EMBODIED ENERGY | ALUMINIUM Reshaping aluminium for a low carbon future The use of recycled materials is critical to minimise embodied energy in aluminium systems. However, industry demand is outstripping supply, which means the sector has to find other ways to reduce aluminiums impact on the environment. John McComb, of Reynaers Aluminium UK, reports on the latest low carbon innovations A luminium, with its lightweight structure and resistance to corrosion, offers some important performance benefits, which have led to it being specified on some of the worlds highest-profile buildings. It also has excellent recycling properties, retaining performance characteristics, but as with all construction products, we are not able to produce a perfect product with no environmental impact. As is the case with many different materials, the energy-intensive production process of aluminium is an area that the industry has sought to improve. Optimising the use of recycled aluminium is, of course, a critical route to reducing embodied carbon. Using only a fraction of the energy needed to produce the primary product, recycled aluminium has a far lower level of embodied carbon, averaging around 0.5 tonnes CO2e per tonne. As aluminium can be infinitely recycled without incurring any loss in quality, this is a sound proposition, and 92-98% of aluminium used in the building industry in Europe is recycled in some way. However, availability is an issue as recycled material becomes a victim of its own popularity, with demand outstripping supply. This means that, to meet the volumes construction projects need, primary aluminium remains a key source. Lets take a closer look at what is being done to ensure an increasing supply of lower carbon aluminium. Evolving production methods In Europe, primary aluminium is typically produced with a carbon footprint of around 9.34kg CO2e per kg aluminium, including extrusion although, across the world, this can be higher, depending on how the power used for production is generated. As this is the principal source of carbon, changes to how manufacturers power their processes 50 September 2023 www.cibsejournal.com John McComb says united action will cut CO2 emissions How manufacturers power their processes such as switching to renewable energy can have a dramatic impact on carbon footprint such as switching to renewable energy can have a dramatic impact on carbon footprint. In some countries, aluminium production is already moving to renewables, which is helping to cut embodied carbon. For example, hydropowered plants are producing aluminium with embodied carbon levels of 4kg CO2e per kg aluminium. Innovation is playing an important part in identifying ways to cut emissions even further. Where changes to the Hall-Hroult process the main method of aluminium production have been put in place, this has increased efficiency, further helping to cut emissions. Broadening the use of these changes will create an even bigger impact. Other developments include replacing carbon anodes in the production process with a ceramic material that leads to only oxygen being emitted. Using this method in combination with sustainable energy will have a significant impact on driving down carbon levels in aluminium. While changes are being introduced to support low carbon aluminium, supply remains limited. As a member of European Aluminium, Reynaers is committed to supporting work to reduce carbon in aluminium and to find sustainable solutions. In 2022, the weighted average carbon footprint of the aluminium billets used to extrude our aluminium profiles in Duffel, Belgium, amounted to 3.96kgCO2e. In 2022, we had a 44% share of low carbon primary aluminium and a 32% share of recycled aluminium. We are on a continual path to improve our carbon footprint, to achieve science-based targets, as outlined in Reynaers Act1, by 2030. As awareness grows of where carbon levels are an issue, the focus on making the necessary changes to support sustainable building design will intensify. Innovation and investment are central to making efficient, lasting change in the production process to create more low carbon aluminium. Reynaers has taken a strong position in implementing more sustainable practices. Reynaers Act sets out our commitment as a company to develop more circular products, improve thermal efficiency and cut the companys direct carbon emissions by 46% and indirect carbon emissions by 55% by 2030, as well as to source low carbon aluminium. Through determined and united action, the carbon footprint of the built environment will continue to decrease. CJ JOHN MCCOMB is technical services director at Reynaers Aluminium UK References: 1 Reynaers Act, Reynaers Aluminium website bit.ly/CJRayAct