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Rio Tinto eyes a giant hot-brick battery to cut fossil fuel use
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Rio Tinto and California-based Rondo Energy have begun engineering and design work on a large thermal energy storage project at Rio Tinto's Yarwun alumina refinery near Gladstone, Queensland. The project, which Rondo calls Australia's largest planned thermal energy storage system, would use hot bricks to store cheap midday electricity and generate steam after sunset. It aims to reduce the refinery's reliance on coal and natural gas.
Alumina refining is energy-intensive and accounts for a significant share of global industrial emissions. The aluminum sector's refining processes emit roughly 175 million tonnes of carbon dioxide equivalent annually worldwide. Industrial heat demand continues around the clock, even when solar production drops, making storage crucial for decarbonization.
The proposed Yarwun system would have 360 megawatt-hours of thermal storage and deliver up to 30 megawatts of heat. It would charge at up to 78 megawatts of electrical capacity, allowing it to absorb electricity faster than it releases heat. Rio Tinto estimates the battery could supply about 5% of the refinery's steam needs and cut direct emissions by approximately 67,000 metric tons of carbon dioxide per year.
The heat battery would feed into Yarwun's existing steam network, replacing some fossil fuel-based steam generation. This integration could demonstrate how low-cost renewable electricity can be stored as heat to provide reliable, round-the-clock industrial power. If successful, the project could serve as a model for other alumina refineries and energy-intensive industries.
"This project shows how Australia's abundant energy can become a competitive advantage for industry," said Dr. Kira Rundel, Rondo's head of Australia. Armando Torres, Rio Tinto Pacific Operations managing director, noted that reducing emissions from alumina refining is complex, especially for high-pressure steam. He said the study will help determine whether thermal energy storage is a technically and economically viable alternative to fossil fuels.
The Australian Renewable Energy Agency (ARENA) is providing A$3.6 million for the engineering and design study, with up to A$38 million for deployment and A$33.3 million in contingency support. Rio Tinto will match the study contribution. The feasibility study is expected to take about 12 months, after which a decision on proceeding will be made.
