Google builds world’s largest 100-hour battery in Minnesota

Form Energy’s iron-air batteries aim to deliver multiday clean power at lower cost than lithium-ion

By Pareesa Afreen
|
February 28, 2026
Google builds world’s largest 100-hour battery in Minnesota

Google is developing a large renewable energy project in Minnesota, which will be backed by what will be the world’s largest long-duration battery storage facility.

The project, which has been developed in partnership with Xcel Energy, will provide power to a new data centre campus located south of Minneapolis, utilising wind, solar, and a 300-megawatt iron-air battery storage facility, which will be able to provide power for up to 100 hours. It is scheduled for deployment in 2028.

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The technology used for the project’s battery comes from Massachusetts-based Form Energy, which specialises in long-duration battery technology.

While other conventional lithium-ion batteries are only able to provide four to eight hours of stored power, iron-air batteries use a reversible rusting process.

The system operates at roughly one-tenth the cost of lithium-ion, making it viable for multiday backup rather than electric vehicles.

Form Energy co-founder and CEO Mateo Jaramillo said the project confirms the business case for multiday storage and marks the largest announced energy storage project globally.

The development in Minnesota will feature 1.4 gigawatts of wind energy, 200 megawatts of solar energy, and the aforementioned 300-megawatt battery storage.

The batteries have the potential of powering over 200,000 homes when dispatched. The project operates through a new green tariff deal that enables Google to finance its own mix of renewable energy without affecting consumers.

Battery storage technology for long durations is viewed as a vital component in ensuring that the reliability of renewable energy is comparable to that of fossil fuels and nuclear energy. By combining wind, solar, and multiday storage, Google’s Minnesota data centre aims to function with firm, dependable clean energy capacity.

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