Conventional cars produce a lot of heat, some of which gets trapped in cities in summertime. Vehicle heat is one of the main factors behind the “heat island effect,” by which cities get significantly hotter than surrounding countryside, mostly because asphalt and concrete holds in more heat than trees and grass do.
Could switching to electric vehicles, which produce less heat as they move along, help with overall temperatures?
Yes, according to new research led by Jack Liu, a professor at Michigan State University. Liu and his colleagues ran the numbers for Beijing and found that replacing conventional vehicles (CVs) with EVs could reduce the heat there by almost 20%. In 2012, EVs would have lowered “heat island intensity”–the temperature difference between the inner and outer city–by almost 1 degree Celsius.
In addition, the EVs would have reduced the need for buildings to use electricity (which themselves produce heat) by 14.44 million kilowatt-hours, and lowered carbon emissions by more than 10,000 tons for the season.
“EVs emit much less heat than CVs within the same mileage. Therefore, the replacement can mitigate [the heat island effect], which can reduce the amount of electricity consumed daily by air conditioners, benefitting the local and global climate,” the paper, published in Scientific Reports, says.
Via email, Liu says the findings could apply to any large city, particularly megacities with at least 10 million people. Bigger cites are more dense, and therefore have greater buildups of heat and more potential for reductions through EVs.
One slight fly-in-the-ointment is that CV heat might sometimes be useful. EVs use more electricity on cold days to provide the same heating comfort, making their economics less terrific in colder climates. Still, the benefit to big, hot cities could be significant, which is why Liu wants to see more EVs. “More supportive policies towards EVs would help speed up the process of switching from CVs to EVs,” he says.