Triumphal fanfare accompanied the October 2021 passage of a bill that requires utilities in North Carolina to reduce carbon dioxide emissions 70 percent by 2030 compared to 2005 levels.

“Today, North Carolina moves strongly into a reliable and affordable clean energy future,” proclaimed Gov. Roy Cooper upon signing it into law. Andrew Hutson, vice president of the National Audubon Society, praised the law’s “deep cuts to North Carolina’s carbon emissions on a timetable that will help us reduce the worst impacts of our changing climate.”

The law also establishes a 2050 target for complete carbon neutrality for utility companies with more than 150,000 customers in the state. That timeline aligns with a global goal set by the United Nations Intergovernmental Panel on Climate Change, a scientific body that advises world leaders, to keep planetary warming below 1.5 degrees Celsius and ensure “a more sustainable and equitable society.”     

Less than two years later, however, North Carolina’s largest utility, Duke Energy, asked the state utilities commission to relax the company’s decarbonization schedule. As outlined in a plan filed with the utilities commission in August, Duke’s preferred approach to generating electricity would not reach a 70 percent cut until 2035.  

Key to Duke’s request is its proposal to complete two advanced nuclear power plants, one by 2034 and another by 2035. The company cites a caveat buried in state law that allows the utilities commission to push back its targets when authorizing “construction of a nuclear facility or wind energy facility that would require additional time for completion.”

Traditional nuclear power plants, like the fleet of 11 reactors Duke brought online from 1971 to 1987, are built on-site and use regular water as a coolant. Advanced nuclear reactors seek to improve on those technologies, either through standardized, factory-based construction or different coolant systems. Engineers believe those designs can be smaller, safer, and more efficient than the current generation of reactors. 

Gov. Roy Cooper watches as Massachusetts Gov. Charlie Baker testifies at a House Natural Resources Committee hearing on climate change in February 2019. (AP Photo/Cliff Owen)

Nuclear energy represents a comparatively small slice of Duke’s construction plans through 2035—at about 600 megawatts, the two new reactors comprise less than 3 percent of a planned 20.8 gigawatts in new generating capacity over the period. (The utility’s current nuclear fleet can produce about 10.7 gigawatts, about a third of its 32 gigawatts in capacity across North and South Carolina.) But the company says including it is critical for multiple reasons.

State law requires Duke to maintain reliability as it transitions away from fossil fuels, and nuclear provides a steady source of carbon-free power. Including nuclear legally enables Duke to slow its rate of decarbonization, said company spokesperson Bill Norton. He projected that a more gradual approach saves customers about $20 billion through 2050 compared to meeting the 2030 deadline. 

Gaining experience with permitting and building advanced nuclear through 2035 also would lay the groundwork for a much more aggressive rollout of the technology through 2050, the target date for full carbon neutrality. Under Duke’s preferred plan, nuclear would provide about 68 percent of the Carolinas’ electricity in 2050, compared with 46 percent in 2024. Such growth would require completing 38 new reactors between 2034 and 2050.

“To reach carbon neutrality by 2050, to achieve that goal, it’s critical to have carbon-free generation that’s available 24/7, regardless of weather conditions,” Norton said. “The system cannot function reliably on renewables and storage alone—we need a diverse, ‘all of the above’ energy mix.”

But many environmental advocates see Duke’s reliance on advanced nuclear power— which has not yet been commercially deployed anywhere in the United States—as slowing down the rollout of established zero-carbon solutions like solar, wind, and battery storage.

“Duke is largely waiting around for that magical tool,” said Dave Rogers, Southeast deputy regional director for the Sierra Club’s Beyond Coal campaign. “Duke had a huge part in agreeing to when all of these compliance deadlines would be, so for them to just turn around and start asking for extensions is quite frustrating from an advocate perspective.”

The Next Generation

The oldest nuclear facility Duke operates in North Carolina is the Brunswick Nuclear Plant, which first started producing power in 1975. The plant and its supporting facilities sprawl across about 3,000 acres north of Southport, just a few miles from the coast, surrounded by woods and wetlands. 

Its twin reactors, each ensconced in a squat, rectangular tower of brown and gray concrete, together pump out nearly 1,900 megawatts of electricity. The reactors themselves sit just off a canal that connects to the Cape Fear River, from which they draw about a million gallons of water every minute.

The Brunswick Nuclear Power Plant near Southport, N.C. (Photo courtesy of Duke Energy)

Although the Brunswick plant uses what are called “boiling water reactors,” the water from the Cape Fear doesn’t actually come into contact with nuclear material. Instead, the reactors heat water contained in a closed system, which turns into steam and powers a turbine generator. 

The steam then passes over tubes filled with Cape Fear water to cool down, condense back into liquid, and enter the reactors again. Now warmed, the river water shoots back into the canal after a 15-foot drop, churning its surface into foam.    

One class of advanced nuclear technology that Duke proposes to install in the coming years would look quite similar to the Brunswick facility in everything but scale. Through 2044, the utility plans to add 18 “small modular reactors,” or SMRs. These power plants are rated to produce up to 300 megawatts, well under a third of the capacity of each Brunswick reactor, and are built to standardized specifications in factories.

