If you're walking down the right path, eventually you'll make progress. – Barack Obama
The former president was only half right, unfortunately, when he made his famous remark. As all of us know only too well, if you’re headed down the wrong path and you keep going, you will indeed make progress, but perhaps in the wrong direction. Maybe that goes a long way towards explaining how we’ve got ourselves into such a mess with sulphur hexafluoride (SF6) in the energy industry. The excellent insulating properties of this synthetic gas, widely used to quell short-circuiting and arcing in medium- and high-voltage electrical transmission infrastructure, have rather too easily made it the insulating material of choice in transmission equipment the world over. Hespite possibly its greatest drawback – it also happens to be one of the world’s most potent greenhouse gases. In fact, 1kg of SF6 is equivalent to 22,800kgs of carbon dioxide, and, worse still, it persists in the atmosphere for a long time (up to 3,200 years, according to research) because, being synthetic, it naturally resists decomposition processes rather well.
In the roughly 50 years since SF6 was introduced into the energy industry, its use in the transmission network has grown dramatically; even at the beginning of this century, this use accounted for approximately 80% of all SF6 produced, according to one study. And as the infrastructure ages, more of this gas leaks out into the atmosphere, making an ever greater contribution to climate change.
With global warming increasing as it is, we need to get rid of this damaging substance as quickly as we can. But how? It won’t be easy, even in a developed economy such as the UK, according to a report written in 2018 for the Climate Change Committee. The publication points out that the replacement of infrastructure, such as that in large substations, is slow and expensive, and that the total costs of replacing all or part of the equipment in the UK are difficult to determine, owing to the size of the industry.
But we have to start our journey sometime, and the sooner the better. What other choice have we got?
So far, the UK energy industry has taken some positive steps towards reducing its dependence on SF6.
In April 2017, for example, National Grid energised the first SF6-free 420 kV gas-insulated line in the newly built Sellindge substation, located in Kent and connecting to the French electricity transmission network. So-called gas-insulated lines contain high-voltage cabling, and the one at Sellindge, supplied by GE, uses a gas mixture called g3 that doesn’t boost global warming.
In March of this year, Scottish and Southern Electricity Networks (SSEN) Transmission announced that its Fort Augustus and New Deer substations in Inverness-shire will adopt g3 equipment in place of that using SF6. The New Deer site will see the world’s largest volume of the g3 gas installed at one location, while the Fort Augustus substation will be the first transmission site in the country to have a fully g3-insulated substation.
When it comes to renewable energy, there’s more good news. Only this month, East Anglia's biggest offshore windfarm powered up for the first time; Siemens supplied the high-voltage components called switchgear, which, instead of using the traditional SF6, contain climate-friendly vacuum technology and clean air.
These are all positive, and very necessary, steps along the right path, but they will need to be followed by even more companies if we are to save our planet from global warming. It won’t be easy, but then choosing the right path – and keeping to it – isn’t always.