Is there a place for SF₆ in the transition towards a low carbon future in transport, energy and industry?

The recent drive for electrification has led to a dramatic increase in the use of Sulphur Hexafluoride (SF₆). A dielectric gas, SF₆ is used to prevent short circuits and catastrophic incidents within the electrical industry. Despite its desirable electrical insulation properties, SF₆ is a highly potent greenhouse gas with a global warming potential (GWP) 23,500 times greater than that of CO₂.

In a bid to reach targets set to combat climate change, we are seeing a large increase in the number of sustainable forms of energy such as wind, solar and gas. In turn, this has driven an increase of SF₆ usage in high voltage applications such as switchgears and circuit breakers. Beside the industrial applications, SF₆ is used in medical applications as an ultrasound contrast agent and as a tamponade gas in ophthalmology.
Benefits to using SF₆ include excellent insulation, non-inflammable and chemical stability, minimum maintenance, outstanding arc quenching properties and reduced electrical clearances.

So, where’s the catch? In 2017 within the EU alone, emissions of SF₆ cost the climate the equivalent of putting an extra 1.3 million cars on the road. A study from the University of Cardiff found that across all transmission and distribution networks, the amount of SF₆ used was increasing by 30-40 tonnes per year. The global installed base of SF₆ is expected to grow by 75% by 2030.

According to a recent BBC article on climate change, the most important means by which SF₆ gets into the atmosphere is from leaks in the electrical industry. A sustainable replacement for SF₆ is unlikely to be made available anytime soon, however actions can be taken to ensure better gas monitoring and management to reduce SF₆ leakage.
 

 

SF₆ occurs naturally in trace quantities in sulphur and uranium bearing rocks, but the SF₆ used commercially is man-made. SF₆ is widely used by the electricity industry throughout the world in medium and high voltage switchgear and circuit breakers, because it is extremely effective as an electrical insulator and for quenching electric arcs. Some of the key advantages of SF₆ over compressed air or oil in such applications are longer equipment lifetime, reduced maintenance and higher reliability. SF₆ also poses no risk of land or water contamination, as with oil-filled equipment. 
 
Arced SF₆ gas is poisonous and imperfect joints lead to leaks of SF₆. Being odourless and colourless, relying on human senses alone in an electric power station, medical environment or semi-conductor manufacturing plant to detect SF₆ is not accurate and potentially very dangerous. So we must look for a technical solution to monitor for traces of SF₆.

SF₆ in its pure state is inert, colourless, tasteless, non-flammable and non-toxic. It is heavier than air and can accumulate in cable trenches, pits and tunnels. A volume greater than 19% in the air may cause asphyxiation. An appropriate risk assessment should be undertaken in order to determine if work areas are classified as confined spaces, in which case appropriate control measures for access must be implemented. In addition, the toxic solid by-products of SF₆ which form fine powders such as aluminium fluoride (AlF₃), copper fluoride (CuF₂), and wolfram oxide (WO₃) can be present as a result of interaction with Teflon, copper and tungsten contacts, and aluminium from shields. These fine powders are toxic if ingested or inhaled, causing eye, nose and throat irritation, pulmonary oedema, and other lung damage, skin and eye burns, nasal congestion, bronchitis, and rashes.

Shawcity offers handheld, portable and continuous fixed monitoring solutions for applications ranging from spot checks through to accurate measurement. Using negative ion capture (NIC) our devices can measure leaks as low as 1 x 10⁻⁸ml/sec, with no need for carrier gasses or radioactive sources. Basic SF₆ monitoring can be as easy as ‘switch on and go’.
 

 

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