A Life Cycle Impact Assessment Study on Sulfur Hexafluoride (SF6) as a Gas Insulator

A lifecycle environmental impact analysis was conducted for SF6 used as an insulating gas in electrical devices. Eight scenarios with different forms of usage as an insulating gas (pure SF6 and gaseous mixture of SF6 with nitrogen) and treatment processes of waste SF6 (e.g., reproduction after decomposition, reuse after purification) are assumed. Energy consumption and emission of pollutants and toxic materials associated with the treatment processes (only the ones associated with the operations were considered) were estimated for each scenario. Based on the inventory analysis, life-cycle energy consumption, global warming potential, acidification potential, eutrophication potential, generation of photochemical oxidants, and generation of substances having adverse health impacts, were evaluated as the factors denoting environmental impacts. The life-cycle energy consumption can be significantly reduced by the use of the gaseous mixture of SF6 and nitrogen because the energy consumption required for producing SF6, a major energy consumption process, can be reduced at the amount of SF6 replaced by nitrogen compared to that for the scenarios with using pure SF6. The scenarios reusing the degraded SF6 after purification can reduce the life cycle energy consumption. On the other hand, emission of the pollutants associated with the transportation process, which will enhance the risks for acidification, eutrophication, generation of photochemical oxidants, will be increased by using the gaseous mixtures, mainly due to the larger burdens.