A Comparative Life-Cycle Assessment Between NbTi and Copper Magnets

Abstract

Magnetic resonance imaging (MRI) devices can utilize either a conventional copper magnet or a superconducting NbTi magnet. In this study, copper and NbTi large bore magnets were designed by numerical optimization procedure for optimum wire length. The optimized magnets represent roughly the main coils of an MRI system. Then, life cycle assessment (LCA) was used to compare the environmental impact of these two types of magnets. LCA is an established tool to investigate the interaction between a product and the environment. In the inventory phase of LCA all material inputs, energy consumption, wastes and emissions to air and water are assessed, beginning from the extraction of raw materials and ending to the delivery of products from the factories. The optimization results showed that the construction of the copper magnet requires much more wire than the NbTi one. However, the manufacturing of NbTi/Cu wire requires more raw materials and is more energy-intensive than the manufacturing of copper wire per unit ton. Thus, more wastes and emissions to air and water are generated during the production of NbTi/Cu wire, but when the magnets were compared the results became reversed.