Direct and Indirect CO2 Equivalent Emissions from Primary Aluminium Production

Abstract

Although modern aluminium smelters using 100% green electrical energy generation can achieve on-site emissions of about 2 kg CO2 equivalents per tonne of aluminium produced (t CO2e/t Al), the total global average emissions from primary aluminium production from bauxite mine-to-metal ingot are much larger, about 16.5 t CO2e/t Al. Two thirds of the total average emissions arise because fossil fuels, dominated by coal and to a lesser extent natural gas, are the source of energy used to generate electricity. However, indirect emissions associated with site services and upstream emissions associated with mining, refining, and delivering materials are also significant contributors, and all these are considered in this paper. Arising from this analysis, we question whether the reference target proposed by the Aluminium Stewardship Initiative (ASI) that the on-site direct and indirect emissions from all present and future smelters shall be below 8 t CO2e/t Al by 2030 or earlier, are the appropriate one. Since the global impact is the total mine to metal emissions, this number is what impacts the public, and also customers and downstream users. Surely the numerical value should be changed accordingly on a science based approach.