Depletion of mineral resources is a widely used impact category in life cycle impact assessment. Traditionally, the stock-to-use ratio is the basis for characterisation factors, but this approach is criticised, as it is very difficult to define the stocks. Several alternative methods are used to derive characterisation factors. One of these methods, the Surplus Energy concept, has been used in the Eco-indicator 99 method. This concept uses the grade-tonnage relationships of the most commonly used metals to determine the additional energy required to extract a metal at some point in future. The benefit of this approach is that it uses the concept of marginal damage, and that it is based on geostatistic theories. In this study, this concept has been further developed. Instead of using grade-tonnage relationships per metal, we use grade-tonnage relationships of 50 deposit types. Because many deposit types produce more than one metal, and because many metals are found in more than one deposit type, we use economic allocation principles to construct the surplus energy for 18 metals. The new method is based on a more realistic description of the origins of metals: metals can be produced from different sources. A practical benefit is that the method also takes into account metals that are only, or mostly produced as a by-product, such as silver and gold.
|Number of pages||2|
|Publication status||Published - 2006|
|Event||SETAC North America 27th Annual Meeting - Montréal, Canada|
Duration: 5 Nov 2006 → 9 Nov 2006
|Conference||SETAC North America 27th Annual Meeting|
|Period||5/11/06 → 9/11/06|
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