Rio Tinto plans 360 MWh heat battery, Australia’s largest for Yarwun alumina refinery - AL Circle

Rio Tinto is building a 360 MWh heat battery at its Yarwun alumina refinery in Queensland. The battery will store thermal energy and supply it to the refinery's calcination process, allowing the facility to shift electricity demand away from peak hours and reduce reliance on the grid during periods of high prices or tight supply.

Where this fits

This is a cost-driven response to grid unreliability and price volatility driven by weather-dependent renewable supply. Rio Tinto is, in effect, adding a buffer layer to its own operations because the grid cannot reliably meet industrial demand. It signals that firms now factor in the cost of grid instability: they either invest in on-site storage, accept higher operating costs, or relocate. That shifts the burden of managing Australia's renewable transition from the electricity system onto heavy industry. The alternative, a firm, dispatchable backbone of nuclear or gas, would flatten that cost curve and leave Rio Tinto's capital freed for production, not grid hedging.

What it means

Australia's alumina refineries are globally competitive on energy cost and grid reliability. When major industrial users begin self-insuring against grid volatility through on-site batteries and storage, it signals that the wholesale electricity market is becoming less reliable and more expensive in real time. The 360 MWh battery is a rational business decision; it is also proof of cost being absorbed downstream. That cost, capital locked in storage, operational complexity, and the energy losses inherent in thermal storage, will show up in alumina prices and competitiveness. It will not show up in the headline cost-per-megawatt-hour of renewable generation. This is how whole-system economics work.