“There are 16 gigawatts of new coal-fired generation coming online in the next few years,” said Kevin Book, an energy policy analyst at FBR Capital Markets. “They may well be the last plants.”

Mr. Rogers, 61, may adhere to the pro-coal sentiments of many of his peers, but he is hardly a typical captain of the energy industry. Five years ago, he began advocating for climate change legislation at a time when some companies were still saying human activity had nothing to do with global warming. Mr. Rogers, a native of Birmingham, Ala., considers himself an environmentalist and calls his decision to move forward with the new plant, made shortly after he became chief of Duke in April 2006, a difficult one.

The estimated 240 million tons of carbon dioxide that will be generated over the 40-year life of the plant, known as Cliffside, will probably never be captured, when or if such technology becomes viable. Most proposals to capture gas involve injecting it deep into the earth. But in North and South Carolina, where Duke operates, the underground rock is too porous to contain any gas.

“There’s always been a tension between affordability and clean,” Mr. Rogers said in mid-January, sipping a cappuccino on his way to a meeting in Washington with Carol M. Browner, the White House coordinator of energy and climate policy. “Ultimately we need to be able to meet the energy needs of our customers. That’s my biggest obligation.”

Fulfilling that responsibility through renewable energy wasn’t an option, he said. Duke, which gets 71 percent of its electricity from coal, has only recently delved into solar energy, promising to buy the entire output of a large solar farm in North Carolina and it is seeking final approval to put solar panels on rooftops at hundreds of customer sites. Its first purchase from a wind farm has started flowing to customers in Indiana. All that combined, though, will give Duke only 124 megawatts of energy, compared with 800 planned from Cliffside.

Hoping to mitigate some of the environmental impact of Cliffside, Mr. Rogers has promised to shut down more than an equal amount of older, more polluting power plants by 2018.

Environmentalists are not impressed. They say that Mr. Rogers hasn’t pushed for clean energy with the same vigor he has expended on Cliffside; for instance, he personally lobbied North Carolina utility regulators for Cliffside but not for the solar program. “Among the utility guys he’s the most dangerous because he talks a good game, but his actions are among the worst,” said Bruce E. Nilles, who oversees anti-coal initiatives for the Sierra Club.