An electric car gets ready to roll.

An electric car gets ready to roll. Credit: Kiyoshi Ota/Bloomberg /Getty

Energy

Cars that are good for the air but bad for the grid

Drivers who charge plug-in cars at home could harm power infrastructure.

Plug-in electric vehicles are lauded for their low emissions, but could cause headaches for utility companies by creating spikes in power demand.

Previous studies have tended to assume that drivers would charge such vehicles when overall power demand is lowest. Matteo Muratori at the US National Renewable Energy Laboratory in Golden, Colorado, used models to predict what would happen if drivers plugged in their vehicles as soon as they got home.

Muratori found that if every home in a six-household neighbourhood had a plug-in electric vehicle, the peak demand on the electrical transformer serving that neighbourhood could rise by as much as 60%. That’s enough to shorten a transformer’s lifespan.

Future studies should analyse drivers’ willingness to postpone charging to periods when power demand is low, Muratori says.