OPINION PIECE 27
Aluminium’s journey to ZERO Carbon By Tim Murray*
Today sustainability and going “Green” have become of paramount importance to the world. This has challenged all companies review their business models and, in many cases, reinvent themselves. Nowhere is this more evident than in the large industrial industries such as aluminium. Being the former CEO of Aluminium Bahrain I can tell you aluminium is an amazing material that is used in almost everything we touch, whether it be your iPhone, a soda can, or the car you drive. In addition, we cannot forget the critical role aluminium will play in the Electric Vehicle (EV) revolution given its lightweight properties, conductivity and ability to be infinitely recycled. Fortunately for the world aluminium is the second most abundant element on the planet however the process to produce primary aluminium generates large amounts of CO2 emissions. The process of smelting aluminium from the processed bauxite (i.e. Alumina) is power intensive process resulting in the generation of CO2 emissions especially when using energy from fossil fuels. Today the world produces approximately 68 million metric tons (mt) of primary aluminium annually with an average CO2 footprint of 17 mt for every 1 mt of aluminium produced (yes you read that correctly!). So this equates to 1.2 billon mt of CO2 generated from the production of primary aluminium each year.
The average CO2 footprint for a smelter varies drastically depending upon the power source used, for example aluminium produced from coal-based electricity generates around 20 mt of CO2 whereas the if it is from renewable power (e.g. Hydro or Wind) then there is only 4 mt of CO2 . The vast majority of the 68 million mt tons of primary aluminium is produced using coal fired power stations, typically in China and India. In terms of aluminium produced from renewable power there is approximately 15 million mt produced annually (or only 22% of the total). So we have a long way to go to shift to all renewable power. Even if a smelter has renewable power there is still 4 mt of CO2 produced. Obviously, the ability of an existing smelter to change their power source is not really an option. So how can we address the 4 mt which is not related to power generation? The below chart breaks down the elements which make up the remaining 4 mt of CO2 from aluminium production. The biggest area of CO2 emission reduction relates to the use of the Carbon Anode in the aluminium electrolysis process (accounts for 1.8 mt of CO2 for every 1 mt of aluminium production). I will do my best to explain the aluminium electrolysis process in simple terms. In order produce aluminium you need to split the aluminium from the oxygen in
Alumina. This is done in a reduction cell (commonly called a pot) where Alumina (which looks like sand) is continuously fed into molten liquid bath in which a Carbon Anode is submerged then hit with large amounts of electricity to complete the process (on average 15 mega-watts of power is needed to produce 1 mt of aluminium). As a result of the electrolysis process the aluminium reduces to the bottom of the pot (hence the term Reduction Lines) and the remaining oxygen eats away the Carbon Anode in the pot. This is a continuous process which runs 365 days a year 24 hours a day and you need to replace the Carbon Anode every 27 days. Ok, I know this was way too much technical talk but hopefully you understand why a Carbon Anode is important. It is possible to replace the Carbon Anode with what is called an Inert Anode, a technology developed by Alcoa many years ago. However, this technology has never been fully scaled for commercial production. The Inert Anode is made of specialty alloyed steel bars thereby replacing the need for the Carbon Anode in the process. I know this sounds simple and you may ask why are we not doing this? The simple answer it is not so easy! But there is a company called Elysis (located in Canada) which is a joint venture between Alcoa, Rio Tinto and the Canadian government focused
ZC
*Tim Murray, CEO of Cardinal Virtues Consulting (former CEO of Aluminium Bahrain). Aluminium International Today
Tim Murray column.indd 1
July/August 2022
06/07/2022 11:30:46
