In a new paper, a team of Yale researchers assesses the “criticality” of all 62 metals on the Periodic Table of Elements, providing key insights into which materials might become more difficult to find in the coming decades, which ones will exact the highest environmental costs — and which ones simply cannot be replaced as components of vital technologies.
During the past decade, sporadic shortages of metals needed to create a wide range of high-tech products have inspired attempts to quantify the criticality of these materials, defined by the relative importance of the elements’ uses and their global availability.
Many of the metals traditionally used in manufacturing, such as zinc, copper, and aluminum, show no signs of vulnerability. But other metals critical in the production of newer technologies — like smartphones, infrared optics, and medical imaging — may be harder to obtain in coming decades, said Thomas Graedel, the Clifton R. Musser Professor of Industrial Ecology at the Yale School of Forestry & Environmental Studies and lead author of the paper.
The study — which was based on previous research, industry information, and expert interviews — represents the first peer-reviewed assessment of the criticality of all of the planet’s metals and metalloids.
“The metals we’ve been using for a long time probably won’t present much of a challenge. We’ve been using them for a long time because they’re pretty abundant and they are generally widespread geographically,” Graedel said. “But some metals that have become deployed for technology only in the last 10 or 20 years are available almost entirely as byproducts. You can’t mine specifically for them; they often exist in small quantities and are used for specialty purposes. And they don’t have any decent substitutes.”
These findings illustrate the urgency for new product designs that make it easier to reclaim materials for re-use, Graedel said.
The paper, published in the Proceedings of the National Academy of Sciences, encapsulates the Yale group’s five-year assessment of the criticality of the planet’s metal resources in the face of rising global demand and the increasing complexity of modern products.
According to the researchers, criticality depends not only on geological abundance. Other important factors include the potential for finding effective alternatives in production processes, the degree to which ore deposits are geopolitically concentrated, the state of mining technology, regulatory oversight, geopolitical initiatives, regional instabilities, and economic policies.
In order to assess the state of all metals, researchers developed a methodology that characterizes criticality in three areas: supply risk, environmental implications, and vulnerability to human-imposed supply restrictions.