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The Yarwun heat battery would store 360 MWh of heat, not electricity, and deliver 30 MW of heat output. Rio Tinto estimates it could supply around 5% of the refinery's steam needs.
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Image from Rondo Energy's release on the Rio Tinto project, which would be delivered at the Yarwun alumina refinery near Gladstone, Queensland.
Image: Rondo Energy
Source · Press image from the Rondo Energy newsroom, used for news reporting.
Rio Tinto and Rondo Energy have started engineering and design work on a heat battery rated at 30 MW of heat output and 360 MWh of thermal storage at the Yarwun alumina refinery near Gladstone, Queensland, Electrek reported on Oct. 21.
The 360 MWh is stored heat, not electricity; the unit charges at 78 MW and delivers 30 MW of heat, according to Electrek.
Illustration (AI-generated)
The system would charge on cheap midday electricity, store the energy as heat in refractory bricks and release it as steam into the refinery's existing steam network after sunset. The Australian Renewable Energy Agency (ARENA) lists the electrical charging capacity at 78 MW, so the unit can take in power faster than it gives heat back, according to Electrek. These are thermal figures: 360 MWh is stored heat, not grid-exportable electricity.
A 78 MW charging load that follows the solar day is the kind of flexible demand grid planners want: it soaks up surplus daytime generation and lets the refinery make steam after the sun sets without burning coal or gas for that share. The scale is modest for the plant. Rio Tinto estimates the battery could cover around 5% of Yarwun's steam needs and cut direct emissions by about 67,000 metric tons of carbon dioxide a year, Electrek said.
ARENA is providing A$3.6 million for the engineering and design study, and Rio Tinto is matching that amount. If the project goes ahead, ARENA would provide up to A$38 million for deployment, plus a further A$33.3 million in contingency support. Rio Tinto says its total investment over the project's life would exceed ARENA's funding if deployment goes ahead. The feasibility study is expected to take about 12 months.
Rondo's design heats refractory bricks with electricity and holds the energy as high-temperature heat. pv magazine Australia reported that Rondo says it delivers steam or hot air at up to 1,000°C and claims a round-trip efficiency above 98%. That efficiency is a vendor claim, and the companies have not published test data for Yarwun.
The two companies describe the project as one of the first large-scale demonstrations of thermal storage for industrial process heat and a world first for the alumina industry. Armando Torres, managing director of Rio Tinto Pacific Operations, said the study will determine whether thermal storage is a technically and economically viable alternative to fossil fuels for part of Yarwun's steam requirements.
This is a study, not a construction decision. Whether the bricks can deliver reliable high-pressure steam through the refinery's current equipment, and at a cost that beats coal and gas, is what the 12-month work is meant to settle. No construction schedule or total project cost has been published, and ARENA's deployment funding depends on the study's outcome.
