A huge tax break, but skepticism that drivers will leave gas behind.

By NELSON D. SCHWARTZ

COPENHAGEN - Is saving $40,000 at the showroom enough to get drivers behind the wheel of an electric car? With a program in the works to add easy access to charging stations, Denmark is about to find out.

For all their potential, electric cars have always been the subject of more talk than action, and only a handful are on the road in Denmark. But now the biggest Danish power company is working with a Silicon Valley startup in a $100 million effort to wire the country with charging poles as well as service stations that can change out batteries in minutes.

The government offers a minimum $40,000 tax break on each new electric car - and free parking in downtown Copenhagen.

But even in Denmark, one of the most environmentally conscious nations in the world, skepticism abounds. It is not clear that car buyers can be persuaded to make the switch.

“There is a psychological barrier for consumers when their car is dependent on a battery station,” warned Henrik Lund, a professor of energy planning at Aalborg University. “It’s risky.”

The Silicon Valley company, Better Place, is making a big push in Denmark and in Israel. That makes those two countries the world’s most important test cases for the idea that electric motors and batteries can supplant the petroleum-burning engines that have powered cars for more than a century.

By revamping the power grid, Dong Energy, Better Place’s partner and the biggest utility in Denmark, wants to power the anticipated fleet of electric cars with wind energy, which already supplies nearly 20 percent of the country’s power.

With Better Place and the smart grid working together, cars would charge up as the winds blow at night, when power demand is lowest. Charging would soak up the utility’s extra power and sharply shrink the carbon footprint of electric vehicles.

“We’re the perfect match for a windmill- based utility,” said Shai Agassi, Better Place’s founder and chief executive. “If you have a bunch of batteries waiting to be charged, it’s like having a lot of buckets waiting for rain.”

Mr. Agassi has cast his company’s efforts in moral terms, because of the large contribution that gasoline and diesel cars make to global warming. But so far, the results are falling short of the rhetoric.

In January 2009, Mr. Agassi promised that Denmark would have 100,000 charging spots in place and several thousand cars on the road by 2010. But with that deadline approaching, no Better Place cars are on the road and only 55 charging spots are ready. According to Better Place, 2011 has always been the target for its mass debut .

Better Place’s vision calls for a network of stations where a robotic device could replace a battery . These switching stations are needed because batteries have a limited range of about 160 kilometers, and recharging takes up to five hours . Consumers would buy the cars but get batteries from Better Place and pay a fee for the kilometers they drive .

But even local supporters of Better Place worry that the switching stations, which could cost as much as $1 million each to build, are impractical, largely because the stations may need to stock a wide range of batteries to accommodate cars from different manufacturers.

“I’m skeptical about the infrastructure,” said Klaus Bondam, Copenhagen’s mayor for technical and environmental administration. “It won’t work unless it’s standard on every electric vehicle produced.”

So far, only one automaker, Renault Nissan, has agreed to make cars that work with Mr. Agassi’s switching stations.

“In every industry, the incumbent always said it’ll never change,” he said. “The mainframe guys said people will never need PCs.”