Gases for electric insulation are essential for various types of highvoltage power equipment. Sulfur hexafluoride (SF 6 ) has been a dielectric medium commonly used in electrical grids for decades but it is the most potent industrial greenhouse gas. The continuous increase of SF 6 emissions in the atmosphere exerts a significant impact on global warming. The identification of suitable drop-in replacements for all SF 6 -filled apparatuses has been elusive experimentally and theoretically. We claim that tetrafluoropropyne, C 3 F 4 , is a breakthrough in chemical alternatives to SF 6 . The performance of C 3 F 4 was assessed systematically in a 6-dimensional manner, including dielectric strength, liquefaction temperature, global warming potential, thermal stability, toxicity, and arc interruption. On the basis of the extensive ab initio calculations, it has been demonstrated rigorously that C 3 F 4 is an environmentally sustainable solution that may fulfill the complex combination of performance, stability, safety, and environmental properties, namely, the dielectric strength is about 50% higher than that of SF 6 , the boiling point is −50 °C, the GWP for 100 year time horizons is only 3, the decomposition temperature is above 600 °C, the toxicity is as low as HFOs, and the interruption capability is twothirds of SF 6 . Two protocols are suggested for the practical use of C 3 F 4 . First, equivalence to 0.5 MPa SF 6 could be obtained by filling 0.33 MPa C 3 F 4 pure gas and lead minimum operating temperature down to −21 °C. Second, by taking advantage of synergism effect, the 40% C 3 F 4 /60% CO 2 mixture is a viable alternative to SF 6 with the operating temperature −30 °C without causing any environmental and safety concerns. The present theoretical work sheds new light on the challenging topic of the development of alternative dielectric gases and may stimulate experimental tests on the electrical applications of C 3 F 4 in the future.
