Harmonization of LCA methodologies for the metal and mining industry

The metal and mining industry routinely conducts life cycle assessment studies to monitor and document the potential environmental impacts of their products. These studies are typically conducted independently by the various commodity associations. To facilitate alignment of these methodologies, a working group comprised of interested industry organizations and their representatives was formed to propose uniform recommendations for key methodological choices. Existing methodologies used by the participating associations were reviewed to identify areas of alignment as well as areas which could benefit from discussions and alignment. Recommendations for selected topics were then developed through a series of moderated discussions among the participating organizations throughout 2012 and 2013. Efforts were taken in the creation of the document to ensure alignment with the international standards ISO 14040 (2006) and ISO 14044 (2006). Four methodology issues were chosen to be addressed with respect to industry alignment: system boundary, recycling allocation, co-product allocation, and impact assessment categories. Recommendations for system boundary conclude that boundaries should include end-of-life disposal and recycling and, whenever possible, the product use phase, particularly for material and product comparison. For co-product allocation methods, the recommendations were based on the type of co-products being produced and included a range of options to guide practitioners’ decisions. It was recommended for recycling allocation that practitioners use the avoided burden methodology. Lastly, for the life cycle impact assessment stage, it was recommended that life cycle assessments (LCAs) on metal and mining products should report the following impact categories: global warming potential, acidification potential, eutrophication potential, photochemical oxidant creation potential, and ozone depletion potential. It was recommended that inclusion of other impact categories will be periodically re-evaluated by the metal industry. Further, the recommendation is that, while impact categories included are limited to the five above, all life cycle inventory (LCI) datasets themselves should contain accurate and comprehensive inventory data, given reasonable accessibility and data collection cost constraints. Methodological alignment for LCA studies in the metal and mining industry will lead to improved consistency and applicability of the LCA data and results. Specifically, these recommendations improve the consistency of decisions regarding system boundary, recycling allocation, co-product allocation, and impact assessment categories. Further research is suggested to improve the specificity of certain recommendations (e.g., allocation), as well as expand the scope of the harmonization efforts to include other methodological decisions.