The vast majority of electric car owners charge their cars at home at night or overnight. According to a new study from Stanford University, we’re doing it wrong. If the prevalence of charging electric vehicles at home at night or overnight shifts to charging during the day as more cars go electric, this will curb the additional cost of the electric system, according to a new study from Stanford University.
In March, the research team published a paper describing a charging demand model they created that can be applied to a range of demographic and other factors. In the new study, published Sept. 22 in the journal Nature Energy, they applied their model to the entire western U.S. and examined how the region’s electric grid will be stressed by 2035 due to the growth of electric vehicle ownership. They found that the rapid growth of electric vehicles alone could increase peak electricity demand by as much as 25 percent over a little more than a decade, assuming that residential nighttime charging continues to dominate.
To limit the high cost of all this new generation and storage capacity, drivers should shift to charging at work or public charging stations during the day, which would also reduce greenhouse gas emissions, the researchers said. The finding has policy and investment implications for the region and its utilities, especially since California moved in late August to ban the sale of gasoline-powered cars and light trucks starting in 2035.
In February, California’s cumulative electric vehicle sales reached 1 million units, or 6 percent of cars and light trucks. The state’s goal is to have 5 million electric vehicles on the road by 2030. When electric vehicle penetration reaches 30 to 40 percent of cars on the road, the grid will experience significant stress without major investments and changes in charging habits. Building this infrastructure requires significant lead time and cannot be done overnight.
Studies show that with less home charging and more daytime charging, the western U.S. will need less generating capacity and storage, and won’t waste as much solar and wind energy. Once 50% of the cars on the roads in the western U.S. (where about half of the population lives in California) are powered by electricity, more than 5.4 gigawatts of energy storage would be needed if charging habits were to continue as they are today. This is equivalent to the capacity of five large nuclear power reactors. If there were a significant shift to charging at work rather than at home, the energy storage required for electric vehicles would be reduced to 4.2 gigawatts.
