The global transition to renewable energy systems will be mineral intensive and, under the current linear economy conditions,...
The global transition to renewable energy systems will be mineral intensive and, under the current linear economy conditions,...
Primary aluminum production is one of the world’s most GHG-intensive industries, and also one where GHG accounting methods have become the most fully developed. GHG reporting for the primary aluminum sector has largely consolidated under the International Aluminium Institute’s (IAI) guidance, although Environment Canada (EC) guidance remains active and Chinese aluminum smelters will soon additionally be required to report their emissions under the China National Development and Reform Commission’s (China NDRC) guidelines, meant to support the development of the Chinese emissions trading system. The IAI method largely follows best GHG accounting practices, but aspects of it can be improved, and differences compared to other methods highlight open areas of contention. The most critical points identified are the following:
Reporting requirements differ substantially between the three methods examined, and are the primary driver of different emissions reporting outcomes as measured in the included case study. EC, designed to contribute to a national GHG inventory, adopts a flexible boundary which only covers processes taking place onsite. China NDRC uses activity data on fuels consumed to measure emissions from combustion without providing adequate clarity on which combustion processes must be included. IAI provides a cradle-to-gate emissions boundary in its most recent Good Practice Guidance for Calculation of Primary Aluminum and Precursor Product Carbon Footprints. In practice, however, many producers reporting emissions through the London Metals Exchange continue to use an older version of IAI guidance that allows users to choose between three levels of system boundary disclosure. No phase-out plan for this older guidance has yet been published. China NDRC and EC provide no details on how casthouse emissions should be included, while IAI does not adequately specify which casting and recasting operations need to be included. All three methods also fail to provide guidance for emissions from processes tied to semi-fabrication such as extrusion and rolling, which often take place within the scrap remelting and refining facilities of primary aluminum producers. These differences need to be reconciled to yield fully comparable and standardized data, and to simplify the accounting process for recyclers.
Upstream emissions sources are not included by EC, and China NDRC only includes emissions from upstream energy production. IAI provides a partial list of emissions factors for upstream inputs in its Scope 3 Calculation Tool, but does not describe how these factors are obtained. All three methods also lack specific guidance for tracking and reporting fugitive emissions, upstream or direct.
Accounting methods in the aluminum sector largely exclude the possibility of assigning emissions credits for byproducts with potential uses in other sectors. This avoids the possibility of double counting emissions credits when those other sectors are involved. While the suitability of the waste products and other outputs produced by each metals sector for reuse in other sectors may differ, and legal barriers prevent the reuse of aluminum waste products such as red mud, the approach to credits within the metals sector as a whole should be reconciled to determine how it can be harmonized in a way that best incentivizes decarbonization across the entire sector.
Updated Intergovernmental Panel on Climate Change (IPCC) guidance means that guidelines provided by EC and China NDRC on how to estimate PFC emissions from electrolysis are now inconsistent with the latest international recommendations. These guidelines should be updated, and regional and national regulations on measuring PFC emissions should also be updated to reflect these changes.
China NDRC and EC do not touch on incorporation of scrap into final products, even though scrap usage forms an important part of the pathway to reducing emissions in the aluminum sector. IAI imposes transparency requirements on inclusion of pre-consumer and post-consumer scrap, but does not recommend a method for calculating and allocating emissions associated with this scrap because the aluminum industry itself has not reached consensus on the most appropriate method. IAI has shared and documented a number of potential equations for scrap allocation (derived from ISO standards) available in a draft document for public review, but has not yet provided a definitive equation to clarify how users should assign emissions from primary aluminum production, pre-consumer scrap, and post-consumer scrap when calculating a final product carbon footprint.
