STANFORD, California — Charging your electric car overnight to have it ready in the morning seems like a good idea in theory. But in reality, research suggests this does more harm in the long run. Stanford scientists say it costs more to charge your electric car overnight and can strain your local power grid.
Instead, researchers suggest drivers should switch to charging their vehicle at work or at public charging stations. Another added benefit of daytime charging at a public station is that it reduces greenhouse gas emissions.
Now that the effects of climate change are clearer than ever: frequent wildfires, widespread flooding and stronger hurricanes—car companies expect people to invest in electrically powered cars in the future. For example, California residents are expected to buy more electric cars as the state plans to ban the sale of gasoline cars and light trucks by 2035.
“We encourage policymakers to consider usage tariffs that encourage day charging and incentivize investment in charging infrastructure to move drivers from home to work for charging,” said the study’s co-senior author Ram Rajagopal, an associate professor of civil and environmental engineering at the University of Groningen. Stanford University, in a pronunciation..
So far, electric cars have accounted for a million or 6% of California car sales. The state’s goal is to increase that number to five million electric vehicles by 2030. However, the study authors say that the transition from gas to electric will put pressure on the electricity grid when 30% to 40% of the cars on the road.
“We were able to show that with less home charging and more daytime charging, the western US would need less generating capacity and storage, and it wouldn’t waste as much solar and wind energyexplains Siobhan Powell, a doctor of mechanical engineering and lead author of the study. “And it’s not just California and western states. All states may need to rethink electricity pricing structures as their EV charging needs increase and their grid changes.”
If half of the vehicles in the western United States are electric, the team estimates it would require more than 5.4 gigawatts of energy storage, equivalent to five large nuclear reactors, to charge the cars. However, if people charged their electric cars at work rather than at home, electricity demand is expected to drop to 4.2 gigawatts.
California currently uses hours of use to encourage people to use electricity at night, such as running the dishwasher and charging cars. However, the authors claim that with growing demand of electric cars, this strategy is outdated and will soon lead to high demand with low supply. More specifically, the teams say that if a third of homes charged their electric cars at 11 p.m. or when electricity rates drop, the local electricity grid would become unstable.
“The findings of this article have two profound implications: the first is that the price signals are not aligned with what would be best for the network – and for taxpayers. The second is that it calls for investment in a charging infrastructure for where people work,” said Ines Azevedo, associate professor of energy science and engineering and co-senior author.
“We need to act quickly towards decarbonising the transportation sector, which is responsible for the bulk of California’s emissions,” Azevedo added. “This work provides insight into how to get there. Let’s make sure we pursue policies and investment strategies that enable us to do this in a way that is sustainable.”
The study was published in Nature Energy.