It will take years before there are enough electric cars and gas–electric hybrids on the road to put much of a dent in the output of the electrical grid. But once they do roll out en masse, these vehicles (and their drivers) will have to be smart about when they recharge so that utilities can avoid spikes in grid demand and drivers can avoid spikes in their electric bills. This puts carmakers and utility companies on the spot to develop a uniform technology that lets cars communicate with the grid, and vice versa.
Ideally, drivers will be able to program the start time for charging, the rate they want to pay, and the time needed to complete charging, says Nancy Gioia, Ford Motor Co.'s director of Sustainable Mobility Technologies and Hybrid Vehicle Programs. "As electric vehicles hit the road, you need to predict what technology you need to have out there to be able to use the extra capacity in the system at off-peak hours," she adds.
A common scenario depicting how so-called "smart charging" will work: Electric vehicle (EV) drivers return home from work in the evening after having used some portion of the battery charge during the day. They plug into an outlet (most likely in their garage, if they have one) and use in-car controls to set a timer that dictates the period when the battery actually draws juice for its recharge. If drivers get home at 6 P.M., for example, they might want to wait until 9 P.M. to avoid overburdening the electric grid—and possibly to get a better price for the electricity.
"The reason we want to have vehicles talking to utilities is primarily so we can make sure that we don't make any peak loads worse than they are today," says Britta Gross, General Motors's manager of Hydrogen and Electrical Infrastructure Development. Utilities do not want EVs adding significantly to peak demands, she adds, because the peak defines how many more power-generation plants utilities have to build.
"Some utilities will have very advanced technology in homes, but others won't for some time to come," Gross says. "We have to make sure the vehicle works in that sort of broadly defined environment." Although GM's OnStar in-car communication service seems well suited to become a part of any smart-charging system that must connect with utility companies, Gross points out, "we haven't talked about is how this relates with OnStar."
OnStar is like a help desk for drivers, using Global Positioning System (GPS) satellite and cellular technology to connect both the vehicle and driver to accident assistance operators, driving directions and other services, wherever they are. "Everyone is in agreement with what the physical connector will look like, but until we have common standards," she says, "it doesn't make sense to go too far down the road."
Ford, on the other hand, expects its SYNC in-car communications system will play a big role in tying in with home owners' smart meters to determine how much vehicle batteries need to be charged, how long it will take, and when to charge them, Gioia says. Ford claims that more than one million of the vehicles it has sold have SYNC systems.
Whereas OnStar and SYNC may be important as stepping stones to smart charging systems, the technology will not take off until utility companies and EVs have a single, standard protocol for communicating. (Imagine the mess if different car companies each wanted to send data to and from utilities in their own way.)
"We have the technology but need to create standards to make sure it can connect with all of the smart metering technology out there," says Mark Duvall, director of Electric Transportation at the Electric Power Research Institute (EPRI), a Palo Alto, Calif.–based group of energy researchers funded primarily by the electric utility industry. "If we do these simple things there's more than enough capacity in the electrical system to charge all of these vehicles with very little additional investment in the grid."
The Society of Automotive Engineers's (SAE) Hybrid Task Force began working early last year, with input from carmakers, utilities and suppliers, to develop a standard that will connect any vehicle to one of hundreds or even thousands of different smart-metering systems or other external devices that want to communicate with plug-in vehicles, says Duvall, who is also co-chair of the SAE task force. "It's a step-by-step process," he says, "one that I hope we'll be able to finish in the next 18 months or so. I would personally like to see the things that we are working on here start to show up in new vehicles in the next few years."
Source : Scientific American, 29/09/09
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