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A Much-Needed Smart Grid Solution for the Potent EV Overcrowding Problem

One of the big, unaddressed problems of charging EVs, especially when their numbers start to grow, is the risk of grid overload as a result of clustering -- the pricey early cars are likely to be concentrated in upper-income neighborhoods where green interest is high. And the grid is so "dumb" that its ability to know whom in a given area is charging stops at the local transformer. It knows there's a big power drain, but it can't pinpoint it to specific houses or buildings.

The Prosser Group is a new charging company with a server-type software solution aimed at managing local electric resources holistically, and making sure that an overload doesn't leave cars stranded without power.

EVs, said Prosser Group CEO Ron Prosser, are "birds of a feather" that will cluster together. "People in higher socio-economic groups are more likely to rationalize the extra cost of early EVs, and that means very concentrated distribution of the cars," he said. "But as the cost comes down through a variation on Moore's Law, more people will buy them and the overload problem will be even bigger. We're imagining a gas station that wants to provide kilowatts instead of gasoline, but may not have the capacity."

The server (which could be located in a building, or installed in conjunction with Prosser's AeroVironment-sourced chargers) is designed to manage the load. If five cars are plugged in, it might decide to charge only two of them in a given hour, but still ensuring they're all charged in a timely fashion. If a building's elevator is idle, for instance, it might redirect resources from that for EV charging.

It's a big picture system, but locally based, and it can even turn off big-load air conditioning temporarily on hot peak-load days. "Our system is like a real-time energy broker that manages power from wherever it's available to wherever it's needed," Prosser said.

By March, Prosser will have the first in a series of demonstration projects operating, and all of them will be online by the end of June. Prosser said the probable locations include a convenience store in Long Island City, a fast-food restaurant in Westchester, a natural foods supermarket and parking lot in Manhattan, and a major car rental agency at LaGuardia Airport in Queens. The quick-serve restaurant's resources will include a generator that runs on its own fry oil, and several of the locations will have solar panels and battery back-up systems.

The company is focused on the New York area, and is a partner with New York's big Con Edison utility in $45 million in smart grid stimulus funding (it's part is $10 million). According to Prosser, the issue is the "last mile," from that transformer to the charging cars. And its plan draws in all of a building's electric resources, including possible diesel back-up generators, battery storage (possibly in existing uninterruptible power supply form) and maybe even a solar panel on the roof, to be turned on when needed to charge the cars.

Prosser recently analyzed a typical charging hot spot of the future -- a movie theater parking lot -- and discovered that if 25 of the 250 cars in the lot were plugged in, an overload condition was likely. Con Ed's default is simply to then switch the charging stations off, but Prosser maintains that he can keep them going 24/7, without adding any new power plants.

It's plain that, with 100-mile range, EVs work best as short-haul urban vehicles, but city dwellers don't have garages. So Prosser (soon to change its name to something more fitting its EV role) is focused on solutions for the parking garages that could end up bearing a lot of the load. If 50 cars need to be recharged on a given night, Prosser said, it can stagger their connections to the grid and still ensure that all of them will be ready to go in the morning.

Systems like this will be vital once EV charging moves to 480-volt Level III fast charging, which takes only half an hour but uses a heavy jolt of electricity. Managing fast charging is still embryonic, because the U.S. has yet to settle on a standard for it (though the Japanese have CHAdeMO up and running). But ECOtality says it will be putting fast chargers in select BP gas stations. So that's a great big electric load, coming soon to a high-rent district near you.


Photo: Flickr/Felix Kramer
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