Category: Technology | Published: 2026-03-05
The World's Largest Battery System
Google has announced plans to build the world's largest battery storage system at its new data centre in Pine Island, Minnesota. The project, valued at close to one billion dollars, will use iron-air battery technology developed by Form Energy to deliver 100 continuous hours of backup power - more than four days of uninterrupted supply.
The system represents a step change in how large-scale data centres are powered, moving away from traditional fossil fuel backup generators towards long-duration clean energy storage.
How Iron-Air Batteries Work
Unlike the lithium-ion batteries found in phones, laptops and electric vehicles, iron-air batteries use a fundamentally different chemistry based on the reversible rusting of iron.
During discharge, oxygen is drawn into the battery cells, causing the iron to oxidise (rust) and release electrical energy. During charging, the process reverses - the rust is converted back to iron, and the oxygen is released. The raw materials are abundant and inexpensive, which gives iron-air technology a significant cost advantage.
Form Energy's system is estimated to cost around 20 dollars per kilowatt-hour, roughly three times cheaper than equivalent lithium-ion systems. The trade-off is that iron-air batteries are physically larger and heavier, making them unsuitable for mobile applications but ideal for stationary grid-scale storage.
The Numbers Behind the Project
The Pine Island installation will be Google's first data centre in Minnesota. The battery system alone will deliver 300 megawatts of power with a total energy capacity of 30 gigawatt-hours - making it the largest battery by energy capacity anywhere in the world, dwarfing the UAE's 19 gigawatt-hour lithium-ion project.
The data centre's full clean energy mix includes:
- 1,400 megawatts of wind power
- 200 megawatts of solar power
- 300 megawatts / 30 gigawatt-hours of iron-air battery storage
The total renewable energy capacity comes to 1.9 gigawatts. Google will fund the entire project through a "Clean Energy Accelerator Charge" tariff, meaning there will be no impact on local residents' electricity bills. Battery installation is scheduled for 2028.
Why This Matters for Data Centres
Data centres are among the most energy-intensive facilities in the modern economy. They require constant, reliable power - any interruption can affect millions of users and businesses simultaneously. Traditionally, data centres have relied on diesel generators as backup power, which are effective but produce significant carbon emissions.
The shift towards long-duration battery storage addresses both reliability and sustainability. A 100-hour battery system can bridge extended periods of low renewable generation, such as several consecutive cloudy or windless days, without needing to fall back on fossil fuels. Standard lithium-ion batteries typically provide only four to eight hours of backup, which limits their usefulness for extended outages.
For Google, which has committed to running its operations on carbon-free energy around the clock by 2030, iron-air batteries offer a practical path towards that target.
The Broader Industry Trend
Google is not alone in investing in next-generation energy storage. Microsoft, Amazon and Meta are all pursuing large-scale clean energy projects to power their growing data centre estates. The rapid expansion of AI workloads has made energy consumption one of the most pressing challenges in the technology sector.
The International Energy Agency has reported that global spending on data centres will reach approximately 580 billion dollars this year, overtaking investment in new oil supply projects for the first time. Electricity use from data centres is projected to roughly triple by 2035, driven largely by AI.
What This Means for UK Businesses
Whilst the Pine Island project is in the United States, the implications are relevant globally. As cloud providers invest in cleaner, more resilient infrastructure, UK businesses that rely on cloud services will benefit from improved reliability and reduced environmental impact across the supply chain.
For organisations with sustainability targets or ESG reporting obligations, the energy source of their cloud infrastructure is becoming an increasingly important consideration. Choosing providers that are actively investing in clean energy can support those commitments.
The development of affordable long-duration storage also has broader implications for the UK's own energy transition. If iron-air battery technology proves successful at scale, it could play a role in stabilising the UK grid as the country moves towards greater reliance on renewable energy sources.
This is a space worth watching. The technology that powers the world's data centres today will shape the cost, reliability and environmental footprint of the digital services we all depend on.