Environment & Energy
3:30 am
Mon February 3, 2014

New Method of Charging Electric Cars Could Bring Savings

A new study by a team of researchers at Carnegie Mellon University suggests that electric car owners can cut costs if they forfeit control over when to charge their vehicles.

The study found that allowing the power grid to control charging is more beneficial than charging the vehicles during peak electricity times.

“The idea is that if you just plug in an electric vehicle now when you get home from work, you’re asking the electricity grid to provide you with a maximum charging rate until that battery is full and then the vehicle just sits there until you’re ready to use it again,” said Jeremy Michalek, researcher and associate professor of mechanical engineering.

The most cost-effective way to do it, Michalek said, is to “smooth out the demand for charging overnight while you’re not using the vehicle.” That way, the grid operator will have the option to use less expensive power generation options.

This would require electric car owners to surrender some control over when they charge their vehicles. Michalek did acknowledge the risk of not having a charged vehicle in emergency situations, but said the risk is minimized with hybrid cars, which have a gasoline alternative.

“Plug-in hybrid electric vehicle owners may be more willing to give the grid operator a little bit of that flexibility,” Michalek said.

Controlled charging could also reduce the demand during times of less wind generation, which would make renewable energy sources “more attractive.”

“That way, we don’t have to make up the difference in generation with some other plant like a natural gas power plant,” Michalek said.

If electric cars become a more substantial part of the vehicle fleet in the future, Michalek said controlled charging could cut the cost of generating electricity to charge the vehicles in half. However, there is no certainty that electric cars will gain that type of popularity.

Michalek does think that if studies can show electric cars to be more cost-effective, they can be more “acceptable to the mainstream.”

“Our supply of petroleum is limited and more than that, if we burn all the petroleum we can find, we have a major problem with the climate,” Mihalek said. “So there’s an effort to try to find an alternative source and electric vehicles are one of the most promising near-term solutions.”

The study appeared in February’s edition of the journal Applied Energy and was funded by the National Science Foundation and the CMU RenewElec project.