The Australian Renewable Energy Agency (ARENA) has allocated $32.1 million in funding to Rio Tinto for the implementation of hydrogen calcination technology at the Yarwun Alumina Refinery in Gladstone, Queensland. This project aims to test the viability of utilizing green hydrogen to reduce emissions at the refinery.
The trial involves the use of a 2.5-megawatt (MW) electrolyzer, capable of producing approximately 250 tonnes of hydrogen annually. The hydrogen will replace fossil gas in one of the refinery’s calciners by employing retrofitted hydrogen burners. The electrolyzer will draw power from the same sources as the refinery, and large-scale generation certificates (LGCs) will be surrendered by operator Sumitomo Corporation to offset the emissions associated with the project. However, the commissioning of the project is not expected until 2025.
Alumina, which is derived from bauxite, serves as a precursor to the production of aluminum. The refining of alumina is a particularly energy-intensive and emissions-heavy process, making it one of the most challenging industries to decarbonize due to limited commercially viable low-emission alternatives.
Currently, alumina refining accounts for approximately 3 percent of Australia’s annual greenhouse gas emissions and consumes over 221 petajoules of energy each year, surpassing the energy consumption of Tasmania or the Northern Territory. The majority of emissions, around 95 percent, result from the onsite consumption of fossil fuels for process heating.
To address these challenges, ARENA stepped in to subsidize a portion of the total $111.1 million cost of the Yarwun project. Fortune 500 company Sumitomo, which reported a profit of Y565.2 billion ($6 billion) in fiscal 2022, will own and operate the electrolyzer, supplying hydrogen directly to the Yarwun plant operated by Rio Tinto, a company that reported an after-tax profit of $12.42 billion in 2022.
A feasibility study supported by ARENA with a $580,000 grant in 2021 suggests that the use of hydrogen in the calcination process, which involves removing chemically bound water associated with alumina at temperatures exceeding 900 degrees Celsius, can significantly reduce greenhouse gas emissions. When hydrogen is utilized instead of fossil gas, the calcination process generates steam, which can be utilized in other stages of the refining process.
ARENA CEO Darren Miller emphasized the significance of this pilot project for the Australian alumina industry, stating that its success could pave the way for broader industry deployment and highlight the importance of low-cost green hydrogen in decarbonizing large-scale industrial emitters. ARENA has been closely monitoring alumina refining, having published its Alumina Decarbonisation Roadmap in 2022. The agency has also provided funding to Alcoa for testing electric calcination and mechanical vapor recompression in previous years, exploring various avenues to reduce emissions in the alumina industry, including the use of electric boilers and on-site thermal energy storage.
The utilization of green hydrogen at the Yarwun Alumina Refinery presents a significant opportunity to mitigate greenhouse gas emissions and foster a more sustainable alumina industry in Australia. By embracing innovative technologies and exploring the potential of green hydrogen, Rio Tinto and its partners are taking a crucial step towards achieving a greener future and contributing to global decarbonization efforts.
