Comparative Life Cycle Assessment of Different Cooling Systems for High-Temperature Superconducting Power Cables

This study conducts a comparative life cycle assessment of two different types of cooling systems for a 1 km long, 10 kV concentric three-phase high-temperature superconducting cable. In an open cooling system, the required cooling energy is provided by evaporating liquid nitrogen in a subcooler resulting in a constant loss of liquid nitrogen. As a consequence, liquid nitrogen must constantly be reproduced and transported to the cooling unit. Alternatively, a closed cooling system can be used in which liquid nitrogen is electrically re-cooled using a cryocooler. This results in a higher on-site electricity consumption but simultaneously removes any liquid nitrogen losses. It is shown that the use of a closed cooling system does not only reduce the total system losses but also improves the environmental performance by 4–24% depending on the examined environmental impact category. If the cryocooler is powered by renewable energies only, the environmental savings can be increased even further.