After part of a cooling tower collapsed last August at the only nuclear power plant in Vermont, the company that runs it blamed rotting wooden timbers that it had failed to inspect properly. The uproar that followed rekindled environmental groups' hopes of shutting down the aging site.
The proposed closure, albeit a long shot, has gained some support this year among Vermont politicians. The discussion here is bringing into sharp relief a conflict between two objectives long held by environmentalists: combating nuclear power and stopping global warming.
Nuclear plants supply nearly 20 percent of the electricity in the United States, and they do so without emitting the carbon dioxide that is the principal cause of global warming. The 36-year-old plant in Vermont, which feeds into the regional power grid, represents a third of the state's electrical generation.
Antinuclear advocates who are arguing for closure hope to replace the lost electricity with renewable generation from wind turbines, solar power and the combustion of plant material. Additionally, they cite the potential for cutting electrical demand by making homes and businesses more efficient.
Even so, some environmentalists have reluctantly acknowledged that no combination of renewable power and improved efficiency can replace the plant, called Vermont Yankee, at least in the near term. Instead, the state would probably have to tap the northeastern U.S. grid - which derives more than half its energy from fossil fuels - for extra power.
"We'll likely have to go to the market, and that will mean an increase in Vermont's electricity portfolio that comes from fossil fuels," said Andrew Perchlik, director of Renewable Energy Vermont, a group that promotes clean power, speaking about the prospect of the plant's closure. He faulted the state government and power companies for not focusing earlier on renewable energy, saying that if they had done so, "We wouldn't be in this predicament."
The Vermont debate comes as interest in nuclear power is increasing across the United States, driven by rising demand for power as well as emissions concerns.
Like other plants nationwide, Vermont Yankee is seeking a 20- year extension of its operating license from the U.S. Nuclear Regulatory Commission, the agency that oversees the country's reactors. A decision, which could allow the plant to keep operating until 2032, is expected this year. Several utilities, encouraged by the U.S. government, are considering building new nuclear reactors for the first time in three decades.
In Vermont, home to many people with a back-to-the-land viewpoint, surveys show that people want to move away from fuels like coal and oil that emit large amounts of carbon dioxide. They also support renewable energy.
But the same surveys show less consensus on nuclear power. At energy workshops last year, nearly two-thirds of the participants said Vermont utilities should stop buying power from the nuclear plant - unless fossil fuels and out-of-state nuclear power were the alternatives, in which case more than half would continue with Vermont Yankee.
Not counting dams, another low-emission energy source that many environmental groups oppose, renewable power makes up just 2.5 percent of the electricity generation in the United States. That figure is higher in Vermont, at 6 percent, but renewable sources are still a long way from supplying the bulk of the state's power.
Starting from these slim figures, many advocacy groups hope to achieve a nuclear-free mix supplied by local renewable sources. State researchers estimate that as much as 48 percent of Vermont's power could one day come from local renewables, including small hydropower projects.
"When you look at all the scenarios for climate change, nuclear is not a must-do," said James Moore, a clean-energy advocate for the Vermont Public Interest Research Group, a group that opposes the nuclear plant.
But utilities in Vermont, like their counterparts elsewhere in the country, argue that environmentalists are deluded if they believe a low-emission future can be achieved without nuclear power. They note the intermittent nature of power sources like windmills and solar panels, and say the United States 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 largest utility in the state, 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 renewable sources, he said, but closing Vermont Yankee would make maintaining clean and low-cost power "much more difficult."
Even as some Vermonters argue for more renewable power, proposals to build it have hit snags. Vermont has only has one commercial wind farm, 11 turbines located 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 a 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," Perchlik, of Renewable Energy Vermont, said. "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 emit high levels of pollution.
The best bet for reducing the state's emissions may be energy efficiency, in which Vermont already excels. Since 2000, an outfit called Efficiency Vermont has urged homeowners and businesses to use energy-efficient light bulbs and appliances. State officials say they believe it has already cut power demand slightly this way.
Concerns about the Vermont Yankee nuclear plant, in the town of Vernon, focus on the disposal of spent nuclear fuel, a nationwide problem, and on more localized concerns about safety.
Last August, Vermonters were shocked to see images of water gushing out of a huge pipe onto a heap of collapsed wooden beams. A portion of one of the plant's two cooling towers had fallen after decay weakened the wood. No radioactivity was released, but Entergy, the plant's operator, labored to explain how it could have missed such an obvious problem.
Rob Williams, an Entergy spokesman, said the event "certainly impacted reliability, but the safety was not at all impacted." Major repairs and improvements to both cooling towers have just been completed, he said, with crucial timbers replaced by fiberglass- reinforced plastic.
The Vermont Legislature has already voted to tighten plant oversight, and next year it is likely to take a vote on shutting down the plant, though whether the state would actually have the power to do that is unclear. The U.S. Nuclear Regulatory Commission licenses and regulates all reactors, and some experts predict lawsuits if Vermont attempts a shutdown.