10 Key Facts About Mike Cannon-Brookes' Massive Bet on Thermal Storage

Billionaire tech entrepreneur Mike Cannon-Brookes is making headlines again, this time with a monumental investment in thermal energy storage. Through his family office Grok Ventures, he’s backing one of the world’s largest battery projects—a gigawatt-scale thermal storage system in the United States. But what does this mean for the future of renewable energy? Here are ten essential facts to understand this game-changing move.

1. What Is Thermal Energy Storage?

Unlike conventional lithium-ion batteries, thermal storage systems capture energy as heat rather than chemical energy. They use materials like molten salt, graphite, or specialized ceramics to store heat at high temperatures. When electricity is needed, the stored heat is converted back into power via a heat engine. This technology is particularly good at storing large amounts of energy for hours—or even days—making it a key asset for balancing renewable sources like solar and wind.

2. Who Is Mike Cannon-Brookes?

Co-founder of Australian software giant Atlassian, Cannon-Brookes is one of the country’s wealthiest individuals. He is also a prominent climate activist and investor in clean energy. Through Grok Ventures, he has backed numerous renewable projects, including the massive Sun Cable solar farm and the Tesla Big Battery in South Australia. His latest move into thermal storage underscores his commitment to disruptive tech that can decarbonize the grid.

3. The Scale: A Gigawatt-Sized Leap

This project is not your typical battery. It’s one of the first gigawatt-scale thermal storage installations ever built. For perspective, a gigawatt-hour (GWh) can power hundreds of thousands of homes for one hour. With thermal storage’s ability to hold energy for long durations, this facility could provide reliable backup power for entire communities, effectively replacing fossil-fuel peaker plants.

4. Why Thermal Storage Matters Now

As renewable penetration grows, grid operators face challenges in managing intermittent supply. Thermal storage offers a cost-effective way to store huge amounts of energy for longer periods—often at a lower levelized cost than lithium-ion for durations over four hours. This makes it ideal for shifting solar power into the evening or storing wind energy for calm days.

5. How It Compares to Lithium-Ion Batteries

Lithium-ion batteries excel at short-duration, high-power applications like frequency regulation. However, they degrade over time and are not as economical for long-duration storage. Thermal systems, on the other hand, can last for decades with minimal degradation and use inexpensive, abundant materials. The trade-off is slower response times and lower round-trip efficiency, but for bulk energy shifting, thermal wins hands-down.

6. Grok Ventures: The Financial Backbone

Cannon-Brookes’ investment vehicle, Grok Ventures, provided the capital that allowed the US thermal storage company to proceed with its first gigawatt-scale project. This funding de-risks the technology and sends a strong signal to other investors that thermal storage is ready for prime time. Grok has a track record of backing breakthrough climate solutions, often providing early-stage patient capital.

7. A First-of-Its-Kind Project

While thermal storage has been used in concentrated solar power plants for years, this is the first stand-alone, gigawatt-scale battery using thermal technology that does not rely on solar capture. It can be charged from any electricity source—renewable or otherwise—making it a versatile grid asset. The project is expected to break ground in the US within the next two years.

8. Impact on Renewable Integration

By providing affordable, long-duration storage, this plant will help utilities increase their renewable energy share without compromising grid reliability. It can absorb excess solar and wind power that would otherwise be curtailed, and dispatch it during peak demand. This effectively makes renewables dispatchable, a critical step toward a zero-carbon grid.

9. Potential Locations and Markets

While the exact location hasn’t been disclosed, likely candidates include Texas (ERCOT), California, or the Southwest—regions with high solar penetration and growing energy storage mandates. The technology is modular, so future projects could be sited near retiring coal plants, reusing infrastructure while providing clean firm power.

10. What This Means for the Global Storage Market

Cannon-Brookes’ bet on thermal storage could catalyze a wave of investment in alternative storage technologies. If successful, it will demonstrate that thermal storage is commercially viable at scale, potentially rivaling pumped hydro and lithium-ion for certain applications. This diversifies the energy storage portfolio, making the grid more resilient and accelerating the clean energy transition worldwide.

Conclusion

Mike Cannon-Brookes’ investment in a gigawatt-scale thermal battery is a bold statement: the future of energy storage is not just about lithium-ion. As this project moves from announcement to operation, it may well redefine how we think about large-scale storage and inspire similar projects globally. For anyone following the shift to renewable energy, this is a milestone worth watching.