U.S. Department of Energy Awards $350 Million for Utility-Scale 24-Hour Iron-Flow Battery Systems

WASHINGTON, DC — Accelerating the commercial deployment of non-lithium energy storage technologies capable of balancing renewable power across multiple days, the United States Department of Energy (DOE) announced $350 million in demonstration grant awards through the Office of Clean Energy Demonstrations (OCED) on Monday, funding four utility-scale long-duration energy storage (LDES) facilities across four states.

The competitive awards support the construction and commercial grid integration of 24-hour duration iron-flow, zinc-bromine, and compressed air energy storage systems with a combined energy capacity exceeding 3,000 megawatt-hours (MWh). Unlike conventional lithium-ion batteries—which typically discharge power for only four to eight hours—these non-flammable, earth-abundant flow battery chemistries are engineered to store excess daytime solar and nighttime wind power for up to 24 continuous hours, discharging clean electricity during multi-day heatwaves, winter freezes, and prolonged grid outages.

Multi-State Utility-Scale Demonstration Facilities

The funding packages provide cost-share capital to major electrical utilities and clean energy storage innovators. Selected demonstration sites include:

• ERCOT Grid Stabilization Project (Texas - $105 Million): Constructing a 100 MW / 2,400 MWh iron-electrolyte flow battery system in West Texas, designed to capture surplus solar and wind power and provide continuous emergency power during severe winter storm events.
• Desert Southwest Solar Storage Hub (Arizona - $90 Million): Installing an 80 MW / 1,600 MWh zinc-hybrid flow battery facility paired directly with a 300 MW solar field to supply uninterrupted evening cooling power to the Phoenix metropolitan grid.
• California Independent System Operator Integration (California - $85 Million): Building a 60 MW / 1,440 MWh long-duration storage installation in Kern County to replace retiring natural gas peaker plants and eliminate transmission line curtailment.
• Midwest Wind Firming Facility (Minnesota - $70 Million): Constructing an iron-air commercial battery system paired with regional wind farms, delivering firm, dispatchable baseload clean power to regional rural electric cooperatives.

"To achieve a fully reliable, 100% clean electrical grid, America needs energy storage that can last not just for a few hours, but for full days at a time," Energy Secretary Jennifer Granholm stated. "By investing in domestic iron-flow and advanced non-lithium battery technologies manufactured right here in the United States, we are insulating our communities from extreme weather blackouts and building a stronger, more resilient energy economy."

Energy Storage Association and Grid Operators Endorse

The American Clean Power Association (ACP) and regional transmission operators praised the federal demonstration grants, emphasizing that non-lithium flow batteries eliminate supply chain exposure to overseas critical mineral imports while delivering zero thermal runaway fire risk.

"Long-duration flow batteries represent the missing puzzle piece for deep electrical grid decarbonization," said Jason Burwen, Vice President of Energy Storage at ACP. "These commercial-scale demonstration projects prove that earth-abundant chemistry like iron and water can cost-effectively replace fossil peaker generation and maintain complete grid reliability around the clock."

Utility labor unions praised the projects for including Project Labor Agreements (PLAs), ensuring high-wage union electrical engineering and construction jobs across all four project sites.

Construction Groundbreaking Schedule

Civil site engineering and long-lead component manufacturing will commence in late autumn 2026. On-site installation and commercial grid interconnection commissioning across all four utility storage sites will proceed through 2028.