The shift to electric vehicles and plug-in hybrids heralds a major change for automotive technologies, one that will ripple out to many fields. One of the foremost is the electrical grid that will power these electrified vehicles while also drawing power from a car’s battery pack during peak usage periods.
Electrified vehicles will significantly alter the demand for fuel while also reducing the cost of operating a car. Chevrolet Volt users can recharge battery packs for just a few cents, saving substantial amounts and spending little on fuel.
“The median Volt driver does 66% of all driving is on electric power,” said Michael J. Bly, Executive Director, Group Global Functional Leader for Global Electrical Systems, Infotainment & Electrification at General Motors. “Drivers are getting 900 to 1000 mi on a 9-gal gas tank.”
As more EVs connect to the electrical power grid, power distribution patterns will change significantly, according to panelists of the “Energy Smart: Connected Vehicles and New Opportunities” presentation on April 24 at the SAE 2012 World Congress. The power needed to recharge EVs won’t require significant upgrades until vehicle volumes are quite high.
“One EV attached to the grid will create about a 25% increase for an average home, which is about like adding an air conditioner,” said Glen Stancil, Vice President at NRG Energy EV Services.
However, significant changes will be required if EVs fulfill a secondary role: providing power that utility companies can use to help them meet peak demands. Vehicles can sell energy back to utilities at peak times, typically late afternoons on hot days, then recharge batteries later so the vehicles can be driven home from work. Vehicle makers note that to date, usage patterns have been largely for a few short runs per day, such as driving to and from work.
“Over 90% of the Leafs are parked at a given time,” said Minoru Shinohara, Senior Vice President, Nissan Motor Co.
He explained that the Leaf’s batteries have about 24 kW hours capacity, which roughly matches the average home demands, which range from 20-30 kW·h. However, utility companies must make many changes before it’s viable to use EV batteries as a power source. Smart-grid technologies must be installed, and consumer costs for energy must be priced at different rates depending on the time of day.
“The reality is that the smart grid is not very smart,” Bly said. “If we don’t get it operating intelligently pretty soon, consumers will give up on the smart grid. We also need more time-of-day charging. That’s still a small percentage of the market.”
Panelists generally agreed that such changes are going to occur over the next few years. Vehicle batteries are making big advances, and smart-grid technologies are also moving swiftly.
“The cost of wind energy has gone from 20 cents per kW·h to about 5 cents, which is competitive with conventional rates,” said Mark Little, Senior Vice President & Director, GE Global Research. “Solar has gone from 30-40 cents to 10-11 cents per kW·h. That type of innovation will also occur in EVs.”
Along with these technical changes, panelists noted that the U.S. must standardize many of its grid technologies. There are more than 3000 utility companies in the U.S., and many of them use different technologies. That will hamper efforts to recharge vehicles during low-demand periods and make it difficult for vehicle owners to provide power to utility companies.
“We have a lot to do in grid energy management,” Little said. “We need improved software to manage energy distribution.”