Liquefied Natural Gas for Superconducting Energy Pipelines: A Feasibility Study on Electrical Insulation

A superconducting energy pipeline is an integrated system for fuel delivery and power transmission. In the energy pipeline, direct current (DC) power is carried by superconducting tapes with almost no loss. Moreover, liquefied natural gas (LNG) is used not only as one kind of clean energy but also as a cooling medium. However, the lack of data on the electrical insulation characteristics of LNG (especially the resistance to breakdown and flashover) restricts the development of a superconducting energy pipeline. Therefore, this paper focuses on solving a series of problems (such as gas tightness, overpressure, and high voltage) in LNG insulation testing, obtaining the electrical failure data of multicomponent LNG, and analyzing the behavior of electric breakdown and flashover in LNG. The test results show that LNG as a dielectric cooling medium has remarkable performance in withstand voltage to replace the liquid nitrogen/liquid tetrafluoromethane (LN2/LCF4) binary mixtures. The research could offer key technical support for the superconducting energy pipeline and also provide a reference for the study of electrical properties on other cryogenic fuels.