Aluminium has caught the attention of policymakers and industry experts as a lightweight, recyclable metal that can be used in various industries, starting from automobile and aerospace engineering to infrastructure and construction. Most aluminium products can be recycled for decades- a fact that has earned aluminium the badge of ‘green metal.’

However, despite all its positive attributes, one of the main drawbacks of aluminium production is that it is energy-intensive and results in a massive volume of carbon emission. As the world moves toward sustainability, the aluminium industry’s emission issue cannot be ignored. Therefore, top aluminium producers worldwide are working towards reducing their carbon footprint by leveraging various renewable energy sources.

One such organisation is the mining major Rio Tinto, which has joined hands with Australian Renewable Energy Agency (ARENA) to research if hydrogen can replace natural gas in alumina refining. Australia is the largest producer of bauxite as well as the largest exporter of alumina globally. However, since the alumina smelting process has a high carbon footprint, the project has been undertaken to replace fossil fuels with hydrogen.

Rio Tinto is conducting this experiment in its Yarwun alumina refinery in Gladstone, Queensland, Australia. The mining company is spending 1.2 million AUD on the project.

Why is the industry shifting its focus from natural gas to hydrogen?

The most straightforward answer would be to decarbonise the aluminium industry. An elaborated version of the question is why experts choose hydrogen over another renewable energy source. The answer lies in the following four reasons:

• Hydrogen does not produce smoke, so when it burns only steam is produced.
• The steam produced can be captured and used further in the refining process. Rio Tinto is also studying if hydrogen can be extracted from the water after the steam cools off. 9 kgs of water is needed to make 1 kg of hydrogen. Therefore, to achieve maximum sustainability the aluminium industry will need renewable energy and renewable water. Furthermore, if the steam from the hydrogen-fired calciner can substitute fossil fuels in the refining process, then 50% of the operation will be decarbonised.
• The renewable hydrogen production process can use other renewable energy sources such as solar or wind power.
• Hydrogen’s combustion properties make the element a top choice. While extracting alumina from bauxite, it must be heated at 1000 degrees celsius in calciners, which are large heaters. Undoubtedly, it is an energy-intensive process and such high temperatures can only be achieved in a few ways. Hydrogen’s combustion capabilities may come in handy here.

Besides renewable power sources and water supply, the industry will also need cost-efficient technology. For industry-wide adoption of hydrogen, it must be inexpensive, and the new system should be easily integrated with the existing production line without making significant alterations. Rio Tinto engineers are also looking at making such facilities a reality.

This project will not only broaden the possibilities of decarbonising the aluminium industry and give an insight into the technicalities of using renewable hydrogen as a power source but also pave the way for attaining sustainability in other energy-intensive industries.

Australia’s commitment towards sustainability in the aluminium industry:

The Australian aluminium industry is taking individual measures to ensure sustainability across the industry and working closely with other bodies and councils towards the same goal. The Australian Aluminium Council and its members are committed to the sustainable production of bauxite, alumina and aluminium. Additionally, the Australian Aluminium Council is a member of the Aluminium Stewardship Initiative (ASI). It operates across the value chain collaboratively to encourage responsible production, sourcing and stewardship of aluminium.

Lastly, the Australian Aluminium Council actively participates in the International Aluminium Institute (IAI). The IAI aims to promote a more comprehensive understanding of its activities and demonstrate its responsibility concerning all key sustainability issues – environmental, health, safety and recycling across the global aluminium industry.