adoption is still comparatively unequal in most places – wealthier populations with a higher amount of white residents tend to have a higher share of EVs, the researchers report. However, this inequality is improving with time.
• Charger access has not improved: While equality in EV ownership has improved with time, the new research finds that the distribution of charging infrastructure has not. The team found worsening equality over time in all but five states.
• Specific patterns differ significantly between states and cities: Individual states, as well as some of the largest urbanized areas, demonstrate a wide range of inequality associated with income and race. In New Jersey, most EV charging equipment is located in more affluent census blocks. In Mississippi, EV charging equipment is more prevalent in lower-income census blocks, while EV ownership is more prevalent in higher-income populations. This leaves lower-income communities shouldering infrastructure they can’t use unless EV adoption strategies are also part of just transitions. While South Dakota has one of the best income equalities for both EVs and charging equipment, the state has the most significant racial inequalities. California is the opposite, with one of the largest income inequalities for EVs and chargers, but one of the best racial equalities. When it comes to city-level data, the study found that EV charging equipment is more prevalent in parts of cities that are more affluent and home to a higher share of the white population.

“Distribution patterns are highly specific to particular locations, and so must be the accompanying solutions,” Sovacool said. “With greater equality in the distribution of charging infrastructure, and efforts to lower costs for EVs generally, more communities can share in the benefits of vehicle electrification.”