An overabundance of electric vehicles charging overnight could cause grid overload.
Public charging stations and more daylight charging will be necessary as the number of electric vehicles on the road increases to prevent power networks from being overloaded.
Alterations to the power infrastructure will be necessary to keep up with the rising demand for charging stations as the number of people who own electric vehicles continues to rise.
If most drivers keep charging their cars at home at night, the rise in electric car ownership could put a pressure on power networks. Estimates show that by 2035, half of all drivers would be using electric vehicles, making daytime charging choices a must for the western US power infrastructure to keep up with demand.
Computer models have found that the charging habits of drivers and the number of publicly and privately accessible charging stations may have a significant impact on peak net electricity demand. Peak net electricity demand is the highest electrical power demand minus the power provided by solar and wind power.
When states attain 50% EV ownership, there may be an increase in peak net electricity demand of 25%, and at higher EV ownership rates, this increase may exceed grid capacity. This is especially true if drivers predominantly charge their vehicles at home during the night. However, limiting the growth of peak net electricity consumption to just 7.5% by increasing daytime charging opportunities could help minimise the costs of upgrading grid capacity.
Siobhan Powell, now at the Swiss Federal Institute of Technology in Zurich, Switzerland, but formerly of Stanford University in California, led the study. “One of the big results from our study is that just making the shift of which charging infrastructure you build and where you encourage people to charge is a huge difference in the result for the grid,” Powell says.
Powell and her team of researchers modelled the charging habits of 27,700 owners of electric vehicles in the San Francisco Bay Area on computers. The computer models were able to anticipate the potential effects on the western US power system, which serves 11 states, including California, of a future population of 48.6 million electric vehicle drivers.
Ram Rajagopal of Stanford University notes that the data demonstrate how a change to daytime charging patterns could assist the western US grid in effectively utilising its abundant solar electricity. Instead of forcing power grid operators to spend money on greater energy storage to save solar electricity for nighttime charging, daytime charging can take advantage of solar power when it is instantly available.
Simulations indicated that, compared to a status quo scenario in which most drivers charged overnight at home, a decrease of $700 million to $1.5 billion in energy storage needs for the grid might be realised if more drivers charged during the day.
According to Gil Tal of UC Davis, who was not engaged in the study, the goal of having 50% of personal automobiles be electric by 2035 seems ambitious. As more people are working from home, he said, some electric cars may be charged at home during the day, which could help reduce the expected rise in overnight charging demand. He concludes that the study's findings are positive and show that widespread adoption of electric cars in the future should be feasible.
According to Tal, “their analysis is demonstrating that demand for electricity from transportation is particularly variable demand.” As an added bonus, “and many of the issues can be resolved by shifting the time of use and the day of use.”
While this investigation was underway, in November 2021, Congress enacted and President Joe Biden signed into law an infrastructure plan that includes $7.5 billion for a national network of charging stations for electric automobiles.
Rajagopal explains that the decision was “based on other considerations” rather than an assessment of the effect on the power grid. But as it turned out, everything fell into place just so for this.