The first domino fell in Duke Energy Carolinas territory, which serves 2.5 million residential, commercial and industrial customers. Starting at midnight on Christmas Eve, utility officials cut back power at the Dan River combined cycle plant, which runs largely on natural gas, to 360 MW, roughly half of its capacity, said Sam Holeman, vice president of transmission. (This is also known as derating.) Some of the plant’s instrumentation had frozen, and to prevent the facility from failing altogether, operators had to reduce the strain. The Buck plant in Salisbury encountered low pressure issues and had to be derated after peak energy usage had passed.
Solar energy “performed as expected,” Duke officials said, although it was not available overnight during the peak hours of 2 to 6 a.m.