Ameresco has announced the development and commercial operation of a 50-MW/200 MWh battery energy storage system (BESS) in Arizona, marking the largest behind-the-meter project in the state. The project achieved commercial operation in October 2025, representing what the company describes as a significant advancement in Arizona's energy infrastructure.

Project Location and Client Details

The BESS was developed in Kingman, Arizona, for Nucor, the largest steel producer in North America. The battery system is installed at a Nucor substation within Mohave Electric Cooperative's territory and is operated by Arizona Electric Power Cooperative (AEPCO), a member of the Arizona G&T Cooperatives.

Nucor's bar mill at the Kingman location is undergoing a major expansion that includes installing a new electric arc furnace. This expansion is designed to boost the facility's production capacity to 600,000 tons annually, strengthening Nucor's operational capabilities at the site.

Construction and Technical Specifications

Construction of the battery energy storage system began in December 2024. The project features 58 Tesla Megapack 2XL units operating under a 20-year Storage Services Agreement (SSA). The Ameresco-owned battery system provides 50 MW of power capacity with 200 MWh of energy storage capability.

The project operates as a behind-the-meter system, meaning it is connected directly to Nucor's facility rather than feeding power directly into the broader electrical grid. This configuration allows the battery system to serve the specific energy needs of the steel production facility.

Solar Component and Energy Transition

In addition to the battery storage system, Ameresco will deliver a 25 MW AC solar asset as part of the comprehensive energy solution. The solar component is scheduled to begin operation in 2026, further supporting Nucor's energy transition and site expansion efforts.

The combination of battery storage and solar generation represents an integrated approach to meeting the energy demands of the expanded steel production facility while incorporating renewable energy sources.

Grid Stability and Operational Benefits

Ameresco's onsite battery asset is designed to help stabilize the electric load from Nucor's new arc furnace, reducing strain on the electrical grid. The battery system works by smoothing energy demand, which makes it easier for the utility to manage power fluctuations associated with the high-energy steel production process.

The energy storage system also boosts the use of renewable energy at the facility. By storing energy during periods of lower demand and releasing it during peak usage, the battery system helps optimize the integration of renewable energy sources into the facility's operations.

The electric arc furnace installation is a key component of Nucor's facility expansion, and the battery storage system addresses the specific challenges posed by the variable, high-intensity energy demands of steel production equipment.

Advisory and Contracting Support

GreenFront Energy Partners served as an advisor to Nucor on the contracting and structuring of both solar and storage solutions at the Kingman facility. This advisory role encompassed developing the comprehensive energy strategy, which includes both the battery storage system and the planned solar installation.

The 20-year Storage Services Agreement structure provides a long-term operational framework for the battery energy storage system, ensuring sustained performance and maintenance over the project's operational lifetime.

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