Google’s new 1.9 gigawatt clean energy deal includes a massive battery that lasts for 100 hours

Google announced Tuesday that it will build a data center in Minnesota powered by 1.9 gigawatts of clean energy, including a massive 300-megawatt battery produced by startup Form Energy.

The new data center, Google’s first in Minnesota, will be located on Pine Island, about an hour southeast of Minneapolis.

The technology company is working with Xcel Energy to build 1.4 gigawatts of wind and 200 megawatts of solar. Both will feed the model’s battery, which will be able to provide its rated power for 100 hours. At 30 gigawatt-hours, it will be the largest battery in the world, helping the data center run on clean energy for longer periods of time.

Such long-lasting batteries help renewable energy sources continue to provide power at night or during quiet periods, “stabilizing” the energy supply, as experts call it. Grid-scale lithium-ion batteries already do this, but for shorter periods.

Form Energy batteries are different from most other grid-scale batteries. While today’s typical grid-scale batteries use lithium-ion technology repurposed from chemicals used in the automotive industry, Form batteries store energy by rusting and deoxidizing iron.

When oxygen from the air flows over the iron grits inside the battery, it rusts the iron, generating electricity in the process. To charge, the electrical current deoxidizes the rust, turning it back into metallic iron and releasing oxygen in the process, which is drawn from the battery.

As battery chemistry improves, the model’s iron-air cells are heavy and inefficient. Typical iron-air batteries can only provide 50% to 70% of the energy used to charge them, compared to over 90% for lithium-ion batteries. But despite all its downsides, it comes with a very big upside: it’s incredibly cheap. The model says 1 kilowatt-hour of storage would eventually cost just $20 using their technology, which is at least three times cheaper than lithium-ion batteries.

The new bill also introduces a wonky utility fee structure in Minnesota that aims to help utilities adopt clean technologies without running afoul of regulators, which push utilities to use the cheapest source of electricity.

Google first developed the concept in Nevada, where it bought power from geothermal startup Fervo. The agreement between Google and Xcel, alternately called a “clean transition tariff” or a “clean energy acceleration fee,” allows the utility to accept projects that regulators might consider too risky, with the tech company paying a premium to ensure ordinary taxpayers are not left with the liability.

Both solar and wind are proven technologies, but Form’s iron-air batteries are still relatively new. The startup’s first battery is currently being installed in Minnesota in collaboration with cooperative utility Great River Energy, and will store 150 MWh for 100 hours, sending 1.5 MW to the grid at peak.

Form manufactures its batteries at a factory in West Virginia. The company has raised $1.4 billion to date, according to PitchBook data.