Gold from copper mining as a case study for allocation in life cycle assessment

Abstract Allocation in multi-output life cycle assessment (LCA) systems has been extensively discussed in literature. Common approaches to address allocation include system subdivision or expansion, physical cause-and-effect relationships, and distribution based on allocation factors such as product mass or revenue. In this study, we critically examine these allocation methods using the example of the Finnish copper–gold mine Kevitsa. We demonstrate that the prioritization of allocation methods prescribed by ISO 14044 is often inapplicable. We argue that this issue is partly rooted in the strong association of LCA with natural sciences, such as environmental science, toxicology, mathematics, and physics. This alignment frequently results in allocation choices that fail to reflect the benefit of the product system, as benefit is not an inherent property of a material but rather a subjective preference within the economic system. For illustration, we use CO 2 as a numerical example in one impact category, though allocation plays an equally important role across all impact categories. Moreover, we contend that for processes producing a primary product alongside valuable by-products, a case differentiation instead of a rigid hierarchy should be considered—a perspective not adequately captured by the current allocation standard. We advocate for a more transparent and comparable allocation framework in LCA that prioritizes the benefit of the product system over strict adherence to natural laws.