FIGURE 2-1 Possible energy-critical elements (ECEs).
SOURCE: Dr. Robert Jaffe, APS and MRS (2011).
Eggert recently chaired the National Research Council (NRC) Committee on Critical Mineral Impacts on the U.S. Economy, which released the report Minerals, Critical Minerals, and the U.S. Economy (NRC, 2008). That report used a two-dimensional diagram to represent supply risk along the horizontal axis and impact of supply restrictions along the vertical axis (Figure 2-2). Thus, an element farther from the origin (such as A in the diagram) would be more critical than an element closer to the origin (B).
Using this framework, the committee conducted a preliminary analysis of 11 critical elements and element families (Figure 2-3). The platinum-group elements, the rare earths, manganese, indium, and niobium were most critical in this analysis. An important point to draw from this analysis is that criticality is a matter of degree, not an either-or characteristic. "There is a tendency to say, What is the list of critical elements? But it's not the list [that is important] but where a particular element falls within a range of high or low criticality." said Eggert.
FIGURE 2-2 Mineral criticality depends on both supply risks and the impact of supply restrictions.
SOURCE: NRC (2008).