Cannon-Brookes bankrolls one of biggest batteries in the world, in huge bet on thermal storage

Australian software billionaire Mike Cannon-Brookes has thrown more of his financial weight behind a US thermal battery storage company, allowing Antora Energy to reach financial close on plans for its first giga-scale project.

The Cannon-Brookes private investment vehicle, Grok Ventures, is the only external investor in Project Big Stone in South Dakota, a 5 gigawatt-hour (GWh) thermal battery located at a bioprocessing facility owned by the world’s largest biofuel producer, Poet. 

The company declined to say how much was invested in the project.

Antora has installed some 200 thermal batteries, housed in containers, at the site with commissioning starting in March. The company says the project will be fully operational later this year, and took just 12 months to build from breaking ground to “energy delivery”.

Heat from the battery will be sold to Poet under a long-term offtake agreement. 

Thermal batteries use electricity to heat blocks made of carbon, as in the case of Antora, or other materials such as salt or metals to store heat. 

Those blocks retain that heat at high temperatures for up to days at a time, which can be used for industrial heat or converted back into electricity through a heat exchange system. 

At 5 GWh, that size puts Project Big Stone in the realm of the biggest batteries in the world — although the needs of data centres are already making single-digit gigawatt-hour storage seem small.

Xcel Energy and Google, for instance, struck a deal in February for 30 GWh of storage that includes a iron-air battery system by Form Energy.

“This is where Grok invests: backing pioneering teams solving the energy transition’s most consequential industrial challenges,” said Grok Ventures’ Ridhaa Ahmed in a statement. 

“Antora has developed a genuinely compelling solution with technology that delivers industrial decarbonisation without operational or commercial compromise.”

Antora co-founder David Bierman says the company is working with Grok “to explore opportunities” in Australian industrial sites, joining a small number of other companies seeking to do something similar.

In Australia, Rondo Energy is trying to build a presence while locally-founded MGA Thermal is grinding toward commercialising its own version of the technology. 

Edge technology is not new for Cannon-Brookes, who is involved in some of the more ambitious energy projects in Australia.

He won the battle for the massive Sun Cable solar and battery project 2023, forcing out fellow billionaire Andrew Forrest, who disagreed with the sub-sea component. Sun Cable is still pursuing the strategy, although its near term plans are focused on providing green power solutions to Australian-based energy users.

Cannon-Brookes also launched an ambitious bid for Australia’s biggest coal generator, AGL. It did not succeed, and while Grok ended up as the biggest shareholder, it did stymie efforts to split the company into two distinct businesses.

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