In light of the recent COP-26 conference in Glasgow, SUEUAA co-I, Professor Kamal Ketuly from the University of Duhok stresses the importance of public awareness of the green house gas, Sulphur Hexaflouride. Increasing public awareness is of course an important aspect of regional and city engagement of academics. Here are his thoughts:. 

The manmade synthetic, sulphur hexafluoride (SF6) is a long-lived, highly potent greenhouse gas and responsible for ozone depletion. It has been extensively used worldwide with a growing product demand since early 1960s in the power and energy industry for the manufacturing of high voltage transformers, switchgear, circuit breakers, wind power generators and in the medical industry. SF6 is a non-flammable, colourless, odourless, tasteless, nontoxic and relatively unreactive gas. However, under high-pressure conditions in an electrical discharge or sunlight and UV radiations, pure SF6 readily decomposes and produces chemically active, toxic by-products: oxyfluoride and di-sulfur decafluoride.  And the possible formation of the toxic SF4, SF2, S2F10, SO2, SOF2, SOF4, SO2F2, SOF10, S2O2F10, HF, and H2S during degradation of SF6 is well documented. There are no known natural sources of SF6 on earth. It is an efficient absorber of infrared radiation. The effective trapping of infrared radiation results in an increase of the average temperature of the atmosphere due to balance shifting between the incoming and outgoing radiation. The effect is known as the greenhouse effect, and the gases responsible for it are frequently referred to as greenhouse gases. Such gases are both man-made and naturally occurring (e.g., CO2, CH4, N2O which could also be increased during pollution episodes) or purely manmade gases [e.g., fully fluorinated (FFC) and chloro-,fluoro-carbon (CFC) and bromo-carbon compounds]. With anything occurring or created naturally, nature can understand it and handle it but for anything made or synthesised by human (unnatural) means then nature cannot handle it or digest or understand it and this will cause imbalances and disruption of the natural world and long-term global environmental effects. Gas insulated systems (GIS) are now a major component of power transmission and distribution networks all over the world. GIS is exclusively used above 400kV, having all components interconnected and insulated via compressed SF6 (i.e., circuit breakers, disconnectors, grounding switches, bush bars, potential transformers, power transformers, cable insulation) and wind turbines electric generators (these are supposed to be Eco Green?). The electrical power industry uses approximately 80% of the SF6 produced worldwide. The rest of SF6 production is used in aluminium and magnesium foundries, semiconductor technology, other manufacturing processes (e.g., plasma processing), or even specific tasks such as thermal insulation, scuba diving, sound insulation, torpedo propeller quieting, insulation for AWACS radar domes, atmospheric trace gas studies, leak testing, land permeability detection for nuclear waste deposition and is extensively used in the medical industry for non-invasive surgeries.

SF6 and its degradation products are now known to have a global warming potential that is 25,000 times greater than that of CO2 and methane and it contributes to stratospheric ozone depletion as the CFC gases. However, the atmospheric lifetime of SF6, when estimated on the basis of the negative ion model, is found to range between 800 and 3200 years. Because SF6 is now extensively used, concerns have been raised about its long-term environmental impact. Due to strong economic implications, and although it is included under the 1997 Kyoto Protocol, there are no enforced worldwide regulations to control SF6 production levels, handling, and disposal. Without disposal methods that actually destroy SF6, it can be expected that all of the SF6 that has been or will be produced will eventually end up in the atmosphere. As a result, the concentration of SF6 in the earth atmosphere has been increasing rapidly over the last decades. During this period the annual rate of increase for SF6 at altitudes between 17 to 30 km was 8.0 ±. That was the highest rate of increase given between all examined ozone depleting or potent greenhouse compounds. 

Due to its enormous global warming potential, SF6 is now being systematically monitored by a number of air sampling programs. 

The global sulphur hexafluoride (SF6) market size is expected to witness a significant growth over the Segment Forecasts period, 2019 – 2025. This is owing to its rising demand as a dielectric medium for electrical & electronic appliances.

Kamal Aziz Ketuly

Professor of Medical Chemistry, M.Appl.Sc. & Ph.D. (Glasgow)


24 November 2021