DATE: September 13, 2019
SNIP: 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.
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 23,500 times more warming than carbon dioxide (CO2). It also persists in the atmosphere for a long time, warming the Earth for at least 1,000 years.
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.
Researchers at the University of Bristol who monitor concentrations of warming gases in the atmosphere say they have seen significant rises in the last 20 years.
“We make measurements of SF6 in the background atmosphere,” said Dr Matt Rigby, reader in atmospheric chemistry at Bristol.
“What we’ve seen is that the levels have increased substantially, and we’ve seen almost a doubling of the atmospheric concentration in the last two decades.”
The most important means by which SF6 gets into the atmosphere is from leaks in the electricity industry. Electrical company Eaton, which manufactures switchgear without SF6, says its research indicates that for the full life-cycle of the product, leaks could be as high as 15% – much higher than many other estimates.
Concentrations in the atmosphere are very small right now, just a fraction of the amount of CO2 in the air.
However, the global installed base of SF6 is expected to grow by 75% by 2030.
Another concern is that SF6 is a synthetic gas and isn’t absorbed or destroyed naturally. It will all have to be replaced and destroyed to limit the impact on the climate.
Developed countries are expected to report every year to the UN on how much SF6 they use, but developing countries do not face any restrictions on use.
Right now, scientists are detecting concentrations in the atmosphere that are 10 times the amount declared by countries in their reports. Scientists say this is not all coming from countries like India, China and South Korea.
One study found that the methods used to calculate emissions in richer countries “severely under-reported” emissions over the past two decades.