A Private Network for Recharging Cars

A prototype of the charging stations that would be sprinkled across the Houston area.A prototype of the charging stations that would be sprinkled across the Houston area.

A utility with operations around Texas is planning a network of 50 to 150 charging stations for electric cars in the Houston metropolitan area to eliminate “range anxiety,” and is talking with Nissan, Toyota and others about offering auto buyers a package that includes network access and a home charger.

The company, NRG, hopes to offer packages ranging from $49 a month, for cars with both electric motors and gasoline engines like the Chevy Volt that would not need access to the scattered charging stations, to $79 a month, for buyers of the Nissan Leaf.

The network, called eVgo, will be the first private one for charging, said David Crane, the chief executive of NRG, which is based in Princeton, N.J. In a conference call with reporters, he said Thursday that a combination of home and public charging stations would “make the electric vehicle more affordable and practical, which we believe will significantly close the decision gap.”

The plan is to have 50 charging stations installed by the middle of next year; these would deliver three or four miles of range for each minute of charging time.

Customers would primarily charge their vehicles at home overnight, but if they miscalculated and were far from home with no charge or if they had a long itinerary around the Houston area, they could conveniently get a partial charge.

He acknowledged that the market was uncertain; he said that he hoped for 1,000 subscribers within a year and that the market would later accelerate “at warp speed” as more electric vehicles came on the market.

The concept transforms charging stations into something akin to premium lounges at airports, or even automatic teller machines, available by subscription in diverse locations. NRG has not worked out how, or if, it would accommodate non-subscribers who wanted to use the public charging stations.

The venture is one of several possible financial approaches to the problem of charging a vehicle away from home. Another would be to have a regulated utility company install the same hardware and put the cost into its rate base so that all customers would pay for it, as they would for a new substation or for a transformer hanging on a utility pole.

Mr. Crane contends that his unregulated, all-you-can-eat subscription approach could be installed much faster. His company is negotiating with retail stores, parking lot landlords and others.

NRG has a deal with Nissan for the car company to offer the subscription service to people shopping for its all-electric Leaf, which is just arriving in showrooms. Negotiations continue with Hertz and others.

AeroVironment, an electric vehicle pioneer, will make the charging stations. The ones that will be installed in houses will cost NRG $1,500 to $2,000; customers will sign a three-year subscription agreement, and the charge will be added to the customer’s home electric bill.

The home chargers run at 220 volts, the same as a clothes dryer or electric oven, and deliver alternating current, the kind found on the grid, to the vehicle. On board the vehicle a device called an inverter converts the alternating current to direct current, the type used by the batteries.

But in this process, the inverter is a bottleneck. It is sized for converting energy from the battery back into alternating current for use in the car’s electric motor, and is not big enough for fast charging.

But AeroVironment has a different design for the public chargers. Those will use industrial-grade power and perform the conversion to direct current, thus bypassing the car’s inverter. As a result, they can run at much higher power levels.

In fact, the home model runs at 3.3 kilowatts (which is about the same as three hand-held hair dryers), and the commercial model, at 50 kilowatts, according to Kristen Helsel, a vice president of AeroVironment.

Ms. Helsel said that while the Leaf and the Volt are charged at 3.3 kilowatts, models introduced in coming years would probably be charged at 6.6 kilowatts, which would cut the time for a full charge down to two or three hours, versus four to six hours now.

She called the combination of her company’s two products, the home charger and the distributed public chargers, “a complete ecosystem.” In the long term, the system might also be used to recharge coming vehicles like the plug-in version of the hybrid Prius, so that a customer with a 10-minute errand at a drugstore, for example, could leave with that car’s small battery pack fully charged.

The public stations are for daytime charging, for the most part, but NRG has its eye on a broader goal, building a bigger market for energy at night. The company owns a share of two nuclear reactors 90 miles from Houston andwants to add two new ones.

Nuclear plants produce electricity around the clock, but nighttime demand and load are low and so are prices, which sometimes drop to zero. Adding millions of electric vehicles, which would charge mostly at night, would create a market that a round-the-clock generator could serve, he has said in various presentations



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