Charging cars at home at night is not the way to go, Stanford study finds
The move to electric vehicles will result in large costs for generating, transmitting, and storing more power. Shifting current EV charging from home to work and night to day could cut costs and help the grid, according to a new Stanford study.
by Mark Golden | Thursday, September 22, 2022
The vast majority of electric vehicle owners charge their cars at home in the evening or overnight. We’re doing it wrong, according to a new Stanford study.
In March, the research team published a paper on a model they created for charging demand that can be applied to an array of populations and other factors. In the new study, published Sept. 22 in Nature Energy, they applied their model to the whole of the Western United States and examined the stress the region’s electric grid will come under by 2035 from growing EV ownership. In a little over a decade, they found, rapid EV growth alone could increase peak electricity demand by up to 25%, assuming a continued dominance of residential, nighttime charging.
To limit the high costs of all that new capacity for generating and storing electricity, the researchers say, drivers should move to daytime charging at work or public charging stations, which would also reduce greenhouse gas emissions. This finding has policy and investment implications for the region and its utilities, especially since California moved in late August to ban sales of gasoline-powered cars and light trucks starting in 2035.
“We encourage policymakers to consider utility rates that encourage day charging and incentivize investment in charging infrastructure to shift 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 Stanford.
There’s more at the original, and there’s no paywall to stymie you.
The authors believe that people should charge their Teslas and Chevy Dolts at work, rather than at home. Great idea, except there is no guarantee that your employer is going to add the infrastructure, and if he does, he’s going to need to recoup that cost: he’s going to charge employees for using the at-work charging stations, for both the installation costs and the sparktricity used.
One of the problems is the extreme egocentrism of the authors. It’s far too easy for people to think of their situations as the only situations. When they have an assigned parking space at a prestigious university, they might not consider that far more people work at places like Seven/Eleven, where management isn’t likely to run the power lines and install the stations for their minimum wage employees — who can’t afford a plug-in electric vehicle in the first place — to use. Perhaps they are unfamiliar with trades employees, who go to different jobsites across their area.
Once 50% of cars on the road are powered by electricity in the Western U.S. – of which about half the population lives in California – more than 5.4 gigawatts of energy storage would be needed if charging habits follow their current course. That’s the capacity equivalent of 5 large nuclear power reactors. A big shift to charging at work instead of home would reduce the storage needed for EVs to 4.2 gigawatts.
Storage capacity is a huge issue: solar plants generate exactly zero electricity at night, which means that charging your plug-in electric car after you get home from work means that most of the charging will be done after sundown. That means you will be drawing power not from the hundred-acre solar farm, but from the batteries to store the electricity the solar farm generated during the day.
More, electricity generated and going into the battery system before going to your home is less efficient than going from the solar plant directly to your home; there is increased energy loss due to the second stop.
Another issue with electricity pricing design is charging commercial and industrial customers big fees based on their peak electricity use. This can disincentivize employers from installing chargers, especially once half or more of their employees have EVs. The research team compared several scenarios of charging infrastructure availability, along with several different residential time-of-use rates and commercial demand charges. Some rate changes made the situation at the grid level worse, while others improved it. Nevertheless, a scenario of having charging infrastructure that encourages more daytime charging and less home charging provided the biggest benefits, the study found.
It also means that charging your car at work means that you will be paying not the residential power rate, which normally drops after 11:00 PM, but the commercial rate your employer is paying. It will cost you more to charge at work than at home, not even counting the charges the employer will have to put in place to pay for the employee charging stations.
It seems as though the global warming climate change emergency activists all had this great idea, that everyone should drive a plug-in electric car — excluding, of course, the activists who don’t think people should have privately owned vehicles in the first place — but they never really thought through the problems.