Mike Cannon-Brookes, through his investment firm Grok Ventures, has backed one of the world’s largest thermal battery storage projects. The investment will support US-based Antora Energy in developing the 5 GWh “Project Big Stone” thermal battery facility in South Dakota.
Grok Ventures has enabled US-based thermal storage company Antora Energy to reach financial close for “Project Big Stone,” a 5 GWh thermal battery project in South Dakota. The project is being developed at a bioprocessing facility owned by POET, one of the world’s largest biofuel producers.
The investment marks another major climate-tech bet by Cannon-Brookes, who has increasingly positioned himself as one of the most aggressive private backers of renewable energy infrastructure globally through Grok Ventures and related investment vehicles.
Thermal Storage Gains Momentum
Unlike lithium-ion battery systems that store electricity electrochemically, thermal batteries store energy in the form of heat and later convert it for industrial use or power generation. The technology is increasingly attracting interest as industries seek long-duration storage solutions capable of decarbonising high-temperature industrial processes.
The 5 GWh scale of the Antora project places it among the largest energy storage installations announced globally, highlighting growing investor confidence in alternative storage technologies beyond conventional lithium-ion batteries.
The development also comes amid rapidly rising global demand for long-duration storage systems as grids integrate higher shares of solar and wind power. Recent energy transition forecasts suggest battery storage deployment is accelerating worldwide alongside falling renewable energy costs.
Grok Expands Climate Investment Portfolio
Cannon-Brookes, widely known as the co-founder and CEO of enterprise software company Atlassian, has in recent years transformed Grok Ventures into a major climate investment platform focused on decarbonisation technologies, renewable energy, electrification and storage.
As per its official website, the company has invested in roughly 30 companies dealing in renewable energy and the sustainability spectrum. Some of the notable names include AGL, Antora Energy, Brighte, and Suncable. Grok Ventures portfolio has seen 2 unicorns, 1 IPO and 6 acquisitions including key companies like Airwallex, Spaceship and Culture Amp.
One of Grok’s most prominent investments remains SunCable, the massive Australia-Asia renewable energy export project that aims to develop giant solar and battery infrastructure in Australia. Grok Ventures took control of Sun Cable in 2023 after the project entered administration following a dispute between its original backers. Sun Cable’s plans include supplying renewable electricity across Australia and potentially exporting power to Singapore through a subsea transmission network. The project has since evolved to include potential opportunities for renewable-powered AI and hyperscale data centres.
Another notable investment includes a $100 million funding led by Grok in Brighte, household solar and battery funding outfit.
Cannon-Brookes has also made investments in AGL Energy, with Grok settling a 11.28% stake purchase in AGL Energy worth A$650 million ($455.33 million) with J P Morgan. It pushes for a faster transition away from coal-fired power generation and toward renewables and storage infrastructure.
Grok Ventures has increasingly focused on investments linked to clean energy, battery storage, electrified transport, and industrial decarbonisation. Through its growing portfolio of renewable energy and climate-tech companies, the firm aims to support the global transition toward net-zero emissions and large-scale clean energy deployment.
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