But utilities in Vermont, like their counterparts elsewhere in the country, argue that environmental advocates are mistaken if they believe a low-emission future can be achieved without nuclear power. They note the intermittency of power sources like windmills and solar panels, and argue that the nation needs more, not fewer, big power plants that emit no carbon dioxide.

“Vermont is in an enviable position right now,” said Steve Costello, a spokesman for the state’s largest utility, Central Vermont Public Service. “We have arguably the cleanest power in the country from an air-emissions standpoint, and we have the lowest rates in the Northeast.”

His utility is willing to build more renewables, he said, but closing Vermont Yankee would make maintaining clean and cheap power “much more difficult.”

Even as some Vermonters argue for more renewable power, proposals to build it have hit snags.

Vermont has only one commercial wind farm, 11 turbines along a mountain ridge. They have less than 1 percent of the capacity of Vermont Yankee, a relatively small nuclear plant.

Other proposed projects have been stalled by local opposition. One wind project would infringe on bear habitat. Another won approval from state regulators, but a local group filed a court appeal to block it.

“Vermont is very protective of its environment regulation,” said Mr. Perchlik of Renewable Energy Vermont. “It’s not going to be done Texas-style, where you can get a permit in a month.” He nonetheless hopes that wind turbines can provide 20 percent of Vermont’s electricity by 2015.

Besides tapping into the Northeastern grid, Vermont could import more power from Hydro Quebec, a giant dam system in Canada that already accounts for a third of Vermont’s electricity, but that would probably help push up prices. Solar power is also costly. Burning wood chips or other plant material is one option  Burlington already has such a plant  but a large one would face pollution and other problems.