Keywords: substitutions, magnets
Summary:Substitutions are at the heart of the clean energy transition. While most people think substitution is about a finding a replacement material as good as the one that is critical, in fact, this is just one aspect of the substitution strategy. Substitution, the replacement of one item for another, can be applied at four levels. First is element-for-element substitution. This can be total replace a critical element with one that is readily accessible in the quantities needed. Second is a material-by-material substitution. This is what is commonly thought of when substitution is thought of i.e., an “drop in” alternate that is better, cheaper, and less reliant on critical materials. History tells us this is a rare case indeed. Third is a process-by-process substitution and is often associated with manufacturing innovations that are driven by lowering costs through energy reduction, reduced material usage or environmental improvements. Finally the fourth substitution is a system for system replacement and this is exactly what we are striving for in the clean energy transition. For each of these there is a time component to be considered when reacting to criticality crises which influence the rate at which substitutions can be an effective strategy to mitigate supply chain vulnerabilities.