SMRs employ the same principles as other water-cooled reactors, explained Chris Nolan, Duke’s vice president of new nuclear generation strategy and regulatory engagement. But their modest size and modular construction, he continued, should make them cheaper and quicker to deploy than the utility’s current nuclear fleet.

Chris Nolan, Duke’s vice president of new nuclear generation strategy and regulatory engagement. (Photo courtesy of Duke Energy)

Because they put out less heat overall, SMRs are also designed to cool more easily than current reactors, making them safer to operate. “It’s really the pinnacle of reactor design for the industry as we’ve known it since the 1960s,” Nolan said.

While Nolan emphasized that Duke hasn’t committed to a specific SMR technology, he noted that the utility’s representatives regularly visit nuclear developers to stay abreast of their nascent reactors. He mentioned GE Hitachi’s BWRX-300, the first of which is slated for deployment in Ontario; NuScale’s VOYGR, set for a debut in Idaho; and Holtec’s SMR-160+, which could be installed first in Michigan, as projects of particular interest.

(After The Assembly spoke with Nolan, NuScale announced that it would cancel the Idaho reactors, citing a lack of customers for the power they would produce. The estimated cost of that electricity had increased from $55 to $89 per megawatt-hour over the course of the project.) 

Duke has flagged a potential location for the first of two SMRs expected to provide the new nuclear capacity by 2035 outlined in its carbon plan: the Belews Creek Steam Station in rural Stokes County, about 20 miles northeast of Winston-Salem. The reactor would replace existing coal generation at the site. Norton said the second reactor would “likely be at a second coal community not yet determined.”

The other advanced nuclear design Duke is following is the Natrium reactor that TerraPower and GE Hitachi are designing and building in Wyoming. The utility is providing three full-time employees to the effort as part of a $1.3 billion grant from the U.S. Department of Energy. Nolan is on the project’s advisory board.

Rather than water, Natrium uses liquid sodium as a coolant, allowing it to operate more efficiently and at higher temperatures than current-generation reactors. The design pumps that excess heat into tanks of molten salt; Natrium can then tap the heat to generate steam and boost the plant’s power production when other electricity supplies aren’t available.

“In the evening, when you lose the contribution from solar, the turbine can truly load follow, and it can ramp up from 345 to 500 megawatts for up to six hours,” Nolan explained. Integrating thermal storage lets the reactor operate closer to its full capacity and provide more power at times when it’s not competing with solar, which is more economical for the company.

Of Duke’s planned nuclear expansion, 20 new units by 2050 would be this type of reactor plus storage, with the first added in 2038. The utility has yet to identify potential sites for any of those reactors. 

‘Unicorn Technology’

As Duke’s critics are quick to point out, however, all of these advanced nuclear projects are still in some stage of development. The Nuclear Regulatory Commission has only certified the NuScale SMR, approving its design as safe and effective, and that approval applies to an early iteration of the reactor. The version the company is marketing on its website remains under review.

A coalition of 14 environment and clean energy groups blasted SMRs and other advanced nuclear as “unicorn technology” in a 2021 report about Duke’s power plans, including the Sierra Club, Asheville-based MountainTrue, and Vote Solar. Duke should stop talking about technology that is not yet commercially available and “start investing more in solar, energy efficiency and demand response technologies that are zero-emitting and available now,” the coalition wrote.

Jake Duncan, Southeast regulatory director for Vote Solar, told The Assembly that his organization’s assessment hasn’t changed since then.

“Every single nuclear plant built in this country in the last 40 years has seen drastic cost overruns, drastic delays, and sometimes fraud. There’s absolutely no reason, I think, that SMRs will be any different,” Duncan said. “There’s a narrative going on that they will succeed where every other nuclear project has failed, and I just don’t buy that without any evidence.”    

Duncan and others cite Duke’s experience with the Westinghouse AP1000, a larger reactor based on modular principles that the utility had aimed to install near Gaffney, South Carolina. After spending over $517 million on planning and licensing costs, Duke canceled the project in 2017, noting Westinghouse’s bankruptcy and uncertainty about other projects using the technology. (The only AP1000 units built in the United States so far, located in Georgia, were completed earlier this year, seven years after their target date and roughly $17 billion over budget.)

The two new generating unites at the Vogtle Electric Generating Plant in Waynesboro, Georgia, on May 26, 2023. (Yomiuri Shimbun via AP Images )

Nolan said that the lessons learned from that failure are informing Duke’s approach to new nuclear reactors. The company no longer seeks to build plants that are the first of their kind, instead letting other utilities take the risk of deploying entirely novel technology. 

On the regulatory side, Duke is pursuing permits to resolve environmental and site safety concerns with the NRC before committing to specific reactors. The company started developing a permit application for Belews Creek in August, hoping to submit to federal regulators in 2025 and receive approval in 2027.

“What we learned is the importance of standardization, the importance of design finality, and the importance of being true to the modular model,” Nolan said. “Duke stopped before it went to the field because we didn’t have design finality from Westinghouse, and that turned out to be a good decision.”        

