A ban on SF6 in the energy sector is overdue
By Kevin Nesdale, General Manager, Power Distribution Systems & Services at Eaton ANZ
Wednesday, 04 August, 2021
With international pressure mounting on Australia to adopt more ambitious climate goals, there are steps the energy sector can take to assist in this task.
A significant reduction in the use of SF6 in the medium-voltage electrical sector is one of these steps, and would send a message to the world that Australia is taking action.
While it has been recently reported that renewable energy is booming in Australia, one unintended but hugely hazardous consequence is going largely unnoticed: a rise in emissions of the powerful greenhouse gas sulfur hexafluoride. Also known as SF6, this substance is widely used across the electrical industry within switchgear, from large power stations to wind turbines to electrical substations, to prevent short circuits and accidents — reducing the chances of electrical accidents and fires. However, this gas tops the Intergovernmental Panel on Climate Change’s (IPCC) list of extremely harmful greenhouse gases, with a global warming potential 23,500 times greater than CO2. SF6 is extremely persistent, and can take as long as 3200 years to disappear from the atmosphere. It can also be a threat to personnel in case of significant leakage. Alternative solutions to SF6 already exist, and provide similar insulating properties, with minimal cost or technical barriers to adoption.
What are the risks?
SF6’s primary threat is environmental. In 2018, measurements in the EU showed that SF6 emissions had a global warming impact equivalent to 6.7 million tons of CO2 — comparable to 1.3 million cars being driven for a year. In Australia, CSIRO’s analysis shows that SF6 emissions increased by 27% between 2012 and 2018.
While most SF6 switchgear equipment comes with sealed tanks, no equipment is fully leak-proof. Worse, there could still be many models in the field with high leak rates. Our own studies show there could be up to 15% SF6 leakage during the full lifecycle of a switch.
Unfortunately, these emissions could accelerate in the near future without SF6-free alternatives. As we shift towards renewable energies in the upcoming decades, large power plants are set to be replaced by smaller wind turbines and photovoltaic banks, increasing the volume of connections to the electricity grid and the demand for switchgear. If these new installations keep using SF6-insulated equipment, we could see a sharp increase in its concentration in the atmosphere.
Finally, SF6 presents a risk for personnel. Being heavier than air, it spreads in low-lying areas, which could be a danger for staff working in pits and trenches, potentially causing asphyxiation. Although significant leaks are very rare, the older the equipment gets, the higher the risk.
The EU has already banned the use of SF6 in many applications and industries and is likely to introduce regulations to phase it out of the medium-voltage energy sector later this year. At this stage in Australia, the conversation has only just begun.
Why are regulations needed?
Alternatives to SF6 in switchgear have existed for years, but the uptake has been slow. A study published in the EU showed that whilst most energy players are expecting a decrease in the use of SF6, a majority of respondents said policies and regulations would be the main factor in their decision to adopt SF6-free alternatives. They also said financial incentives and a complete ban on the gas are two of the most useful policies to promote these alternatives. Clearly, government guidance is a key influence in the industry’s decision-making and would be a catalyst for rapid change. As there are no significant technological or cost barriers to eliminating SF6 from our electrical networks, government policy could assist in implementing this change.
What are the alternatives?
Safe and reliable alternatives have now existed for many years. Compact switchgear using cast resin insulation instead of gas has been around since the 1960s and cast resin insulation combined with vacuum switching technology since the late 1980s.
These alternative technologies have improved and now have comparable current ratings, short circuit ratings and physical size to SF6 options, removing technical barriers to their deployment. These are suitable for many applications, including solar plants, windfarms, commercial industrial buildings, data centres, road and rail infrastructure and large grid operators, and have proven to be more reliable for frequent switching, necessary in large wind and solar parks for example.
Whilst upfront costs are about 15–20% higher than SF6-insulated equipment, the total cost of ownership ends up being lower with a decrease in required maintenance. Indeed, there is no need to maintain, top up, test, inspect and report on, and dispose of SF6 anymore.
There is little we can do with the SF6 we have already sent in the atmosphere, but continuing to use SF6 is a legacy we don’t want to leave, especially when proven alternatives exist. Changes to phase out SF6 could be the small push the sector needs to wave this harmful gas goodbye.
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