Electric cars may become new norm

Engineers recently assessed the possibility of widespread usage of electronic vehicles in America. (credit: courtesy of Engineers recently assessed the possibility of widespread usage of electronic vehicles in America. (credit: courtesy of

Energy — particularly renewable energy — plays a large factor in many aspects of today’s society and has increased public interest in energy-conserving products such as electric vehicles (EVs). However, despite the increase in EV usage, recent findings by Carnegie Mellon researchers suggest that the large-scale success of EVs is limited by a lack of residential parking.

Elizabeth J. Traut, a mechanical engineering doctoral student; Tsu-Wei Charlie Cherng, who recently received his master’s degree in mechanical engineering; Chris Hendrickson, a civil and environmental engineering professor; and Jeremy J. Michalek, a professor of mechanical engineering and public policy, examined the availability of parking and charging for EVs in the United States.

The term EV encompasses plug-in hybrid electric vehicles (PHEVs), which run on gasoline and electricity, and battery electric vehicles (BEVs), which run solely on electricity. Currently, EV sales make up less than 0.6 percent of total car sales.

“There are a number of reasons why there’s interest in EVs,” Hendrickson said. “First, there are the energy security issues. Most motor vehicles run off of petroleum, and there are issues with supply security and imports. Second, if we move toward renewable power and the power grid system, then we can reduce greenhouse gas emissions.”

Hendrickson explained that their research stemmed from the idea that most people would only buy EVs if they could charge their EV at home. The goal of the research was to look at the availability of charging at home for EVs from a vehicle perspective instead of a housing perspective. Previous research on charging availability was based on whether a household had a potential spot where an EV could be charged. This research determined that approximately 50 percent of households had a designated parking spot.

“We were interested in looking at it from the vehicle perspective,” Hendrickson said. “It turns out that those residences that have a dedicated parking spot often have multiple vehicles and only have one parking spot.”

Ultimately, through the combination of data from the Residential Energy Consumption Survey and the American Housing Survey, the researchers found that approximately 25 percent of vehicles have access to reasonable home charging. “This is good news and bad news,” Hendrickson explained. “It’s good news because people can buy EVs up to that 25 percent level. It’s bad news because after that 25 percent level owners of EVs are going to have to make changes to ensure that parking is available.”

Some recent predictions for EV adoption suggest that the number of EV owners will greatly increase in the near future. The Electric Power Research Institute (EPRI) claims that PHEV sales could be as high as 80 percent by 2050. The research on parking and charging availability, however, says that parking infrastructure will have to be developed in order for EVs to cross the 25 percent level.

The research also touched upon the implications of parking and charging availability in urban areas compared to rural areas. It was found that charging availability was lower in urban areas than in rural areas, meaning that the challenges of EV adoption will be more severe in urban locations. The study also concludes that public charging infrastructure, although not easily instigated, will be necessary if EVs are to be adopted in urban areas.

Despite promising results, Hendrickson admits that there are still many factors that the research did not take into account. “The numbers are indefinite for a number of reasons,” Hendrickson said. “There are rental properties where owners might not permit charging stations and rental properties where you have common garages with electricity paid for by the owner.”

Hendrickson also explains that many households have garages full of belongings other than cars. These garages were considered viable charging options in the research, even though in reality they are not. Finally, Hendrickson mentions the issue of safety.
“It’s more attractive to charge an EV in a garage where you are protected from the rain and everything else and there are no safety issues, than sitting the EV in a driveway to charge,” he said.

Renewable energy and EVs are crucial for a future with better energy security and a cleaner environment. This research has provided information on the obstacles that must be overcome in order to better incorporate EVs into modern society.