Yet waiting for certainty takes time, and the schedules for several technologies the utility has identified as promising are already slipping. In its original Carolinas Carbon Plan, filed in May 2022, Duke said it expected development on the Natrium and BWRX-300 reactors to wrap up by 2028; its August plan pushes those targets to 2030 and 2029, respectively.

Nolan said questions about the delays should be directed to the companies developing the technologies. Jon Allen, a spokesperson for GE Hitachi, said he wasn’t familiar with Duke’s planning documents but that the company’s goal remains to have the first BWRX-300 completed by 2028.

A conceptual design rendering for the BWRX-300 small modular reactor, being designed by Wilmington-based GE Hitachi. (Graphic courtesy of the U.S. Nuclear Regulatory Commission)

Spokespeople for TerraPower responded to emailed questions about the Natrium project with a general statement. The company said over 900 engineers were helping to design the plant, with plans to seek a construction permit in 2024 and begin building “non-nuclear parts of the plant” later that year.

TerraPower CEO Chris Levesque has previously blamed delays on the loss of Russia as a nuclear fuel supplier following the country’s invasion of Ukraine. Asked about that situation, company representatives provided a July press release announcing a partnership with Centrus Energy Corp. to expedite domestic fuel production at a facility in Ohio.     

Pathways and Preferences

Although Duke has signaled its desires for slower decarbonization and more nuclear power, authority to approve the plan rests with the state utilities commission. The commission could choose one of the two alternative approaches Duke outlined in its August filing, which would reach 70 percent carbon emissions reductions by 2030 or 2033, or dictate a different plan that complies with the carbon law.

A decision is expected by the end of 2024. The commission has yet to schedule public hearings on the matter, but interested parties can submit comments through its website by referencing the case’s docket number, E-100 Sub 190. Sam Watson, general counsel for the commission, said its members cannot comment on pending proceedings. 

Rogers with the Sierra Club says that the utility has inflated the cost of quicker decarbonization. Because state law requires the utilities commission “to achieve the least cost path” for compliance with emissions targets, he argues, Duke is unfairly tipping the scales toward its preferred plan.

The company’s filing says it would have to collect $139 billion from customers through 2050 to build the infrastructure for meeting the 70 percent target by 2030, compared with $119 billion over the same period to meet the target by 2035. The typical customer’s bill would see an average rate increase of 4.5 percent every year from now to 2033 under the first scenario, subject to regulator approval; it would only go up by 2.8 percent annually under the second proposal.

But Duke’s estimates for the capital expenses of a 2030 decarbonization pathway, Rogers points out, tack on an extra 20 percent to its usual cost projections. Norton, the company spokesperson, said the higher cost reflects the logistical challenges of an “extremely accelerated time frame” for buying and deploying renewables.

Rogers contends that assumption isn’t grounded in reality, saying that other jurisdictions have rolled out massive amounts of renewables quickly and affordably. He points to Texas, which the U.S. Energy Information Administration expects will add 7.7 gigawatts of solar and 2 gigawatts of wind production in 2023 alone—more than the total renewable capacity Duke would have to add to meet the 2030 target.

“Duke is a pretty small piece of the overall global pie around batteries, solar panels, etc. To say that them going a little bit faster is going to completely increase the cost across an entire market is just ridiculous,” Rogers said.

State Sen. Julie Mayfield, a Democrat from Buncombe County. (Photo courtesy of the N.C. General Assembly)

There’s also some uncertainty over whether the utilities commission has the power to delay emissions cuts based solely on Duke’s inclusion of nuclear. Julie Mayfield, a Democratic state senator from Buncombe County who was deeply involved in negotiations over the state law, said that was lawmakers’ intent.

“There was no disagreement on this at all, as I recall, that we needed to allow that deadline to slide if [Duke was] committed to and in the process of building wind and/or nuclear,” Mayfield told The Assembly.

In a brief responding to Duke’s plan filed with the state utilities commission last October, Democratic Attorney General Josh Stein took issue with that interpretation. 

“Contrary to Duke’s reading, the provision was not meant to give the Commission unlimited discretion to delay—for an indeterminate amount of time—as long as a wind or nuclear facility is included in a Carbon Plan,” Stein wrote. “It does not allow the Commission to pursue a plan from the outset that does not aim to achieve the carbon reduction targets.”

If the commission approves a plan that Stein believes is illegal, he could ask the courts to weigh in. Nazneen Ahmed, a spokesperson with the attorney general’s office, said she could not comment on Duke’s proposal and Stein’s potential response. 

“However, our office remains committed to ensuring that Duke is delivering clean, affordable energy to North Carolina customers as quickly as possible,” Ahmed continued. “We will be carefully scrutinizing Duke’s most recently filed carbon plan to ensure that it complies with the law.”  

Daniel Walton is an Asheville-based freelance reporter covering science, sustainability, and political news. He was previously the news editor of Mountain Xpress and has written for The Guardian, Civil Eats, and Sierra. Contact him at