Duke Energy Corporation (DUK) shares climbed Wednesday after the utility announced it brought a major battery storage project online at what used to be a coal-burning power plant in the Carolinas.

The company completed a 50-megawatt, four-hour battery energy storage system at the former Allen coal plant site on Lake Wylie. At $100 million, the project came in under budget and ahead of its original timeline. Final operational testing is wrapping up this month.

Scaling Up Storage

But Duke isn't stopping there. Starting in May, the utility plans to build an even bigger battery on the same property—a 167-megawatt, four-hour system that will occupy about 10 acres of the former emissions control site. That'll be Duke's largest battery project to date.

Both lithium-ion installations qualify for federal investment tax credits worth roughly 40% of project costs, including an additional 10% bonus for reinvesting in the local energy community. That's real money that helps offset the sticker price.

"We're building new resources to keep the Carolinas' economy thriving," said Kendal Bowman, Duke Energy's North Carolina president. He emphasized that repurposing the retired coal site while tapping federal incentives helps reduce costs for customers and supports regional economic growth.

Why Batteries Matter

Utility-scale batteries serve as a bridge during periods when renewable generation dips—think cold mornings before sunrise when solar panels aren't producing much. They also store excess power from sources like nearby nuclear generation, then discharge it when demand peaks.

Duke's 2025 Carolinas Resource Plan outlines an aggressive expansion: about 6,550 megawatts of battery capacity by 2035. That volume of storage could theoretically support power needs for more than 5 million homes during peak demand periods.

The utility says it's maintaining a diverse energy mix including solar, storage, nuclear, and natural gas to meet rapidly growing electricity demand across its service territory of 8.6 million electric customers in North Carolina, South Carolina, and other states.

Price Action: Duke Energy shares rose 1.32% to $117.40 on Wednesday.