Electric vehicles are not expected to cripple the nation’s electric grid with their thirsty recharging needs. However, as more of the vehicles come online, electric providers should start thinking about how to manage the car-charging and encourage plugging in when electricity demand is low, say electric power supply researchers. “We want utilities to be working with charging station companies, manufacturers of vehicles and other aggregators to steer that load into the valleys of the load profile so that it doesn’t necessarily increase the peak on a load profile,” said Chris Nelder, a manager with the Rocky Mountain Institute, where he leads the EV-Grid Integration project. Nelder spoke recently during one of the RMI’s Facebook Live segments. Experts agree the impacts electric vehicles now have on the grid are minimal, given the relatively small numbers in circulation. However, all indications point to continued growth in the battery-electric and plug-in electric hybrid markets, as costs come down. More EV models coming onto the market at a closer price parity to gas-powered cars could translate into significantly more widespread adoption by 2020, said Nelder. “Over the next couple of years we think there will be maybe 45 or 50 different models of EVs on the road and available in the U.S., and that’s going to change the game in a big way,” he added. “I think we’re going to see a significant uptick of electric vehicles in this country by 2020. So effectively that’s right around the corner,” said Nelder. “Which means if you consider the long lead time for utility investment, for infrastructure, you’ve really got to start thinking about building it now.” Utility providers like San Diego Gas & Electric, which covers all of San Diego and southern Orange counties in California, has about a half-dozen EV programs that mostly focus on expanding charging opportunities to a number of locations and purposes, such as the Port of San Diego, San Diego International Airport, park-and-ride lots, multifamily housing developments and even shuttle services. “So we’re expanding beyond the passenger vehicle market into commercial and industrial segments,” said Helen Gao, communications manager at San Diego Gas & Electric. SDG&E has other programs that encourage electric car owners to charge during “off peak” times by offering reduced electric rates. One program, known as Power Your Drive, notifies participants a day in advance when the next day’s lowest rates will occur. “If you are in that program, you get hourly, day-ahead pricing, so that you know when is the best time to charge,” said Gao. The rate is based on “grid conditions,” which means the rates will be different for different areas. Programs like these, say officials, are a way for the electric utilities to manage the electric vehicle load without having to make costly upgrades in areas like power generation or distribution. “Just across the board, we are working on rate structures that help us accommodate electric vehicles in a way that would not require a new transmission line, or major infrastructure investments,” said Gao. If electric cars are to have any effect on the electric grid, it will not likely put strains on the power generation component or even tax the distribution network on a large scale, said Matteo Muratori, a transportation and energy systems engineer at the U.S. Department of Energy’s National Renewable Energy Laboratory. But where electric providers may start to see the system struggle is at the neighborhood level. A set of homes — 6 to 10 — are typically connected to a distribution transformer, those round grey devices seen on power poles. “Those are designed to support the load of the houses connected to them,” said Muratori, author of the NREL research paper “Impact of Uncoordinated Plug-in Electric Vehicle Charging on Residential Power Demand.” If several of those residents acquire electric cars, this could add significantly to the power demands of the neighborhood, possibly taxing the distribution infrastructure, according to Muratori. “Basically, adding this additional load that was not planned for when the infrastructure was built, is going to have an impact on the distribution infrastructure,” he explained. “And even at low adoption levels, the impact can be fairly significant. As utilities plan for this infrastructure, that will last decades, they should keep EVs well in mind, and consider that additional load, especially as we move forward into the future, and we imagine that adoption of PEVs could take over and increase significantly compared to today’s level.” One of the ways consumers can help to manage their draw on the electric power infrastructure is not only keeping in mind when they charge their cars, but how. Charging devices are essentially divided into three categories. A Level 1 charger is the slowest. It operates with a standard wall outlet and charges at about 1 kilowatt per hour, which means if your car has a 60-kilowatt battery, common in cars like the Chevrolet Bolt, it would take 60 hours to recharge a completely dead battery. Level 2 chargers are much faster and devour more electricity, and will charge an electric Bolt in a third of the time it takes to charge with a Level 1 charger. (Level 3 chargers are super-fast, and would not be found in home settings.) “When we look at what people need, most drivers for the vast majority of their charging, are just fine with a Level 1,” said Muratori. In California, about half of EV owners use a Level 1 charger, while the other half use Level 2 chargers. “Once you spend the money to install a Level 2 charger in your garage, you’re very unlikely to go back and use a Level 1 charger,” said Muratori. However, using a Level 2 “impacts the grid a lot more,” he added, a point many electric car owners are not aware of. Electric company officials say the EV landscape is a complex one, with an increasing number of vehicles, with different battery capacities and varying charging rates, requiring continued monitoring by electric providers. “With the evolution of the market, and the maturation of the market, it’s hard to foresee into the future what sorts of upgrades might be needed, because the market is changing,” said Gao. “It’s a very dynamic and complex situation, and we intend to monitor it closely, and do the research that’s needed.”
Growth in Electric Car Ownership Presents Challenges to the Grid
With a significant number of electric cars expected on the road by 2020, power supply researchers say now is the time for strategies that can balance power demands without a costly upgrade to the power grid.
Power grid researchers weigh in on how electric cars could affect power distribution issues today, and in the future.