State regulators are holding public hearings next week on Wednesday and Thursday regarding Duke Energy’s proposed gas combustion turbines at the utility’s Marshall Steam Station on Lake Norman. Duke Energy Carolinas applied for a certificate of public convenience and necessity in March.
The generators are part of the utility’s plan to meet state energy needs and emission goals.
The power plant currently houses four units capable of generating 2,078 megawatts through the combustion of coal and gas. The new turbines would replace the two smaller generators onsite in 2029, providing more power without burning coal.
“A few decades ago, coal was about half of our generation in the Carolinas,” said Bill Norton, a Duke Energy spokesperson. “Today, it’s down to about 10%.”
Coal-burning generators ran more often to provide the around-the-clock foundation for North Carolina’s energy supply. Nuclear energy has since replaced coal in that role, and coal-burning generators, like the units at the Marshall Steam Station, now provide power to the grid when energy demand is high, turning on during peak demand hours.
However, the coal-burning units, the newest of which is over 50 years old, take hours to ramp up. The proposed combustion turbines, also called “peakers,” turn on quickly and provide energy during hours of high electrical demand.
“Let’s say the clouds move in, and solar capacity comes way down on the system, these combustion turbines can ramp up much more efficiently than coal units are doing right now,” Norton said.
Opponents of natural gas expansion in the Carolinas say that increased battery storage could fill a similar role during periods of high demand.
“Battery storage systems are a really cost-effective replacement that can be charged with clean energy during the day,” said Will Scott, southeast climate and clean energy director at the Environmental Defense Fund.
The new combustion units would receive gas supplied by existing lines that Duke subsidiary Piedmont Natural Gas connected when the utility retrofitted Marshall Steam Station to burn gas in 2021. The proposed combustion turbines are planned to launch with 30% hydrogen capability, meaning they can co-fire with hydrogen. The new units would require additional upgrades to generate power without fossil fuels.
Scott said new battery systems would also take advantage of existing energy infrastructure, while new gas combustion turbines would be expensive to build and only operate a small percentage of the time.
Compared to the coal-burning units the gas turbines would replace, the new generators would produce electricity with fewer emissions at a rate of 82% less nitrogen oxides, 92% less sulfur dioxide and 40% less carbon dioxide per megawatt hour.
Duke Energy Carolinas is scheduled to retire the remaining coal-burning generators at the end of 2031. The company has not determined what generation will replace those units.
The commission will host the in-person hearing at the Catawba County Courthouse in Newton on Wednesday, June 5 at 7 p.m. Individuals have until 5 p.m. on Thursday, May 30, to register for the virtual hearing Thursday, June 6 at 6:30 p.m.
