Posted on: 2nd March 2022 by Dr. Michael Kenyon
Sustainability in the aluminium industry is a hot topic right now. With COP26 now a distant memory, it is up to industry and governments to implement ‘green’ strategies and new technologies. The aim is to achieve significant reductions in global greenhouse gas (GHG) emissions in order to keep global warming below 2 °C (vs pre-industrial levels, i.e. the Beyond 2 Degrees Scenario, or B2DS). Ideally it should be below 1.5 °C.
The aluminium industry accounts for around 2 – 3% of global GHG emissions annually. Therefore, it has a responsibility to help tackle climate change. This blog explores the origins of GHG emissions in the aluminium supply chain and solutions to reduce them.
Aluminium’s environmental impact
In 2018 a total of 51 billion tonnes of CO2 equivalence was emitted. Of this, the aluminium industry emitted 1.1 billion tonnes from a total production of 95 million tonnes (Mt) of aluminium. 66% of the aluminium came from a primary source, and 34% from a secondary source e.g. from recycling of pre- and post-consumer scrap. The majority (~94%) of the 1.1. billion tonnes CO2 eq. contribution resulted from the production of primary aluminium.
There are four major stages to producing pure aluminium. These are; raw extraction of bauxite ore (an ore with a high content of aluminium in the form of an oxide call alumina), bauxite refining to alumina, and alumina reduction to liquid aluminium via smelting (electrolysis). Finally, casting the liquid aluminium turns it into ingot or other product forms. There are emissions related to all four process steps. However, it is the large quantity of electrical power required for the smelting stage that contributes the most.
Historically, electricity for smelting has predominantly come from non-renewable sources e.g. coal or natural gas fired power stations. Figure 1  shows a breakdown of the aluminium sector emissions in 2018. It includes primary production, recycling of aluminium and semi-fabrication such as rolling and extrusion.
The targets needed for a reduction in emissions
The International Aluminium Institute (IAI) using the International Energy Agency (IEA) datasets, has modelled the GHG reductions necessary across the operations highlighted in Figure 1.
Figure 2  shows the sector emissions ‘allowed’ under the two global targets. The total sector emissions need to be reduced by 77% by 2050 to achieve the B2DS target. This is in combination with a forecast growth of 80% in the global aluminium market from 95 Mt (2018) to 178 Mt (2050) highlighted in Figure 3 . Consequently, it’s a daunting target.
How can the aluminium industry achieve the emission reductions?
There are three main pathways that the industry needs to address in order to achieve the reductions discussed above. These are;
- Electricity decarbonisation,
- Recycling end-of-life scrap,
- Direct process emission reductions.
The remainder of this blog will discuss the first and third pathways. I will cover recycling and end-of-life scrap treatment in a future blog. However, we already have several blogs on this topic, which you can find here.
The electrolytical nature of the smelting process cannot be avoided. Even by implementing as much recycling as possible in the future, we will still need primary aluminium to sustain the predicted market growth. It is therefore imperative that all primary aluminium supply chains switch to utilising renewable energy sources. Some regions are already using renewable power supplies such as hydropower, wind or even solar. For example, Emirates Global Aluminium produces thousands of tonnes of aluminium a year using 100% solar power provided by Dubai Electricity and Water Authority, Figure 4 .
The reduction in emissions when utilising renewables for primary production is significant. Figure 5 shows such an effect . By utilising 100% renewables compared to a traditional (and still heavily used) coal fired source, the industry can reduce the footprint per 1 tonne of primary aluminium from ~20 tonnes of CO2 eq. to 5 tonnes of CO2 eq. Consequently, the contribution from the production of electricity becomes marginal, and the focus shifts to other emissions such as the direct process emissions.
Direct emissions reduction and thermal energy
As can be seen from figures 1 and 5, another large contributor to primary aluminium production occurs from direct process emissions. This mainly relates to the carbon anodes which form part of the electrolysis process. The oxygen from the breakdown of the alumina (Al2O3), reacts with the carbon anode to produce CO2 directly.
Research into inert anode technology has been ongoing for 20+ years. This technology reduces the direct smelting process GHG emissions to zero, as well as producing oxygen as a by-product. Recently, ELYSIS inert anode technology has been proven on the lab scale . Apple, a non-equity investor in the technology, ABInBev (for Michelob Ultra cans) and Audi (for the wheels on its eTron GT) have already used aluminium produced during the development of ELYSIS. As a result, researches are working on the scale up to enable them to produce significant quantities of commercial primary aluminium .
Final thoughts on aluminium industry sustainability
As we’ve seen from the recent COP26 conference, the largest regional emitters of GHG’s do not give us hope that government interventions will achieve the necessary emissions reductions. However, the aluminium industry is aware of its environmental issues and is working to put in place the solutions discussed above to try and achieve the targets that will help tackle climate change.
Finally, if you’ve enjoyed reading this blog and want to know more about sustainability and the aluminium industry, you might want to read this one too: Life Cycle Assessment and Sustainability Analysis
 International Aluminium Institute (IAI), B2DS-aligned GHG emissions by Unit Process-Methodology, 2021.
 IAI, 1.5 Degrees Scenario; A Model to Drive Emissions Reduction, 2021
 EGA/DEWA, https://www.ega.ae/en/products/celestial, accessed 11/11/2021.
 IAI, Aluminium Sector Greenhouse Gas Pathways to 2050, 2021.
 Elysis, https://www.elysis.com/en/carbon-free-aluminium-smelting-a-step-closer-elysis-advances-commercial-demonstration-and-operates, accessed 21/12/2021