Electric cars could break the grid if future drivers stick to today’s routines

"The rise in electric-vehicle ownership could overload the electric grid unless charging becomes a daytime activity.

The electric-car boom could put a strain on power grids in the years to come, if most drivers charge their vehicles at home overnight1.

Siobhan Powell at Stanford University in California and her colleagues modelled the charging demand for electric cars in 11 Western US states in 2035, according to various levels of electric-vehicle ownership. They used the results to predict the corresponding loads on the region’s grid. 

By 2035, the grid is expected to have excess capacity during the day, thanks to solar power; however, regional demand for electricity is highest in the early evening.

The demand for electricity would surpass grid capacity once more than 59% of the region’s cars were electric, if most drivers charged their vehicle at home and electricity prices encouraged them to start charging at 9 p.m., the team found. Assuming the same prices and driver behaviour, the peak demand for electricity from fossil fuels would increase by up to 25% over expected 2035 levels in a typical weekday if half of the cars in use were electric. 

However, if drivers charged their vehicles during the day, at work or using public chargers, the increase in peak net electricity demand would be less than 10%." [1]

1. Nature 610, 10 (2022)