Duke’s New South Carolina Energy Plan: More of Almost Everything
Before a utility builds a power plant—and long before customers begin paying for it—the utility develops a plan for meeting future electricity needs. This is often called an integrated resource plan, or IRP.
An IRP forecasts how much electricity customers will need and considers the resources that could meet that demand, including power plants, renewable energy, battery storage and programs that reduce electricity use. Although an IRP does not authorize every proposed project, it can shape billions of dollars in future investments—and, ultimately, customers’ electric bills.
That is why IRPs may be the most important decisions about our electric bills that happen before we use any electricity.
South Carolina’s major utilities file a comprehensive IRP every three years, with updates in between. In August, Duke Energy filed its new 2026 plan with the Public Service Commission of South Carolina.
While this is a South Carolina proceeding, Duke operates and plans its electricity system across both Carolinas. The resources in the plan would serve the combined system, not South Carolina alone.
South Carolina’s planning process has evolved
South Carolina strengthened utility planning through the Energy Freedom Act in 2019. The law turned IRPs into formal proceedings in which regulators must decide whether a utility’s proposal is the most reasonable and prudent way to meet future energy needs.
Duke’s first comprehensive plan under the law was filed in 2020. The Commission found several deficiencies and required Duke to modify it to fix problems in how Duke modeled renewables and fossil fuel resources.
Duke filed its next comprehensive plan in 2023. The Commission approved that plan in November 2024, paving the way for Duke to build substantial new gas infrastructure and a meaningful amount of solar and storage.
Now, less than a year after Duke filed a related plan in North Carolina, its outlook has already changed considerably.
Data centers have changed the picture
The central story of Duke’s new IRP is rapid growth in electricity demand, driven largely by proposed data centers, manufacturing facilities and other major developments.
Duke expects its winter peak demand to grow by more than 10,000 megawatts, or approximately 30%, over the planning period. In response, it proposes adding more of nearly every major resource.
Compared with last year’s North Carolina plan, Duke now proposes to build its sixth new combined-cycle gas plant several years earlier, by 2034. It also adds more gas peaking plants, which generally operate during periods of especially high demand.
Solar and battery storage grow substantially as well. Including projects already under development, Duke’s recommended portfolio contains roughly 18,500 megawatts of new solar and nearly 13,000 megawatts of battery storage through 2041. The plan also includes new nuclear generation and a small amount of onshore wind near the end of the planning period.
Duke also proposes delaying the retirement of the 713-megawatt Mayo coal plant in North Carolina by one year, from 2031 to 2032.
Under an even higher load forecast, Duke’s model selects two additional combined-cycle gas plants—one in 2035 and another by 2041.
These proposals carry enormous financial consequences. Power plants and transmission lines are expensive, long-lived investments. If the projected data-center demand arrives, Duke will need significant new resources. But if proposed projects are delayed, downsized or never built, existing customers could be left paying for infrastructure developed around demand that did not materialize.
Solar and storage are essential
One of the clearest findings in Duke’s plan is that utility-scale solar and battery storage are not optional extras. They are central to meeting future demand reliably and affordably.
Solar appears in large quantities across many of Duke’s scenarios. The model selects even more solar when electricity demand or natural gas prices are higher, demonstrating solar’s ability to meet growing energy needs while protecting customers from volatile fuel costs.
Battery storage is similarly important. Batteries can save electricity when it is abundant and deliver it when the system needs it most. They can also reduce reliance on gas peaking plants and help Duke integrate more solar.
Duke’s analysis shows that greater energy efficiency and battery deployment could reduce the number of near-term gas peaking units needed. Regulators should closely examine these opportunities before customers are committed to decades of power-plant costs.
Distributed energy deserves a larger role
Duke already operates demand-response and customer-battery programs in South Carolina, and it deserves credit for their recent growth. But the plan still leaves significant room for improvement.
Customer-owned batteries, electric vehicles, smart thermostats and other devices can be coordinated as a community-power network, or also known as a virtual power plant. Together, these resources can reduce demand or supply electricity during critical hours, much like a traditional power plant.
Community-power networks can often be deployed faster than conventional generation. They also leverage private investment and compensate participating customers for helping the grid. Other utilities are moving quickly to scale these programs, but Duke’s plan stops short of presenting a comprehensive VPP strategy that can compete directly with new power plants.
Distributed resources will not eliminate the need for all utility-scale generation. But they can reduce peak demand, make better use of existing infrastructure and potentially avoid or delay some expensive investments.
Is the planning process moving fast enough?
Duke filed its North Carolina plan in October 2025. Less than a year later—and before North Carolina regulators have ruled on it—the new South Carolina filing proposes major changes in the amount and timing of future resources.
That raises an important question: Is the traditional IRP process equipped for the speed and uncertainty of today’s electricity-demand growth?
Regulators should examine how firmly new data-center loads are committed, who pays if projected demand fails to materialize and whether large customers are covering the costs of the infrastructure built to serve them. They should also require Duke to fairly compare traditional power plants with energy efficiency, distributed solar, customer batteries and competitive community-power network programs.
With billions of dollars and future customer bills at stake, South Carolinians need a plan that is not simply bigger, but smarter, more flexible and more protective of the people who will ultimately pay for it.