How to control EV charging costs

Posted by Nino Marchetti, EarthTechling

What is the optimal way to charge electric vehicles that will keep the costs associated with electricity down? Researchers at Carnegie Mellon University may have found one possibility, optimally varying the charging speed of plug-in electric vehicles to cut the electricity cost in half and make it ultimately much more affordable to own one of these forms of green transportation.

Engineering and Public Policy Department (EPP) graduate student Allison Weis and professors Paulina Jaramillo and Jeremy Michalek, said the university, studied the effects of new vehicle charging loads on power plant operations in New York.

tesla charging

© EarthTechling/Nikolai Danko

“Although plug-in electric vehicles currently make up a small percentage of the vehicle fleet, federal and state subsidies are promoting electric vehicle sales, and they may become a significant portion of the fleet in the future,” Weis said. “If owners regularly plug in these electric vehicles when they get home from work, this would add to greater demand, when the most expensive power plants are running.”

But it doesn’t have to be that way, CMU researchers said.

“Controlled charging can shift loads later in the night when cheaper power plants are again available,” said Jaramillo, an assistant professor of EPP. “Controlled charging could also help to manage fluctuations from renewable energy sources like wind and solar power, which change their output as the wind changes and as clouds pass by.”

“It is already cheaper to charge an electric vehicle than fill up a gasoline vehicle,” said Michalek, an associate professor of mechanical engineering and EPP, and director of the Vehicle Electrification Group. “But allowing grid operators to control electric vehicle charging speed could reduce these costs further. We see additional savings up to $70 per vehicle each year or even higher for systems that expect new power plant construction and systems with a lot of wind power.”

* Nino Marchetti, EarthTechling