Aluminium industry seeks innovative technologies to reduce emissions

Aluminium is crucial in numerous technologies essential for facilitating the energy transition. However, it also contributes significantly to CO₂ emissions, accounting for approximately 3 per cent of the world's direct industrial CO₂ emissions, which amounted to 9.4 Gt in 2021, as reported by the International Energy Agency (IEA), the world's leading energy authority. It works with governments and industry to shape a secure and sustainable energy future for all.

Over the past few years, there has been a gradual but minimal decrease in the average emissions intensity of aluminium production. However, to align with the net zero emissions programme by 2050, a more significant decline of approximately 3 per cent per year is necessary until 2030. To achieve this target, the aluminium sector must focus on developing and implementing innovative technologies that can effectively reduce emissions from primary production. Additionally, the industry and its customers must enhance their efforts in collecting, sorting, and recycling scrap to produce secondary aluminium to reduce emissions.

In the past decade, the global aluminium sector has experienced a consistent rise in direct emissions due to increased production. However, in 2019, there was a notable decline in emissions for the first time in ten years, attributed to modest improvements in emissions intensity and production stabilization, as per the IEA report.  Unfortunately, this positive trend has since reversed. In 2021, the sector's direct CO₂ emissions reached 275 Mt, representing a 2 per cent increase compared to the previous year. When accounting for indirect emissions from electricity consumption, the total CO₂ emissions associated with aluminium production amount to approximately 1.1 Gt. Although there has been a slight decline in aluminium's average direct CO2 intensity in recent years, more is needed to meet the desired targets. In contrast, the net zero scenario envisions a decline in emissions intensity of around 3.5 per cent annually until 2030. Hence, the aluminium industry's emissions currently need to be on track to align with these objectives.

Alumina refining and aluminium smelting account for over 90 per cent of direct CO₂ emissions in aluminium production. The remaining emissions come from recycled output, anode production, and casting. To mitigate these emissions, it is crucial to implement near-zero-emission technologies for refining and smelting and increase the proportion of the recycled output using post-consumer scrap. These measures aim to minimize reliance on traditional processes and reduce the overall carbon footprint of aluminium production.

Although the aluminium sector is considered an energy-intensive industry, in recent years, the aluminium sector has witnessed a rise in total energy consumption due to increased production. However, there has been a notable decline in the energy intensity of aluminium production since 2000. This positive trend has been predominantly driven by China, which accounts for 57 per cent of the world's aluminium production. China has consistently adopted advanced aluminium production technologies, shifting electrolytic aluminium production to Yunnan province, which is rich in hydropower supply and trying to transform itself from one of the most energy-intensive aluminium producers to one of the least energy-intensive ones.

China's remarkable progress in reducing energy intensity has played a pivotal role in shaping the global aluminium industry. Having effectively utilized its potential for energy intensity improvements, China has set an example for other countries. Nevertheless, worldwide, energy efficiency enhancement in primary aluminium production has been relatively modest in recent years. Aluminium is majorly produced currently by sourcing energy from fossil fuels. Adopting alternative fuel sources like bioenergy and hydrogen for high-temperature operations is crucial while utilizing nearly emission-free electricity for lower-temperature heating processes is vital to align with the net zero scenarios. This transition in fuel selection is essential for making significant progress towards achieving net-zero emissions.

The demand for aluminium is anticipated to escalate further due to the increasing global population, GDP growth, and the expanding utilization of aluminium in various technologies crucial for transitioning to a net-zero economy. At present, the majority of aluminium primary smelting operations rely on carbon anodes, which result in the release of CO₂ during the electrolysis process. However, there is a promising solution in the form of inert anodes that emit oxygen as they degrade. Expediting this technology's commercialization and initial implementation in the coming years is crucial to align with the net zero scenarios. This scenario envisions the adoption of inert anodes for approximately 10 per cent of primary aluminium production by 2030.

Significantly, notable advancements have been achieved in employing inert anodes for aluminium smelting, fostering optimism and progress. In April 2021, RUSAL's Krasnoyarsk plant in Russia reached a groundbreaking milestone by producing primary aluminium on an industrial scale using inert anodes, accomplishing an impressive output of 1 tonne of aluminium per day per cell. Building on this success, Elysis, a collaborative venture between Alcoa and Rio Tinto located in Quebec, replicated this achievement in November 2021. These commendable developments mark significant steps forward in using inert anodes for aluminium smelting and hold great promise for the future of sustainable and efficient aluminium production.

Aluminium smelting emissions can also be reduced through the implementation of carbon capture and storage (CCS) technology. However, its application in the aluminium industry is more challenging than other industrial processes due to lower concentrations of CO₂.

However, there have been recent announcements by two companies, Aluminium Dunkerque and Norwegian aluminium giant Norsk Hydro, expressing their exploration of CCS options for aluminium production. Hydro has set a target of achieving commercial-scale implementation of CCS by 2030.

The global mining and metal giant Rio Tinto, with the backing of Australia, has revealed plans to conduct a feasibility study exploring the potential use of hydrogen as a source of heat for alumina refining at its Yarwun refinery. This initiative is aimed at reducing emissions associated with the refining process. Alcoa has also made announcements regarding pilot projects in 2021 and 2022. These projects involve the utilization of electrically powered mechanical vapour recompression and electric calcination to replace fossil fuels in the alumina refining process, thereby further reducing environmental impact.