The plants, which could produce a combined 1,240 megawatts, would be located at the Dan River coal-fired plant in Rockingham and the Buck coal-fired site in Rowan County.
Duke would retire four aging coal-fired units, two at each site, after the new gas units are up-and-running, according to the ruling today from the N.C. Utilities Commission. Duke currently uses coal and nuclear to meet about 98 percent of its power needs in the Carolinas.
With approval for new nuclear plants in doubt and the widespread unpopularity of new coal-fired projects, the Charlotte-based utility has turned to natural gas to help it meet intermediate demand.
Duke says natural gas adds more diversity to its fleet and that it would need the plants regardless of nuclear and coal options. The once-popular option has fallen into its own disfavor because of its unpredictable price, which can spike because of hurricanes and other supply issues.
Duke says the plants would serve a specific need. But the plants can be built in just a few years, compared to decade or longer for other plants. They are also cheaper to build and emit far less carbon dioxide than coal-fired plants.
The gas is blamed as a cause of global warming.