Pine Island Data Centre Battery

Executive Overview

The Pine Island Data Centre Battery is a 300 MW / 30 GWh iron-air battery storage system planned for a 480-acre site in Pine Island, Minnesota, developed by Form Energy in partnership with Xcel Energy and Google. The battery is sized to discharge continuously for up to 100 hours and is expected to be the world's largest grid battery by energy capacity upon completion. Google, which is building an adjacent data centre on the same site, paid $1 billion for the battery system and will cover all associated grid infrastructure costs under a new tariff structure, ensuring no cost impact to existing Xcel ratepayers. First module shipments from Form Energy's Weirton, West Virginia factory are targeted for 2028, with the full system expected online in 2029.

How It Works & Differentiation

Form Energy's iron-air battery stores electricity by oxidising iron pellets during discharge — a reversible electrochemical reaction using iron, water, and air — and recharges by reversing the process using electricity. The chemistry uses abundant, low-cost materials at a target system cost of below $20 per kWh, enabling 100-hour continuous discharge at a fraction of the cost of lithium-ion at equivalent duration. Each battery module is approximately the size of a side-by-side washer-dryer unit containing around 30 one-metre-tall cells. At 30 GWh, the Pine Island system is designed to handle multi-day weather events such as polar vortexes and heat domes — precisely the scenarios where lithium-ion systems' four-to-eight hour duration is insufficient for grid reliability.

Commercialization & Traction

The Pine Island battery is the centrepiece of a broader Google-Xcel agreement that also includes 1,400 MW of wind and 200 MW of solar capacity, all expected online in phases from 2028 to 2031. Google will pay all electricity and infrastructure costs and has committed a further $50 million to Xcel's Capacity Connect programme to fund a distributed network of smaller batteries across the grid. The city of Pine Island approved preliminary development plans in December 2025, and the broader agreement is subject to review by the Minnesota Public Utilities Commission. Form Energy, which raised $405 million in a 2024 Series F and has a DOE grant of up to $150 million for its Weirton plant, is planning an IPO in 2027 and expects its factory to reach 500 MW of annual production capacity by 2028.

Scalability & Strategic Context

The Pine Island project represents the largest single deployment in Form Energy's pipeline, which also includes projects in Georgia, Virginia, Colorado, New York, and Maine. The Weirton factory, which sources iron domestically and has been operational for approximately two years producing over 100,000 electrodes, is the manufacturing foundation for this and subsequent projects. Google's decision to directly finance rather than use a PPA structure — a deliberate choice to improve execution certainty for a first-of-kind technology — may become a template for other hyperscalers seeking long-duration storage. Success here would provide the operational and financial data needed to accelerate Form Energy's broader commercial pipeline and validate the 100-hour iron-air platform at utility scale.