BESS Grid Integration: Duke Energy’s 6, 550 MW Target, $100 M Allen Project, and 1, 700 MW RFP for Demand Growth (2025)

BESS Adoption, Duke Energy’s 6, 550 MW Plan to Manage Grid Strain

In 2025, Duke Energy shifted its energy storage strategy from exploratory pilots to the systematic deployment of utility-scale battery energy storage systems (BESS) as a core infrastructure asset. This strategic change is a direct response to unprecedented electricity demand growth, largely driven by data centers and advanced manufacturing in its service territories. The utility’s 2025 activities, centered around its Carolinas Resource Plan, codify BESS as the primary tool for maintaining grid reliability, integrating renewables, and managing extreme peak loads, moving it from a supplementary technology to a foundational component of its future generation mix.

Duke Energy’s Shift from Pilots to Foundational Assets

The period from 2021 to 2024 saw Duke Energy primarily engaged in smaller-scale BESS projects and pilot programs to test technical viability and grid integration. The year 2025 marked a definitive change, with the company initiating large-scale, commercially significant projects. This progression reflects a wider industry trend where utilities, facing accelerating load growth, are now adopting BESS as a mature, cost-effective alternative to traditional peaking power plants. Unlike peers in the oil and gas sector such as Hess Corporation, which have largely avoided direct BESS investment, utilities like Duke Energy and Next Era Energy are making storage a central element of their capital plans.

The 2025 Carolinas Resource Plan

The centerpiece of Duke Energy’s strategy is its 2025 Carolinas Resource Plan, which formalizes the utility’s commitment to massive storage expansion. The plan establishes an aggressive, multi-gigawatt deployment schedule to ensure the grid can handle future demand while meeting state decarbonization mandates.

• The plan proposes a target of adding 5, 600 MW of battery storage in the Carolinas to support grid stability.
• It outlines a long-term projection to integrate 6, 550 MW of battery capacity across its system by 2035 to manage future growth.
• Company filings explicitly recognize solar paired with battery storage as the most cost-effective option for meeting projected demand increases, signaling a permanent shift in resource planning priorities (Short-sighted Duke Energy Plan Recognizes Benefits of Solar …).

Solar-Plus-Storage as a Procurement Priority

Duke Energy’s procurement activities in 2025 confirm its strategic preference for hybrid renewable projects that offer dispatchability. The company issued a major Request for Proposals (RFP) that clearly prioritizes solar projects coupled with battery storage, creating a strong market signal for developers and solidifying the role of BESS in its renewable integration strategy.

• The 2025 RFP for the Carolinas seeks to acquire 1, 700 MW of new solar resources to meet clean energy goals (Duke Energy RFP Carolinas).
• Crucially, the RFP includes a provision for up to 800 MW of the procured solar capacity to be paired with approximately 300 MW of battery storage.
• This structure provides Duke Energy with a firm, dispatchable clean energy resource that can be deployed during peak demand hours, reducing reliance on fossil fuel peaker plants.

$100 M Allen Plant Project, Duke Energy’s Coal-to-Clean Investment

Duke Energy’s 2025 capital strategy for energy storage is defined by two key elements: the tactical repurposing of retired fossil fuel plant sites and the systematic use of federal incentives to improve project economics for ratepayers. This approach allows the company to leverage existing grid interconnection infrastructure while mitigating the high capital costs of BESS deployments, as demonstrated by the successful commissioning of the Allen battery project.

Capital Deployment at Legacy Sites

The company made significant progress on its strategy to transform legacy infrastructure into modern clean energy hubs. The commissioning of two major battery facilities in 2025 provides concrete evidence of this capital plan in action.

• The most prominent project is the $100 million, 50 MW / 200 MWh BESS at the former Allen coal plant site, which came online in November 2025 ahead of schedule and under budget (Duke Energy turns retired coal plant into battery power hub …).
• The company also brought its largest battery facility to date online in Knightdale, North Carolina, a 100 MW / 200 MWh system capable of powering thousands of homes during peak demand (Duke Energy’s largest battery storage facility now open in …).
• These projects contribute to Duke Energy’s operational capacity, which surpassed 300 MW of grid-tied storage in service by year-end, with another 300 MW actively under construction (Energy Storage).

Table: Duke Energy 2025 BESS and Storage Program Investments

Carolinas Focus, Duke Energy’s Response to Regional Data Center Growth

Duke Energy’s battery storage deployment strategy is geographically concentrated in the Carolinas, a direct tactical response to the region’s rapid transformation into a global hub for data centers and advanced manufacturing. Unlike the more geographically diversified BESS strategies of international utilities like Iberdrola, Duke’s focus is regional and purpose-driven, designed to address acute grid strain in North and South Carolina caused by unprecedented industrial load growth that has repeatedly forced the utility to revise its demand forecasts upward.

North Carolina as the Deployment Epicenter

The bulk of Duke Energy’s 2025 activity occurred in North Carolina, which is experiencing intense demand growth. The state’s favorable business environment has attracted numerous large-scale industrial customers, making it the logical center for grid-stabilizing BESS investments.

