Google is making one of the boldest bets yet on long-duration energy storage, agreeing to pay about $1 billion for a multi-day iron-air battery system from Form Energy to support a new data center in Minnesota, according to reporting by The Information. The installation, rated at 300 megawatts for 100 hours, will work alongside 1.4 gigawatts of wind power and 200 megawatts of solar to keep the facility running through long weather lulls and grid hiccups.
It is a watershed moment for long-duration storage: a hyperscale customer committing at utility scale to a technology built for days, not hours. If it performs as promised, the project could reset expectations for how data centers—and power grids—operate with very high shares of renewables.
Why a 100-Hour Battery Matters for Clean Energy
Most grid batteries today are lithium-ion systems designed for 2 to 4 hours. They excel at fast response and daily cycling but struggle to cover prolonged wind and solar droughts that can stretch multiple days, especially in winter. A 100-hour resource changes that equation, turning intermittent generation into firm, schedulable power.
At 300 megawatts across 100 hours, the Form Energy system stores roughly 30,000 megawatt-hours of energy. For perspective, that’s on the order of powering about a million average U.S. homes for a day, based on U.S. Energy Information Administration residential consumption data. For a single data center—where loads frequently exceed 100 megawatts—such multi-day coverage is the difference between curtailing operations and maintaining continuous service.
Multi-day storage also unlocks more value from wind and solar by soaking up excess generation during surges and releasing it steadily during calm, cloudy stretches. That reduces curtailment and diminishes reliance on gas peaker plants, aligning with 24/7 carbon-free energy strategies many tech companies, including Google, have pledged to meet by 2030.
Inside Form Energy’s Iron-Air Battery Chemistry
Form Energy’s battery “breathes” oxygen. During discharge, oxygen enters the cells and rusts iron, releasing electrons as energy. During charging, the process reverses: electricity strips oxygen off the rust, returning it to iron and storing energy. The appeal is pragmatic—iron and air are abundant and inexpensive, and the chemistry is inherently nonflammable, a safety edge over lithium-ion in large stationary installations.
The trade-off is round-trip efficiency. Iron-air systems typically deliver less of the input energy back to the grid than lithium-ion does; industry analyses and company briefings put iron-air efficiencies in the roughly 50% to 60% range versus about 85% to 90% for lithium-ion. For rare, multi-day events, however, duration often matters more than efficiency, and a lower cost per stored kilowatt-hour can outweigh the energy penalty.
A Grid-Scale Bet for Reliable Power at Data Centers
Hyperscale data centers demand rock-solid power quality and uptime, requirements that have historically pushed operators toward diesel generators and firm fossil generation. By pairing 1.4 gigawatts of wind and 200 megawatts of solar with a 300-megawatt, 100-hour battery, Google is effectively assembling a virtual power plant that can ride through multi-day weather events without defaulting to carbon-heavy backups.
The configuration is also a test bed for grid integration. The Midcontinent Independent System Operator region routinely experiences both high wind output and deep lulls. A multi-day battery capable of 30 gigawatt-hours of delivery can smooth regional volatility, potentially provide capacity value during peak stress, and offer ancillary services—while keeping a mission-critical campus running.
Money, Manufacturing, and Momentum in Long-Duration Storage
The reported $1 billion price tag signals real commercial validation for a technology that has lived in pilot mode for years. Form Energy, which has announced utility pilots but not an order of this scale, is also raising a $500 million round and has amassed $1.4 billion in funding to date, according to PitchBook. The company has said it plans to go public next year, a timetable that today’s deal will likely support.
Crucially, Form is standing up domestic manufacturing in West Virginia, repurposing a former steel site in Weirton to produce iron-air cells at volume. Localizing supply chains around iron, steel, and common industrial inputs is central to meeting cost targets and deployment timelines. It also aligns with U.S. industrial policy incentives and the Department of Energy’s push to commercialize long-duration storage through its Long Duration Storage Shot.
Key Signals for the Clean Energy Transition
This deal is less about beating lithium-ion and more about complementing it. Fast, short-duration batteries will remain essential for daily cycling and grid stability. Multi-day iron-air systems fill the critical gap when weather patterns defy day-ahead forecasts, mitigating “Dunkelflaute” events that challenge high-renewables grids in North America and Europe.
What to watch next: guarantees around performance and availability, the balance between charging from on-site renewables versus the grid, and how regulators value multi-day capacity in resource adequacy markets. If the system performs, expect utilities and other hyperscalers to follow—especially in regions where wind and solar potential are high but transmission upgrades lag.
The Information’s $1 billion figure underscores a broader narrative: the cost of firm, clean power for digital infrastructure is becoming a front-page capital expenditure. If Form Energy’s 100-hour battery delivers, it will not just keep one data center online—it could accelerate the maturation of a market segment the International Energy Agency and the U.S. Department of Energy see as pivotal to deep decarbonization.
