Photo: Rondo
Rio Tinto wants to put Australia’s cheap midday electricity to work at its Yarwun alumina refinery – by storing it in hot bricks and using that heat battery to make steam after the sun sets.
The global mining giant and California-based Rondo Energy have started engineering and design work on a huge heat battery near Gladstone, Queensland. Rondo calls it Australia’s largest planned thermal energy storage project and says it would be a first for the alumina industry.
Alumina is a hard white powder made of aluminum and oxygen that’s used to make aluminum metal, sandpaper, and strong ceramics. Globally, aluminum sector refining accounts for roughly 175 million tonnes of carbon dioxide equivalent annually.
It’s still at the study stage, but the potential payoff is substantial. Rio Tinto estimates the battery could supply around 5% of Yarwun’s steam needs and cut the refinery’s direct emissions by about 67,000 metric tons of carbon dioxide annually. It would replace some of the coal and natural gas used to generate steam.
Rondo’s heat battery uses electricity to heat refractory bricks, which can withstand high temperatures. The bricks hold that energy as heat, which is then used to produce steam for the refinery’s existing steam network.
That matters because industrial heat demand doesn’t stop when solar production drops. Rondo’s heat battery charges during hours when electricity is cheap and plentiful, then delivers heat continuously so factories can keep running.
The proposed Yarwun system would have 360 megawatt-hours (MWh) of thermal storage and deliver up to 30 megawatts MW of heat. The Australian Renewable Energy Agency (ARENA) lists its electrical charging capacity at 78 MW, allowing it to take in electricity faster than it releases the stored energy as heat.
For the refinery, another attraction is that the battery would feed into equipment it already uses. The study will assess whether that integration can deliver reliable high-pressure steam at a cost that makes sense.
“This project shows how Australia’s abundant energy can become a competitive advantage for industry,” said Dr. Kira Rundel, Rondo’s head of Australia. “Heat batteries allow manufacturers to use low-cost electricity to produce the reliable, round-the-clock heat their operations need.”
ARENA is providing an initial A$3.6 million for the engineering and design study. If the project moves ahead, the agency will provide up to A$38 million for deployment. There’s also a further A$33.3 million in contingency support.
Rio Tinto will match ARENA’s A$3.6 million study contribution. The company says its total investment over the project’s life is expected to exceed ARENA’s funding if deployment goes ahead.
“Reducing emissions from alumina refining is complex, particularly when it comes to generating the high-pressure steam needed for our operations,” said Rio Tinto Pacific Operations managing director Armando Torres.
“This study will help us determine whether thermal energy storage can provide a technically and economically viable alternative to fossil fuels for part of Yarwun’s steam requirements.”
The feasibility study is expected to take about 12 months.
Read more: Germany is using heated bricks to replace gas-fired industrial boilers
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