Swapping a gas-guzzling automobile for a plug-in electric car has definite environmental advantages. There’s the lack of emissions, for one thing, and electric vehicles (EVs) obviously don’t require drilling for oil, refining it or transporting it. But it’s not as if EVs have no impact on the environment. The power to charge a plug-in EV has to come from somewhere. And that’s got some people worried about just what an influx of EVs might mean for the nation’s electrical grid.

With gas back up to $4 a gallon and generous government incentives for buyers, more than 30,000 EVs are expected to hit the streets in the coming year. Adding an electric car to the driveway can be like adding another house to a neighborhood, says Karl Rábago, vice president of distributed energy services for Austin Energy, the public utility for Austin, Texas. It has led to the perception that EVs could seriously burden electric grids. Should public officials be concerned?

In the near term, the answer is no. Simply put, “We can’t build them that quickly,” says Clay Perry, senior media relations manager for the nonprofit Electric Power Research Institute (EPRI). The Nissan Leaf and the Chevrolet Volt -- the country’s first truly mass-market EVs -- aren’t cheap. The Leaf sells for $33,000; the Volt, $41,000. The high price tags and limited driving distances -- at least until more charging stations are built -- are obstacles to wide-scale adoption of EVs.

In the long term, however, the vehicles may pose more of a problem. If public utilities do nothing and a million electric vehicles flood the market by 2015 -- a target that President Obama has espoused -- then the grid could become overloaded, possibly knocking out power to a home or even a neighborhood.

But if public utilities plan properly, the arrival of the electric vehicle could be met with little more than a hiccup. Both Austin and Los Angeles are trying to get ahead of the EV impact. Austin Energy is offering a rebate of up to 50 percent off the cost and installation of home EV charging stations. To receive the rebate, Austin residents must agree to participate for three years in a pilot program in which they share information about their EV charging habits. “We are providing incentives and tying them to requests for data so we can learn and study the impacts [of EV charging],” says Rábago.

Los Angeles is running an almost identical program. Its public utility is offering residents up to $2,000 to purchase and install home EV charging stations. The first 3,000 to 5,000 Los Angeles Department of Water & Power customers who sign up will be required to participate in its “residential time-of-use rate” program, which provides a significant discount for electrical use during off-peak hours -- weeknights and anytime on weekends.

Austin Energy has been planning for the arrival of electric cars for five years. Its electric vehicle-readiness program will use the data collected from customers participating in the rebate program to develop “smart charging” strategies to prepare the grid for the expected influx of electric vehicles -- research by EPRI indicates there may be as many as 36,000 EVs in the Austin area by 2020. One smart charging strategy includes incentivizing customers to charge their EVs in the middle of the night. Austin Energy’s lowest demand for electricity occurs about 2:30 a.m., which also coincides with the state’s highest production of wind power. (In Los Angeles, the peak hours of wind power production also occur at night.) But even charging an EV during peak hours on a coal-powered electricity grid would still be cleaner than a petroleum-based vehicle, Rábago says.