• The commissioning of the 50 MW Allen plant project and the 100 MW Knightdale facility, both in North Carolina, anchors the company’s BESS fleet in the heart of its highest-growth territory.
• The 2025 Carolinas Resource Plan and its associated 1, 700 MW solar and storage RFP are explicitly designed to serve load in both North and South Carolina, reinforcing the regional focus.
• This concentration allows Duke Energy to target specific grid congestion points and defer costly transmission upgrades that would otherwise be necessary to serve the new industrial load.

Florida as a Technology Proving Ground

While the Carolinas are the focus of commercial-scale deployment, Duke Energy is using its Florida service territory as a proving ground for next-generation storage technologies. This geographic segmentation allows the company to test and de-risk emerging solutions in a controlled environment before considering wider deployment.

• In May 2025, the company announced a pilot project at its Suwannee site in Florida to test a 5 MW sodium-sulfur battery system.
• This system is notable for its eight-hour duration, double that of the four-hour lithium-ion batteries being deployed at scale in the Carolinas, making it suitable for longer-duration energy shifting (Duke Energy tests next-gen energy storage at historic Suwannee site).
• This Florida-based pilot demonstrates a strategic effort to look beyond current technology and prepare for future grid needs that may require storage assets capable of dispatching energy over extended periods.

Duke Energy’s Multi-Technology Approach: From Li-ion to Sodium-Sulfur (2025)

In 2025, Duke Energy executed a dual-track technology strategy, aggressively deploying mature, commercially proven lithium-ion BESS to meet immediate grid needs while simultaneously initiating pilots of next-generation, long-duration storage technologies. This approach demonstrates an understanding that while lithium-ion is the solution for today’s 2-4 hour peak shaving requirements, future grid challenges, driven by higher renewable penetration, will demand a more diverse portfolio of storage durations and chemistries. The strategy also extends to customer-sited assets, maturing the concept of a Virtual Power Plant (VPP) built from residential and commercial batteries.

Commercial Scale Lithium-Ion Deployment

The core of Duke Energy’s near-term strategy relies on the bankability and established supply chains of lithium-ion technology. The projects brought online in 2025 are standard, four-hour duration systems, reflecting the technology’s maturity for utility-scale applications.

• The 50 MW / 200 MWh Allen Plant project and the 100 MW / 200 MWh Knightdale facility both use lithium-ion batteries, a technology that has become the industry standard for short-duration grid services due to its high efficiency and declining costs.
• The four-hour duration of the Allen system is optimized for peak shaving, absorbing excess solar energy during midday and discharging it during the late afternoon and evening ramp in demand.
• This focus on commercially available technology allows for rapid deployment to address urgent grid reliability concerns created by surging industrial demand.

Piloting Long-Duration Sodium-Sulfur Storage

Looking beyond immediate needs, Duke Energy is actively exploring alternatives to lithium-ion to address the future requirement for long-duration storage. The Suwannee pilot project is a key element of this forward-looking technology maturation strategy.

• The Florida-based pilot of a 5 MW sodium-sulfur battery marks a deliberate step into long-duration energy storage (LDES), as this system can store and discharge energy for up to eight hours.
• This is a critical test case, as LDES is seen as essential for maintaining grid stability in a system with very high levels of intermittent renewables like solar and wind.
• By testing alternative chemistries like sodium-sulfur, Duke Energy is de-risking future procurement and gaining operational experience with technologies that could complement or eventually replace lithium-ion for certain grid applications.

SWOT Analysis, Duke Energy’s BESS Strategy and Market Position

Duke Energy’s aggressive 2025 pivot to BESS leverages its incumbent utility advantages and proactive response to demand, positioning it as a leader in grid-scale storage deployment. However, this large-scale buildout introduces significant execution risks tied to supply chain stability and cost management. The company’s success will depend on its ability to navigate these external pressures while maintaining regulatory support for its capital-intensive plans.

Table: SWOT Analysis for Duke Energy Energy Storage and Battery Initiatives for 2025

Scenario Modeling for Duke Energy’s VPP and Future Grid Deferral

If Duke Energy successfully scales its customer-sited battery programs like Power Pair and Power Manager through 2026, watch for formal regulatory filings in the Carolinas that seek to quantify the capacity value of this Virtual Power Plant (VPP) and use it to officially defer or cancel specific, high-cost transmission and distribution capital projects. Such a move would validate the VPP as a non-wires alternative and establish a new precedent for how utilities invest in and manage grid infrastructure.

• If This Happens: Duke Energy achieves high enrollment in its residential and commercial battery incentive programs, creating a dispatchable VPP of several hundred megawatts.
• Watch This Signal: Look for proposals within its next resource plan or in separate regulatory filings that directly credit the VPP with deferring a named substation upgrade or transmission line project, assigning a specific dollar value to the avoided cost. The utility already stated it could use its VPP 30 to 36 times a year to displace the need for expensive peaker plants (Duke Energy wants to spend on battery incentives to save on …).
• These Could Be Happening: This would signal a fundamental shift in utility capital planning, moving investment from centralized steel-in-the-ground infrastructure to distributed, customer-owned assets. It could also create a blueprint for other vertically integrated utilities like Shell, which are exploring VPPs, to follow in regulated markets, changing the financial model for grid modernization.

The questions your competitors are already asking

This report covers one angle of Duke Energy’s battery storage strategy. The questions that matter most depend on your work.

• Other US utilities building batteries for data center demand
• Lithium ion battery supply chain forecast
• US coal plants converted to battery storage
• Utility virtual power plant pilot results

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