How does sf6 get into the atmosphere

But leaks of the little-known gas in the UK and the rest of the EU in were the equivalent of putting an extra 1. Levels are rising as an unintended consequence of the green energy boom. Cheap and non-flammable, SF6 is a colourless, odourless, synthetic gas. It makes a hugely effective insulating material for medium and high-voltage electrical installations. It is widely used across the industry, from large power stations to wind turbines to electrical sub-stations in towns and cities.

It prevents electrical accidents and fires. However, the significant downside to using the gas is that it has the highest global warming potential of any known substance. It is 23, times more warming than carbon dioxide CO2. It also persists in the atmosphere for a long time, warming the Earth for at least 1, years. The way we make electricity around the world is changing rapidly. Where once large coal-fired power stations brought energy to millions, the drive to combat climate change means they are now being replaced by mixed sources of power including wind, solar and gas.

This has resulted in many more connections to the electricity grid, and a rise in the number of electrical switches and circuit breakers that are needed to prevent serious accidents.

Collectively, these safety devices are called switchgear. The vast majority use SF6 gas to quench arcs and stop short circuits. Across the entire UK network of power lines and substations, there are around one million kilograms of SF6 installed.

A study from the University of Cardiff found that across all transmission and distribution networks, the amount used was increasing by tonnes per year. This rise was also reflected across Europe with total emissions from the 28 member states in equivalent to 6. It likely forms via an electrically induced decomposition reaction of SF 6 :. S 2 F 10 has a toxicity four times that of phosgene, COCl 2! Its toxicity emanates from the disproportionation reaction:. The SF 6 is inert but the SF 4 hydrolyses in the lungs to lethal sulfurous and hydrofluoric acid.

As a result, there has been an increase in the number of connections to the electricity grid compared with the traditional fossil power stations, with the consequential rise in the use of switchgear to deal with arcing and to stop short circuits.

Unfortunately, this growing usage of SF 6 continues unabated due to the technological and economical challenges of switching to more environmentally benign alternatives. In an effort to ameliorate the rise of these emissions into the atmosphere, regulations are being imposed on producers and users that include recycling and minimizing of SF 6 emissions during various operation, maintenance and refill processes.

Furthermore, companies are being required to monitor and report the cradle-to-grave SF 6 emissions from their operations, beginning with production and including transportation, distribution, commissioning, service inspection, maintenance, and end-of-life collection. While thermochemical, electrochemical, and photocatalytic means of converting CO 2 into value-added chemicals, pharmaceuticals, polymers, and fuels are under active development, similar attention to SF 6 appears to be minuscule or completely lacking.

With this background as inspiration, the gauntlet is thrown down to chemists and chemical engineers to rise to the challenge of solving the looming SF 6 problem, keeping in mind the health and safety toxicity issues of bi-products associated with the chemistry of SF 6. Sulfur hexafluoride SF 6 is a synthetic fluorinated compound with an extremely stable molecular structure. Because of its unique dielectric properties, electric utilities rely heavily on SF 6 in electric power systems for voltage electrical insulation, current interruption, and arc quenching in the transmission and distribution of electricity.

Yet, it is also the most potent greenhouse gas known to-date. Over a year period, SF 6 is 22, times more effective at trapping infrared radiation than an equivalent amount of carbon dioxide CO 2. SF 6 is also a very stable chemical, with an atmospheric lifetime of 3, years.

As the gas is emitted, it accumulates in the atmosphere in an essentially un-degraded state for many centuries. Thus, a relatively small amount of SF 6 can have a significant impact on global climate change. Disconnectors and ground switches use SF 6 primarily for insulation, and individually, they contain only slightly less SF 6 than a circuit breaker. These devices are used to isolate portions of the transmission system where current flow has been interrupted using a circuit breaker.

The atmospheric concentration of the highly-potent greenhouse gas SF6 has never been higher. Fingers have been pointed at the expanding renewables industry, but is that a fair assessment? Sulphur hexafluoride, commonly known as SF 6 , has made a splash in the mainstream media of late. SF 6 is certainly no secret in the Norwegian energy industry. Its use is highly regulated, and many of its users are working together to share experience and come up with viable alternatives:. She is secretary of the SF 6 User Group , an association of 47 public and private companies all openly sharing their experiences with SF 6.

Since , the user group has collected data on emissions and reported them to the Norwegian Environment Agency. The equipment is very reliable but any failure makes a big impact, so everyone is keen to share knowledge and experience.

SF 6 is used not in the turbine itself, but in the switchgear that controls the current generated by the turbine. But there is nothing unique about wind turbines. The gas is used in switchgear in many other power applications. SF 6 has two uses: as an interruption agent and an insulator. Typically, a mechanical circuit breaker is used inside a pocket of SF 6 gas that to extinguish the electric arc. However, comparing wind turbines with other power applications of SF 6 must be set in context.

A substation for overhead power lines may require several tonnes, creating a substantially bigger environmental problem should a leak occur. Bodies including the European Union are known to be considering a ban on SF 6 at low-to-medium voltage levels in the future. However, it is true to say there is no short-term catch-all fix. One leading alternative, vacuum technology, just solves the interruption aspect.