Google to build Minnesota data center with 100-hour iron-air battery

Google announced Tuesday that it will build its first Minnesota data center in Pine Island, located about an hour southeast of Minneapolis. The facility will be backed by 1.9 gigawatts of clean power. To supply this, Google is working with utility partner Xcel Energy to build 1.4 gigawatts of wind power and 200 megawatts of solar power. This generation will feed a 300-megawatt battery system supplied by Form Energy. The battery will be capable of delivering its rated power for 100 hours, yielding a total energy capacity of 30 gigawatt-hours.

This long-duration system is designed for “firming”—the process of helping renewable energy sources provide power during lulls, such as at night or when the wind drops. Unlike typical grid-scale batteries that repurpose lithium-ion technology, Form Energy’s batteries store energy by rusting and deoxidizing iron. While these iron-air cells are relatively less efficient than lithium-ion batteries—delivering 50% to 70% of the energy used to charge them, compared with upwards of 90% for lithium-ion—they are significantly cheaper. Form Energy states that its technology will ultimately cost $20 per kilowatt-hour of storage, which is at least three times cheaper than lithium-ion.

Form Energy, which manufactures its batteries at a factory in West Virginia, has raised $1.4 billion to date. While the technology is relatively new, the startup is also installing its first battery in Minnesota with cooperative utility partner Great River Energy. That system will store 150 megawatt-hours of energy for 100 hours, delivering a peak output of 1.5 megawatts to the grid.

To facilitate the project, Google and Xcel Energy are utilizing a “clean transition tariff,” also known as a “clean energy accelerator charge.” This utility fee structure allows the utility to accept projects that might be considered risky by regulators, who typically push utilities to use the cheapest available electricity. Under the agreement, Google pays a premium to ensure regular ratepayers do not bear the financial risk. Google previously developed this tariff model in Nevada in partnership with geothermal startup partner Fervo.

Why it matters

This project demonstrates a scalable model for tech giants to fund long-duration energy storage, using a new utility fee structure to bypass regulatory hurdles that typically block experimental clean energy adoption.