Sulphur Hexafluoride

I’ve been involved with the design of several Gas Insulated Switchgear projects (Structure, not the Electrical components). This afternoon, I learned that the insulating gas, sulphur hexafluoride is the worst greenhouse gas going. From the BBC:

“It’s the most powerful greenhouse gas known to humanity, and emissions have risen rapidly in recent years, the BBC has learned.

Sulphur hexafluoride, or SF6, is widely used in the electrical industry to prevent short circuits and accidents.

But leaks of the little-known gas in the UK and the rest of the EU in 2017 were the equivalent of putting an extra 1.3 million cars on the road.

However, the significant downside to using the gas is that it has the highest global warming potential of any known substance. It is 23,500 times more warming than carbon dioxide (CO2).”

GIS systems are often used for wind turbine projects. It’s time this product was removed from current and future use. Current installations should be cleared up with zero tolerance for leakage.


As SF6 is much denser than air, I wonder what the mechanism is that makes it a greenhouse gas.

The old refrigerants like Freon I believe rise into the upper atmosphere and get broken into highly reactive chlorine compounds. ( I might be wrong about that… It is Friday and time to go home and have a cold one.)

@Makesparks From what I understand SF6 still disperses into the upper atmosphere… Freon, on the other hand, works as a catalyst and continues to do damage. It doesn’t break down. The gift that keeps on giving.


I imagine it’s just its potency as an IR absorber. I tried to do a FTIR trace contaminants check on an air sample a couple of years ago, only to discover that somebody had put a puff of SF6 through the spectrometer the month before. There was still a huge peak there masking everything I was looking for.

@zeusfaber It’s pretty potent stuff… I was unaware of it.


My one round with such gases was in the form of CF3Br or Halon 1301.
The test had to release 1000 cubic feet of it.

I looked for alternatives, but the risk of test failure was high if a substitute would be used. The cost of redesign and retest was so high that Halon 1301 was the only choice.

@SparWeb Thanks… I’ve been involved with numerous GIS systems, and was unaware of the downside.


I know that California has mandated a phase out plan for the use of SF6 (later years for higher voltage levels). Here is a pretty informative article discussing what PG&E has done/is doing to find alternatives to SF6:

Thanks dauwerda… addressing Climate Change is going to mean some major restructuring of our infrastructure.